WO2016030537A1

WO2016030537A1 - X-ray device for imaging a region of interest of a patient

Info

Publication number: WO2016030537A1
Application number: PCT/EP2015/069811
Authority: WO
Inventors: Sven Weichert
Original assignee: Koninklijke Philips N.V.
Priority date: 2014-08-29
Filing date: 2015-08-29
Publication date: 2016-03-03

Abstract

The present invention relates to an X-ray device which comprises a motion detection system or functionality which analyses the movement of the collimated extremity of the patient and which controls and determines the actual release of X-ray radiation after the user has pressed or activated the exposure switch. A camera may be used, which, for example, can be built into the collimator of the X-ray device, and which takes images of the collimated extremity and compares them, in order to identify the movement of the patient. An X-ray exposure will only be released by the control unit after an activation of the exposure switch, as soon as a movement of the extremity is within a predefined maximum bandwidth.

Description

X-ray device for imaging a region of interest of a patient

FIELD OF THE INVENTION

The present invention relates to medical imaging and motion detection of patients that are examined by imaging devices. In particular, the present invention relates to an X-ray device for imaging a region of interest of a patient, a method for controlling an X- ray imaging process, a program element for controlling an X-ray imaging process and a computer-readable medium on which a computer program for controlling an X-ray imaging process is stored.

BACKGROUND OF THE INVENTION

A lot of images in the radiology department need to be re-taken due to the movement of the patient. In general it is difficult to judge from the control room if the patient is moving and when it is the best moment to release the exposure. Also pre-mature babies up to young kids are the most difficult group for radiographers, as they tend to move a lot during the examination. An X-ray needs to be re-taken in case the image quality is not sufficient to make diagnoses. This is especially in neonatal intensive-care units (NICU) and paediatric departments a big issue, as it results into an increased average X-ray dose per patient.

Radiology equipment has typically a 2-step exposure switch to overcome this problem. In Phase 1 the system gets pre-activated and the tube is getting ready for exposure. In Phase 2 the tube releases its radiation. The far distance, in case the radiographer releases the exposure from the control room, and the heavy movements of small kids make it nevertheless very hard for the radiographer to define the best moment to release the exposure. In China one can see nowadays many hospitals where the radiographer stays during the entire examination in the control room. Here similar issues are to be expected. SUMMARY OF THE INVENTION

There may be a need to provide for an improved X-ray imaging of patients which move during the imaging process.

The object of the present invention may be seen as the provision of an improved X-ray process, in particular for situation where the patients move. The object of the present invention is solved by the subject matter of the independent claims. Further advantages and embodiments of the present invention are provided in the dependent claims.

The present invention similarly pertains to the X-ray device, the method for controlling an X-ray imaging process, the program element and the computer-readable medium, although specific embodiments of the present invention will only be described hereinafter in the context of for example the X-ray device or the method. Synergistic effects may arise from different combinations of the embodiments although they might not be described hereinafter in detail.

Further on, it shall be noted that all embodiments of the present invention concerning a method, might be carried out with the order of the steps as described, nevertheless this has not to be the only and essential order of the steps of the method. The herein presented methods can be carried out with another order of the disclosed steps without departing from the respective method embodiment, unless explicitly mentioned to the contrary hereinafter.

According to an exemplary embodiment of the present invention, an X-ray device for imaging a region of interest of a patient is presented. The X-ray device comprises an X-ray imaging device for generating X-ray images of the region of interest of the patient and comprises a motion detection device for detecting a motion of the patient. Furthermore, the X-ray device comprises an exposure switch to be activated by a user to start an X-ray exposure by the X-ray imaging device. Furthermore, a control unit is provided, which is configured to cause the X-ray imaging device to generate an X-ray image of the region of interest of the patient as soon as a patient motion detected by the motion detection device is below a predetermined threshold, when the exposure switch is in an activated state.

Advantageously, when using the X-ray device of the present invention, after activating the exposure switch thus putting the switch in its activated state, the radiographer can be sure that the system releases the exposure always at the moment, where the patient movement is below a predetermined threshold, in other words when the patient is moving the least.

The solution as presented herein will help to reduce the stress of the radiographer during challenging examinations of for example very small kids. In accordance with the invention, an automatic exposure release mechanism of the X-ray device is provided. Advantageously, the radiographer does not have to judge from the control room if the patient is moving and when the best moment to release the exposure occurs. By means of the control unit as described before and hereinafter, X-ray images do not have to be re-taken as the image quality of the X-rays by setting the predetermined threshold correspondingly already meets the user requirements. This reduces the average radiation dose of the patient.

In other words, the control unit of the X-ray device of the present invention may cause an X-ray exposure to be released automatically based on the state of the exposure switch and based on the currently detected movement of the patient. More in particular, the control unit causes an X-ray exposure to be started once the detected patient movement is below a predetermined threshold, when the exposure switch is in its activated state.

The exposure switch is the component of the X-ray device by means of which the user triggers the X-ray exposure process. In principle, this exposure switch may be embodied in various ways, for example as a knob, a mechanical button, a button on a display or may also be a receiver which receives e.g. electromagnetic signals sent out from the user by means of for example a remote control. Of course, also other embodiments of the exposure switch, which are currently available or which will be developed in future, can be realized without departing from the scope of the present invention. It should be noted that the term "exposure button" is synonymously used herein with the term "exposure switch".

The control unit is configured to activate the X-ray imaging device such that the X-ray imaging device generates an X-ray image of the region of interest of the patient. In principle, the control unit of the present invention controls the release of the exposure and provides an auto-exposure mechanism based on the signals and/or information received from the motion detection device. Therefore, this may also be seen as an auto-exposure release mechanism through motion detection of the patient.

In particular, the control unit causes the X-ray imaging device to generate, i.e., to emit, the X-rays when the exposure switch is in its activated state but only when the patient motion detected by the motion detection device since the activation of the exposure switch is below the predetermined threshold.

More in particular, an X-ray exposure may be released as soon as a patient motion is below the threshold. For example, if the motion detection device establishes that the patient is not moving when the user activates the exposure switch, an X-ray exposure may be released immediately following the activation of the switch. If, on the other hand, the motion detection device established that the patient is moving too much at the time of activating the exposure switch, release of the X-ray exposure is delayed until the patient has stopped moving or at least his movement has been reduced to a level below the

predetermined threshold. This pre-set threshold may be stored in the X-ray device itself, e.g. on a storage unit, but may also be stored at a remote location, e.g. on a storage medium in the control room, where the user re-sets the threshold according to his current needs/desires. The X-ray device may contact such a remote storage unit or database via a wireless or a wire bound communication using available technologies. Details hereabout will be explained in more details hereinafter.

It may be seen as a gist of the present invention to provide for a motion detection device in an X-ray device which analyses the movement of the region of interest, for example a collimated extremity, of the patient and which cooperates with a control unit that controls and determines the actual release of X-ray radiation after the user has pressed or activated the exposure switch.

In an embodiment, a camera may be used as the motion detection device, which, for example, can be built into the collimator of the X-ray device, and which takes images of the collimated extremity and compares them, in order to identify the movement of the patient. Exposure will only be released by the control unit in case it is determined from the camera images that the movement of the extremity is within a predefined maximum bandwidth. The radiographer can change the maximum values or even overrule the system at any time, in order to keep him in control of the entire procedure. Further details will be explained and elucidated with exemplary embodiments hereinafter.

Furthermore, the camera used in an embodiment of the present invention may be any camera which facilitates imaging of the region of interest, like for example the extremity of the patient. Electromagnetic radiation of various wavelengths may be used but also other technologies may be applied in order to detect the motion of the patient. In particular, ultrasound may also be applied alternatively or in addition to an electromagnetic radiation based camera. Devices already known or devices that will be developed in future which facilitate a patient motion detection can be applied without departing from the scope of the present invention.

According to another exemplary embodiment of the present invention, the motion detection device is configured to conduct a patient motion measurement after the exposure switch was activated by the user. In other words, in this embodiment the camera is configured upon receiving a signal that the exposure switch has been activated by the user to take images of the collimated extremity and to compare them constantly.

In an embodiment, the motion detection device can be configured to regularly conduct a patient motion measurement after the exposure switch was activated. The frequency of taking and comparing pictures can be set by the user and examples will be given hereinafter in more detail. The camera may receive the signal directly from the exposure switch but may also be activated by the control unit when the exposure switch was activated. Both options can be realized with the non-limiting exemplary X-ray device shown in Fig. 2.

According to another, further specified embodiment the control unit is further configured to abort an ongoing X-ray exposure if the detected patient motion is above the predetermined threshold for a predetermined time frame. The time frame which defines when an X-ray process is automatically aborted by the device can be set by the user at the X-ray device or also from a remote location like the control room.

Thus, in this embodiment, the motion detection device continues to detect a patient motion measurement after the X-ray exposure has been released and X-rays are being generated. When it is found that the detected patient movement has increased to an extent that it exceeds the predetermined threshold, and continues to exceed the threshold for a predetermined time frame, the X-ray exposure may be aborted.

In general, the motion detection device may be configured to start a regular survey of the patient motion after the exposure switch has been pressed or activated by the user, in any case before releasing an actual X-ray exposure but preferably also while X-rays are being generated. Corresponding signals may be exchanged between the exposure switch and the motion detection device. This may be also gathered from the non-limiting and exemplary example shown in Fig. 2. For example, the motion detection device may be configured to take or capture live images of the coUimated anatomy from the moment that the user presses the exposure switch. It may take images in a predefined interval, for example every 1, 2, 5, 10, 20, 50 milliseconds or even more milliseconds, and may compare each new image with older images, for example with the most recent one. Software processes and computer program elements may be used to detect a motion or movement of the patient within the motion detection device. Details about the preferred motion detection will be explained hereinafter in more detail. Further, the abortion can be caused by the control unit or can also be caused by another device of the X-ray device. Further, the comparison unit may measure e.g. the shift of nodal points in x- and y-direction. The difference or delta values, i.e., the Δ values, of the shift in x- and y-direction, i.e., the measured motion of the patient, are calculated and compared with values stored in for example a database. The X-ray tube of the X-ray device finally releases radiation as soon as these parameters are below a predefined threshold value. These values can be defined during clinical studies or may be taken from textbooks. If these values can't be reached, which means that the patient moves constantly too much, within a given time frame, the X-ray device of this exemplary embodiment of the present invention will abort the exposure process.

According to another exemplary embodiment of the present invention, the X- ray device is configured to provide after the abortion of the X-ray exposure process the following functionalities:

a) an additional activation of the exposure switch,

b) an increase of the predetermined threshold, and

c) deactivation of the control unit and manual release of X-ray radiation of the X- ray imaging device.

After the abortion of the process and an optional visual and/or audio feedback for the user, the radiographer or user may then have three options at the X-ray device of the present invention to proceed. He may press an exposure button again and wait if the system will automatically release radiation this time. Thus, the X-ray device is configured after a first abortion to be manually activated again by the user when pushing/using the exposure switch. The user may also increase the values and may thus tolerate more movement of the patient and may press the exposure button again. The X-ray device of the presented embodiment may thus provide for a user interface or for a component at which the user can increase or decrease the values of the threshold. The X-ray device may automatically present this user interface on a display to the user with said functionalities after a first automatic abortion took place. In a third option the user may deactivate the auto-exposure release function and may continue manually with manually releasing the X-ray radiation. Therefore, the X-ray device of this exemplary embodiment is configured to be deactivated by the user such that the auto-exposure release function is switched off. A further specified embodiment which also comprises inter alia said three functionalities of the embodiment described before will be explained in the context of Fig. 5.

According to another exemplary embodiment of the present invention, the motion detection device comprises a comparison unit and a camera wherein the camera is configured upon activation of the exposure switch by the user to generate images of the patient. The comparison unit is configured to determine a motion of the patient based on a comparison of images of the camera.

In a preferred embodiment, a mini-camera which is built into the collimator of the X-ray device may be used. It starts capturing live images of the collimated anatomy from the movement that the radiographer presses the exposure switch. Furthermore, the comparison may be configured to calculate differences between objects of subsequent images of the camera such that a motion is determined based on such calculations.

According to another exemplary embodiment of the present invention, the camera of the motion detection device is configured to generate pictures in a predefined interval after the exposure switch was activated by the user. The comparison unit is configured to compare a new picture of the camera with the most recent picture that has been generated or that was generated by the camera. In other words, the comparison unit is configured to compare a new picture of the camera with a most recently generated picture of the camera. The camera may be configured to take images in a predefined interval, for example every 5, 10, 20, 50, 100 or 200 or even more milliseconds. The comparison unit may compare each new image always with the most recent one. Software means, e.g. a computer program element that is carried out by a calculation unit/processor as described herein processes the digital images by analyzing and comparing patterns. In a further exemplary embodiment said software means may identify at least 5, 10, 20, 50 or 100 or even more nodal points in some or in each pictures generated by the camera of the motion detection device. This anatomy print may be used as a basis for a comparison with data from the previous made image. The comparison unit may measure the shift of each nodal point in x- and y-direction. The Δ values of the shift in x- and y-direction, which may be seen as the measured motion of the patient, are calculated, and compared with the threshold, stored on a storage unit of the X-ray device or in a database to which the X-ray device has a remote access via for example wireless communication. The X-ray device then independently and automatically decides by means of the control unit whether X-rays are to be emitted from the X-ray source of the X-ray imaging device or not.

According to another exemplary embodiment of the present invention, a method for controlling an X-ray imaging process is presented. The method comprises the steps of receiving an activation signal of an exposure switch of an X-ray device when an X- ray image of the region of interest of the patient is desired by a user. Furthermore, a motion of the patient is detected by a motion detection device which may be part of the X-ray device. It is checked in a further step, whether the detected motion of the patient is below a predetermined threshold. This determination may be carried out e.g. in a control unit or in a comparison unit of an X-ray device, but may also be carried out at a remote location outside of the X-ray device. As a further step, the presented method comprises activating an imaging device of the X-ray device for the generation of the X-rays/for generating the X-ray image only when the detected motion of the patient is below the predetermined threshold, i.e., the predetermined threshold value.

In other words this method ensures that an X-ray exposure is only caused when the movement of the patient since the activation of the exposure switch by the user is within a predetermined range or below the threshold. This method may be carried out by the X-ray device as presented before and hereinafter and it may be carried out completely automatically upon activation of the exposure switch. Moreover, this method may be supplemented by additional method steps as of embodiments described herein. Based on a motion detection of the patient, this method provides for an auto-exposure release mechanism which can be realized and embodied in a control unit of the X-ray device. In an exemplary embodiment of the present invention, the method may be carried out by a camera or a mini- camera which is built into the collimator and which is able to capture an image of the collimated patient anatomy. The camera can be configured to capture an image e.g. every few milliseconds. The collimated area and the camera view don't need to be identical.

Furthermore, software means like program elements described herein may be used which process the digital images and calculate the Δχ and Ay values. Predetermined threshold or predetermined threshold values may be stored a storage unit of the X r-ray device or in a database and which comprise Δχ and Ay values per patient group, for example per neonatal group, pre-mature group, per babies or per elderly group or the like. The values for the Δχ and Ay values stored in the database can be based on clinical studies and they determine when the tube should expose radiation.

According to another exemplary embodiment of the present invention, a program element for controlling an X-ray imaging process is presented, which program element, when being executed by a calculation unit/processor, is adapted to carry out the previously described and hereinafter described method steps.

According to another exemplary embodiment of the present invention, a computer-readable medium, in which a computer program for controlling an X-ray imaging process is stored, is presented, which, when being executed by a calculation unit/processor, is adapted to carry out the method step as presented herein.

The computer program element may be part of a computer program, but it can also be an entire program by itself. For example the computer program element may be used to update an already existing computer program to get to the present invention. The computer readable medium may be seen as a storage medium, such as for example, a USB stick, a CD, a DVD, a data storage device, a hard disk, or any other medium on which a program element as described above can be stored.

These and other features of the invention will become apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 schematically shows a flow diagram of a method according to an exemplary embodiment of the present invention.

Fig. 2 schematically shows an X-ray device according to an exemplary embodiment of the present invention.

Fig. 3 shows a comparison between two images of the camera of the motion detection device according to an exemplary embodiment of the present invention.

Fig. 4 schematically shows a head of an X-ray device comprising a camera according to an exemplary embodiment of the present invention.

Fig. 5 schematically shows a flow diagram of a method according to an exemplary embodiment of the present invention

In principle, identical parts are provided with the same reference symbols in the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 shows a method for controlling an X-ray imaging process. This method is illustrated by a flow diagram comprising steps SI to S4. This embodiment of the present invention may be supplemented by additional method steps and may be carried for example by an X-ray device as described herein in the context of various embodiments. In step SI, an activation signal of an exposure switch of an X-ray device is received when an X-ray image of the region of interest of the patient is desired by a user. In other words, in this situation the radiographer has pressed the exposure switch. This signal may be forwarded to a control unit of a respective X-ray device as will be explained in more detail with respect to Figs. 2 and 5. A motion of the patient is detected by a motion detection device of the X-ray device in step S2. Various means may be used in order to determine the movement of the patient. In particular, a camera or a mini-camera which is built into the collimator of the X-ray head can be used. The collimated area and the camera view don't need to be identical. In step S3 it is determined whether the detected motion of the patient is below a predetermined threshold. For this, a calculation unit or a comparison unit may be used which may be embodied as a processor for example. Furthermore, software means and computer program elements that process the digital images and calculate for example Δχ and Ay values in subsequent images of the camera can be used. Furthermore, the imaging device of the X-ray device is activated for the generation of the X-ray only, when the detected motion of the patient is below the predetermined threshold. This is shown with method step S4 in Fig. 1. In case the movement of the patient is too high, the X-ray exposure is not caused or triggered by the X-ray device. Therefore, this method may be seen as an auto-exposure release mechanism which is based on the motion detection of a patient. The device which facilitates an automatic process upon activation of the exposure switch can be exemplarily embodied as follows. An X-ray device which comprises a motion detection system or functionality may be used which analyses the movement of the collimated extremity of the patient and which controls and determines the actual release of X-ray radiation after the user has pressed or activated the exposure switch. A motion detection camera may be used, which, for example, can be built into the collimator of the X-ray device, and which takes images of the collimated extremity and compares them, in order to identify the movement of the patient. Exposure will only be released by the control unit in case the movement of the extremity is within a predefined maximum bandwidth. In an embodiment the radiographer can change the threshold values. Optionally, for example in case of emergency, the radiographer may even overrule the system at any time, in order to keep him in control of the entire procedure.

According to another exemplary embodiment of the present invention, Fig. 2 shows an X-ray device 200. The X-ray device comprises an X-ray imaging device 202 which takes X-ray images of the patient 201. A motion detection device 203 is shown in Fig. 2 which detects a motion of the patient. The motion detection device 203 comprises a camera 207 and a comparison unit 206. The camera is positioned at the collimator of the head 211 of the X-ray device. The camera 207 may be embodied in various different ways according to different embodiments. For example, a single wavelength or multi- wavelength configuration is possible and also the application in combination or as an alternative of ultrasound is possible without departing from the scope of the present invention. The X-ray radiation is shown in Fig. 2 with reference sign 209. As can be gathered from Fig. 2, the collimated area and the camera view don't need to be identical. However, in an exemplary embodiment of the present invention, the collimated area and the camera view are identical. Furthermore, the X-ray device of Fig. 2 comprises the exposure switch 204 which can be activated by a user when he wants to start the X-ray exposure process. The exposure switch 204 is connected ireless or wire-bound to the control unit 205 which is configured to activate the X-ray imaging device to generate an X-ray image of the region of interest of the patient.

Furthermore, a storage device 208 is comprised on which the predetermined threshold is stored. The comparison unit 206 is connected to the storage medium 208 such that the comparison unit may compare the currently detected motion of the patient with the predetermined threshold value stored in storage medium 208. Furthermore, the exposure switch 204 is connected with camera 207, as the camera 207 does capturing live images of the patient upon activation of the exposure switch 204. As can be seen in Fig. 2, control unit 205 is connected with the X-ray head 211 such that the control unit can cause the exposure of X-ray radiation by means of the control signal. However, the control unit 205 is configured to cause the X-ray imaging device 202 to generate the X-ray image after the exposure switch was activated by the user only when the detected motion of the patient is below a

predetermined threshold. The device 200 may take images in a predefined interval, for example every 1, 2, 5, 10, 20, 50 milliseconds or even more milliseconds, and may compare each new image with older images, for example with the most recent one.

In another exemplary embodiment which is based on the embodiment of Fig.

2, the X-ray device aborts the X-ray exposure process after an activation of the exposure switch by the user if the motion of the patient which was since then detected exceeds the predetermined threshold within a given predetermined time frame. Such a system may then give the radiographer or user a visual and/or audio feedback. The user may then have three options to proceed. First he may again press the exposure switch 204 and may wait if the X- ray device will release radiation at this time. He may also increase the values of the predetermined threshold that are acceptable for the user and may again press the exposure switch 204. Such an increase of the predetermined threshold values may be done via a user interface which is not shown in Fig. 2. Furthermore, as a third option, the user may deactivate the auto-exposure release function and may continue manually by releasing the X-ray radiation manually.

According to another exemplary embodiment of the X-ray device of Fig 2, the apparatus 200 is configured to provide the user with a visual feedback signal and/or an audio feedback signal after the abortion of the exposure process. Different means like e.g. lights, flashlights, LEDs, or a loudspeaker for visually or acoustically warn or inform the user may be used. The control unit 205 may send a corresponding signal to the respective component. For example, the comparison unit may measure the shift of nodal points in x- and y-direction. The Δ values of the shift in x- and y-direction, i.e., the measured motion of the patient, are calculated and compared with values stored in for example a database. The X-ray tube of the X-ray device finally releases radiation as soon as these parameters are below a predefined threshold value. These values can be defined during clinical studies or may be taken from textbooks. If these values can't be reached, which means that the patient moves constantly too much, within a given time frame, the X-ray device may in an exemplary embodiment of the present invention abort the exposure process.

Fig. 3 shows a comparison 300 between two pictures of a camera of the comparison unit 206 of an X-ray device according to the present invention. The comparison 300 shows two pictures of two legs 301 and 302 of the patient and also an object of the patient, like a part of a skirt, is shown at two different locations 302 and 303. Based on this object and its different locations, a shift in x-direction 305 and a shift in y-direction 304 can be determined by the comparison unit of the motion detection device of the present invention. Of course also other means and processes for detecting a motion besides determining shifts in x-direction and shifts in y-direction which are known to the skilled person can be used.

Furthermore, Fig. 4 shows a head 400 of an X-ray device in which the collimator 401 comprises an additional camera 402. The camera 402 is configured upon activation of the exposure switch 204 to frequently generate images of the patient, e.g. every 5 milliseconds, within a given time frame/time interval of for example 30 seconds or 1 minute. Of course also other values can be set by the user for the frequency of image capturing and/or for the time interval. Images of such a camera 402 are sent to a comparison unit to determine a motion of the patient based on a comparison of images of the camera 402. This embodiment can be combined with any of the embodiments described herein, for example with the X-ray device 200 of Fig. 2.

Fig. 5 schematically shows a flow diagram of a method for controlling an X- ray imaging process according to another exemplary embodiment of the present invention. The flow diagram 500 of Fig. 5 starts with the initial activation or pressing of the exposure switch at stage 501. The camera as described herein takes a photo of the region of interest, for example of an extremity of the patient at stage 502. Furthermore, at stage 503, another, subsequent photo of the region of interest of the patient is taken by the camera. At stage 504 it is calculated a Δ between the x and y values. The decision process shown in Fig. 5 and implemented in an X-ray device of the present invention or carried out by a method according to the present invention now bifurcates into the two possible options 506 and 505. In case the calculated Δ values in x- and y-direction are smaller than the predetermined threshold the tube of the X-ray device automatically releases X-ray radiation and generates an X-ray image of the patient. This is shown in Fig. 5 at stage 505. However, in case the calculated Δ values in x- and y-direction are larger than the predetermined threshold the system or the method determines at stage 507 whether a predetermined time since the start of the X-ray exposure process at stage 501 already exceeds a given and predetermined time frame. In the exemplary embodiment shown in Fig. 5, this time frame is 10 seconds, however, of course other values may be used in other exemplary embodiments. In case this time frame is not exceeded, the process goes on at stage 508 and again another picture is generated by the camera for another comparison with the picture generated at stage 502. No abortion is caused. In case the time since the start of the process exceeds the predetermined time frame, the system and the method implementing the features of the embodiment of Fig. 5 automatically abort the X-ray exposure process. Three different options are subsequently provided for the user in this exemplary embodiment. The user may again activate the exposure switch which is shown in Fig. 5 by arrow 509. Furthermore, the user may also modify the limit set for the Δχ and Ay values which may be seen as amending the

predetermined threshold. This is shown by stage 510 in Fig. 5. As a third option, the user may deactivate 511 the auto-exposure release function and may manually release X-ray radiation 512 of the X-ray imaging device. Due the working principle and automatic decision making of the system and method of Fig. 5 the radiographer can be sure that the system releases the exposure always at the moment, where the patient is moving the least. The patient will be exposed to a low radiation dose, as the risk of an image re-take significantly drops by using the method and system described by Fig. 5. This solution will help to reduce the stress of the radiographer during challenging examinations of for example very small kids.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from the study of the drawings, the disclosure, and the appended claims. In the claims the word "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items or steps recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored and/or distributed on a suitable medium such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

CLAIMS:

1. An X-ray (200) device for imaging a region of interest of a patient (201), the X-ray device comprising:

an X-ray imaging device (202) for generating X-ray images of the region of interest of the patient,

a motion detection device (203) for detecting a motion of the patient, an exposure switch (204) to be activated by an user to start an X-ray exposure, and

a control unit (205) configured to cause the X-ray imaging device to generate an X-ray image of the region of interest of the patient as soon as a patient motion detected by the motion detection device is below a predetermined threshold, when the exposure switch is in an activated state.

2. X-ray device according to claim 1,

wherein the motion detection device is configured to conduct a patient motion measurement after the exposure switch was activated by the user.

3. X-ray device according to claim 1 or 2,

wherein the control unit is further configured to abort an X-ray exposure process if the detected patient motion is above the predetermined threshold for a

predetermined time frame.

4. X-ray device according to claim 3,

wherein the X-ray device is configured to provide the user with a visual feedback signal and/or an audio feedback signal after the abortion of the exposure process.

5. X-ray device according to one of claims 3 or 4,

wherein the X-ray device after the abortion provides the user with the following alternative functionalities to proceed:

a) an additional activation of the exposure switch, b) an increase of the predetermined threshold, and

c) a deactivation of the control unit and manual release of X-ray radiation of the X-ray imaging device.

6. X-ray device according to any of the preceding claims,

wherein the motion detection device comprises a comparison unit (206) and a camera (207),

wherein the camera is configured upon activation of the exposure switch by the user to generate images of the patient, and

wherein the comparison unit is configured to determine a motion of the patient based on a comparison of images of the camera.

7. X-ray device according to claim 6,

wherein the X-ray imaging device comprises a collimator (401), and wherein the camera of the motion detection device is positioned at the collimator of the X-ray imaging device.

8. X-ray device according to one of claims 6 or 7,

wherein the camera of the motion detection device is configured to generate pictures in a predefined interval after the exposure switch was activated by the user, and wherein the comparison unit is configured to compare a new picture of the camera with a most recently generated picture of the camera.

9. X-ray device according to any of claims 6 to 8,

wherein the comparison unit is configured to identify a predefined number of nodal points in pictures of the camera of the motion detection device, and

wherein the comparison unit is configured to compare the identified nodal points of a picture of the camera with the identified nodal points of a previous picture of the camera.

10. X-ray device according to one of claims 6 to 9,

wherein the comparison unit is configured to measure a shift in x-direction and a shift in y-direction of a specific object in two pictures of the camera of the motion detection device.

11. X-ray device according to one of the preceding claims,

wherein the predetermined threshold is stored in the X-ray device or in a database as a shift in x-direction and in y-direction.

12. A method for controlling an X-ray imaging process, the method comprising the steps:

receiving an activation signal of an exposure switch of an X-ray device when an X-ray image of the region of interest of the patient is desired by a user (SI),

detecting a motion of the patient by a motion detection device (S2), determining whether the detected motion of the patient is below a predetermined threshold (S3), and

activating an imaging device of the X-ray device for generating the X-ray image as soon as the detected motion of the patient is below the predetermined threshold (S4).

13. A computer program element for controlling an X-ray device according to any one of claims 1 to 11 , which program element, when being executed by a processor, is adapted to carry out the steps of a method according to claim 12.

14. A computer-readable medium, on which a computer program element according to claim 13 is stored.