CN118121223A - Collimator, radiation detection device and radiation imaging system - Google Patents
Collimator, radiation detection device and radiation imaging system Download PDFInfo
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- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
- A61B6/03—Computed tomography [CT]
- A61B6/032—Transmission computed tomography [CT]
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/52—Devices using data or image processing specially adapted for radiation diagnosis
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/58—Testing, adjusting or calibrating thereof
- A61B6/582—Calibration
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
- G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
- G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators
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Abstract
The application discloses a collimator, a radiation detection device and a radiation imaging system, wherein the collimator comprises a plurality of collimating sheets concentrically arranged around a central shaft, the main bodies of the collimating sheets are conical and are arranged around a common conical point, and a gap extending from the conical point to the conical bottom is formed between adjacent collimating sheets; the plurality of collimating sheets enable photons emitted from an object to be detected to be emitted along the gaps of the adjacent collimating sheets to form cone-shaped photon beams with multiple cone angles, so that two-dimensional cone-shaped detection of the photons is realized. According to the embodiment of the application, the photons emitted by the object to be detected can form the conical photon beam with multiple conical angles, so that the two-dimensional conical surface detection of the photons is realized, the detection device only moves on a plane, and the three-dimensional image reconstruction can be realized without rotating around the object to be detected.
Description
Technical Field
The present application relates to the field of image processing technologies, and in particular, to a collimator, a radiation detection device, and a radiation imaging system.
Background
Currently, with the wide application of nuclear medicine technology in clinical diagnosis and life science research, single photon imaging devices such as gamma cameras, SPECT/CT and the like are playing an increasingly important role in diagnosis and treatment of diseases.
Some conventional nuclear medicine imaging devices typically include a collimator, a scintillation crystal, a photomultiplier tube, and a data analysis computer at the front end of the crystal. Collimators generally include pinhole collimators, parallel hole collimators, and fan collimators. The collimator is capable of confining scattered photons, allowing gamma photons of a particular incident direction to interact with the crystal. And calculating the position information of gamma photon deposition through the incidence direction information of the collimator and the position circuit, so that the response line information of the gamma photons can be obtained.
In carrying out the application, the inventors have found that the prior art has at least the following problems:
When the nuclear medicine image equipment performs plane scanning, a two-dimensional projection image of the nuclide distribution of the object to be detected can be obtained. When the device rotates around the object to be detected for one circle, 360-degree response line information on a fault plane can be obtained, and a two-dimensional fault image of the distribution of the nuclide in the object to be detected is obtained through image reconstruction. By means of three-dimensional reconstruction of the two-dimensional tomographic images, three-dimensional images can be obtained, i.e. essentially the conventional nuclear medicine imaging device can only perform two-dimensional reconstruction, in other words only planar photography or three-dimensional image display in two dimensions can be realized.
In view of this, it is necessary to invent a nuclear medicine imaging device capable of realizing image reconstruction in a true three-dimensional sense.
The description of the background art is only for the purpose of facilitating an understanding of the relevant art and is not to be taken as an admission of prior art.
Disclosure of Invention
Accordingly, the present application is directed to a collimator, a radiation detection device and a radiation imaging system that address at least one of the problems of the prior art.
According to a first aspect of the present application, there is provided a collimator comprising: and the plurality of collimating sheets are concentrically arranged around the central shaft, the main bodies of the collimating sheets are conical and are arranged around a common conical vertex, gaps extending from the conical vertex to the conical bottom are formed between the adjacent collimating sheets, and the plurality of collimating sheets enable photons emitted from an object to be detected to be emitted along the gaps of the adjacent collimating sheets to form a conical photon beam with multiple conical angles so as to realize two-dimensional conical surface detection of the photons.
According to one embodiment of the application, the plurality of collimating sheets near the central axis are formed in a funnel shape, and both ends of each of the collimating sheets are provided with openings.
According to one embodiment of the present application, the cone angles corresponding to the plurality of collimating sheets are uniformly distributed in an arithmetic progression or an arithmetic progression.
According to one embodiment of the application, the inner diameter of the collimator sheet closest to the central axis is 0.1 cm to 1 cm.
According to one embodiment of the application, the cone angle of the collimator sheet closest to the central axis is in the range of 0-8 degrees.
According to one embodiment of the application, the collimating sheet further comprises a special-shaped collimating sheet surrounding the funnel-shaped collimating sheet, and the projection of the conical bottom surface of the special-shaped collimating sheet on the outermost layer along the direction perpendicular to the central axis is polygonal.
According to one embodiment of the application, one of the end faces of the collimator has the same shape as the end face of the coupled detector.
According to one embodiment of the application, the shape of the projection of the conical bottom end surface of the collimator away from the conical top point along the direction perpendicular to the central axis is circular.
According to a second aspect of the present application there is provided a radiation detection device comprising a collimator as described above; a detector; the detector is coupled to the collimator and configured to detect photons emitted from the collimator to achieve two-dimensional cone detection of photons.
According to one embodiment of the application, the detector is a semiconductor detector configured to directly convert the photons into an electrical signal.
According to one embodiment of the application, the detector is a scintillation detector comprising a scintillation crystal coupled to the collimator and converting the photons into visible light and a photoelectric conversion device converting the visible light into an electrical signal.
According to a third aspect of the present application there is provided a radiation imaging system comprising a radiation detection device as described above; and a radius acquisition module communicatively coupled to the detector to acquire a cone angle of the cone-shaped photon beam.
According to one embodiment of the application, the radius acquisition module comprises a radius calculation circuit, wherein the radius calculation circuit calculates the radius of the photon emitted by the object to be detected, the distance between the vertex of the cone and the detector surface, and the cone angle of the cone-shaped photon beam.
According to one embodiment of the application, the radiation imaging system is a gamma camera performing single photon emission computed tomography imaging.
According to an embodiment of the present application, the radiation imaging system further includes a multi-cone angle data acquisition module configured to acquire multi-cone angle data of different parts of the object to be detected, where the multi-cone angle data is data detected by the detector after the photons are emitted through different gaps of the multi-cone angle collimator, and the data includes different cone angle information corresponding to the photons; a three-dimensional image reconstruction module configured to reconstruct a three-dimensional image based on the multi-cone angle data.
According to one embodiment of the present application, the three-dimensional image reconstruction module includes: a computing module configured for solving an expression of a three-dimensional distribution density function of radionuclides in the object under test using an analytical method based on the multi-cone angle data; substituting coordinates of different parts of the object to be detected into the obtained expression based on the expression of the three-dimensional distribution density function to obtain a value of the pixel point; the three-dimensional image reconstruction module is configured to reconstruct a three-dimensional image of the radionuclide in the object to be detected based on the values of the pixel points.
According to one embodiment of the application, the three-dimensional image reconstruction module comprises a display module configured to display the three-dimensional image.
According to one embodiment of the present application, the calculating module solves the expression of the three-dimensional distribution density function by using an analytic method based on the multi-cone angle data, and the three-dimensional density reconstruction analytic function model is:
Wherein θ, x, y are multi-cone angle data obtained by moving the radiation imaging apparatus in a plane to detect an object to be detected, θ is a cone angle, And z is the distance between the object to be detected and the coupling surface of the collimator and the detector, and x and y are coordinates in an x-y plane corresponding to different z values.
According to one embodiment of the application, the three-dimensional density reconstruction analytic function model is obtained by obtaining an integral function model which represents the multi-cone angle data by using a three-dimensional distribution density function of the radionuclide in the object to be detected through surface integral along a cone surface with an opening angle of twice cone angle, and carrying out Fourier transformation, bezier function expression, hank transformation and inverse Fourier transformation on the integral function model.
According to one embodiment of the application, the radiation imaging system further comprises: a plane shifting device configured to move the radiation imaging device on a plane to obtain multi-cone angle data of different parts of an object to be detected; a data storage transmission module configured to store and transmit the multi-cone angle data; the three-dimensional image reconstruction module is in communication connection with the data storage transmission module to receive the multi-cone angle data and reconstruct a three-dimensional image based on the multi-cone angle data.
According to the embodiment of the application, the photons emitted by the object to be detected form the cone-shaped photon beam with multiple cone angles, so that the two-dimensional cone-shaped detection of the photons is realized, the multiple cone-angle data are conveniently obtained, the point-by-point scanning is only required to be carried out through the movement on the plane of the radiation imaging device with the collimator, the circumferential scanning is not required to be carried out by rotating around the object to be detected, the image reconstruction in the true three-dimensional sense can be realized without arranging a circle of detectors around the object to be detected, the three-dimensional image reconstruction is carried out by an analysis method, iteration is not required, and the reconstruction speed is high.
According to the embodiment of the application, the radiation imaging system is adopted to collect the cone-shaped photon beams emitted by the object to be detected on the detector, the cone angle range of incidence of the cone-shaped photon beams is obtained through the radius calculation module, and the multi-cone angle data are obtained, so that the multi-cone angle data of three-dimensional image reconstruction can be obtained by moving the radiation detection device on a plane to perform detection scanning, one circle of rotation around the object to be detected is not needed, one circle of detector is not needed to be distributed around the object to be detected, the three-dimensional image can be obtained only by moving the radiation detection device on the plane, and the three-dimensional image reconstruction in a real three-dimensional sense is realized, and the image quality is good.
In addition, the embodiment of the application can acquire multi-cone angle data by utilizing the radiation imaging device by converting photons into the conical photon beam, so that an analytical function model can be reconstructed through the three-dimensional density in the three-dimensional image reconstruction module based on the multi-cone angle data, and an analytical method is adopted to solve the expression of the three-dimensional distribution density function; the application can solve the expression of the three-dimensional distribution density function of the radionuclide in the object to be detected by adopting the analysis method suitable for cone beam CT, expands the analysis processing method, and reconstructs the three-dimensional density distribution of the radionuclide of the object to be detected by adopting the analysis method, namely, the analysis method is adopted to reconstruct the three-dimensional image, iteration is not needed, and the reconstruction speed is high.
Optional features and other effects of embodiments of the application are described in part below, and in part will be apparent from reading the disclosure herein.
Drawings
The accompanying drawings, in which like or similar reference numerals refer to like or similar elements and which are not limited to the scale shown in the drawings, illustrate embodiments of the application in detail, and wherein:
FIG. 1 is a schematic perspective view of a collimator according to an embodiment of the present application;
FIG. 2 is a side view of a collimator according to the embodiment of FIG. 1;
FIG. 3 is a top view of a collimator according to the embodiment of FIG. 1;
FIG. 4 is a cross-sectional view of the collimator along the A-A direction according to the embodiment of FIG. 2;
FIG. 5 is a schematic perspective view of a collimator according to another embodiment of the application;
FIG. 6 is a side view of a collimator according to the embodiment of FIG. 5;
FIG. 7 is a top view of a collimator according to the embodiment of FIG. 5;
FIG. 8 is a cross-sectional view of the collimator along the B-B direction according to the embodiment of FIG. 6;
FIG. 9 is a schematic perspective view of a radiation detection device according to one embodiment of the present application;
FIG. 10 is a side view of a radiation detection device according to the embodiment of FIG. 9;
FIG. 11 is a cross-sectional view of the radiation detection device along the A-A direction according to the embodiment of FIG. 10;
FIG. 12 is a cross-sectional view of a radiation detection device according to another embodiment of the present application taken along the direction A-A in FIG. 10;
FIG. 13 is a schematic perspective view of a radiation detecting device according to another embodiment of the present application;
FIG. 14 is a side view of a radiation detection device according to the embodiment of FIG. 13;
FIG. 15 is a cross-sectional view of the radiation detection device in the direction B-B in accordance with the embodiment of FIG. 14;
FIG. 16 is a cross-sectional view of a radiation detection device according to another embodiment of the present application taken along the direction B-B in FIG. 14;
FIG. 17 is a schematic side view of a radiation imaging apparatus according to one embodiment of the application;
FIGS. 18 (A) -18 (B) are cross-sectional views of radiation imaging apparatus according to various embodiments of the present application;
FIG. 19 is a schematic side view of a radiation imaging apparatus according to another embodiment of the application;
FIGS. 20 (A) -20 (B) are cross-sectional views of radiation imaging apparatus according to various embodiments of the present application;
Fig. 21 is a block diagram showing the structure of an image reconstruction apparatus according to an embodiment of the present application;
FIG. 22 is a corresponding model of the three-dimensional Cartesian coordinates and three-dimensional polar coordinates of a cone-shaped photon beam in accordance with the present application;
Fig. 23 (a) -23 (B) are three-dimensional images reconstructed under different conditions by a radiation detection device according to the present application.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent. The exemplary embodiments of the present invention and the descriptions thereof are used herein to explain the present invention, but are not intended to limit the invention.
The term "comprising" and variations thereof as used herein means open ended, i.e., "including but not limited to. The term "or" means "and/or" unless specifically stated otherwise. The term "based on" means "based at least in part on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment. The term "another embodiment" means "at least one additional embodiment". The terms "first," "second," and the like, may refer to different or the same object. Other explicit and implicit definitions are also possible below.
Specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.
The collimator, the radiation detection device and the system provided by the application can be applied to single-photon imaging equipment such as gamma cameras, single-photon emission computed tomography (SPECT) equipment, single-photon emission computed tomography (SPECT) equipment and single-photon Computed Tomography (CT) equipment. The detector may include a plurality of probes, the line connecting the radiation emission point and the crystal deposition location of the detector being a line of response (i.e., LOR), and one or more lines of response may be formed on each probe pair.
Fig. 1 shows the structure of a collimator according to an embodiment of the present application. As shown in fig. 1-4, the collimator 100 includes a plurality of collimating sheets 110, 120 concentrically arranged around a central axis, the plurality of collimating sheets having a common cone apex, a projected shape of an end surface of the collimator away from the cone apex in a direction perpendicular to the central axis being identical to a shape of an end surface of a detector coupled thereto, wherein the plurality of collimating sheets enable photons emitted by an object to be detected to be emitted along a gap between adjacent collimating sheets to form a cone-shaped photon beam having multiple cone angles, so as to achieve two-dimensional cone-surface detection of the photons. The cone apex according to the embodiments of the present application specifically refers to a common intersection point of cone-shaped photon beams. The multiple cone angles in the embodiment of the application, in particular to the directions of photons propagating from the top point to the cone bottom in the interval of any adjacent conical collimating sheets, can be regarded as forming the same cone angle, however, the cone angles corresponding to different intervals can be distributed within a certain angle range, such as from 0 degrees to 60 degrees, so that photons propagating in different intervals have different cone angles. The maximum cone angle of the multi-cone angle tapered photon beam in embodiments of the application is determined, i.e., the opening angle of the tapered photon beam is determined, and in one example, the maximum cone angle may be 60 °. The collimator of the application is a converging collimator which can converge photons emitted by an object to be detected to form a converging cone-shaped photon beam with multiple cone angles. According to the application, by adopting the collimator, photons emitted by the object to be detected form a conical photon beam with multiple cone angles, so that the two-dimensional conical surface detection of the photons is realized, the detection device only moves on a plane, and three-dimensional image reconstruction can be realized without rotating around the object to be detected.
Preferably, the projection of the end face of the collimator, which is close to the apex of the cone, in the direction perpendicular to the central axis is not smaller in size than the end face of the detector coupled thereto, so as to ensure that all the multi-cone angle photon beam rays emitted by the object to be detected can be detected by the detector.
In the embodiment of the application, the object to be detected can be a living organism, such as a human, an animal and the like, and can be specifically a radionuclide in the living organism.
In the embodiment of the application, the plurality of collimating sheets close to the central axis are funnel-shaped collimating sheets 110, the end part of the funnel-shaped collimating sheet 110 of the innermost layer close to the cone apex is provided with a hole 130, and the inner diameter of the hole 130 is 0.1-1 cm, so as to ensure that the two-dimensional cone projection of photons is acquired as many as possible in the detection range of the maximum cone angle.
In the embodiment of the application, the cone angle range of the funnel-shaped collimating sheet at the innermost layer is 0-8 degrees, so that the two-dimensional cone projection of photons is acquired as many as possible in the detection multi-cone angle range of the maximum cone angle, and the detection data acquired in the angle range is beneficial to the follow-up three-dimensional image reconstruction, so that the reconstructed three-dimensional image is clearer, the pixel value is higher, and the reconstruction quality is better.
In the embodiment of the present application, the differences between the cone angles of adjacent collimating sheets of the plurality of collimating sheets 110, 120 may or may not be identical. May be set according to specific needs.
In the embodiment of the present application, when the shape of the end face of the detector coupled to the collimator is circular, correspondingly, the shape of the projection of the end face of the collimator, which is far from the cone apex, along the direction perpendicular to the central axis may be circular, and in this case, the plurality of collimating sheets are all funnel-shaped. In one example, the inner diameter of the circle of the projection of the end face of the collimator remote from the cone apex in a direction perpendicular to the central axis is no more than 25 cm.
In an embodiment of the present application, when the shape of the end face of the detector coupled to the collimator is polygonal, accordingly, the shape of the projection of the end face of the collimator, which is far from the cone apex, in the direction perpendicular to the central axis may be polygonal, and the collimating sheet includes a plurality of funnel-shaped collimating sheets located in the middle and a special-shaped collimating sheet surrounding the funnel-shaped collimating sheets, and the main body of the special-shaped collimating sheet is still substantially a part of the funnel shape, but the projection of the edge of the special-shaped collimating sheet in the direction perpendicular to the central axis is polygonal. By way of illustration and not limitation, polygons may include triangles, quadrilaterals, pentagons, etc., as shown in fig. 3 as rectangles. In one example, the sides of the polygon are no more than 30 cm long.
Embodiments of the present application also provide a collimator 100', as shown in fig. 5-8. The difference between the collimator in this embodiment and the collimator in the embodiments shown in fig. 1-4 is that the collimator in the embodiment of the present application is an inverted diffusion collimator, which performs a diffusion function on photons emitted from an object to be detected, so as to form a diffused cone-shaped photon beam with multiple cone angles. It includes a plurality of collimating sheets 110', 120' arranged concentrically around a central axis in an inverted manner corresponding to the above-described embodiment, and the end of the innermost funnel-shaped collimating sheet 110' near the apex of the cone has a hole 130', and in one example, the hole 130' has an inner diameter of 0.1 cm to 1 cm, to ensure that a two-dimensional cone projection of as many photons as possible is obtained within a range of maximum cone angle detection multi-cone angles. Preferably, the size of the end face of the collimator for coupling is not smaller than the size of the end face of the detector coupled thereto, so as to ensure that all the multi-cone angle cone-shaped photon beam rays emitted by the object to be detected can be detected by the detector.
In addition, the embodiment of the application also provides a radiation detection device 10. As shown in fig. 9-10, the radiation detection device 10 includes: a detector 200; a collimator 100 coupled to the detector 200 such that photons emitted from an object to be detected can be emitted in the form of a cone-shaped photon beam having a plurality of cone angles; the detector 200 is used for detecting photons emitted from the collimator 100, so as to realize two-dimensional cone detection of the photons. The collimator adopted in the embodiment of the application is the collimator described in the embodiment shown in fig. 1-4, namely, the converging collimator. The radiation detection device of the embodiment of the application gathers the cone-shaped photon beams with multiple cone angles emitted by the object to be detected on the detector to obtain the data with multiple cone angles, so that the data with multiple cone angles for reconstructing the three-dimensional image can be obtained by moving the radiation detection device on a plane to perform detection scanning, one circle of rotation around the object to be detected is not needed, one circle of detector is not needed to be distributed around the object to be detected, the three-dimensional image can be obtained by only moving the scanning on the plane, the three-dimensional image reconstruction in the real three-dimensional sense is realized, and the image quality is good.
In an embodiment of the present application, as shown in fig. 11, the detector 200 is a scintillation detector, including a scintillation crystal 210 and a photoelectric conversion device 220, and by way of illustration and not limitation, the scintillation crystal 210 may be a lutetium yttrium silicate scintillation crystal (LYSO), a NaI scintillation crystal, a LaBr 3:ce scintillation crystal, a GAGG (Ce) (Cerium-doped Gadolinium Aluminum Gallium Garnet, cerium doped gadolinium aluminum gallium garnet) scintillation crystal, and the like, where the scintillation crystal has advantages of high light output, high energy resolution, short decay time, and the like; the photoelectric conversion device 220 may employ a silicon photomultiplier (SiPM) or a photomultiplier tube. In such a detector, the scintillation crystal 210 absorbs radiation energy and produces a number of photons of visible light corresponding to the energy, and the photoelectric conversion device 220 is configured to receive the batch of photons produced by the scintillation crystal and convert the photons into an electrical signal.
In one embodiment, the end face dimension of the scintillator crystal 210 coupled to the collimator 100 is not greater than the end face dimension of the collimator 100 coupled thereto to ensure that all multi-cone angle cone-shaped photon beams emitted by the object to be detected are detected by the detector.
In another embodiment of the present application, such as the radiation detection device 10 'shown in fig. 12, the detector 200' is a semiconductor detector. The semiconductor detector may include, but is not limited to, amorphous selenium, cadmium telluride (CdTe), cadmium zinc telluride (CdZnTe, CZT), cadmium selenide (CdSe), and the like. The semiconductor detector does not need to convert photons into visible light by a scintillator or fluorescent material, but rather generates electron-hole pairs when photons are irradiated to a direct detection material, and the electrons and holes form currents under the action of an externally applied bias electric field, i.e., the photons are directly converted into electric signals. In a preferred example, the end face dimension of the detector 200' coupled to the collimator 100 is no greater than the end face dimension of the collimator 100 coupled thereto to ensure that all multi-cone angle cone-shaped photon beams emitted by the object to be detected are detected by the detector.
In addition, the embodiment of the application also provides another radiation detection device 10". The difference between this embodiment and the radiation detection apparatus 10 shown in fig. 9-11 is that the radiation detection apparatus according to the embodiment of the present application employs a diffuse collimator (particularly shown in fig. 5-8).
As shown in fig. 13-14, the radiation detection apparatus 10 "includes: a detector 200; a collimator 100' coupled to the detector 200 on a surface of the detector 200 facing the object to be detected such that photons emitted by the object to be detected form a cone-shaped photon beam having a plurality of cone angles and are emitted along a cone-shaped path; the detector 200 is used for detecting photons emitted from the collimator 100' along a tapered path, so as to realize two-dimensional tapered surface detection of the photons. According to the radiation detection device, the cone-shaped photon beams with multiple cone angles emitted by the object to be detected are diffused to the detector to obtain the multi-cone-angle data, so that the multi-cone-angle data of three-dimensional image reconstruction can be obtained by moving the radiation detection device on a plane to perform detection scanning, one circle of rotation around the object to be detected is not needed, one circle of detector is not needed to be distributed around the object to be detected, a three-dimensional image can be obtained by only moving the radiation detection device on the plane, three-dimensional image reconstruction in a real three-dimensional sense is realized, and the image quality is good.
With respect to the specific construction and design of the detector, reference is made to the radiation detection device 10, 10' of the embodiment shown in fig. 9-11.
In one embodiment, referring to FIG. 15, the end face of the scintillator crystal 210 coupled to the collimator 100 'is no larger than the end face of the collimator 100' coupled thereto to ensure that all multi-cone angle cone-shaped photon beams emitted by the object to be detected are detected by the detector.
In another embodiment of the present application, as shown in fig. 16, the dimension of the end surface of the detector 200' coupled with the collimator 100' is not greater than the dimension of the projection of the end surface of the collimator 100' away from the cone apex in the direction perpendicular to the central axis, so as to ensure that all cone-angle cone-shaped photon beams emitted by the object to be detected can be detected by the detector.
Multiple taper angles
The embodiment of the application also provides a radiation imaging device 1. As shown in fig. 17, the radiation imaging apparatus 1 includes: a detector 200; a collimator 100 coupled to the detector 200 on a surface of the detector 200 facing the object to be detected such that photons emitted from the object to be detected form a cone-shaped photon beam having a plurality of cone angles and are emitted along a cone-shaped path; a radius acquisition module 300 communicatively coupled to the detector 200 to calculate a cone angle for acquiring the cone-shaped photon beam; the detector 200 is used for detecting the conical photon beam emitted from the collimator along the conical path so as to realize two-dimensional conical surface detection of photons, and obtain multi-cone angle data of the conical photon beam emitted by at least one part of the object to be detected. The multi-cone angle data refer to data detected by the detector after photons are emitted from different gaps of the multi-cone angle collimator, and the data comprise different cone angle information corresponding to the photons. .
According to the radiation imaging device, the cone-shaped photon beams with multiple cone angles emitted by the object to be detected are converged on the detector, the incident cone angle range of the cone-shaped photon beams is obtained through the radius calculation module, and the multi-cone angle data are obtained, so that the multi-cone angle data of three-dimensional image reconstruction can be obtained by moving the radiation detection device on a plane to perform detection scanning, one circle of rotation around the object to be detected is not needed, one circle of detector is not needed to be distributed around the object to be detected, a three-dimensional image can be obtained only by moving the radiation detection device on the plane, and three-dimensional image reconstruction in a real three-dimensional sense is realized, and the image quality is good.
In an embodiment of the present application, as shown in fig. 18 (a) -18 (B), the radius acquisition module 300 includes a radius calculation circuit, which calculates a radius of a photon emitted from an object to be detected (i.e., a distance between a position of an incidence point of the photon on the detector surface and a central axis of the collimator) and a distance between a cone vertex and the detector surface, and calculates a cone angle of the cone-shaped photon beam. The common intersection point of the conical photon beams is taken as a conical vertex O 1, the conical vertex O 1 is positioned on the central axis of the collimator, the distance from the conical vertex O1 to the contact surface of the collimator and the detector is h, the distance from the incident point of the photon incident on the surface of the detector to the central axis of the collimator where the conical vertex O 1 is positioned is taken as a radius r, then the conical angle theta=arctg (r/h) of the conical photon beams can be obtained through calculation by using an arctangent function, and the angle range which can be detected by the detector of the radiation imaging device is [0, theta ].
The embodiment of the application also provides another radiation imaging apparatus 1'. As shown in fig. 19, the radiation imaging apparatus 1' of the embodiment of the present application is different from the radiation imaging apparatus 1 of the embodiment shown in fig. 17 in that the collimator is an inverted diffuse collimator. According to the radiation imaging device, the cone-shaped photon beams with multiple cone angles emitted by the object to be detected are diffused to the detector, the incident cone angle range of the cone-shaped photon beams is obtained through the radius calculation module, and the multi-cone angle data are obtained, so that the multi-cone angle data of three-dimensional image reconstruction can be obtained by moving the radiation detection device on a plane to perform detection scanning, one circle of rotation around the object to be detected is not needed, one circle of detector is not needed to be distributed around the object to be detected, a three-dimensional image can be obtained only by moving the radiation detection device on the plane, and three-dimensional image reconstruction in a real three-dimensional sense is realized, and the image quality is good.
In an embodiment of the present application, as shown in fig. 20 (a) -20 (B), the radius acquisition module 300 includes a radius calculation circuit, which calculates a radius of a photon emitted from an object to be detected (i.e., a distance between a position of an incidence point of the photon on the detector surface and a central axis of the collimator) and a distance between a cone vertex and the detector surface, and calculates a cone angle of the cone-shaped photon beam. The cone angle θ ' =arctg (r '/h ') of the cone-shaped photon beam can be obtained by calculation using an arctangent function with the common intersection point of the cone-shaped photon beams as a cone apex O 2, the cone apex O 2 being located on the central axis of the collimator, the distance from the cone apex O 2 to the contact surface of the collimator and the detector being h ', and the distance from the incident point position of the photon incident on the surface of the detector to the central axis of the collimator where the cone apex O 2 is located being a radius r '. The detector of the radiation imaging apparatus can detect an angular range of 0, theta'.
In an embodiment of the present application, the collimator in the radiation imaging apparatus is the radiation imaging apparatus described in the foregoing embodiment.
In an embodiment, the radiation imaging apparatus is a gamma camera performing single photon emission computed tomography imaging.
The specific design of the detector in the embodiments of the present application may refer to the foregoing embodiments.
In addition, the embodiment of the application also provides an image reconstruction device 400. As shown in fig. 21, the image reconstruction apparatus 400 includes: the multi-cone angle data acquisition module 410 is configured to acquire multi-cone angle data of different parts of an object to be detected, where the multi-cone angle data is data detected by the detector after photons are emitted from different gaps of the multi-cone angle collimator, and the data includes different cone angle information corresponding to the photons; the three-dimensional image reconstruction module 420 reconstructs a three-dimensional image based on the multi-cone angle data. The multi-cone angle data refer to data detected by the detector after photons are emitted from different gaps of the multi-cone angle collimator, and the data comprise different cone angle information corresponding to the photons.
In an embodiment, the multi-cone angle data is multi-cone angle data obtained by using the radiation imaging device with the collimator in the foregoing embodiment, photons are converted into cone-shaped photon beams by the collimator, so that an expression of a three-dimensional distribution density function can be solved by using an analytical method based on the multi-cone angle data through a three-dimensional density reconstruction analytical function model in the three-dimensional image reconstruction module 420, and an expression of a three-dimensional distribution density function of a radionuclide in an object to be measured can be solved by using an analytical method applicable to cone-beam CT, that is, an expression of the three-dimensional distribution density function can be solved by using an analytical method including fourier transform and radon transform, that is, a three-dimensional image capable of reflecting a three-dimensional density distribution condition of a radionuclide in the object to be measured is reconstructed by using an analytical method including fourier transform and radon transform. For the specific operation of fourier transform and radon transform, reference may be made to the prior art, and no further description is given here. The embodiment of the application expands the analysis processing mode, and the three-dimensional density distribution of the radionuclide of the object to be detected is reconstructed by adopting the analysis method, namely the three-dimensional image is reconstructed by adopting the analysis method, iteration is not needed, and the reconstruction speed is high.
In one example of the present application, as an illustration and not limitation, the multi-cone angle data acquisition module may include a data transmission port for receiving the multi-cone angle data transmitted by the data storage transmission module and transmitting the multi-cone angle data received thereby to the three-dimensional image reconstruction module for three-dimensional image reconstruction.
In one embodiment of the present application, the three-dimensional image reconstruction module includes: a computing module configured for solving an expression of a three-dimensional distribution density function of radionuclides in the object under test using an analytical method based on the multi-cone angle data; substituting coordinates of different parts of the object to be detected into the obtained expression based on the obtained expression of the three-dimensional distribution density function of the radionuclide in the object to be detected so as to obtain a value of the pixel point; and a three-dimensional image reconstruction module configured to reconstruct a three-dimensional image of the three-dimensional density distribution of the radionuclide in the object to be measured based on the values of the pixel points obtained by the calculation module.
In an embodiment, the cone angle three-dimensional distribution density function calculation module adopts an analytic method to solve the expression of the three-dimensional distribution density function based on the multi-cone angle data, which comprises obtaining a three-dimensional density reconstruction analytic function model, specifically, substituting the multi-cone angle data into the three-dimensional density reconstruction analytic function model, so as to obtain the expression of the three-dimensional distribution density function of the radionuclide in the object to be detected.
In one embodiment, the three-dimensional density reconstruction analytic function model obtained by the calculation module is:
the above functional model is to reconstruct the expression of the three-dimensional distribution density function by using the multi-cone angle data.
Where θ, x, y are multi-cone angle data obtained by moving a radiation imaging apparatus including a collimator and a detector in a plane to detect an object to be detected, specifically θ is a cone angle (see radiation imaging apparatus embodiment, which may be obtained by calculation),And z is the distance between an object to be detected and the contact surface of the collimator and the detector, and x and y are coordinates in an x-y plane corresponding to different z values. Transmitting the multi-cone angle data (x, y, theta) acquired by the radiation imaging device to a multi-cone angle data acquisition module 410, then utilizing a three-dimensional density reconstruction analytic function model acquired by a calculation module in a three-dimensional image reconstruction module 420, namely formula (19), solving a three-dimensional distribution density functional expression of the radionuclide in the object to be detected by utilizing an analytic method based on the multi-cone angle data, substituting coordinates (x, y, z) of different parts of the object to be detected into the obtained three-dimensional distribution density functional expression to acquire a value of a pixel point, and finally reconstructing a three-dimensional image of the three-dimensional density distribution of the radionuclide in the object to be detected by utilizing the three-dimensional image reconstruction module based on the pixel value point acquired by the calculation module.
In an example, the three-dimensional density reconstruction analytic function model represented by the above formula is obtained by obtaining an integral function model which represents the multi-cone angle data by carrying out surface integral on a three-dimensional distribution density function of the radionuclide in the object to be detected along a cone surface with an opening angle being twice the cone angle, and carrying out Fourier transformation, bezier function expression, hank transformation and inverse Fourier transformation on the integral function model.
Specifically, the steps of obtaining the three-dimensional density reconstruction analytical function model are exemplified as follows:
with the human body as the object to be detected, as shown in fig. 22, the coordinates of the cone vertex o' of the collimator are set to be (x, y, 0), the three-dimensional distribution density function of the radionuclide in the human body is set to be ρ (x, y, z), the cone angle is θ, and then the projection on the cone angle θ is the surface integral of the function ρ (x, y, z) along the cone surface with the opening angle 2θ. The projection p (x, y, θ) onto the cone angle θ is derived as:
Equation (11) is an integral function model in which the multi-cone angle data is expressed by surface integral of a three-dimensional distribution density function of the radionuclide in the object to be detected along a cone surface with an opening angle of twice cone angle, and fourier transformation on variables x and y is obtained on two sides of the integral function model shown in the above equation (11):
exchanging integration sequence to obtain:
Further obtain:
Wherein, Expression (14) is expressed by a Bessel function, and the expression is obtained:
Simplifying the formula to obtain:
equation (16) is a hank transform for the variable z, and the hank inverse transform is obtained by equation (10):
Namely:
replacing the integral variable, i.e., converting tg θ to (dtgθ=sec 2 θdθ), gives:
the inverse fourier transform of ω x,ωy was obtained on both sides of equation (18):
Equation (19) is a three-dimensional density reconstruction analytical function model, namely an accurate expression of a three-dimensional distribution density function is reconstructed by using multi-cone angle data. Where θ, x, y are multi-cone angle data obtained by moving a radiation imaging apparatus including a collimator and a detector in a plane to detect an object to be detected, specifically θ is a cone angle (see radiation imaging apparatus embodiment, which may be obtained by calculation), And z is the distance between an object to be detected and the contact surface of the collimator and the detector, and x and y are coordinates in an x-y plane corresponding to different z values. Transmitting multi-cone angle data (x, y, theta) acquired by a radiation imaging device to a cone multi-cone angle data acquisition module 410, then utilizing a three-dimensional density reconstruction analytic function model acquired by a calculation module in a three-dimensional image reconstruction module 420 to obtain a three-dimensional distribution density functional expression of the radionuclide in the object to be detected by utilizing an analytic method based on the cone multi-cone angle data, substituting coordinates (x, y, z) of different parts of the object to be detected into the obtained three-dimensional distribution density functional expression to obtain a value of a pixel point, and finally reconstructing a three-dimensional image of the three-dimensional density distribution of the radionuclide in the object to be detected by utilizing the three-dimensional image reconstruction module based on the value of the pixel point obtained by the calculation module.
In an embodiment, the three-dimensional image reconstruction module includes a display module to enable visualization of the three-dimensional image. The display module may be implemented by using a device in the prior art, which is not described herein.
The radiation imaging system of the embodiment of the application gathers the cone-shaped photon beams with multiple cone angles emitted by the object to be detected on the detector, acquires the incident cone angle range of the cone-shaped photon beams through the radius calculation module, and acquires the multi-cone-angle data, so that the multi-cone-angle data of three-dimensional image reconstruction can be obtained by moving the radiation detection device on a plane for detection scanning, one circle of rotation around the object to be detected is not needed, one circle of detector is not needed to be distributed around the object to be detected, the three-dimensional image can be obtained only by moving the radiation detection device on the plane, and the three-dimensional image reconstruction in the true three-dimensional sense is realized with good image quality.
In addition, the embodiment of the application acquires multi-cone angle data by using a radiation imaging device with a collimator, converts photons into cone photon beams through the collimator, so that an analytical function model can be reconstructed through three-dimensional density in a three-dimensional image reconstruction module based on the multi-cone angle data, an expression of a three-dimensional distribution density function can be solved by adopting an analytical method, and an expression of a three-dimensional distribution density function of radionuclide in an object to be detected can be solved by adopting an analytical method applicable to cone beam CT, namely, an expression of the three-dimensional distribution density function can be solved by adopting an analytical method comprising Fourier transformation and Ladong transformation, namely, a three-dimensional image of three-dimensional distribution of radionuclide in the object to be detected can be reconstructed by adopting an analytical method comprising Fourier transformation and Ladong transformation. For the specific operation of fourier transform and radon transform, reference may be made to the prior art, and no further description is given here. Therefore, the application expands the analysis processing method, and the three-dimensional density distribution of the radionuclide of the object to be detected is reconstructed by adopting the analysis method, namely the three-dimensional image is reconstructed by adopting the analysis method, iteration is not needed, and the reconstruction speed is high.
In an embodiment of the present application, the plane shifting device may be implemented by using the prior art, which is not described herein. The radiation imaging device performs plane movement by the plane displacement device, and the plane movement range of the radiation imaging device is as follows: the cone angle θ is calculated by the radiation imaging apparatus (see the radiation imaging apparatus embodiment in particular), i.e. the detected angle range is [0, θ ], and the plane movement range of the radiation imaging apparatus is (x, y) e [ -z ] sin θ, z ] sin θ ] x [ -z ] sin θ, z ] sin θ ] with the distance of the object to be detected from the contact surface of the collimator with the detector being z. The radiation imaging device is enabled to move in the range in the x-y plane through the plane shifting device, multi-cone angle data of different parts of an object to be detected are obtained, the data are transmitted to the data storage and transmission module for storage and transmission, the data storage and transmission module transmits the obtained multi-cone angle data of different parts of the object to be detected to the multi-cone angle data obtaining module 410 in the image reconstruction device, then the three-dimensional density reconstruction analytic function model (formula (19) obtained by the calculating module in the three-dimensional image reconstruction module 420 is utilized, the three-dimensional distribution density functional expression of the radionuclide in the object to be detected is solved through the analytic method based on the multi-cone angle data, coordinates (x, y, z) of different parts of the object to be detected are substituted into the obtained three-dimensional distribution density functional expression, so that values of pixel points are obtained, and finally the three-dimensional image of the three-dimensional density distribution of the radionuclide in the object to be detected is reconstructed through the three-dimensional image reconstruction module based on the points of the pixel values obtained by the calculating module.
In the embodiment of the present application, regarding the reconstruction of a three-dimensional image using a three-dimensional density reconstruction analytical function model, that is, equation (19), an application example is as follows:
the three-dimensional density reconstruction analytical function model (19) is a generalized integral, i.e. at θ=pi/2 at sec theta = +++ infinity, the limit cancellation of the integrand can be utilized. Assuming an isotropic single point source at (0, z 0) with cone angle acquisition range of θε [0, pi/3 ], a translational scan range of a radiation imaging apparatus in a radiological imaging system is Assuming that z 0 =1, the sampling number of the cone angle θ is 16, the sampling numbers of x and y are 32, based on the sampling data, reconstructing a three-dimensional image by using a three-dimensional density reconstruction analytic function model, namely formula (19), and partially reconstructing the three-dimensional image, wherein the reconstructed three-dimensional image of the three-dimensional distribution density function on the x-y plane when z=1 is shown in fig. 23 (a), it can be seen that the three-dimensional distribution density function is almost a point source when the distance z=1 between the object to be detected and the contact surface of the collimator and the detector, and accords with the actual situation; as shown in fig. 23 (B), the reconstructed three-dimensional image of the three-dimensional distribution density function on the x-y plane when z=2 shows that the three-dimensional distribution density function is almost everywhere zero when z=2, and it should be noted that, unlike the pixels in fig. 23 (a), the actual characterization effect in fig. 23 (B) is that the three-dimensional distribution density function is almost everywhere zero when z=2. Since it is assumed that there is a single point source at z 0 =1 for which the three-dimensional image reconstructed using the three-dimensional density reconstruction analytic function model, i.e., equation (19), the three-dimensional distribution density function in the x-y plane is shown as one point source at z=1 and is almost everywhere zero at z=2, this application example demonstrates the practicality of the three-dimensional density reconstruction analytic function model, i.e., equation (19).
In the embodiment of the application, the radiation imaging device can realize the image reconstruction in the true three-dimensional sense only by scanning the radiation imaging device point by point on the x-y plane through the plane displacement device without circumferential scanning around the object to be detected, and the three-dimensional image reconstruction is carried out through an analysis method without iteration, so that the reconstruction speed is high.
Various embodiments are described herein, but the description of the various embodiments is not exhaustive and the same or similar features or portions between the various embodiments may be omitted for the sake of brevity. Herein, "one embodiment," "some embodiments," "example," "specific example," or "some examples" means that it is applicable to at least one embodiment or example, but not all embodiments, according to the present application. The above terms are not necessarily meant to refer to the same embodiment or example. Those skilled in the art may combine and combine the features of the different embodiments or examples described in this specification and of the different embodiments or examples without contradiction.
The exemplary systems and methods of the present application have been particularly shown and described with reference to the foregoing embodiments, which are merely examples of the best modes for carrying out the systems and methods. It will be appreciated by those skilled in the art that various changes may be made to the embodiments of the systems and methods described herein in practicing the systems and/or methods without departing from the spirit and scope of the application as defined in the following claims.
Claims (20)
1. A collimator, comprising:
A plurality of collimating sheets concentrically arranged around a central axis, wherein the main bodies of the collimating sheets are conical and are arranged around a common conical vertex, and gaps extending from the conical vertex to a conical bottom are formed between adjacent collimating sheets; the plurality of collimating sheets enable photons emitted from an object to be detected to be emitted along gaps of adjacent collimating sheets to form cone-shaped photon beams with multiple cone angles, so that two-dimensional cone-shaped detection of the photons is achieved.
2. The collimator of claim 1, wherein a plurality of collimating sheets near the central axis are formed in a funnel shape, and each of the collimating sheets has an opening at both ends thereof.
3. The collimator of claim 2, wherein cone angles corresponding to the plurality of collimating sheets are uniformly distributed in an arithmetic series or an arithmetic series.
4. The collimator of claim 2, wherein the inner diameter of the collimating sheet closest to the central axis is 0.1 cm to 1 cm.
5. The collimator of claim 2, wherein the cone angle of the collimator sheet closest to the central axis ranges from 0 degrees to 8 degrees.
6. The collimator of claim 2, wherein the collimating sheets further comprise shaped collimating sheets surrounding the funnel-shaped collimating sheets, and wherein the conical bottom surfaces of the outermost shaped collimating sheets are polygonal in projection in a direction perpendicular to the central axis.
7. The collimator of claim 1, wherein one of the end faces of the collimator has the same shape as the end face of the coupled detector.
8. The collimator of claim 1, wherein the shape of the projection of the cone bottom end surface of the collimator away from the cone apex in a direction perpendicular to the central axis is circular.
9. A radiation detection device, comprising:
The collimator of any one of claims 1-8; and
A detector; the detector is coupled to the collimator and configured to detect photons emitted from the collimator to achieve two-dimensional cone detection of photons.
10. The radiation detection apparatus as recited in claim 9, wherein the detector is a semiconductor detector configured to directly convert the photons into electrical signals.
11. The radiation detection apparatus as recited in claim 9, wherein the detector is a scintillation detector comprising a scintillation crystal coupled to the collimator and converting the photons to visible light and a photoelectric conversion device converting the visible light to an electrical signal.
12. A radiation imaging system, comprising:
The radiation detection apparatus as recited in any one of claims 9-11; and
And the radius acquisition module is in communication connection with the detector to acquire the cone angle of the conical photon beam.
13. The radiation imaging system of claim 12, wherein the radius acquisition module comprises a radius calculation circuit that calculates a radius of incidence of photons emitted by the object to be detected on the detector surface, a distance of a cone apex from the detector surface, to calculate a cone angle of the cone-shaped photon beam.
14. The radiation imaging system of claim 12, wherein the radiation imaging system is a gamma camera performing single photon emission computed tomography imaging.
15. The radiation imaging system of claim 12, further comprising:
the multi-cone angle data acquisition module is configured to acquire multi-cone angle data of different parts of an object to be detected, wherein the multi-cone angle data are data detected by the detector after photons are emitted from different gaps of the multi-cone angle collimator, and the data comprise different cone angle information corresponding to the photons;
and a three-dimensional image reconstruction module configured to reconstruct a three-dimensional image based on the multi-cone angle data.
16. The radiation imaging system of claim 15, wherein said three-dimensional image reconstruction module comprises:
A computing module configured for solving an expression of a three-dimensional distribution density function of radionuclides in the object under test using an analytical method based on the multi-cone angle data; substituting coordinates of different parts of the object to be detected into the obtained expression based on the expression of the three-dimensional distribution density function to obtain a value of the pixel point;
the three-dimensional image reconstruction module is configured to reconstruct a three-dimensional image of the radionuclide in the object to be detected based on the values of the pixel points.
17. The radiation imaging system of claim 16, wherein the three-dimensional image reconstruction module comprises a display module configured to display the three-dimensional image.
18. The radiation imaging system of claim 16, wherein the computing module to solve the expression of the three-dimensional distribution density function using an analytical method based on the multi-cone angle data comprises to obtain a three-dimensional density reconstruction analytical function model, the three-dimensional density reconstruction analytical function model being:
Wherein θ, x, y are multi-cone angle data obtained by moving the radiation imaging apparatus in a plane to detect an object to be detected, θ is a cone angle, And z is the distance between the object to be detected and the coupling surface of the collimator and the detector, and x and y are coordinates in an x-y plane corresponding to different z values.
19. The radiation imaging system of claim 18, wherein the three-dimensional density reconstruction analytic function model is obtained by obtaining an integral function model that represents multi-cone angle data by surface integration of a three-dimensional distribution density function of a radionuclide in an object to be detected along a cone surface with an opening angle of twice cone angle, and performing fourier transform, bezier function expression, hank transform, inverse fourier transform processing on the integral function model.
20. The radiation imaging system of claim 15, further comprising:
a plane shifting device configured to move the radiation imaging device on a plane to obtain multi-cone angle data of different parts of an object to be detected;
a data storage transmission module configured to store and transmit the multi-cone angle data;
the three-dimensional image reconstruction module is in communication connection with the data storage transmission module to receive the multi-cone angle data and reconstruct a three-dimensional image based on the multi-cone angle data.
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2022
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