WO2025027586A1

WO2025027586A1 - Magnetic field probe for determining a disposition to an implantable marker using additional detection zones

Info

Publication number: WO2025027586A1
Application number: PCT/IB2024/057525
Authority: WO
Inventors: Bram SCHERMERS; Adrianus Cornelis Petrus Van Leijsen; Vladislava Vladimirova DINKOVA
Original assignee: Sirius Medical Systems BV
Current assignee: Sirius Medical Systems BV
Priority date: 2023-08-03
Filing date: 2024-08-03
Publication date: 2025-02-06
Anticipated expiration: 2026-02-03
Also published as: NL2035534B1

Abstract

During both invasive and non-invasive treatments and therapies, it is important that health professionals be able to accurately locate magnetic markers. A magnetic field probe (101, 102, 103, 104) is provided comprising a distal end (160), a first magnetic sensor (111), close to the distal end (160), and a second magnetic sensor (112) to determine magnetic field vectors of an implantable marker (200); arranged to define a distal marker detection zone (190), extending more distally away from the distal end and to define a flank marker detection zone (192, 194), extending more transversely and/or more radially away from the longitudinal axis or plane (151, 152, 153); arranged to determine if the angular disposition and/or distance coincides with the flank marker detection zone; and arranged to alter, attenuate and/or suppress processing of field vector determinations if a disposition (170) to the marker does not coincide with the flank marker detection zones. The more flank locations may be perceived being to a side and behind the distal end of the magnetic field probe, providing a more intuitive magnetic probe for finding implantable markers, particularly in situations where a magnetic probe reference has passed the implantable marker.

Description

MAGNETIC FIELD PROBE FOR DETERMINING A DISPOSITION TO AN

IMPLANTABLE MARKER USING ADDITIONAL DETECTION ZONES

FIELD

The present disclosure relates to a magnetic field probe for determining a disposition to an implantable marker, a detection unit comprising the probe and a method of detecting a disposition to an implantable marker.

BACKGROUND

During both invasive and non-invasive treatments and therapies, it is important that health professionals be able to accurately locate areas of interest in tissues. Frequently, professionals rely on sight and manual manipulation to find and remember areas of interest, often marking an outer surface of skin. Imaging techniques and/or imaging equipment, such as X-ray and/or ultrasound, may also be used to assist in locating areas of interest - however, this use relies on the availability of equipment, the technology being able to distinguish areas of interest from surrounding tissue, and the skills of professionals in interpreting the images. In addition, health professionals performing specialized treatments may not have access to imaging equipment, or be competent to interpret images, requiring a different specialist. Inaccuracies in being able to locate the areas of interest may mean that not all the area of interest is treated, or the treatment is incomplete.

Due to advancing diagnostic screening procedures and improving imaging modalities and associated image quality, various types of cancer are increasingly diagnosed at an early stage. In principle, early detection is beneficial to patients as it allows typically more conservative treatment approaches, where late-stage detection is typically associated with more elaborate treatments. For example, late-stage detection of tumors (for breast) may require frequent monitoring of tumor growth, surgery to remove the tumorous tissue, or even mastectomy.

Paradoxically, for health professionals, conservative treatment on very early-stage tumors is challenging - because these tumors are frequently very small and not distinguishable by vision or by touch from the surrounding healthy tissue. These lesions are also referred to as ‘non-palpable’. Without intrinsic means to differentiate the tissue of interest from the healthy tissue that surrounds it, health professionals require intra-operative guidance to increase their probability of localizing the full extent of non-healthy tissue, while reducing the regions of healthy tissue exposed to both invasive and non-invasive treatments and therapies.

This is a problem for both therapeutic and cosmetic procedures and treatments, including measurement and scanning, tumor size measurement and monitoring, removal of tumors, removal of polyps, cosmetic surgery, removal and/or correction of tissues, localization of implanted devices - for example, birth-control devices such as Implanon, may need to be localized.

Both wired and wire-free localization technologies are generally used prior to treatments. Wire guided localization (WGL) comes in the form of a (variety) of anchored wires that are typically placed on the day of surgery and of which the wire protrudes from the breast to be used to guide the subsequent surgery. Associated with various well-described disadvantages, wire-free localization technologies have emerged to advance the surgical field. These newer solutions for marking and locating an area of interest include the use of radio-active markers, but the use of radio-active materials is tightly controlled and regulated. Electro-magnetic and RFID (Radio-Frequency Identification) markers have also been developed, but these are bulky and prone to failure. Any inaccuracy in locating the area of interest may result in an incomplete treatment, increasing the risk that the invasive or non-invasive treatment of the area of interest is not successful, and/or that additional invasive or non-invasive treatments. Recently, the use of implantable magnetic markers (seeds) has been proposed. These provide a higher degree of safety compared to radio-active markers, but still require considerable effort by the healthcare professional to detect the disposition (localization) of the implantable marker. This becomes even more difficult when very small magnetic markers are used to mark very small areas of interest. In order to optimally support healthcare professionals, it is important to provide both distance and direction to the marked location. It is an object of the invention to provide improved directionality detection for magnetic markers or induced magnetic beacons.

GENERAL STATEMENTS

According to a first aspect of the present disclosure, there is provided a magnetic field probe for determining one or more dispositions to an implantable marker, the implantable marker being arranged to generate, in use, a magnetic field, the magnetic field probe comprising: a distal end suitable for being disposed proximate to an animal or human body; a first magnetic sensor arranged close to the distal end and disposed along a first probe transverse axis or plane; a second magnetic sensor, disposed along a second probe transverse axis or plane and disposed between the first magnetic sensor and a proximal end; wherein the first magnetic sensor and the second magnetic sensor are arranged to determine, in use, one or more magnetic field vectors of the implantable marker; and a processor, arranged to collect measurement values from the first magnetic sensor and from the second magnetic sensor, and further arranged to determine, in use, one or more magnetic field vectors of the implantable marker; the processor arranged: to define one or more distal marker detection zones, extending more distally away from the distal end of the magnetic field probe along a probe longitudinal axis or plane, wherein the probe longitudinal axis or plane is perpendicular to the first probe transverse axis or plane and perpendicular to the second probe transverse axis or plane; to define one or more flank marker detection zones, extending from the first probe transverse axis or plane to the second probe transverse axis or plane and extending more transversely and/or more radially away from the probe longitudinal axis or plane; to determine one or more angular dispositions and/or one or more distances to the implantable marker using the one or more magnetic field vectors; to determine that the one or more angular dispositions and/or one or more distances fall within the one or more flank marker detection zones if the angular disposition and/or distance substantially coincide with one or more flank marker detection zones; and o alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more angular dispositions and/or one or more distances to the implantable marker do not coincide with the one or more flank marker detection zones.

Such a magnetic field probe may advantageously define one or more distal marker detection zones more distally away from a distal end of the probe to enable a user to distinguish different types of magnetic field information in more distal locations relative to the probe. These more distal locations may be perceived by a user as being in front of the distal end of the magnetic field probe. Additionally or alternatively, such a magnetic field probe may advantageously define one or more flank marker detection zones away from a flank of the probe to enable a user to distinguish different types of magnetic field information in more flank locations relative to the probe. These more flank locations may be perceived by a user as being to a side of the magnetic field probe. Additionally or alternatively, these more flank locations may be perceived by a user as providing magnetic field information behind the distal end of the magnetic field probe, providing a more intuitive magnetic probe for finding implantable markers, particularly in situations where the magnetic probe reference has passed the implantable marker.

Configurations that may increase the intuitiveness of use include arranging the one or more flank marker detection zones to extend from an axis or plane comprising one or more physical and/or virtual positions passing through the distal end; arranging the second magnetic sensor to be close to the proximal end of the magnetic field probe; arranging the one or more flank marker detection zones to extend to an axis or plane comprising one or more physical and/or virtual positions passing through the proximal end; arranging the one or more flank marker detection zones to extend to an axis or plane comprising one or more physical and/or virtual positions passing through a flank of the magnetic field probe; and/or arranging the one or more flank marker detection zones to be substantially symmetrical about the probe longitudinal axis or plane.

Configurations that may be advantageous include arranging one or more cross-sections in a plane through a marker detection zone to comprise a portion with a circular, oval, elliptical, triangular, rectangular, square cross-section, or any combination thereof; arranging one or more marker detection zones to comprise one or more portions with an arc, segment, cylindrical, cone shape, or any combination thereof; arranging one or more marker detection zones to comprise one or more portions with a parabolic, linear or hyperbolic shape; arranging two or more marker detection zones to share one or more boundaries; and/or arranging two or more marker detection zones to differ by one or more parameters selected from the group comprising of: an extent, a shape, an orientation, a disposition, a scaling, a resolution, an angular boundary, a longitudinal extent, a transverse extent, or any combination thereof.

According to a further aspect of the present disclosure, the processor is arranged to define one or more proximal marker detection zones, extending more proximally away from the proximal end of the magnetic field probe along the probe longitudinal axis or plane. Additionally or alternatively, the magnetic probes described herein may advantageously define one or more proximal marker detection zones more proximally away from the proximal end to enable a user to distinguish different types of magnetic field information in more proximal locations relative to the magnetic field probe. These more proximal locations may be perceived by a user as being behind the proximal end of the magnetic field probe.

Configurations that may also increase the intuitiveness of use include arranging the processor to determine one or more angular dispositions and/or one or more distances to the implantable marker with respect to a magnetic probe reference comprising: one or more virtual positions along a probe longitudinal axis or plane, one or more physical and/or virtual positions along an axis or plane passing through a distal end, one or more physical and/or virtual positions along an axis or plane passing through a proximal end, one or more physical and/or virtual positions along an axis or plane passing through a flank, one or more virtual positions along a probe transverse axis or plane, or any combination thereof.

According to a further aspect of the current disclosure, the magnetic field probe comprises at least one further magnetic sensor, and wherein the first magnetic sensor, the second magnetic sensor and the at least one further magnetic sensor are comprised in one or more ID, 2D, or 3D arrays.

According to a further aspect of the current disclosure, the processor is arranged to configurable by a user.

By providing two or more software-configurable marker detection zones of interest, a user may select, arrange and/or configure a configuration particularly suited to, for example, the expected location of the implantable marker in the human or animal body, the expected proximity, the expected magnetic field strength, and the expected marker orientation. The user may also select, arrange and/or configure a configuration that they have personally found to be particularly efficient for marker localization. As the two or more detection zones may be arranged in several dimensions, two or more of these shapes and cross-sectional shapes may be combined. Simple shapes may be used and/or complex shapes. The two or more marker detection zones may also be selected, arranged and/or configured to adopt a certain configuration, depending on the expected (by the user) proximity and/or orientation to the implantable marker. This may also be automated to a degree, depending on the measured and/or estimated proximity and/or orientation (by the probe). Any combination of different degrees is also possible.

A further advantage of providing one or more software-configurable marker detection zones of interest is that a user may select, arrange and/or configure two or more marker detection zones. This may provide, for example, a coarse/fine marker detection zone configuration - as the distal end of the probe gets closer to the implantable magnetic marker, a marker detection zone with a smaller angle may further increase the accuracy and sensitivity.

Another advantage of providing one or more software-configurable detection zones of interest is that a user may arrange and/or configure any number of marker detection zones. Another advantage is that a user may select, arrange and/or configure additional marker detections zones with different degrees of special overlap. These may be substantially fixed, dynamic or any combination thereof.

According to a further aspect of this disclosure, a magnetic field probe is provided for determining one or more dispositions to an implantable marker, the implantable marker being arranged to generate, in use, a magnetic field, the magnetic field probe comprising: a distal end suitable for being disposed proximate to an animal or human body; a first magnetic sensor arranged close to the distal end and disposed along a first probe transverse axis or plane; a second magnetic sensor, disposed along a second probe transverse axis or plane and disposed between the first magnetic sensor and a proximal end; wherein the first magnetic sensor and the second magnetic sensor are arranged to determine, in use, one or more magnetic field vectors of the implantable marker; and a processor, arranged to collect measurement values from the first magnetic sensor and from the second magnetic sensor, and arranged to determine, in use, one or more magnetic field vectors of the implantable marker; the processor being arranged: to define one or more flank marker detection zones, extending from the first probe transverse axis or plane to the second probe transverse axis or plane and extending more transversely and/or more radially away from a probe longitudinal axis or plane, wherein the probe longitudinal axis or plane is perpendicular to the first probe transverse axis or plane and perpendicular to the second probe transverse axis or plane; to define one or more proximal marker detection zones, extending more proximally away from the proximal end of the magnetic field probe along the probe longitudinal axis or plane; to determine one or more angular dispositions and/or one or more distances to the implantable marker using the one or more magnetic field vectors; to determine that the one or more angular dispositions and/or one or more distances fall within the one or more flank marker detection zones, if the angular disposition and/or distance coincides with one or more flank marker detection zones; and to alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more angular dispositions and/or one or more distances to the implantable marker do not coincide with the one or more flank marker detection zones.

The magnetic probes as described herein may advantageously define one or more flank marker detection zones away from a flank of the probe to enable a user to distinguish different types of magnetic field information in more flank locations relative to the probe. These more flank locations may be perceived by a user as being to a side of the magnetic field probe. Additionally or alternatively, these more flank locations may be perceived by a user as providing magnetic field information behind the distal end of the magnetic field probe. Additionally or alternatively, the magnetic probes described herein may advantageously define one or more proximal marker detection zones more proximally away from the proximal end to enable a user to distinguish different types of magnetic field information in more proximal locations relative to the magnetic field probe. These more proximal locations may be perceived by a user as being behind the proximal end of the magnetic field probe.

Configurations that may also increase the intuitiveness of use include arranging the processor, to determine one or more angular dispositions and/or one or more distances of the implantable marker with respect to a magnetic probe reference comprising: one or more virtual positions along a probe longitudinal axis or plane, one or more physical and/or virtual positions along an axis or plane passing through a distal end, one or more physical and/or virtual positions along an axis or plane passing through a proximal end, one or more physical and/or virtual positions along an axis or plane passing through a flank, one or more virtual positions along a probe transverse axis or plane, or any combination thereof; and/or arranging the processor to alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more angular dispositions and/or one or more distances to the implantable marker do not coincide with the one or more flank marker detection zones and do not coincide with one or more proximal marker detection zones.

According to a further aspect of this disclosure, the processor is arranged to determine one or more distances to the implantable marker with respect to a magnetic probe reference comprising: one or more physical and/or virtual positions along an axis or plane passing through a distal end, one or more physical and/or virtual positions along an axis or plane passing through a proximal end, one or more virtual positions along a probe transverse axis or plane, or any combination thereof.

By detecting in a flank (or more transverse or more radial) direction, depth distance and/or depth direction may be indicated, providing a more intuitive magnetic probe for finding implantable markers, particularly in situations where a magnetic probe reference has passed the implantable marker. Additionally, it may be advantageous for a user to be able to determine a posterior limit of tissue to be treated by deliberately passing the magnetic marker by a distance equal to an expected extent of the tissue to be treated.

According to a further aspect of this disclosure, a detector unit is provided for detecting one or more dispositions and/or distances to an implantable marker, the detector unit comprising a display and comprising one or more magnetic field probes according to any preceding claim, wherein the processor is arranged to indicate to the user a result of the determination of one or more dispositions and/or distances on the display. Optionally, tit may be advantageous to arrange the processor to indicate one or more marker detection zones on the display.

According to a further aspect of this disclosure, a method is provided for determining one or more dispositions to an implantable marker, the implantable marker being arranged to generate, in use, a magnetic field, the method comprising: providing a magnetic field probe comprising a processor and a distal end, the magnetic field probe comprising: a first magnetic sensor close to the distal end and disposed along a first probe transverse axis or plane; a second magnetic sensor, disposed along a second probe transverse axis or plane and disposed between the first magnetic sensor and a proximal end; arranging the processor to collect measurement values from the first magnetic sensor and from the second magnetic sensor; arranging the processor to determine, in use, one or more magnetic field vectors of the implantable marker; arranging the processor to define one or more distal marker detection zones, extending more distally away from the distal end of the magnetic field probe along a probe longitudinal axis or plane, wherein the probe longitudinal axis or plane is perpendicular to the first probe transverse axis or plane and perpendicular to the second probe transverse axis or plane; arranging the processor to define one or more flank marker detection zones, extending from the first probe transverse axis or plane to the second probe transverse axis or plane and extending more transversely and/or more radially away from the probe longitudinal axis or plane; determining one or more angular dispositions and/or one or more distances to the implantable marker using the one or more magnetic field vectors; determining that the one or more angular dispositions and/or one or more distances fall within the one or more flank marker detection zones if the angular disposition and/or distance coincides with one or more flank marker detection zones; and altering, attenuating and/or suppressing processing of one or more magnetic field vector determinations if the one or more angular dispositions and/or one or more distances to the implantable marker do not coincide with the one or more flank marker detection zones.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of some embodiments of the present disclosure, and the manner in which the same are accomplished, will become more readily apparent upon consideration of the following detailed description of the disclosure taken in conjunction with the accompanying drawings, which illustrate preferred and exemplary embodiments, and which are not necessarily drawn to scale, wherein:

FIG. 1 depicts a schematic longitudinal cross-section through a magnetic field probe according to this disclosure;

FIG. 2A to FIG. 2D depict schematic longitudinal cross-sections through magnetic field probe configurations according to this disclosure;

FIG. 3 depicts a schematic longitudinal cross-section through a magnetic field probe and marker detection zones according to this disclosure; FIG. 4 depicts a schematic end-view of a magnetic field probe with a display and a schematic transverse cross-section through marker detection zones according to this disclosure;

FIG. 5 A to FIG. 5B depict schematic top-views of magnetic field probes with displays and schematic longitudinal cross-sections through marker detection zones according to this disclosure;

FIG. 6Ato FIG. 6B depict schematic top-views of magnetic field probes with displays and schematic longitudinal cross-sections through marker detection zones according to this disclosure;

FIG. 7Ato FIG. 7E depict schematic top-views of magnetic field probes with displays and schematic longitudinal cross-sections through marker detection zones according to this disclosure; and

FIG. 8Ato FIG. 8B depict schematic top-views of magnetic field probe with displays and schematic longitudinal cross-sections through marker detection zones according to this disclosure.

DETAILED DESCRIPTION

In the following detailed description, numerous non-limiting specific details are given to assist in understanding this disclosure. It will be obvious to a person skilled in the art that the computer processing part of the method may be implemented on any type of standalone system or client-server compatible system containing any type of client, network, server, and database elements.

FIG. 1 depicts a longitudinal cross-section through a first embodiment magnetic field probe (a first magnetic probe) 101 for determining one or more dispositions (localization) to an implantable marker (seed) 200. These dispositions may include one or more angular dispositions, one or more distance dispositions (distances), or any combination thereof. In the context of this disclosure, an angular disposition may be considered to be the same as an angular arrangement - it is an angular component in the relative position of the implantable marker 200 relative to the probe. The implantable marker 200 is depicted schematically with a circular cross-section. However, the first magnetic probe 101 may be arranged to localize markers (seeds) having any physical shape or combinations of shapes, any material or any combination or materials, any physical cross-section or any combinations of physical cross-sections, and any combinations thereof. In general, physical properties are less relevant for localization. In general, magnetic properties during use are more relevant for localization. However, the first magnetic probe 101 may be arranged to localize implantable markers 200 having any magnetic-field shape or combinations of magnetic-field shapes, any magnetic-field cross-section or any combinations of magnetic-field cross-sections, and any combinations thereof. Because localization is in 3D, an implantable marker 200, such as a cylindrical permanent magnet, may generate one or more isotropic magnetic-fields in one or more orientations and one or more anisotropic fields in one or more orientations. The schematic use of a circular cross-section for an implantable marker 200 should therefore be considered to represent an orientation with an isotropic field, an anisotropic field, or any combination thereof. To make it easier to compare the different views of the same and different embodiments, axes have also been defined as used in each drawing. As depicted in FIG. 1, the plane of the drawing (the paper) is in X 600 and Y 700, substantially perpendicular to each other. The X axis 600 runs from bottom to top and the Y axis 700 runs from right to left. The Z axis 800 is substantially perpendicular to X 600 and Y 700 and exits the plane of the drawing (out of the paper).

A longitudinal axis 151 (or longitudinal plane 151) of the first magnetic probe 101 is schematically depicted here as being substantially parallel to the Y axis 700 in the crosssection depicted. In all cases, the drawings represent 2D views of 3D objects, so extents and axes should be interpreted as only indicating their forms through these exemplary cross-sections. In some examples, the extents and axes may be the same in other cross- sectional planes. In some examples, the virtual and physical objects depicted may be fully or partially symmetrical about an axis. In some examples, a depiction of an axis may represent an exemplary cross-section through a plane. In some examples, the virtual and physical objects depicted may be fully or partially symmetrical about a plane.

As depicted, the implantable marker 200 (or magnetic marker 200) may be implanted at or below an outer surface of skin 300 to mark an area of interest. The area of interest may be on an outer surface of skin 300. The implantable marker 200 is arranged to generate, in use, a magnetic field. For example, the implantable marker 200 may comprise one or more magnetic dipoles.

The implantable marker 200 may be implanted in an outer surface of skin 300, just under an outer surface of the skin 300, a few millimeters or a few centimeters below an outer surface of the skin. The implantable marker 200 may also be localized using the first magnetic probe 101 if it is not considered implanted, for example, when attached to an outer surface of skin 300 or inserted into an orifice of the human or animal body. The implantable marker 200 may be implanted in any convenient way, such as by injection. The injection may be, for example, into soft tissue or organs, or delivery via a bronchoscope to lung bronchii, or coloscope to colon. The method of implantation may depend on, for example, the degree of implantation, the subsequent procedure to be performed, the size of the area of interest, the location of the area of interest, the type of tissue in the area of interest, and the type of tissue surrounding the area of interest. The implantable marker 200 may be implanted immediately before detection or some time earlier. Optionally, implantation may be assisting and/or guided using imaging techniques and/or imaging equipment, such as ultrasound, x-ray, mammography, stereotactic, CT, MRI-guided, or any combination thereof.

For example, a suitable marker 200 comprise one magnetic dipole may be approximately cylindrical with a diameter of 1.45mm, a length of 2.19 mm and a remnant field (Br) of 1.43 T (Neodymium N52), or a diameter of 1.75mm, a length of 5 mm and a remnant field (Br) of 1.43 T (Neodymium N52). A marker with a diameter of 1 ,45mm and a length of 4.7mm may also be suitable. A marker with a diameter of 1 ,45mm and a length of 4.6mm may also be suitable. A marker with a diameter of 1 ,00mm and a length of 7.4mm may also be suitable. As higher grades of neodymium become available, they may also be advantageously used with the embodiments of this disclosure.

Additionally or alternatively, the implantable marker 200 may comprise one or more induced magnetic dipoles. As the magnetic field probe 101 determines the angular dispositions of the implantable marker 200 based on the property of dipole fields, the arrangement of the implantable marker 200 to produce such a field is less important. Combinations of techniques may also be used to generate a plurality of induced and/or permanent magnetic dipoles.

The first magnetic probe 101 comprises a distal end 160 suitable for being disposed proximate to an animal or human body. The first magnetic field probe 101 may extend between a proximal end 165 and a distal end 160 along the first probe longitudinal axis or plane 151. The proximal end 165 and/or distal end 160 may be associated with one or more physical and/or virtual positions. For example, virtual positions may be along an axis and/or plane. For example, physical positions may be extents of the first magnetic field probe 101, such as one or more portions of a housing and/or a display. The proximal end 165 and distal end 160 are further explained in relation to FIG. 2A below.

Optionally, the first magnetic field probe 101 may extend between a first flank 162 and a second flank 167 along one or more transverse axes or planes, arranged perpendicular to the first probe longitudinal axis or plane 151. The first flank 162 and/or second flank 167 may be associated with one or more physical and/or virtual positions. For example, virtual positions may be along an axis and/or plane. For example, physical positions may be extents of the first magnetic field probe 101, such as one or more portions of a housing and/or a display. The first flank 162 and second flank 167 are further explained in relation to FIG. 2A below.

The first magnetic probe 101 may optionally be further arranged to determine one or more angular dispositions in one or more dimensions between a first magnetic probe reference (not depicted) and the implantable marker 200. These one or more angular dispositions may comprise, for example, an angular disposition 170 in one or more XY planes 600, 700 as depicted in FIG. 1. Additionally or alternatively, these one or more angular dispositions may comprise, for example, an angular disposition (not depicted) in one or more YZ planes 700, 800. Additionally or alternatively, these one or more angular dispositions may comprise, for example, an angular disposition (not depicted) in one or more XZ planes 600, 800. Additionally or alternatively, these one or more angular dispositions may comprise any combination of angular dispositions in one or more planes and/or one or more directions. Additionally or alternatively, the first magnetic probe 101 may be arranged to determine one or more distances in one or more dimensions from a first magnetic probe reference (not depicted) to the implantable marker 200.

The first magnetic probe reference (not depicted) may comprise, for example, one or more virtual positions along a longitudinal axis or plane, such as the first longitudinal axis or plane 151. Additionally or alternatively, the first magnetic probe reference (not depicted) may comprise one or more physical and/or virtual positions along an axis or plane passing through a distal end 160, one or more physical and/or virtual positions along an axis or plane passing through a proximal end 165, one or more physical and/or virtual positions along an axis or plane passing through a flank, such as a first flank 162 or a second flank 167, one or more virtual positions along a probe transverse axis or plane, such as a first probe transverse axis or plane 181 or a second probe transverse axis or plane 182, or any combination thereof.

The first magnetic probe 101 comprises at least a first magnetic sensor 111 and a second magnetic sensor 112, arranged to determine, in use, one or more magnetic field vectors of a local magnetic field (Bx, By, Bz) generated by the implantable marker 200 in use. These properties may be used by a software algorithm to determine one or more dispositions, for example, the angular disposition 170 depicted in FIG. 1. In the example depicted in FIG. 1, the first magnetic sensor 111 is arranged close to the distal end 160 and disposed along the first probe transverse axis or plane 181. The second magnetic sensor 112 is disposed along the second probe transverse axis or plane 182 and disposed between the first magnetic sensor 111 and the proximal end 165 of the first magnetic probe 101. The first probe transverse axis or plane 181 may also be described the probe distal transverse axis or plane 181. The second probe transverse axis or plane 182 may also be described as the probe proximal transverse axis or plane 182.

It may be advantageous if the first magnetic sensor 111 is arranged at the distal end 160. Additionally or alternatively, it may be advantageous if the second magnetic sensor 112 is arranged close to the proximal end 165. Additionally or alternatively, it may be advantageous if the second magnetic sensor 112 is arranged at the proximal end 165. The proximal end 165 and distal end 160 are not depicted in detail in FIG. 1, but they are further explained in relation to FIG. 2A below.

The at least two magnetic sensors 111, 112 are arranged to determine, in use, one or more B-field 3D vector measurements of the implantable marker’s 200 magnetic field. For example, the magnetic sensor output may be a 3D vector of a B-field. With two or more magnetic sensors 111, 112, one or more dispositions of the implantable marker 200 may be determined. At one first measurement associated with the first 111 magnetic sensor and at least one second measurement associated with the second 112 magnetic sensor, may be used in a software algorithm to determine one or more dispositions of the implantable marker 200, such as the angular disposition 170 depicted in FIG. 1. An angular disposition is a measurement (or estimation) of a direction to the implantable marker 200 associated with the first magnetic probe 101 as a whole. Additionally or alternatively, it may be advantageous to also determine one or more distance dispositions.

The first magnetic field probe 101 may advantageously define one or more distal marker detection zones 190 more distally away from the distal end 160 to enable a user to distinguish different types of magnetic field information 170 in more distal locations relative to the probe 101. These more distal locations may be perceived by a user as being in front of the distal end 160 of the first magnetic field probe 101.

Additionally or alternatively, the first magnetic field probe 101 may advantageously define one or more flank marker detection zones (not depicted) away from a flank 162, 167 of the probe 101 to enable a user to distinguish different types of magnetic field information 170 in more flank locations relative to the probe 101. These more flank locations may be perceived by a user as being to a side of the magnetic field probe 101. Additionally or alternatively, these more flank locations may be perceived by a user as providing magnetic field information 170 behind the distal end 160 of the magnetic field probe 101. The one or more flank detection zones (not depicted) are described below in relation to FIG. 3.

Additionally or alternatively, the first magnetic field probe 101 may advantageously define one or more proximal marker detection zones (not depicted) more proximally away from the proximal end 165 to enable a user to distinguish different types of magnetic field information 170 in more proximal locations relative to the probe 101. These more proximal locations may be perceived by a user as being behind of the proximal end 165 of the first magnetic field probe 101. The one or more proximal detection zones (not depicted) are described below in relation to FIG. 3.

The magnetic sensors described in this disclosure, such as the first magnetic sensors 111 and the second magnetic sensor 112, may be any suitable magnetic field detector, such as magnetometers, flux gate sensors, geomagnetic sensors, Lorentz force digital MEMS, magneto-inductive sensors, magneto-resistive sensors, Hall sensors, magnetic tunnel junctions and any combination thereof. For example, one or more of the magnetic sensors disclosed in PCT application W02021124300A1, published on 24.06.2021, may be used, which are incorporated herein by reference.

For example, in particular, one or more of the magnetic sensors disclosed on pages 16 to 18 of the PCT application W02021124300A1 may be used, which are incorporated herein by reference. Many IC packages are available which are small and contain 3 -axis detection. So a ‘many-axis’ solution may be provided with simple PCB design and preferably a smaller probe diameter. The sensor packages proposed below are examples. They are digital and therefore relatively straightforward to interface as less analog design is required. For example, a 3-axis Hall sensor may be used, which measures three field components Bx, By and Bz using 3 magnetic detectors. Typically such a Hall-sensor is an IC package comprising three (3D) substantially mutually perpendicular detectors, providing measurement of at least three degrees of freedom at approximately the same physical position in the first magnetic probe 101. The magnetic sensors 111, 112 may be the same type or different types. In this disclosure, a sensor and detector are sometimes used interchangeably where it is not important for the technical disclosure.

In general, a sensor is considered to be a single encapsulated package comprising one or more detectors. A sensor with a single magnetic detector may be considered to be a sensor or a detector. If a sensor package comprises two or more detectors with a physical separation and/or a functional separation between detectors sufficiently large to measure substantially different values for a particular B-vector of the implantable marker’s 200 magnetic field, then in the terms of this disclosure, such a package is considered to comprise two or more sensors. So, each of the magnetic detectors may provide a B-vector measurement of the implantable marker’s 200 magnetic field relating to substantially different sensor positions (or dispositions) within the first magnetic probe 101. If a physical separation and/or a functional separation between detectors is too small (they measure substantially the same value for a particular B-vector), then in the terms of this disclosure, such a package is considered to comprise one sensor. So, each of the detectors may provide a vector measurement of the implantable marker 200 relating to substantially the same position (or disposition) within the first magnetic probe 101. Note that in some packages, two or more detectors may be arranged to measure different orientations - for example, some Hall sensor packages comprise three detectors, oriented substantially perpendicular to each other. They are considered as being comprised in the same (one) sensor as they measure B-vectors associated with substantially the same position (or disposition).

The distal end 160 may be arranged to be disposed proximate to an outer surface of skin 300. Additionally or alternatively, the distal end 160 may be arranged to be disposed at a distance from an outer surface of skin 300. For example, a spacer may be used to maintain a fixed distance, or the distance may be zero if the first magnetic probe 101 is further arranged to contact an outer surface of skin 300. For example, the first magnetic probe 101 may be further arranged to be pushed against (or to contact) an outer surface of skin 300 to create an indent which may further reduce the distance between the distal end 160 of the first magnetic probe 101 and the implantable marker 200. In general, the smaller the distance between the first magnetic probe 101 and the implantable marker 200, the greater the amplitude of any signal measured. For example, for some treatments, the distal end 160 of the first magnetic probe 101 may further be arranged to be inserted through an outer surface of skin 300 and/or into a body cavity to further reduce the distance between probe 101 and marker 200. This may be, for example, via a surgical incision or via a body orifice.

Each magnetic sensor 111, 112 measures the B-field 3D vector of any local magnetic field, which may comprise any background magnetic field, such as the Earth’s magnetic field, and any magnetic field of the implantable marker 200. These measurements may be provided to a software algorithm which combines them, together with physical parameters such as orientation, sensitivity, magnetic sensor separation distance, to determine one or more angular dispositions of the magnetic marker 200 relative to a predetermined and/or controlled first magnetic probe reference (not depicted). Additionally or alternatively, the processor (not depicted) may be arranged to determine one or more distances in one or more dimensions to the implantable marker 200. As depicted in FIG. 1, a ID array of at least two magnetic sensors 111, 112 may be used. The sensors 111, 112 are depicted disposed along the longitudinal axis or plane 151 of the first magnetic probe 101, but this is not essential because their relative positions (dispositions) may be determined from measurement and/or design data and taken into account (considered) in the software algorithm. The first magnetic probe 101 is arranged to reference the B-vector measurements from the sensors 111, 112 to a suitable first magnetic probe reference (not depicted). It may be advantageous to use a first magnetic probe reference (not depicted) which provides an intuitive reference for the user, such as a position on a probe housing 140 close to the distal end 160. Additionally or alternatively, it may be advantageous to dispose the first magnetic sensor 111 and the second magnetic sensor 112 along the first longitudinal axis or plane 151, and to comprise the two or more magnetic sensor positions along the first longitudinal axis or plane 151 in the first magnetic probe reference (not depicted) for the one or more angular disposition determinations because this may simplify the geometric conversion of measurement data. Any convenient determination algorithm may be used. For example, one or more of the algorithms disclosed in PCT application W02021124300A1, published on 24.06.2021, which are incorporated herein by reference. For example, in particular, one or more of the algorithms disclosed in PCT application WO2021124300A1 in the following figures: FIG. 3 A depicts a simulated schematic diagram of approximately circular field lines that represent cross-sections of a magnetic field, generated by a magnetic dipole; FIG. 3B depicts the relationship between probe inclination and values of the inclination of the fields in the probe plane; FIG. 4A and 4B depict measurements made at each magnetic sensor as the probe was scanned through different angular dispositions at a fixed inclination; FIG. 5A and 5B depict differences in B-field inclination, measured at distances 15.0mm, 20.0mm and 25.0mm compared to magnetic sensor closest to distal end, namely the sensor at 10.0mm; FIG. 6 depicts an example of differential measurement versus lateral displacement characteristic which may be used to convert the L-R signal from a sensor to lateral displacement; and FIG. 7 depicts an example of expected magnetic field components when the probe points directly towards the magnetic dipole, which are incorporated herein by reference. For example, in particular, one or more of the algorithms disclosed in PCT application WO2021124300A1 in the description explaining following figures: FIG. 3 A, FIG. 3B, FIG. 4A, FIG. 4B, FIG. 5A, FIG. 5B, Fig. 7 and FIG. 7, including the disclosure on page 20, line 7 to page 34, line 18, which are incorporated herein by reference.

FIG. 1 of this disclosure further depicts an example of a marker detection zone extending from the distal end 160 along a first probe longitudinal axis or plane 151 as indicated by the dashed line. In terms of this disclosure, this is an example of a distal marker detection zone 190 (distal detection zone 190). Although depicted with an approximately triangular cross-section in the XY plane 600-700 and substantially symmetrical, this is not essential - any form of cross-section and any combinations of forms of cross-section may be used. For example, a cross-section in one or more planes through the distal marker detection zone 190 may optionally comprise a portion with an approximately circular, arc, segment, oval, elliptical, triangular, rectangular, square cross-section, or any combination thereof. The distal marker detection zone 190 depicted may be mainly determined by a first extent 1190 of the distal marker detection zone 190 in an X-Y plane which may influence a maximum detection distance. The distal marker detection zone 190 depicted may be further determined by a second extent 2190 and a third extent 3190 in an X-Y plane, wherein the second extent 2190 and a third extent 3190 are angular boundaries. The distal marker detection zone 190 depicted may be further determined by the first probe transverse axis or plane 181 as described below in relation to FIG. 2A and FIG. 3. One or more distances between the second extent 2190 and the third extent 3190 of the distal detection zone 190 proximate the distal end 160 may be predetermined and/or controlled. Additionally or alternatively, one or more distances between the first probe transverse axis or plane 181 and the first extent 1190 of the distal detection zone 190 may be predetermined or controlled.

If one or more distal marker detection zones 190 are substantially symmetrical about the longitudinal axis or plane 151, they may provide a more intuitive magnetic probe for finding markers 200, particularly when the first magnetic probe 101 is arranged to be hand-held. For example, the marker detection zone may be defined as a cylinder or a cone-shape. A cone-shaped marker detection zone may further have a parabolic, linear or hyperbolic shape. For example, a parabolic shape may have a wider angle proximate the distal end 160 and a narrower angle remote from the distal end towards a more negative Y 700 disposition. For example, a linear shape may have approximately the same angle proximate the distal end 160 and also remote from the distal end 160 towards a more negative Y 700 disposition - this may also be described as a focused beam. For example, a hyperbolic shape may have a narrower angle proximate the distal end 160 and a wider angle remote from the distal end 160 towards a more negative Y 700 disposition.

One or more marker detection zones, such as one or more distal marker detection zones 190, may be defined using software to function as a software-controlled collimator. For example, during processing of B-field vector measurements, angular dispositions and/or distances that are estimated, measured, and/or determined as being inside a marker detection zone of interest may be given a greater weighting and/or an amplification. Additionally or alternatively, angular dispositions and/or distances that are estimated, measured, and/or determined as being outside the marker detection zone of interest may be given a lower weighting, an alteration, an attenuation and/or a suppression during processing. For example, a suitable weighting, alteration and/or attenuation may be provided during processing by modifying a degree of feedback depending on one or more distances of a marker measurement to a longitudinal axis or plane of a magnetic probe. For example, a suitable weighting, alteration and/or attenuation may be provided during processing by modifying a degree of feedback depending on one or more distances of a marker measurement to a first probe transverse axis or plane and/or to a distal end. For example, a suitable weighting, alteration and/or attenuation may be provided during processing by modifying a degree of feedback depending on one or more distances of a marker measurement to a second probe transverse axis or plane and/or to a proximal end. For example, a suitable suppression may be provided during processing by selecting a feedback for consideration if a marker measurement is determined to be within one or more marker detection zones of interest. For example, a plurality of marker detection zones of interest may be provided during processing with similar or different weightings, attenuations and/or suppressions.

Additionally or alternatively, the software may be arranged during processing to only consider the vector measurements in the disposition calculation if they appear to indicate that the implantable marker 200 falls within one or more marker detection zones of interest. For example, a suitable suppression may be provided during processing by not selecting a feedback for consideration if a marker measurement is determined to be outside the one or more marker detection zones of interest. Additionally or alternatively, one or more extents of the one or more marker detection zones of interest, such as the extent 1190 that the distal detection zone 190 extends, may also be used during processing to determine whether the implantable marker 200 appears to fall within one or more longitudinally-limited marker detection zones of interest.

Defining the one or more marker detection zones of interest in software means that simple shapes, such as cylinders, slits and cones may be used. Additionally or alternatively, complex shapes may also be used - for example, a narrow cone close to the distal end 160 of the first magnetic probe 101, which fans out wider more distally away from the distal end 160 or defines a straight (cylindrical) beam more distally away from the distal end 160. Determining if the implantable marker 200 appears to fall within the one or more marker detection zones of interest may be implemented as a straightforward goniometric test, implementing the desired detection volume. For example, if the implantable marker 200 appears to be at one or more extents 1190, 2190, 3190 depicted of the distal marker detection zone 190, noise may result in a marker 200 being sometimes altered, attenuated and/or suppressed during processing, and sometimes used during processing. Solutions that may be implemented in the determination include: hysteresis for the measurement, where once a marker has been considered to be inside the one or more marker detection zones of interest, movement of a considerable distance and/or angle should occur before the B-field vector measurement is considered to be outside the one or more marker detection zones of interest; considering position uncertainties in the 3D localization output to be one or more heat maps in space, as described in the PCT application W02020111936A1, published on 04.06.2020, where the position uncertainty may be multiplied with the one or more marker detection zones of interest, followed by integration over the volume. If the integral is above a threshold, the values are used in the determination of one or more angular dispositions and/or one or more distances; and shaping the weights of the one or more marker detection zones of interest to be tapered. For example, a magnetic probe as described herein may be arranged to evaluate the B- field vectors and return the Jacobian, which may be used to give an indication of the uncertainty in the estimated marker 200 positions. This is analogous to the approach usually used to mitigate problems with uncertainty in GPS systems.

Additionally or alternatively, a dynamic filter window may be provided in hardware and/or software when considering measurements. For example, a dimension of the dynamic filter window may depend on a degree of movement of a magnetic field probe as described herein. For example, a longer filter window may be selected, arranged and/or configured when a degree of movement of a magnetic field probe as described herein is below a predetermined and/or controlled threshold. This may advantageously increase a degree of reliability and/or reduce a degree of noise. This may also provide a higher degree of accuracy, particularly for more distal marker measurements, where a lower degree of angular accuracy may result in consecutive measurements indicating that the measurements are found in different marker detection zones. For example, a low degree of movement of a magnetic field probe as described herein may be provided by a user holding the magnetic field probe still for a minimum period of time. Optionally, one or more additional sensors may be provided in a magnetic field probe as described herein to measure a degree of movement and/or a degree of change in orientation, such as one or more IMU (inertial measurement unit) sensors and/or one or more background magnetic field sensors.

Optionally, the first magnetic probe 101 may be further arranged to determine a longitudinal and/or transverse angular disposition and/or a distance to the implantable marker 200 with respect to a magnetic probe reference point (not depicted).

In this example, the distal end 160 may arranged to be disposed close to an outer surface of skin 300, wherein the details of the arrangement depend on the intended uses. Additionally or alternatively, the proximal end 165 may be arranged to contact an outer surface of skin 300; to be inserted through an outer surface of skin 300; to be inserted into a body cavity; or any combination thereof.

In this example, the proximal end 165 may arranged to be held by a hand of a user (not depicted), wherein the details of the arrangement depend on the intended uses. Additionally or alternatively, the proximal end 165 may be arranged to be attached to a tool holder. Additionally or alternatively, the proximal end 165 may arranged to be disposed close to an outer surface of skin 300, wherein the details of the arrangement depend on the intended uses. Additionally or alternatively, the proximal end 165 may be arranged to contact an outer surface of skin 300; to be inserted through an outer surface of skin 300; to be inserted into a body cavity; or any combination thereof.

For example, the software algorithm may use the determination that when the inclination (angular disposition) is zero (or when the implantable marker 200 is disposed along the longitudinal axis or plane 151 of the first magnetic probe 101, for example in the Y-Z plane 700-800, the magnetic fields measured at all the sensors 111, 112 disposed along the longitudinal axis or plane are in substantially the same direction. When this is detected with a first magnetic probe 101 arranged as a hand-held probe, the first magnetic probe 101 may “point” substantially in a direction of the implantable marker 200. In hand-held applications, the user may rotate the first magnetic probe 101 to different inclinations, for example in the Y-Z plane 700-800, such that the longitudinal axis or plane 151 has a plurality of orientations with respect to the skin 300. By continuously monitoring the magnetic field vector measurements and determining the degree of deviation (the differences) in field directions measured by each sensor 111, 112, an indication of the relative inclination (angular disposition) to the implantable marker 200 may be provided. When the degree of deviation is below a predetermined threshold, the first magnetic probe 101 will substantially “point” to the implantable marker 200.

If the background field is not sufficiently uniform, or if the background field sensors pick up the dipole field of the implantable marker (not depicted) (because the implantable marker is close to the background field sensors), it may be advantageous to subtract the background field locally. For example, by measuring the gradient of the B-field because the dipole field is varying over space, and assuming that the background field is uniform (at least over the range of the measurement; for example, the distance between two adjacent sensors). This approach may be used with a 3D array with sensitivity to curvature in all three directions 600, 700, 800. A 3D array comprises magnetic field sensors arranged substantially along a plane, and further along at least one axis or plane, substantially perpendicular to said plane. It may also comprise magnetic field sensors arranged substantially along a first plane, and further along a second plane, substantially perpendicular to the first plane. FIG. 2A to FIG. 2D depict schematic longitudinal cross-sections through magnetic field probe configurations according to this disclosure. In particular, FIG. 2A schematically depicts a magnetic field probe configuration for the first embodiment of the magnetic probe 101 (first magnetic probe 101). The first magnetic probe 101 comprises the distal end 160, suitable for being disposed proximate to an animal or human body, wherein the first magnetic sensor 111 is arranged close to the distal end 160, and the first magnetic sensor 111 is disposed along the first probe transverse axis or plane 181. The first magnetic probe 101 comprises the second magnetic sensor 112, disposed along the second probe transverse axis or plane 182, and the second magnetic sensor 112 is disposed between the first magnetic sensor 111 and the proximal end 165.

In the example depicted in FIG. 2A, the first magnetic sensor Ill is arranged close to the proximal end 165. The first magnetic probe 101 comprises a first flank 162 and a comprises a second flank 167. The first magnetic sensor 111 is disposed along the first probe longitudinal axis or plane 151, and the second magnetic sensor 112 is also disposed along the first probe longitudinal axis or plane 151. The first magnetic sensor 111 and the second magnetic sensor 112 are arranged substantially along the Y-axis 700, and arranged on a suitable substrate, such as a PCB, lying in a X-Y plane 600-700. This may be considered a ID sensor array geometry, wherein magnetic field sensors are arranged substantially along an axis or plane.

Optionally, one or more positions of the proximal end 165, the distal end 160, the first flank 162 and/or the second flank 167 may be associated with one or more physical positions of the first magnetic probe 101, such as one or more parts of an optional probe housing 140 and/or an optional display, and may be predetermined and/or controlled to provide intuitive points of reference to the user whereby the user may intuitively understand any instructions provided by the first magnetic probe 101. For example, visual, audio and/or haptic information regarding the estimated distances and directions to the implantable marker 200 may be provided by the first magnetic probe 101 with respect to one or more physical positions. In the example depicted in FIG. 2A, the proximal end 165, the distal end 160, the first flank 162 and the second flank 167 are all associated with one or more physical positions on the optional probe housing 140.

The positions of the first magnetic sensor 111 and/or the second magnetic sensor 112 are associated with one or more virtual positions which are used to directly and/or indirectly define one or more virtual extents for one or more marker detection zones 190, 192, 194, 196. For example, where one or more virtual positions are used to directly define one or more virtual extents for one or more marker detection zones 190, 192, 194, 196, the one or more virtual positions are comprised in one or more virtual extents. For example, where one or more virtual positions are used to indirectly define one or more virtual extents for one or more marker detection zones 190, 192, 194, 196, one or more offsets are applied in hardware and/or software to the one or more virtual positions, and therefore one or more offset virtual positions are comprised in one or more virtual extents for one or more marker detection zones 190, 192, 194, 196. For example, the positions of the first magnetic sensor 111 and/or the second magnetic sensor 112 may be associated with, or mapped/transformed to, one or more physical positions of the first magnetic probe 101 by applying one or more distance and/or angular disposition offsets in the hardware and/or software. For example, the virtual positions of the first magnetic sensor 111 and/or the second magnetic sensor 112 may be associated with, or mapped/transformed to, one or more positions of the proximal end 165, the distal end 160, the first flank 162 and/or the second flank 167 of the first magnetic probe 101 by applying one or more suitable offsets in hardware and/or software. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more physical and/or virtual positions along an axis or plane passing through a distal end 160. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more physical and/or virtual positions along an axis or plane passing through a proximal end 165. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more physical and/or virtual positions along an axis or plane passing through a flank 162, 167. Thereby, by applying one or more suitable offsets, visual, audio and/or haptic information regarding the estimated distances and directions to the implantable marker 200 may be provided by the first magnetic probe 101 with respect to one or more physical and/or virtual points of reference.

Optionally, the processor may be arranged to determine one or more dispositions 170 of the implantable marker 200 with respect to a magnetic probe reference (not depicted) comprising one or more positions along the first probe longitudinal axis or plane 151. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along a second probe longitudinal axis or plane 152. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along a third probe longitudinal axis or plane 153. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along the first probe transverse (or radial) axis or plane 181. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along the second probe transverse (or radial) axis or plane 182.

The first magnetic sensor 111 and the second magnetic sensor 112 are arranged to determine, in use, one or more magnetic field vectors of the implantable marker 200. The processor (not depicted) may be arranged to collect measurement values from the first magnetic sensor 111 and from the second magnetic sensor 112, and arranged to determine, in use, one or more magnetic field vectors of the implantable marker. The processor (not depicted) may be arranged to determine one or more dispositions 170 to the implantable marker 200 using the one or more magnetic field vectors.

FIG. 3 depicts a schematic longitudinal cross-section through the first magnetic field probe 101 and marker detection zones 190, 192, 194, 196 according to this disclosure. The first magnetic probe 101 comprises a processor (not depicted), arranged to define one or more distal marker detection zones 190, extending more distally away from the distal end 160 of the first magnetic field probe 101 along the first probe longitudinal axis or plane 151. The probe longitudinal axis or plane 151 is arranged perpendicular to the first probe transverse axis or plane 181. The probe longitudinal axis or plane 151 is arranged perpendicular to the second probe transverse axis or plane 182.

The processor (not depicted) is arranged to define one or more first flank marker detection zones 192 and/or to define one or more second flank marker detection zones 194. The one or more flank marker detection zones 192, 194 extend from the first probe transverse axis or plane 181 to the second probe transverse axis or plane 182, extending more transversely and/or more radially away from the probe longitudinal axis or plane 151. The first flank marker detection zone 192 may be mainly determined by a first extent 1192 of the first flank marker detection zone 192 in an X-Y plane which may influence a maximum detection distance. The first flank marker detection zone 192 may be further determined by the first probe longitudinal axis or plane 151. The first flank marker detection zone 192 may be further determined by the first probe transverse axis or plane 181 and the second probe transverse axis or plane 182 in an X-Y plane, wherein the first probe transverse axis or plane 181 and the second probe transverse axis or plane 182 are angular boundaries. Additionally or alternatively, one or more distances between the first longitudinal axis or plane 151 and the first extent 1192 of the first flank detection zone 192 may be predetermined or controlled.

The second flank marker detection zone 194 may be mainly determined by a first extent 1194 of the second flank marker detection zone 194 in an X-Y plane which may influence a maximum detection distance. The second flank marker detection zone 194 may be further determined by the first probe longitudinal axis or plane 151. The second flank marker detection zone 194 may be further determined by the first probe transverse axis or plane 181 and the second probe transverse axis or plane 182 in an X-Y plane, wherein the first probe transverse axis or plane 181 and the second probe transverse axis or plane 182 are angular boundaries. Additionally or alternatively, one or more distances between the first longitudinal axis or plane 151 and the first extent 1194 of the second flank detection zone 194 may be predetermined or controlled.

Additionally or alternatively, the one or more flank marker detection zones 192, 194 may extend to an axis or plane comprising one or more physical and/or virtual positions passing through a flank 162, 167 of the first magnetic field probe 101.

The processor (not depicted) is arranged to determine one or more dispositions to the implantable marker 200 using the one or more magnetic field vectors, wherein the one or more dispositions are determined to fall within the one or more flank marker detection zones 192, 194 if the one or more disposition coincide with one or more flank marker detection zones 192, 194. The processor (not depicted) is arranged to alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more dispositions to the implantable marker 200 do not coincide with the one or more flank marker detection zones 192, 194.

As described above in relation to FIG. 1, the first magnetic field probe 101 may advantageously enable a user to distinguish different types of magnetic field information 170 in more distal locations relative to the probe 101.

Additionally or alternatively, the first magnetic field probe 101 may advantageously define one or more flank marker detection zones 192, 194 away from a flank 162, 167 of the probe 101 to enable a user to distinguish different types of magnetic field information 170 in more flank locations relative to the probe 101. These more flank locations may be perceived by a user as being to a side of the magnetic field probe 101. Additionally or alternatively, these more flank locations may be perceived by a user as providing magnetic field information 170 behind the distal end 160 of the magnetic field probe 101. Optionally, one or more flank marker detection zones 192, 194 may be arranged to extend from an axis or plane comprising one or more physical and/or virtual positions passing through the distal end 160 by applying one or more offsets. Additionally or alternatively, one or more flank marker detection zones 192, 194 may be arranged to extend to an axis or plane comprising one or more physical and/or virtual positions passing through the proximal end 165 by applying one or more offsets.

Although the cross-sections depicted in FIG. 3 for the first flank detection zone 192 and for the second flank marker detection zone 194 are substantially the same shape, with similar extents, this is not essential. Additionally or alternatively, the one or more flank marker detection zones 192, 194 may be arranged to be substantially symmetrical about the first probe longitudinal axis or plane 151.

For example, a cross-section in one or more planes through the one or more flank marker detection zones 192, 194 may optionally comprise a portion with an approximately circular, arc, segment, oval, elliptical, triangular, rectangular, square cross-section, or any combination thereof. Additionally or alternatively the one or more flank marker detection zones 192, 194 may comprise a portion with an arc, segment, cylindrical, cone shape, or any combination thereof. Additionally or alternatively, the one or more flank marker detection zones 192, 194 may comprise a portion with a parabolic, linear or hyperbolic shape. Optionally, two or more flank marker detection zones 192, 194 may share one or more boundaries. Optionally, two or more flank marker detection zones 192 differ by a parameter selected from the group comprising of: an extent, a shape, an orientation, a disposition, a scaling, a resolution, an angular boundary, a longitudinal extent, a transverse extent, or any combination thereof.

Additionally or alternatively, the processor may be arranged to define one or more proximal marker detection zones 196, extending more proximally away from the proximal end 165 of the first magnetic field probe 101 along the first probe longitudinal axis or plane 151. The proximal marker detection zone 196 may be mainly determined by a first extent 1196 of the proximal marker detection zone 196 in an X-Y plane which may influence a maximum detection distance. The proximal marker detection zone 196 may be further determined by a second extent 2196 and a third extent 3196 in an X-Y plane, wherein the second extent 2196 and a third extent 3196 are angular boundaries. The proximal marker detection zone 196 may be further determined by the second probe transverse axis or plane 182. One or more distances between the second extent 2196 and the third extent 3196 of the proximal detection zone 196 proximate the proximal end 165 may be predetermined and/or controlled. Additionally or alternatively, one or more distances between the second probe transverse axis or plane 182 and the first extent 1196 of the proximal detection zone 196 may be predetermined or controlled. The one or more proximal marker detection zones 196 may be arranged identically, similarly, or differently, to the one or more distal marker detection zones 190 described herein.

As described above in relation to FIG. 1, the first magnetic field probe 101 may advantageously enable a user to distinguish different types of magnetic field information, such as one or more dispositions 170, in more distal locations relative to the probe 101. Additionally or alternatively, the first magnetic field probe 101 may advantageously define one or more proximal marker detection zones 196 more proximally away from the proximal end 165 to enable a user to distinguish different types of magnetic field information, such as one or more dispositions 170, in more proximal locations relative to the probe 101. These more proximal locations may be perceived by a user as being behind of the proximal end 165 of the first magnetic field probe 101.

It may be advantageous if the first magnetic sensor 111 is arranged to be positioned at the distal end 160. Additionally or alternatively, it may be advantageous if the second magnetic sensor 112 is arranged to be positioned at the proximal end 165.

FIG. 2B to FIG. 2D depict further schematic longitudinal cross-sections through magnetic field probe configurations according to this disclosure with at least three or at least four magnetic sensors 111, 112, 113, 114. The processor may be optionally arranged to consider measurement values from all magnetic sensors 111, 112, 113, 114 for determinations of coincidence with each marker detection zone (not depicted). Alternatively, it may be advantageous to only consider measurement values from two or more particular magnetic sensors for determinations of coincidence with a particular marker detection zone (not depicted). Additionally or alternatively, it may be advantageous to give a greater weighting and/or an amplification to measurement values from two or more particular magnetic sensors for determinations of coincidence with a particular marker detection zone (not depicted). Additionally or alternatively, it may be advantageous to give a lower weighting and/or an alteration, an attenuation and/or a suppression during processing of measurement values from two or more particular magnetic sensors for determinations of coincidence with a particular marker detection zone (not depicted).

For example, a greater weighting and/or an amplification may be given to measurement values from the first magnetic sensor 111 and the second magnetic sensor 112 for determinations of coincidence with a flank marker detection zone (not depicted) defined further away from the first flank 162. For example, a greater weighting and/or an amplification may be given to measurement values from the third magnetic sensor 113 (only depicted in FIG. 2B and FIG. 2C) and the fourth magnetic sensor 114 (only depicted in FIG. 2C and FIG. 2D) for determinations of coincidence with a flank marker detection zone (not depicted) defined further away from the second flank 167. For example, a greater weighting and/or an amplification may be given to measurement values from the first magnetic sensor 111 and the third magnetic sensor 113 (only depicted in FIG. 2B and FIG. 2C) for determinations of coincidence with a distal marker detection zone (not depicted) defined further away from the distal end 160. For example, a greater weighting and/or an amplification may be given to measurement values from the second magnetic sensor 112 and the fourth magnetic sensor 114 (only depicted in FIG. 2C and FIG. 2D) for determinations of coincidence with a proximal marker detection zone (not depicted) defined further away from the proximal end 165

FIG. 2B schematically depicts a magnetic field probe configuration for the second embodiment of the magnetic probe 102 (second magnetic probe 102). The second magnetic probe 102 comprises a distal end 160, suitable for being disposed proximate to an animal or human body, wherein a first magnetic sensor 111 is arranged close to the distal end 160, and the first magnetic sensor 111 is disposed along a first probe transverse axis or plane 181. The second magnetic probe 102 comprises a second magnetic sensor 112, disposed along a second probe transverse axis or plane 182, and the second magnetic sensor 112 is disposed between the first magnetic sensor 111 and a proximal end 165. In the example depicted in FIG. 2B, the first magnetic sensor 111 is arranged close to the proximal end 165. The second magnetic probe 102 comprises a first flank 162 and comprises a second flank 167. The second magnetic probe 102 depicted in FIG. 2B is the same as the first magnetic probe 101 depicted in FIG. 2A, except for the differences al to a5: al) the first magnetic sensor 111 is disposed along the second probe longitudinal axis or plane 152, and the second magnetic sensor 112 is also disposed along the second probe longitudinal axis or plane 152. a2) the second magnetic probe 102 comprises a third magnetic sensor 113, disposed along the first probe transverse axis 181. The third magnetic sensor 113 is disposed along the third probe longitudinal axis or plane 153. The third magnetic sensor 113 is arranged to determine, in use, one or more magnetic field vectors of a local magnetic field (Bx, By, Bz) generated by the implantable marker 200 in use. These properties may be used by a software algorithm to determine one or more dispositions. a3) no magnetic sensors are physically disposed along the first longitudinal axis or plane 151. a4) a 2D sensor array of at least three magnetic sensors 111, 112, 113 may be used. a5) optionally, the processor may be arranged to determine one or more dispositions of the implantable marker 200 with respect to a magnetic probe reference (not depicted) comprising one or more virtual positions along the first probe longitudinal axis or plane 151. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along a second probe longitudinal axis or plane 152. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along a third probe longitudinal axis or plane 153. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along the first probe transverse (or radial) axis or plane 181. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along the second probe transverse (or radial) axis or plane 182.

In the example depicted in FIG. 2B, the first magnetic sensor 111 of FIG. 2B is arranged to provide the same functionality as described above for the first magnetic sensor 111 of FIG. 1 and FIG. 2A , the second magnetic sensor 112 of FIG. 2B is arranged to provide the same functionality as described above for the second magnetic sensor of FIG. 1 and FIG. 2A, and the third magnetic sensor 113 is arranged to provide measurement values to the processor for determining, in use, if the angular disposition and/or distance coincides with one or more marker detection zones of interest (not depicted).

FIG. 2C schematically depicts a magnetic field probe configuration for the third embodiment of the magnetic probe 103 (third magnetic probe 103). The third magnetic probe 103 comprises a distal end 160, suitable for being disposed proximate to an animal or human body, wherein a first magnetic sensor 111 is arranged close to the distal end 160, and the first magnetic sensor 111 is disposed along a first probe transverse axis or plane 181. The third magnetic probe 103 comprises a second magnetic sensor 112, disposed along a second probe transverse axis or plane 182, and the second magnetic sensor 112 is disposed between the first magnetic sensor 111 and a proximal end 165. In the example depicted in FIG. 2C, the first magnetic sensor 111 is arranged close to the proximal end 165. The third magnetic probe 103 comprises a first flank 162 and comprises a second flank 167.

The third magnetic probe 103 depicted in FIG. 2C is the same as the first magnetic probe 101 depicted in FIG. 2 A, except for the differences bl to b6: bl) the first magnetic sensor 111 is disposed along the second probe longitudinal axis or plane 152, and the second magnetic sensor 112 is also disposed along the second probe longitudinal axis or plane 152. b2) the third magnetic probe 103 comprises a third magnetic sensor 113, disposed along the first probe transverse axis 181. The third magnetic sensor 113 is disposed along the third probe longitudinal axis or plane 153. The third magnetic sensor 113 is arranged to determine, in use, one or more magnetic field vectors of a local magnetic field (Bx, By, Bz) generated by the implantable marker 200 in use. These properties may be used by a software algorithm to determine one or more dispositions. b3) the third magnetic probe 103 comprises a fourth magnetic sensor 114, disposed along the second probe transverse axis 182. The fourth magnetic sensor 114 is disposed along the third probe longitudinal axis or plane 153. The fourth magnetic sensor 114 is arranged to determine, in use, one or more magnetic field vectors of a local magnetic field (Bx, By, Bz) generated by the implantable marker 200 in use. These properties may be used by a software algorithm to determine one or more dispositions. b4) no magnetic sensors are physically disposed along the first longitudinal axis or plane 151. b5) a 2D sensor array of at least four magnetic sensors 111, 112, 113, 114 may be used. b6) optionally, the processor may be arranged to determine one or more dispositions of the implantable marker 200 with respect to a magnetic probe reference (not depicted) comprising one or more virtual positions along the first probe longitudinal axis or plane 151. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along a second probe longitudinal axis or plane 152. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along a third probe longitudinal axis or plane 153. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along the first probe transverse (or radial) axis or plane 181. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along the second probe transverse (or radial) axis or plane 182.

In the example depicted in FIG. 2C, the first magnetic sensor 111 of FIG. 2D is arranged to provide the same functionality as described above for the first magnetic sensor 111 of FIG. 1 and FIG. 2 A , the second magnetic sensor 112 of FIG. 2C is arranged to provide the same functionality as described above for the second magnetic sensor of FIG. 1 and FIG. 2A, and the third magnetic sensor 113 and the fourth magnetic sensor 114 are arranged to provide measurement values to the processor for determining, in use, if the angular disposition and/or distance coincides with one or more marker detection zones of interest (not depicted).

FIG. 2D schematically depicts a magnetic field probe configuration for the fourth embodiment of the magnetic probe 104 (fourth magnetic probe 104). The fourth magnetic probe 104 comprises a distal end 160, suitable for being disposed proximate to an animal or human body, wherein a first magnetic sensor 111 is arranged close to the distal end 160, and the first magnetic sensor 111 is disposed along a first probe transverse axis or plane 181. The fourth magnetic probe 104 comprises a second magnetic sensor 112, disposed along a second probe transverse axis or plane 182, and the second magnetic sensor 112 is disposed between the first magnetic sensor 111 and a proximal end 165. In the example depicted in FIG. 2D, the first magnetic sensor 111 is arranged close to the proximal end 165. The third magnetic probe 103 comprises a first flank 162 and comprises a second flank 167.

The fourth magnetic probe 104 depicted in FIG. 2D is the same as the first magnetic probe 101 depicted in FIG. 2 A, except for the differences cl to c5: cl) the first magnetic sensor 111 is disposed along the second probe longitudinal axis or plane 152, and the second magnetic sensor 112 is also disposed along the second probe longitudinal axis or plane 152. c2) the fourth magnetic probe 104 comprises a third magnetic sensor 113, disposed along the first probe transverse axis 181. The fourth magnetic sensor 114 is disposed along the third probe longitudinal axis or plane 153. The third magnetic sensor 113 is arranged to determine, in use, one or more magnetic field vectors of a local magnetic field (Bx, By, Bz) generated by the implantable marker 200 in use. These properties may be used by a software algorithm to determine one or more dispositions. c3) no magnetic sensors are physically disposed along the first longitudinal axis or plane 151. c4) a 2D sensor array of at least three magnetic sensors 111, 112, 113 may be used. c5) optionally, the processor may be arranged to determine one or more dispositions of the implantable marker 200 with respect to a magnetic probe reference (not depicted) comprising one or more virtual positions along the first probe longitudinal axis or plane 151. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along a second probe longitudinal axis or plane 152. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along a third probe longitudinal axis or plane 153. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along the first probe transverse (or radial) axis or plane 181. Additionally or alternatively, by applying one or more suitable offsets, the magnetic probe reference (not depicted) may comprise one or more virtual positions along the second probe transverse (or radial) axis or plane 182.

In the example depicted in FIG. 2D, the first magnetic sensor 111 of FIG. 2D is arranged to provide the same functionality as described above for the first magnetic sensor 111 of FIG. 1 and FIG. 2 A , the second magnetic sensor 112 of FIG. 2B is arranged to provide the same functionality as described above for the second magnetic sensor of FIG. 1 and FIG. 2A, and the fourth magnetic sensor 114 is arranged to provide measurement values to the processor for determining, in use, if the angular disposition and/or distance coincides with one or more marker detection zones of interest (not depicted).

A further advantage of providing a software-configurable detection zone is that two or more marker detection zones may be arranged, with differing extents, different shapes, different angular boundaries, different longitudinal extents, different transverse extents, and any combination thereof. These two or more marker detection zones may share one or more boundaries, be contiguous along one or more axes, be non-contiguous along one or more axes, or any combination thereof.

FIG. 5 A to FIG. 5B depict schematic top-views of magnetic field probes with a display, an enlargement of one or more portions of the display, and a schematic longitudinal crosssection through a marker detection zone according to this disclosure.

In the examples depicted in FIG. 5Ato FIG. 5B, the magnetic field probe 101, 102, 103, 104 is provided with a probe display 130 having a distance value display 132. The magnetic field probe 101, 102, 103, 104 is arranged to define a distal marker detection zone 190, extending more distally away from a probe distal transverse axis or plane 181 along a probe longitudinal axis or plane 151, 152, 153. The magnetic field probe 101, 102, 103, 104 is arranged to determine and display one or more distance values 132 to the implantable marker 200. Therefore, in the examples depicted in FIG. 5 A to FIG. 5B, the magnetic field probe 101, 102, 103, 104 is arranged to detect only in a forward (or more distal) direction (forward-looking), and arranged only to determine and display a distance value 132 to the implantable marker 200.

In the example depicted in FIG. 5A, the implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the distal marker detection zone 190, and a distance value 132 to the marker of "20" is determined and displayed 132. In the example depicted in FIG. 5B, the implantable marker 200 is at the same distance from the magnetic probe as in the example depicted in FIG. 5 A. In the example depicted in FIG. 5B, the implantable marker 200 is not determined by the magnetic field probe 101, 102, 103, 104 to fall within the distal marker detection zone 190, so no meaningful distance value 132 to the marker can be determined, and is displayed 132. The examples depicted in FIG. 5 A to FIG. 5B may only provide the user with distance values 132 when the implantable marker 200 is positioned more distally (more forward) to the magnetic field probe.

FIG. 6A to FIG. 6B depict examples of magnetic field probes that may provide a more intuitive visual feedback to a user about how to find the implantable marker 200. FIG. 6A to FIG. 6B depict schematic top-views of magnetic field probes with a display, an enlargement of one or more portions of the display, and schematic longitudinal crosssections through one or more marker detection zones according to this disclosure. All embodiments of magnetic field probes disclosed herein may be arranged to define the one or more marker detection zones as depicted in FIG. 6Ato FIG. 6B. The one or more marker detection zones 190, 192, 194, 196 depicted in FIG. 6 A to FIG. 6B are functionally the same as the one or more marker detection zones as depicted in FIG. 3. If required, different shapes, different extents and/or different symmetries may be defined for the marker detection zones 190, 192, 194, 196 depicted in FIG. 6 A to FIG. 6B.

In the examples depicted in FIG. 6Ato FIG. 6B, the magnetic field probe 101, 102, 103, 104 is provided with a probe display 130, wherein the probe display 130 comprises an optional distance value display 132 and an optional detection zone display 137. The probe display 130 is provided on a "top-surface" of the magnetic field probe 101, 102, 103, 104 lying in a plane comprising an X-axis 600 and a Y-axis 700 (an X-Y 600, 700 plane). The magnetic field probe 101, 102, 103, 104 extends from a probe distal transverse (or radial) axis or plane 181 to a probe proximal transverse (or radial) axis or plane 182. Optionally, the probe display 130 may be arranged at an angle to the "top-surface" of the magnetic field probe 101, 102, 103, 104 to provide an improved visibility for a user, for example in an "angled-back" configuration.

The magnetic field probe 101, 102, 103, 104 is arranged to define one or more distal marker detection zones 190, extending more distally away from the probe distal transverse axis or plane 181 of the magnetic field probe 101, 102, 103, 104 along a probe longitudinal axis or plane 151, 152, 153. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to define one or more first flank marker detection zones 192 and/or to define one or more second flank marker detection zones 194. The one or more flank marker detection zones 192, 194 extend from the first probe transverse axis or plane 181 to the second probe transverse axis or plane 182, extending more transversely and/or more radially away from a probe longitudinal axis or plane 151, 152, 153. Although the cross-sections depicted in FIG. 6Ato FIG. 6B for the one or more first flank marker detection zones 192 and for the one or more second flank marker detection zones 194 are substantially the same shape with similar extents, this is not essential. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to define one or more proximal marker detection zones 196, extending more proximally away from the probe proximal transverse axis or plane 182 of the magnetic field probe 101, 102, 103, 104 along the probe longitudinal axis or plane 151, 152, 153. In the examples depicted in FIG. 6Ato FIG. 6B, the magnetic field probe 101, 102, 103, 104 is arranged to determine, in use, one or more magnetic field vectors of the implantable marker 200, and is arranged to determine and display one or more distance values 132 to the implantable marker 200 with reference to a magnetic probe reference 121 comprising one or more physical and/or virtual positions at the intersection of the probe longitudinal axis or plane 151, 152, 153 and of the probe distal transverse axis or plane 181.

In the examples depicted in FIG. 6 A to FIG. 6B, the magnetic field probe 101, 102, 103, 104 is arranged to detect in a forward (or more distal) direction (forward-looking), arranged to detect in a side (or more flank) direction (side looking), arranged to determine and display 137 the detection zone 190, 192, 194 where the implantable marker 200 is detected, and arranged to determine and display a distance value 132 to the implantable marker 200. The magnetic field probe 101, 102, 103, 104 may optionally also be arranged not to detect in a forward (or more distal) direction (forward-looking). The magnetic field probe 101, 102, 103, 104 may optionally also be arranged to detect in a backward (or more proximal) direction (backward-looking) if one or more proximal marker detection zones 196 are defined. The magnetic field probe 101, 102, 103, 104 is arranged to be held by a hand of a user (not depicted). The one or more active marker detection zones 190, 192, 194, 196 and the display 130 are therefore arranged to provide a user with visual feedback about how to find the implantable marker 200.

In the example depicted in FIG. 6A, the implantable marker 200 is at a particular distance from the magnetic probe reference 121. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more distal marker detection zones 190, and a distance value 132 to the marker of "20" is determined and displayed on the distance value display 132. In addition, a detection in the one or more distal marker detection zones 190 is indicated in the detection zone display 137 by modifying a visual aspect, such as a fill pattern, of a corresponding display region. In the example depicted in FIG. 6B, the implantable marker 200 is at the same distance from the magnetic probe reference 121 as in the example depicted in FIG. 6 A. In the example depicted in FIG. 6B, the implantable marker 200 is not determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more distal marker detection zones 190. However, in the example depicted in FIG. 6B, the implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more first flank marker detection zones 192, and a distance value 132 to the marker of "20" is determined and displayed on the distance value display 132. In addition, a detection in one or more first flank marker detection zones 192 is indicated in the detection zone display 137 by modifying a visual aspect, such as a fill pattern, of a corresponding display region.

Optionally, it may be advantageous to arrange the magnetic field probe 101, 102, 103, 104 to only detect in one or more flank marker detection zones 192, 194. Optionally, it may be advantageous to arrange the magnetic field probe 101, 102, 103, 104 to only detect in one or more flank marker detection zones 192, 194 extending away from one flank of the magnetic field probe 101, 102, 103, 104 (single-sided detection). Optionally, it may be advantageous to arrange the magnetic field probe 101, 102, 103, 104 to only detect in one or more proximal marker detection zones 196. Optionally, it may be advantageous to arrange the magnetic field probe 101, 102, 103, 104 to only detect in the combination of one or more flank marker detection zones 192, 194 and one or more proximal marker detection zones 196.

Optionally, it may be advantageous to arrange the magnetic field probe 101, 102, 103, 104 to indicate a detection close to a boundary of one or more marker detection zones 190, 192, 194, 196 by modifying a visual aspect of one or more non-corresponding display regions 137, such as an adjacent display region 137. Optionally, it may be advantageous to arrange the magnetic field probe 101, 102, 103, 104 to indicate a detection in one or more marker detection zones 190, 192, 194, 196 by modifying a visual aspect of a corresponding display region and one or more non-corresponding display regions 137, such as one or more adjacent display regions 137 and/or one or more opposite display regions 137. For example, it may be advantageous to indicate 137 to a user a detection in one or more first flank marker detection zones 192 as a detection in all first flank marker detection zones 192, a detection in one or more second flank marker detection zones 194 as a detection in all second flank marker detection zones 194, or a detection in one or more flank marker detection zones 192, 194 as a detection in all flank marker detection zones 192, 194. For example, it may be advantageous to indicate 137 to a user a detection in a flank marker detection zone 192, 194 or a detection in a proximal detection zone 196 as a detection in all flank marker detection zones 192, 194 and in all proximal detection zones 196.

The examples depicted in FIG. 6Ato FIG. 6B may provide the user with distance values 132 when the implantable marker 200 is positioned more distally (more forward) or more flanking to the magnetic field probe. Although one or more relevant detection zones 190, 192, 194, 196 are indicated on the detection zone display 137, no information is provided about where the implantable marker 200 is positioned in the one or more relevant detection zones 190, 192, 194, 196.

FIG. 7Ato FIG. 7E depict examples of magnetic field probes that may provide a more intuitive visual feedback to a user about how to find the implantable marker 200. FIG. 7A to FIG. 7E7D depict schematic top-views of magnetic field probes with a display, an enlargement of one or more portions of the display, and schematic longitudinal crosssections through one or more marker detection zones according to this disclosure. All embodiments of magnetic field probes disclosed herein may be arranged to define the one or more marker detection zones as depicted in FIG. 7A to FIG. 7E. The marker detection zones 190, 192, 194, 196 depicted are functionally the same as those depicted in FIG. 6 A to 6B. If required, different shapes, different extents and/or different symmetries may be defined for the marker detection zones 190, 192, 194, 196 depicted in FIG. 7Ato FIG. 7E. In the examples depicted in FIG. 7 A to FIG. 7E, the magnetic field probe 101, 102, 103, 104 is provided with a probe display 130, wherein the probe display 130 comprises an optional distance value display 132, an optional central alignment display 134, an optional depth direction display 135, and an optional direction display 136. The probe display 130 is provided on a "top-surface" of the magnetic field probe 101, 102, 103, 104. The magnetic field probe 101, 102, 103, 104 extends from a probe distal transverse (or radial) axis or plane 181 to a probe proximal transverse (or radial) axis or plane 182. In the examples depicted in FIG. 7 A to FIG. 7E, the magnetic field probe 101, 102, 103, 104 is arranged to define one or more distal marker detection zones 190. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to define one or more flank marker detection zones 192, 194. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to define one or more proximal marker detection zones 196.

In the examples depicted in FIG. 7 A to FIG. 7E, the magnetic field probe 101, 102, 103, 104 is arranged to determine and display one or more distance values 132 to the implantable marker 200 with reference to a first magnetic probe reference 121 comprising one or more virtual positions at the intersection of the probe longitudinal axis or plane 151, 152, 153 and of the probe distal transverse axis or plane 181. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to determine and display one or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to determine and display one or more depth directions 135 to the implantable marker 200 with reference to a magnetic probe reference.

In the context of this disclosure, depth may be used in general to describe one or more distances between the implantable marker 200 with respect to a magnetic probe reference comprising: one or more physical and/or virtual positions along an axis or plane passing through a distal end, one or more physical and/or virtual positions along an axis or plane passing through a proximal end, one or more virtual positions along a probe transverse axis or plane 181, 182, or any combination thereof. In the examples depicted in FIG. 7A to FIG. 7E, depth is used in used to describe one or more distances between the implantable marker 200 with respect to a second magnetic probe reference 122 comprising one or more virtual positions along the probe distal transverse axis or plane 181. The probe distal transverse axis or plane 181 may be arranged close to or at the which is arranged close to the distal end of the magnetic probe 101, 102, 103, 104.

In the context of this disclosure, depth direction may be used in general to describe a direction that a magnetic probe reference must be moved to get closer to the implantable marker 200. In the examples depicted in FIG. 7Ato FIG. 7E, depth direction is used to describe a direction that the second magnetic probe reference 122, arranged close to the distal end, must be moved along a probe longitudinal axis or plane 151, 152, 153 to get closer to the implantable marker 200. In the examples depicted in FIG. 4, FIG. 7A to 7E, and FIG. 8 A to 8B, a "+" depth direction is chosen to indicate that the second magnetic probe reference 122, arranged close to the distal end, needs to be moved more forward (as depicted in the negative Y direction 700) to get closer to the implantable marker 200. A depth direction is chosen to indicate that the second magnetic probe reference 122, arranged close to the distal end, needs to be moved more backward (as depicted in the positive Y direction 700) to get closer to the implantable marker 200.

When using conventional magnetic field probes arranged only to detect in a forward (or more distal) direction, the only way to gain information about a location of the implantable marker 200 is to orient a probe longitudinal axis or plane 151, 152, 153 in an estimated direction of the implantable marker 200. With some trial and error, and frequent changes in orientation, it may be possible to determine one or more extents of the implantable marker 200.

By detecting in a flank (or more transverse or more radial) direction, depth distance and/or depth direction may be indicated, providing a more intuitive magnetic probe for finding markers 200, particularly in situations where the second magnetic probe reference 122 has passed the magnetic marker 200 as depicted in FIG. 7D and FIG. 7E. Additionally, it may be advantageous for a user to be able to determine a posterior limit of tissue to be treated by deliberately passing the magnetic marker 200 by a distance equal to an expected extent of the tissue to be treated, as depicted in FIG. 7E.

For example, when determining how and where to make an excision, surgeons aim to remove a tumor in its entirety, leaving no tumorous cells in the body, by removing a cylinder or a sphere of tissue. A center of the sphere or cylinder may be determined using a forward (or more distal) detection, and the information may be used to make a first part of the excision. However, conventional magnetic field probes arranged only to detect in a forward (or more distal) direction provide little assistance to determine one or more posterior extents. By detecting in a flank (or more transverse or more radial) direction, depth distance and/or depth direction may be indicated, allowing the surgeon to deliberately pass the implantable marker 200 as much as is needed, but to not go further than an expected tumor extent.

For example, when using conventional magnetic field probes arranged only to detect in a forward (or more distal) direction inside a deep cavity, it may be necessary for the surgeon to pull a semi-finished specimen out of the body cavity and measuring from the side by scanning using a forward-looking technology, and then guessing the extent of the tumor beyond that location. In practice, the types of tissues treated are often highly flexible, so pulling the tissue and performing a reading might not necessarily correlate with the actual seed location when back inside the cavity. This may result in excising too little tissue or too much healthy tissue, which are both unwanted.

By detecting in a flank (or more transverse or more radial) direction, depth distance and/or depth direction may be indicated, allowing the surgeon to deliberately pass the implantable marker 200, as depicted in FIG. 7E, with the tissue still within the body cavity to provide the most accurate representation of the tissue during excision, which is with no significant force exerted on it. Optionally, the depth value display 133 may be arranged to display the one or more depth distances in millimeters, providing an accurate millimeter-gauge to better determine posterior margins of the tissue to be excised.

In the examples depicted in FIG. 7 A to FIG. 7E, the magnetic field probe 101, 102, 103, 104 is arranged to detect in a forward (or more distal) direction (forward-looking), arranged to detect in a side (or more flank) direction (side looking), arranged to determine and display 136 a direction to where the implantable marker 200 is detected, arranged to determine and display 135 a depth direction to where the implantable marker 200 is detected, and arranged to determine and display a distance value 132 to the implantable marker 200. The magnetic field probe 101, 102, 103, 104 may optionally also be arranged not to detect in a forward (or more distal) direction (forward-looking). The magnetic field probe 101, 102, 103, 104 may optionally also be arranged to detect in a backward (or more proximal) direction (backward-looking) if one or more proximal marker detection zones 196 are defined.

In the examples depicted in FIG. 7 A to FIG. 7E, the magnetic field probe 101, 102, 103, 104 is arranged to be held by a hand of a user (not depicted). The one or more active marker detection zones 190, 192, 194, 196 and the display 130 are therefore arranged to provide a user with visual feedback about how to find the implantable marker 200. In the example depicted in FIG. 7A, the implantable marker 200 is at a first particular distance from the first magnetic probe reference 121. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more distal marker detection zones 190, and a distance value 132 to the marker of "20" is determined and displayed on the distance value display 132. One or more depth directions 135 to the implantable marker 200 from the second magnetic probe reference 122 are determined and displayed on the depth direction display 135 by modifying a visual aspect, such as a indicating a "+" to correspond to the magnetic marker 200 being detected more distally than the second magnetic probe reference 122. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to coincide to a high degree with the probe longitudinal axis or plane 151, 152, 153. Therefore, a detection along the probe longitudinal axis or plane 151, 152, 153 is indicated in the central alignment display 134 by modifying a visual aspect, such as three concentric circles and a cross-hair, in a corresponding display region. The implantable marker 200 is at a particular direction from the first magnetic probe reference 121. One or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121 are determined and displayed on the direction display 136 by modifying a visual aspect, such as an orientation of a pointer.

In the example depicted in FIG. 7B, the implantable marker 200 is at a second particular distance from the first magnetic probe reference 121. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more distal marker detection zones 190, and a distance value 132 to the marker of "22" is determined and displayed on the distance value display 132. One or more depth directions 135 to the implantable marker 200 from the second magnetic probe reference 122 are determined and displayed on the depth direction display 135 by modifying a visual aspect, such as a indicating a "+" to correspond to the magnetic marker 200 being detected more distally than the second magnetic probe reference 122. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to coincide to a medium degree with the probe longitudinal axis or plane 151, 152, 153. Therefore, a detection close to the probe longitudinal axis or plane 151, 152, 153 is indicated in the central alignment display 134 by modifying a visual aspect, such as three concentric circles without a cross-hair, in a corresponding display region. The implantable marker 200 is at a particular direction from the first magnetic probe reference 121. One or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121 are determined and displayed on the direction display 136 by modifying a visual aspect, such as an orientation of a pointer.

In the example depicted in FIG. 7C, the implantable marker 200 is at a third particular distance from the first magnetic probe reference 121 and more distally than the second magnetic probe reference 122. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more distal marker detection zones 190, and a distance value 132 to the marker of "27" is determined and displayed on the distance value display 132. One or more depth directions 135 to the implantable marker 200 from the second magnetic probe reference 122 are determined and displayed on the depth direction display 135 by modifying a visual aspect, such as a indicating a "+" because the depth is more distal. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to coincide to a low degree with the probe longitudinal axis or plane 151, 152, 153. Therefore, a detection away from the probe longitudinal axis or plane 151, 152, 153 is indicated in the central alignment display 134 by modifying a visual aspect, such as two concentric circles without a third concentric circle and without a cross-hair, in a corresponding display region. The implantable marker 200 is at a particular direction from the first magnetic probe reference 121. One or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121 are determined and displayed on the direction display 136 by modifying a visual aspect, such as an orientation of a pointer.

In the example depicted in FIG. 7D, the implantable marker 200 is at the second particular distance from the first magnetic probe reference 121, which is the same distance in the example depicted in FIG. 7B. In the example depicted in FIG. 7D, the implantable marker 200 is more proximally (or less distally) than the second magnetic probe reference 122. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more first flank marker detection zones 192, and a distance value 132 to the marker of "22" is determined and displayed on the distance value display 132. One or more depth directions 135 to the implantable marker 200 from the second magnetic probe reference 122 are determined and displayed on the depth direction display 135 by modifying a visual aspect, such as a indicating a

because the depth is more proximal (or less distal). The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to coincide to a low degree with the probe longitudinal axis or plane 151, 152, 153. Therefore, a detection away from the probe longitudinal axis or plane 151, 152, 153 is indicated in the central alignment display 134 by modifying a visual aspect, such as a circle without concentric circles and without a cross-hair, in a corresponding display region. The implantable marker 200 is at a particular direction from the first magnetic probe reference 121. One or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121 are determined and displayed on the direction display 136 by modifying a visual aspect, such as an orientation of a pointer.

In the example depicted in FIG. 7E, the implantable marker 200 is at a fourth particular distance from the first magnetic probe reference 121, and more proximally (or less distally) than the second magnetic probe reference 122. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more first flank marker detection zones 192, and a distance value 132 to the marker of "55" is determined and displayed on the distance value display 132. One or more depth directions 135 to the implantable marker 200 from the second magnetic probe reference 122 are determined and displayed on the depth direction display 135 by modifying a visual aspect, such as a indicating a because the depth is more proximal (or less distal). The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to coincide to a low degree with the probe longitudinal axis or plane 151, 152, 153. Therefore, a detection away from the probe longitudinal axis or plane 151, 152, 153 is indicated in the central alignment display 134 by modifying a visual aspect, such as two concentric circles without a third concentric circle and without a cross-hair, in a corresponding display region. The implantable marker 200 is at a particular direction from the first magnetic probe reference 121. One or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121 are determined and displayed on the direction display 136 by modifying a visual aspect, such as an orientation of a pointer.

FIG. 8 A to FIG. 8B depict examples of magnetic field probes that may provide a more intuitive visual feedback to a user about how to find the implantable marker 200. FIG. 8A to FIG. 8B depict schematic top-views of magnetic field probes with a display, an enlargement of one or more portions of the display, and schematic longitudinal crosssections through marker detection zones according to this disclosure. All embodiments of magnetic field probes disclosed herein may be arranged to define the one or more marker detection zones as depicted in FIG. 8Ato FIG. 8B. The marker detection zones 190, 192, 194, 196 depicted are functionally the same as those depicted in FIG. 6Ato 6B. Details that are less relevant for explaining the displays have been omitted from the examples depicted in the examples of FIG. 8Ato FIG. 8B. If required, different shapes, different extents and/or different symmetries may be defined for the marker detection zones 190, 192, 194, 196 depicted in FIG. 8 A to FIG. 8B.In the examples depicted in FIG. 8 A to FIG. 8B, the magnetic field probe 101, 102, 103, 104 is provided with a probe display 130, wherein the probe display 130 comprises an optional distance value display 132, an optional central alignment display 134, an optional depth direction display 135, an optional depth value display 133 and an optional direction display 136.

In the examples depicted in FIG. 8Ato FIG. 8B, the magnetic field probe 101, 102, 103, 104 is arranged to define one or more distal marker detection zones 190. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to define one or more flank marker detection zones 192, 194. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to define one or more proximal marker detection zones 196.

In the examples depicted in FIG. 8Ato FIG. 8B, the magnetic field probe 101, 102, 103, 104 is arranged to determine and display one or more distance values 132 to the implantable marker 200 with reference to a first magnetic probe reference 121 comprising one or more virtual positions at the intersection of the probe longitudinal axis or plane 151, 152, 153 and of the probe distal transverse axis or plane 181. The magnetic field probe 101, 102, 103, 104 is further arranged to determine and display one or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121. The magnetic field probe 101, 102, 103, 104 is further arranged to determine and display one or more depth values 135 to the implantable marker 200 from a second magnetic probe reference 122 comprising one or more virtual positions along the probe distal transverse axis or plane 181. The magnetic field probe 101, 102, 103, 104 is further arranged to determine and display one or more depth directions 135 to the implantable marker 200 with reference to the second magnetic probe reference 122.

In the examples depicted in FIG. 8Ato FIG. 8B, the magnetic field probe 101, 102, 103, 104 is arranged to detect in a forward (or more distal) direction (forward-looking), arranged to detect in a side (or more flank) direction (side looking), arranged to determine and display 136 a direction to where the implantable marker 200 is detected, arranged to determine and display 135 a depth direction to where the implantable marker 200 is detected, arranged to determine and display a distance value 132 to the implantable marker 200, and arranged to determine and display a depth value 133 to the implantable marker 200. The magnetic field probe 101, 102, 103, 104 may optionally also be arranged not to detect in a forward (or more distal) direction (forward-looking). The magnetic field probe 101, 102, 103, 104 may optionally also be arranged to detect in a backward (or more proximal) direction (backward-looking) if one or more proximal marker detection zones 196 are defined.

In the examples depicted in FIG. 8Ato FIG. 8B, the magnetic field probe 101, 102, 103, 104 is arranged to be held by a hand of an user (not depicted). The one or more active marker detection zones 190, 192, 194, 196 and the display 130 are therefore arranged to provide a user with visual feedback about how to find the implantable marker 200. In the example depicted in FIG. 8A, the implantable marker 200 is at a first particular distance from the first magnetic probe reference 121, which is the same distance in the example depicted in FIG. 7D. In the example depicted in FIG. 8A, the implantable marker 200 is more proximally (or less distally) than the second magnetic probe reference 122. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more first flank marker detection zones 192, and a distance value 132 to the marker of "22" is determined and displayed on the distance value display 132. One or more depth values 133 from the second magnetic probe reference 122 to the implantable marker 200 are determined, and a depth value 133 to the marker of " 10" is determined and displayed on the depth value display 133. One or more depth directions 135 to the implantable marker 200 from the second magnetic probe reference 122 are determined and displayed on the depth direction display 135 by modifying a visual aspect, such as indicating a

because the depth is more proximal (or less distal). The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to coincide to a low degree with the probe longitudinal axis or plane 151, 152, 153. Therefore, a detection away from the probe longitudinal axis or plane 151, 152, 153 is indicated in the central alignment display 134 by modifying a visual aspect, such as a circle without concentric circles and without a cross-hair, in a corresponding display region. The implantable marker 200 is at a particular direction from the first magnetic probe reference 121. One or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121 are determined and displayed on the direction display 136 by modifying a visual aspect, such as an orientation of a pointer. In the example depicted in FIG. 8B, the implantable marker 200 is at a second particular distance from the first magnetic probe reference 121. In the example depicted in FIG. 8B, the implantable marker 200 is more proximally (or less distally) than the second magnetic probe reference 122. The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more first flank marker detection zones 192, and a distance value 132 to the marker of "55" is determined and displayed on the distance value display 132. One or more depth values 133 from the second magnetic probe reference 122 to the implantable marker 200 are determined, and a depth value 133 to the marker of "35" is determined and displayed on the depth value display 133. One or more depth directions 135 to the implantable marker 200 from the second magnetic probe reference 122 are determined and displayed on the depth direction display 135 by modifying a visual aspect, such as a indicating a because the depth is more proximal (or less distal). The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to coincide to a low degree with the probe longitudinal axis or plane

151, 152, 153. Therefore, a detection away from the probe longitudinal axis or plane 151,

152, 153 is indicated in the central alignment display 134 by modifying a visual aspect, such as two concentric circles without a third concentric circle and without a cross-hair, in a corresponding display region. The implantable marker 200 is at a particular direction from the first magnetic probe reference 121. One or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121 are determined and displayed on the direction display 136 by modifying a visual aspect, such as an orientation of a pointer.

FIG. 4 depicts an example of a magnetic field probe that may provide a more intuitive visual feedback to a user about how to find the implantable marker 200. FIG. 4 depicts a schematic end-view of a magnetic field probe with a display and schematic transverse cross-sections through one or more marker detection zones according to this disclosure. All the embodiments of magnetic field probes disclosed herein may be arranged to define the one or more marker detections zones as depicted in FIG. 4. If required, different shapes, different extents and/or different symmetries may be defined for the marker detection zones 192, 194 depicted in FIG. 4.

In the example depicted in FIG. 4, the magnetic field probe 101, 102, 103, 104 is provided with a probe display 130, wherein the probe display 130 comprises an optional distance value display 132, an optional central alignment display 134, an optional depth direction display 135, an optional depth value display 133 and an optional direction display 136. The probe display 130 is provided on a proximal "end-surface" 165 of the magnetic field probe 101, 102, 103, 104. lying in a plane comprising an X-axis 600 and a Z-axis 800 (an X-Z 600, 800 plane). The magnetic field probe 101, 102, 103, 104 extends from a probe distal transverse (or radial) axis or plane 181 to a probe proximal transverse (or radial) axis or plane 182. Optionally, the probe display 130 may be arranged at an angle to the proximal "end-surface" 165 to provide an improved visibility for a user, for example in an "angled-up" configuration.

In the example depicted in FIG. 4, the magnetic field probe 101, 102, 103, 104 is arranged to define one or more first flank marker detection zones 192 and/or to define one or more second flank marker detection zones 194. The one or more flank marker detection zones 192, 194 extend from the first probe transverse axis or plane 181 to the second probe transverse axis or plane 182, extending more transversely and/or more radially away from a probe longitudinal axis or plane 151, 152, 153. Although the crosssections depicted in FIG. 4 for the one or more first flank marker detection zones 192 and for the one or more second flank marker detection zones 194 are substantially the same shape with similar extents, this is not essential

Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to define one or more distal marker detection zones (not depicted), extending more distally away from the probe distal transverse axis or plane 181 of the magnetic field probe 101, 102, 103, 104 along a probe longitudinal axis or plane 151, 152, 153. Additionally or alternatively, the magnetic field probe 101, 102, 103, 104 may be arranged to define one or more proximal marker detection zones (not depicted), extending more proximally away from the probe proximal transverse axis or plane 182 of the magnetic field probe 101, 102, 103, 104 along the probe longitudinal axis or plane 151, 152, 153.

In the example depicted in FIG. 4, the magnetic field probe 101, 102, 103, 104 is arranged to determine and display one or more distance values 132 to the implantable marker 200 with reference to a first magnetic probe reference (not depicted) comprising one or more virtual positions at the intersection of the probe longitudinal axis or plane 151, 152, 153 and of the probe distal transverse axis or plane 181. The magnetic field probe 101, 102, 103, 104 is further arranged to determine and display one or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference (not depicted). The magnetic field probe 101, 102, 103, 104 is further arranged to determine and display one or more depth directions 135 to the implantable marker 200 with reference to a second magnetic probe reference (not depicted) comprising one or more virtual positions along the probe distal transverse axis or plane 181. The magnetic field probe 101, 102, 103, 104 is further arranged to determine and display one or more depth values 135 to the implantable marker 200 from the second magnetic probe reference (not depicted).

In the examples depicted in FIG. 4, the magnetic field probe 101, 102, 103, 104 is arranged to detect in a side (or more flank) direction (side looking), arranged to determine and display 136 a direction to where the implantable marker 200 is detected, arranged to determine and display 135 a depth direction to where the implantable marker 200 is detected, arranged to determine and display a distance value 132 to the implantable marker 200, and arranged to determine and display a depth value 133 to the implantable marker 200. The magnetic field probe 101, 102, 103, 104 may optionally also be arranged not to detect in a forward (or more distal) direction (forward-looking). The magnetic field probe 101, 102, 103, 104 may optionally also be arranged to detect in a backward (or more proximal) direction (backward-looking) if one or more proximal marker detection zones 196 are defined.

In the example depicted in FIG. 4, the magnetic field probe 101, 102, 103, 104 is arranged to be held by a hand of an user (not depicted). The marker detection zones 192, 194 and the display 130 are therefore arranged to provide a user with visual feedback about how to find the implantable marker 200.

In the example depicted in FIG. 4, the implantable marker 200 is at a first particular distance from the first magnetic probe reference (not depicted). The implantable marker 200 is more proximally (or less distally) than the second magnetic probe reference (not depicted). The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to fall within the one or more first flank marker detection zones 192, and a distance value 132 to the marker of "22" is determined and displayed on the distance value display 132. One or more depth values 133 from the second magnetic probe reference (not depicted) to the implantable marker 200 are determined, and a depth value 133 to the marker of "10" is determined and displayed on the depth value display 133. One or more depth directions 135 to the implantable marker 200 from the second magnetic probe reference (not depicted) are determined and displayed on the depth direction display 135 by modifying a visual aspect, such as indicating a because the depth is more proximal (or less distal). The implantable marker 200 is determined by the magnetic field probe 101, 102, 103, 104 to coincide to a low degree with the probe longitudinal axis or plane 151, 152, 153. Therefore, a detection away from the probe longitudinal axis or plane 151, 152, 153 is indicated in the central alignment display 134 by modifying a visual aspect, such as a circle without concentric circles and without a cross-hair, in a corresponding display region. The implantable marker 200 is at a particular direction from the first magnetic probe reference 121. One or more angular dispositions (or directions) to the implantable marker 200 from the first magnetic probe reference 121 are determined and displayed on the direction display 136 by modifying a visual aspect, such as an orientation of a pointer.

Although the present disclosure has been described in connection with specific exemplary embodiments, it should be understood that various changes, substitutions, and alterations apparent to those skilled in the art can be made to the disclosed embodiments without departing from the spirit and scope of the disclosure as set forth in the appended claims. For example, any of the magnetic field probes disclosed herein may be arranged to provide two or more distal marker detection zones as described in PCT application W02021124300A1, published on 24.06.2021, which are incorporated herein by reference. In particular, one or more of the distal marker detections zones disclosed in PCT application W02021124300A1 in the description explaining following figures: FIG. 8A and FIG. 8B, including the disclosure on page 33, line 13 to page 37, line 7, which are incorporated herein by reference.

Optionally, the magnetic field probes described herein may comprise one or more additional sensors to provide one or more measurements of one or more orientations of the magnetic field probes. For example, a pitch, roll and/or yaw angle of a magnetic field probe. For example, by using measurements from one or more IMU (inertial measurement unit) sensors and/or one or more background magnetic field sensors. These one or more orientations may also be considered when determining the disposition of the implantable marker 200 and/or when determining a configurable aspect of a detection zone. Any other inputs may similarly be used which provide one or more position information. For example, one or more optical sensors, similar to the sensor used for an optical mouse, may be comprised in a magnetic field probe as described herein, and arranged, for example, to determine one or more contact points on an outer surface of skin. It may be advantageous to modify the marker searching parameters in a way that is intuitive to the user by modifying one or more parameters or aspects associated with the one or more detection zones, such as, such as, for example, an extent, a shape, an orientation, a disposition, a scaling, a resolution, an angular boundary, a longitudinal extent, a transverse extent, and any combination thereof.

One or more configurable aspect of a detection zone may be determined automatically by the first magnetic probe based on one or more measurements from one or more sensors and/or based on one or more suitable parameters. Additionally or alternatively, the user may provide one or more parameters to influence the determination.

Additionally or alternatively, the determination may be user selectable. It is particularly intuitive to use distinct detection zones, so that the user may modify their use of the first magnetic probe - for example, larger and quicker movements may be encouraged with a more distally “further away” detection zone, and smaller and slower movements with a less distally “closer by” detection zone.

Additionally or alternatively, the user selection may determine a treatment or therapy. Additionally or alternatively, the user selection determine an invasive or non-invasive use. Additionally or alternatively, the user selection may determine use as a hand-held wand.

Additionally or alternatively, a user may choose a configuration particularly suited to, for example, the expected location of the implantable marker in the human or animal body, the expected proximity, the expected magnetic field strength, and the expected marker orientation. The one or more marker detection zones may also be arranged to adopt a certain configuration, depending on the expected (by the user) proximity and/or orientation to the implantable marker. This may also be automated to a degree, depending on the measured and/or estimated proximity and/or orientation (by the first magnetic probe). Any combination of different degrees of automation is also possible.

Additionally or alternatively, the user may also select a configuration that they have personally found to be particularly efficient for marker localization.

As the one or more marker detection zones of interest may be arranged in several dimensions, one or more of these shapes and cross-sectional shapes may be combined. Simple shapes may be used and/or complex shapes. A further advantage of providing a software-configurable detection zone is that a user may select, arrange and/or configure two or more marker detection zones. This may provide, for example, a coarse/fine marker detection zone configuration - as the distal end of the first magnetic probe gets closer to the magnetic marker, a marker detection zone with a smaller angle may further increase the accuracy and sensitivity.

Optionally, the magnetic field probes as described herein may further comprise a sound transducer, arranged to provide audio feedback, and wherein an audio characteristic of the audio feedback may be arranged by the processor to be different, depending on if one or more dispositions, coincide with one or more flank marker detection zones 192, 194. Additionally or alternatively, an audio characteristic of the audio feedback may be arranged by the processor to be different, depending on if one or more dispositions coincide with the one or more distal marker detection zones 190. Additionally or alternatively, an audio characteristic of the audio feedback may be arranged by the processor to be different, depending on if one or more dispositions coincide with the one or more proximal marker detection zones 196. For example, the audio characteristic which may be different includes a pitch, a volume, a loudness, an amplitude, a spatial location, a duration, a duration of a pause, a tone, a beep, a pause duration between beeps, a frequency, a frequency spectrum, or any combination thereof. If a magnetic field probe as described herein is arranged to define two or more detection zones, a display indication and/or an audio feedback may be different depending on whether one or more dispositions substantially coincide with one or more distal marker detection zones 190, one or more flank marker detection zones 192, 194, one or more proximal marker detection zones 196, or any combination thereof. If a magnetic field probe as described herein is arranged to define two or more detection zones, a display indication and/or an audio feedback may be different depending on whether one or more dispositions do not substantially coincide with one or more distal marker detection zones 190, one or more flank marker detection zones 192, 194, one or more proximal marker detection zones 196, or any combination thereof.

Audio feedback may be provided, for example, similar to the way distance to an object is indicated with an automobile parking sensor with different tones. For example, determining a distance-dependent and/or angular-dependent audio pitch may be provided by arranging the processor to multiply an estimated marker position with a shape of one or more marker detection zones. Alternatively, one or more regions of uncertainty may be multiplied with a shape of one or more marker detection zones. An integral, indicating a degree of belief in one or more dispositions, may be outputted as, for example, a volume of one or more tones, while a pitch of one or more tones may indicate a transverse and/or longitudinal disposition (distance). For example, an inverse relationship may be used between a pause duration between beeps, where a shorter pause indicates a higher degree of proximity (or closeness).

Additionally or alternatively, a sound transducer may be comprised in a detector unit or detector device. The one or more sound transducers may be arranged to indicate to the user one or more aspects of the audio feedback. It may be advantageous for one or more sound transducers to indicate one or more of the same aspects of the audio feedback (mirroring) and/or to indicate one or more different aspects of the audio feedback.

Optionally, a display may be comprised in one or more of the magnetic probes described herein. Additionally or alternatively, a display may be comprised in a detector unit or detector device. The one or more displays may be arranged to indicate to the user one or more results of the determination. It may be advantageous for one or more displays to indicate one or more of the same results of the determination (mirroring) and/or to indicate one or more different results of the determination. Preferably, one or more angular dispositions to the implantable marker 200 are displayed graphically. Additionally or alternatively, one or more detection zones are indicated, providing intuitive feedback. Additionally or alternatively, numbers may be displayed. Optionally, one or more distances (dispositions) may be displayed, for example, as relative values and/or absolute values using values and/or symbols. The distances (dispositions) of the implantable marker 200 may be defined and/or expressed in any convenient parameter, such as microns, millimeters or centimeters. An extent, such as a length, width, and/or thickness of a display element may be varied depending on a distance that a magnetic marker 200 is measured from a probe reference point.

A user may be particularly interested in being provided with an indication of an angular disposition between the first magnetic probe longitudinal axis or plane 151 at a distal end 160 and the implantable marker 200. This is particularly advantageous when the first magnetic probe 101 is arranged to be hand-held by being extended along the longitudinal axis or plane 151, providing an intuitive configuration to determine the direction of the implantable marker 200 relative to a distal end 160 or tip.

Angular dispositions 170 of the implantable marker 200 may be defined and/or expressed in any convenient parameter, such as degrees or radians.

It may also be advantageous to arrange the magnetic probes as described herein to determine angular dispositions 170 in one or more flank marker detection zones 192, 194. For example, by providing a magnetic field probe 101, 102, 103, 104 for determining one or more dispositions 170 to an implantable marker 200, the implantable marker 200 being arranged to generate, in use, a magnetic field, the magnetic field probe 101, 102, 103, 104 comprising: a distal end 160 suitable for being disposed proximate to an animal or human body; a first magnetic sensor 111 arranged close to the distal end 160 and disposed along a first probe transverse axis or plane 181; a second magnetic sensor 112, disposed along a second probe transverse axis or plane 182 and disposed between the first magnetic sensor 111 and a proximal end 165; wherein the first magnetic sensor 111 and the second magnetic sensor 112 are arranged to determine, in use, one or more magnetic field vectors of the implantable marker 200; and a processor, arranged to collect measurement values from the first magnetic sensor 111 and from the second magnetic sensor 112, and further arranged to determine, in use, one or more magnetic field vectors of the implantable marker 200; the processor arranged: to define one or more flank marker detection zones 192, 194, extending from the first probe transverse axis or plane 181 to the second probe transverse axis or plane 182 and extending more transversely and/or more radially away along a probe longitudinal axis or plane 151, 152, 153, wherein the probe longitudinal axis or plane 151, 152, 153 is perpendicular to the first probe transverse axis or plane 181 and perpendicular to the second probe transverse axis or plane 182; to determine one or more angular dispositions 170 and/or one or more distances to the implantable marker 200 using the one or more magnetic field vectors; to determine that the one or more angular dispositions 170 and/or one or more distances fall within the one or more flank marker detection zones 192, 194 if the angular disposition and/or distance coincides with one or more flank marker detection zones 192, 194; and to alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more angular dispositions 170 and/or one or more distances to the implantable marker 200 do not coincide with the one or more flank marker detection zones 192, 194.

Optionally, the processor of such a flank magnetic field probe may be arranged to determine one or more angular dispositions 170 and/or one or more distances to the implantable marker 200 with respect to a magnetic probe reference 121, 122 comprising one or more virtual positions along a probe longitudinal axis or plane 151, 152, 153, one or more physical and/or virtual positions along an axis or plane passing through a distal end 160, one or more physical and/or virtual positions along an axis or plane passing through a proximal end 165, one or more physical and/or virtual positions along an axis or plane passing through a flank 162, 167, one or more virtual positions along a probe transverse axis or plane 181, 182, or any combination thereof.

Optionally, such a flank magnetic probe may be arranged to define one or more proximal marker detection zones 196, extending more proximally away from the proximal end 165 of the magnetic field probe 101, 102, 103, 104 along the probe longitudinal axis or plane

151, 152, 153.

It may also be advantageous to arrange the magnetic probes as described herein to determine one or more dispositions 170 in one or more proximal marker detection zones 196. For example, by providing a magnetic field probe 101, 102, 103, 104 for determining one or more angular dispositions 170 and/or one or more distances to an implantable marker 200, the implantable marker 200 being arranged to generate, in use, a magnetic field, the magnetic field probe comprising: a distal end 160 suitable for being disposed proximate to an animal or human body; a first magnetic sensor 111 arranged close to the distal end 160 and disposed along a first probe transverse axis or plane 181; a second magnetic sensor 112, disposed along a second probe transverse axis or plane 182 and disposed between the first magnetic sensor 111 and a proximal end 165; wherein the first magnetic sensor 111 and the second magnetic sensor 112 are arranged to determine, in use, one or more magnetic field vectors of the implantable marker 200; and a processor, arranged to collect measurement values from the first magnetic sensor and from the second magnetic sensor, and arranged to determine, in use, one or more magnetic field vectors of the implantable marker; the processor being arranged: to define one or more distal marker detection zones 190, extending more distally away from the distal end 160 of the magnetic field probe 101, 102, 103, 104; to define one or more proximal marker detection zones 196, extending more proximally away from the proximal end 165 of the magnetic field probe 101, 102, 103, 104 along a probe longitudinal axis or plane 151, 152, 153, wherein the probe longitudinal axis or plane 151,

152, 153 is perpendicular to the first probe transverse axis or plane 181 and perpendicular to the second probe transverse axis or plane 182; to determine one or more angular dispositions 170 and/or one or more distances to the implantable marker 200 using the one or more magnetic field vectors; to determine that the one or more angular dispositions 170 and/or one or more distances falls within the one or more proximal marker detection zones 196 if the angular disposition and/or distance coincides with one or more proximal marker detection zones 196; and to alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more angular dispositions 170 and/or one or more distances to the implantable marker 200 do not coincide with the one or more proximal marker detection zones 196.

Optionally, the processor of such a proximal magnetic field probe may be arranged to determine one or more angular dispositions 170 and/or one or more distances to the implantable marker 200, and/or to determine one or more distances to the implantable marker 200, with respect to a magnetic probe reference 121, 122 comprising one or more virtual positions along a probe longitudinal axis or plane 151, 152, 153, one or more physical and/or virtual positions along an axis or plane passing through a distal end 160, one or more physical and/or virtual positions along an axis or plane passing through a proximal end 165, one or more physical and/or virtual positions along an axis or plane passing through a flank 162, 167, one or more virtual positions along a probe transverse axis or plane 181, 182, or any combination thereof.

Optionally, such a proximal magnetic probe may be arranged to define to define one or more distal marker detection zones 190, extending more distally away from the distal end 160 of the magnetic field probe 101, 102, 103, 104 along the probe longitudinal axis or plane 151, 152, 153.

The magnetic probes described herein may be advantageously used in a magnetic localization system designed to aid healthcare professionals to better locate areas of interest in soft tissue before invasive or non-invasive treatment. For example, to better locate soft-tissue tumors, such as breast cancer, lymph nodes, melanoma and sarcoma, before invasive or non-invasive treatment. For example, to better locate areas of interest in soft tissue before and/or during a surgical operation.

One or more of the magnetic probes described herein may be comprised in a detector unit or detector device (not shown). For example, the detector unit may be arranged as an interoperative detector unit. It will be clear to the skilled person that functionalities for determining the one or more dispositions may be implemented in the hardware and software of the magnetic probe, or the functionalities may be implemented in the hardware and software of the rest of the detector. Additionally or alternatively, the functionalities may be divided in any convenient way between the one or more magnetic probes and the rest of the detector unit.

A detector unit or detector device for one or more of the magnetic probes described may comprise one or more of the following: an optional electrical and/or mechanical connection, arranged to attach to a proximal end of a magnetic probe. It may be advantageous to make the attachment releasable. The connection may also be wireless, arranged to allow at least data transmission between the magnetic probe and the rest of the detector; a power supply to provide energy to the one or more magnetic probes; a processor, arranged to collect magnetic sensor measurement values, and to determine one or more dispositions and/or distances using an appropriate software.

REFERENCE NUMBERS USED IN DRAWINGS

101 a first embodiment of a magnetic field probe

102 a second embodiment of a magnetic field probe

103 a third embodiment of a magnetic field probe

104 a fourth embodiment of a magnetic field probe

111 a first sensor

112 a second sensor

113 a third sensor

114 a fourth sensor

121 a first magnetic probe reference

122 a second magnetic probe reference

130 a probe display

132 a distance value display

133 a depth value di spl ay

134 a central alignment display

135 a depth direction display

136 a direction display 137 a detection zone display

140 a probe housing

151 a first probe longitudinal axis or plane

152 a second probe longitudinal axis or plane

153 a third probe longitudinal axis or plane

160 a distal end of a probe

162 a first flank of a probe

165 a proximal end of a probe

167 a second flank of a probe

170 an angular disposition or angular component

181 a first probe transverse (or radial) axis or plane

182 a second probe transverse (or radial) axis or plane

190 a distal marker detection zone or plane

1190 a first extent of a distal marker detection zone in X-Y plane

2190 a second extent of a distal marker detection zone in X-Y plane

3190 a third extent of a distal marker detection zone in X-Y plane

192 a first flank marker detection zone

1192 a first extent of a first flank marker detection zone in X-Y plane

194 a second flank marker detection zone

1194 a first extent of a second flank marker detection zone in X-Y plane

196 a proximal marker detection zone

1196 a first extent of a proximal marker detection zone in X-Y plane

2196 a second extent of a proximal marker detection zone in X-Y plane

3196 a third extent of a proximal marker detection zone in X-Y plane

200 implantable (induced) magnetic marker

300 an outer surface of skin

600 X-axis

700 Y-axis

800 Z-axis

Claims

CLAIMS:

1. A magnetic field probe (101, 102, 103, 104) for determining one or more dispositions (170) to an implantable marker (200), the implantable marker (200) being arranged to generate, in use, a magnetic field, the magnetic field probe (101, 102, 103, 104) comprising: a distal end (160) suitable for being disposed proximate to an animal or human body; a first magnetic sensor (111) arranged close to the distal end (160) and disposed along a first probe transverse axis or plane (181); a second magnetic sensor (112), disposed along a second probe transverse axis or plane (182) and disposed between the first magnetic sensor (111) and a proximal end (165); wherein the first magnetic sensor (111) and the second magnetic sensor (112) are arranged to determine, in use, one or more magnetic field vectors of the implantable marker (200); and a processor, arranged to collect measurement values from the first magnetic sensor (111) and from the second magnetic sensor (112), and further arranged to determine, in use, one or more magnetic field vectors of the implantable marker (200); the processor arranged: to define one or more distal marker detection zones (190), extending more distally away from the distal end (160) of the magnetic field probe (101, 102, 103, 104) along a probe longitudinal axis or plane (151, 152, 153), wherein the probe longitudinal axis or plane (151, 152, 153) is perpendicular to the first probe transverse axis or plane (181) and perpendicular to the second probe transverse axis or plane (182); to define one or more flank marker detection zones (192, 194), extending from the first probe transverse axis or plane (181) to the second probe transverse axis or plane (182) and extending more transversely and/or more radially away from the probe longitudinal axis or plane (151, 152, 153); to determine one or more angular dispositions (170) and/or one or more distances to the implantable marker (200) using the one or more magnetic field vectors; to determine that the one or more angular dispositions (170) and/or one or more distances fall within the one or more flank marker detection zones (192, 194) if the angular disposition and/or distance substantially coincide with one or more flank marker detection zones (192, 194); and to alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more angular dispositions (170) and/or one or more distances to the implantable marker (200) do not coincide with the one or more flank marker detection zones (192, 194).

2. The magnetic field probe according to claim 1, wherein the one or more flank marker detection zones (192, 194) extend from an axis or plane comprising one or more physical and/or virtual positions passing through the distal end (160).

3. The magnetic field probe according to any preceding claim, wherein the second magnetic sensor (112) is arranged close to the proximal end (165) of the magnetic field probe (101, 102, 103, 104).

4. The magnetic field probe according to any preceding claim, wherein the one or more flank marker detection zones (192, 194) extend to an axis or plane comprising one or more physical and/or virtual positions passing through the proximal end (165).

5. The magnetic field probe according to any preceding claim, wherein the one or more flank marker detection zones (192, 194) extend to an axis or plane comprising one or more physical and/or virtual positions passing through a flank (162, 167) of the magnetic field probe (101, 102, 103, 104).

6. The magnetic field probe according to any preceding claim, wherein the one or more flank marker detection zones (192, 194) are substantially symmetrical about the probe longitudinal axis or plane (151, 152, 153).

7. The magnetic field probe according to any preceding claim, wherein two or more marker detection zones (190, 192, 194) share one or more boundaries.

8. The magnetic field probe according to any preceding claim, wherein the processor is arranged to define one or more proximal marker detection zones (196), extending more proximally away from the proximal end (165) of the magnetic field probe (101, 102, 103, 104) along the probe longitudinal axis or plane (151, 152, 153).

9. The magnetic field probe according to any preceding claim, wherein the processor is arranged to determine one or more angular dispositions (170) and/or one or more distances to the implantable marker (200) with respect to a magnetic probe reference (121, 122) comprising: one or more virtual positions along a probe longitudinal axis or plane (151, 152, 153), one or more physical and/or virtual positions along an axis or plane passing through a distal end (160), one or more physical and/or virtual positions along an axis or plane passing through a proximal end (165), one or more physical and/or virtual positions along an axis or plane passing through a flank (162, 167), one or more virtual positions along a probe transverse axis or plane (181, 182), or any combination thereof.

10. The magnetic field probe according to any preceding claim, the magnetic field probe (101, 102, 103, 104) comprising at least one further magnetic sensor (113, 114), and wherein the first magnetic sensor (111), the second magnetic sensor (112) and the at least one further magnetic sensor (113, 114) are comprised in one or more ID, 2D, or 3D arrays.

11. The magnetic field probe according to any preceding claim, wherein the distal end (160) of the magnetic field probe (101, 102, 103, 104) is arranged to be disposed proximate to an outer surface of skin (300); to contact an outer surface of skin (300); to be inserted through an outer surface of skin (300); to be inserted into a body cavity; or any combination thereof.

12. The magnetic field probe according to any preceding claim, wherein the magnetic field probe (101, 102, 103, 104) comprises a sound transducer, arranged to provide audio feedback, and wherein an audio characteristic of the audio feedback is arranged by the processor to be different, depending on if the one or more angular dispositions (170) and/or one or more distances coincide with the one or more flank marker detection zones (192, 194) or if the one or more angular dispositions (170) and/or one or more distances coincide with the one or more distal marker detection zones (190).

13. The magnetic field probe according to any preceding claim, wherein the processor is arranged to determine one or more configurable aspects of one or more marker detection zones (190, 192, 194, 196) based on: one or more measurements from one or more sensors; one or more suitable parameters; one or more parameters provided by a user; a selection by a user; or any combination thereof.

14. A magnetic field probe (101, 102, 103, 104) for determining one or more dispositions (170) to an implantable marker (200), the implantable marker (200) being arranged to generate, in use, a magnetic field, the magnetic field probe comprising: a distal end (160) suitable for being disposed proximate to an animal or human body; a first magnetic sensor (111) arranged close to the distal end (160) and disposed along a first probe transverse axis or plane (181); a second magnetic sensor (112), disposed along a second probe transverse axis or plane (182) and disposed between the first magnetic sensor (111) and a proximal end (165); wherein the first magnetic sensor (111) and the second magnetic sensor (112) are arranged to determine, in use, one or more magnetic field vectors of the implantable marker (200); and a processor, arranged to collect measurement values from the first magnetic sensor and from the second magnetic sensor, and arranged to determine, in use, one or more magnetic field vectors of the implantable marker; the processor being arranged: to define one or more flank marker detection zones (192, 194), extending from the first probe transverse axis or plane (181) to the second probe transverse axis or plane (182) and extending more transversely and/or more radially away from a probe longitudinal axis or plane (151, 152, 153), wherein the probe longitudinal axis or plane (151, 152, 153) is perpendicular to the first probe transverse axis or plane (181) and perpendicular to the second probe transverse axis or plane (182); to define one or more proximal marker detection zones (196), extending more proximally away from the proximal end (165) of the magnetic field probe (101, 102, 103, 104) along the probe longitudinal axis or plane (151, 152, 153); to determine one or more angular dispositions (170) and/or one or more distances to the implantable marker (200) using the one or more magnetic field vectors; to determine that the one or more angular dispositions (170) and/or one or more distances fall within the one or more flank marker detection zones (192, 194), if the angular disposition and/or distance coincides with one or more flank marker detection zones (192, 194); and to alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more angular dispositions (170) and/or one or more distances to the implantable marker (200) do not coincide with the one or more flank marker detection zones (192, 194).

15. The magnetic field probe according to claim 14, wherein the processor is arranged to determine one or more angular dispositions (170) and/or one or more distances of the implantable marker (200) with respect to a magnetic probe reference (121, 122) comprising: one or more virtual positions along a probe longitudinal axis or plane (151, 152, 153), one or more physical and/or virtual positions along an axis or plane passing through a distal end (160), one or more physical and/or virtual positions along an axis or plane passing through a proximal end (165), one or more physical and/or virtual positions along an axis or plane passing through a flank (162, 167), one or more virtual positions along a probe transverse axis or plane (181, 182), or any combination thereof.

16. The magnetic field probe according to claim 14 or 15, wherein the processor is arranged to alter, attenuate and/or suppress processing of one or more magnetic field vector determinations if one or more angular dispositions (170) and/or one or more distances to the implantable marker (200) do not coincide with the one or more flank marker detection zones (192, 194) and do not coincide with one or more proximal marker detection zones (196).

17. The magnetic field probe according to any preceding claim, wherein the processor is arranged to determine one or more distances to the implantable marker (200) with respect to a magnetic probe reference (122) comprising: one or more physical and/or virtual positions along an axis or plane passing through a distal end (160), one or more physical and/or virtual positions along an axis or plane passing through a proximal end (165), one or more virtual positions along a probe transverse axis or plane (181, 182), or any combination thereof.

18. A detector unit for detecting one or more dispositions and/or distances to an implantable marker (200), the detector unit comprising a display and comprising one or more magnetic field probes (101, 102, 103, 104) according to any preceding claim, wherein the processor is arranged to indicate to a user a result of the determination of one or more dispositions and/or distances on the display.

19. The detector unit according to claim 18, wherein the processor is arranged to indicate one or more marker detection zones (190, 192, 194, 196) on the display.

20. A method for determining one or more dispositions (170) to an implantable marker (200), the implantable marker (200) being arranged to generate, in use, a magnetic field, the method comprising: providing a magnetic field probe (101, 102, 103, 104) comprising a processor and a distal end (160), the magnetic field probe (101, 102, 103, 104) comprising: a first magnetic sensor (111) close to the distal end (160) and disposed along a first probe transverse axis or plane (181); a second magnetic sensor (112), disposed along a second probe transverse axis or plane (182) and disposed between the first magnetic sensor (111) and a proximal end (165); arranging the processor to collect measurement values from the first magnetic sensor (111) and from the second magnetic sensor (112); arranging the processor to determine, in use, one or more magnetic field vectors of the implantable marker (200); arranging the processor to define one or more distal marker detection zones (190), extending more distally away from the distal end (160) of the magnetic field probe (101, 102, 103, 104) along a probe longitudinal axis or plane (151, 152, 153), wherein the probe longitudinal axis or plane (151, 152, 153) is perpendicular to the first probe transverse axis or plane (181) and perpendicular to the second probe transverse axis or plane (182); arranging the processor to define one or more flank marker detection zones (192, 194), extending from the first probe transverse axis or plane (181) to the second probe transverse axis or plane (182) and extending more transversely and/or more radially away from the probe longitudinal axis or plane (151, 152, 153); determining one or more angular dispositions (170) and/or one or more distances to the implantable marker (200) using the one or more magnetic field vectors; determining that the one or more angular dispositions (170) and/or one or more distances fall within the one or more flank marker detection zones (192, 194) if the angular disposition and/or distance coincides with one or more flank marker detection zones (192, 194); and altering, attenuating and/or suppressing processing of one or more magnetic field vector determinations if the one or more angular dispositions (170) and/or one or more distances to the implantable marker (200) do not coincide with the one or more flank marker detection zones (192, 194).