X-ray image diagnostic system, x-ray image diagnostic method, and program

Abstract

To improve image quality of an X-ray image by grasping an actual irradiated region and accurate irradiated position of a detection element with an X-ray.SOLUTION: An X-ray image diagnostic system comprises: an acquisition unit for acquiring an image obtained by imaging a plurality of detection elements for outputting signals depending on an incident X-ray and a plurality of scattered ray removal boards arranged in at least a channel direction on the side of first surfaces, on which the X-ray is incident, of the plurality of detection elements, from a direction approximately normal to the first surfaces; and a generation unit for generating data on an irradiated region of each of plurality of detection elements on the basis of the image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments disclosed in this specification and the drawings relate to an X-ray image diagnostic system, an X-ray image diagnostic method, and a program. [Background technology]

[0002] In an X-ray CT (Computed Tomography) device, an X-ray image is reconstructed by back-projecting a signal that depends on the X-ray flux onto the center of gravity of the range irradiated by X-rays among the detection elements arranged in a planar shape inside the X-ray detector. In a direct conversion type X-ray detector used in a photon counting CT (Photon Counting Computed Tomography) device, etc., the detection elements can be made much finer than conventional indirect conversion type X-ray detectors by miniaturizing the etching pattern of the electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-229605 A Summary of the Invention [Problem to be solved by the invention]

[0004] Anti-scatter grids such as ASG (Anti-Scatter-Grid) used in X-ray detectors are limited by manufacturing technology and have not yet been miniaturized to the extent that electrode patterns created by etching can be made. This can lead to misalignment between the anti-scatter grid and the electrodes (detection elements), which can cause problems with the image quality of the reconstructed X-ray image. In particular, when multiple detection elements are arranged in one grid of the anti-scatter grid, the effect of this misalignment is significant. In addition, in the conventional method, the irradiated positions are uniquely defined at equal intervals based on the anti-scatter grid, but when multiple detection elements are arranged in one grid, the actual irradiated positions are not at equal intervals, which can cause problems with the image quality of the reconstructed X-ray image.

[0005] The problem to be solved by the embodiments disclosed in this specification and the drawings is to improve the image quality of an X-ray image by grasping the actual irradiated area and the exact irradiated position of the X-ray in the detection element. However, the problem to be solved by the embodiments disclosed in this specification and the drawings is not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] The X-ray imaging diagnostic system of the embodiment includes an acquisition unit that acquires an image of a plurality of detection elements that output signals corresponding to incident X-rays and a plurality of scattered ray removal plates arranged at least in the channel direction on the first surface side on which the X-rays are incident of the plurality of detection elements, taken from a direction approximately normal to the first surface, and a generation unit that generates data regarding the irradiated area of ​​each of the plurality of detection elements based on the image. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of the arrangement of an X-ray CT apparatus according to a first embodiment. [Figure 2A]1 is a diagram for explaining the position of the center of gravity of an area irradiated with X-rays when one detection element is arranged for one grid of an ASG in an X-ray detector according to a conventional technique. [Figure 2B] 4 is a diagram for explaining the center of gravity position of an X-ray irradiated region when a plurality of detection elements are arranged for one grid of an ASG in the X-ray detector according to the first embodiment. FIG. [Diagram 3] 3 is a diagram for explaining a configuration for acquiring data regarding an irradiated area of ​​a detection element by using infrared light (reflected light) according to the first embodiment. FIG. [Figure 4] FIG. 4 is a diagram showing an example of a detection element image generated based on infrared light (reflected light) in the first embodiment. [Diagram 5] 5 is a flowchart showing an example of a calculation process for the center of gravity position of a detection element in the X-ray CT apparatus according to the first embodiment. [Figure 6] 5 is a flowchart showing an example of a reconstruction process of a CT image in the X-ray CT apparatus according to the first embodiment. [Figure 7] FIG. 4 is a diagram showing another example of a detection element image generated based on infrared light (reflected light) in the first embodiment. [Figure 8] 13 is a diagram for explaining a configuration for acquiring data regarding an irradiated region of a detection element by using transmitted light of X-rays according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an X-ray image diagnostic system, an X-ray image diagnostic method, and a program according to an embodiment will be described with reference to the drawings.

[0009] <First embodiment> The X-ray image diagnostic system of the first embodiment includes an X-ray diagnostic device that detects X-rays that have passed through a subject using an X-ray detector to generate an X-ray image of the inside of the subject. In the X-ray image diagnostic system, the range (irradiated area) to which X-rays are actually irradiated is accurately grasped for each detection element included in the X-ray detector, and projection processing is performed based on the center of gravity position of this range, thereby improving the image quality of the generated X-ray image. The X-ray diagnostic device includes, for example, an X-ray CT device, an X-ray diagnostic device using a flat panel detector (FPD), and the like. The X-ray CT device includes, for example, a photon counting CT device using a direct conversion type X-ray detector, an X-ray CT device using an indirect conversion type X-ray detector, and the like. In the following, an X-ray CT device (photon counting CT device) will be described as an example.

[0010] [X-ray CT system configuration] FIG. 1 is a diagram showing an example of the configuration of an X-ray CT apparatus 1 (photon-counting CT apparatus) according to the first embodiment. The X-ray CT apparatus 1 includes, for example, a gantry 10, a bed 30, and a console 40. For convenience of explanation, FIG. 1 shows both a view of the gantry 10 from the Z-axis direction and a view of the gantry 10 from the X-axis direction, but in reality, there is only one gantry 10. In the first embodiment, the rotation axis of the rotating frame 17 in a non-tilted state or the longitudinal direction of the top board 33 of the bed 30 is defined as the Z-axis direction, an axis perpendicular to the Z-axis direction and horizontal to the floor surface is defined as the X-axis direction, and a direction perpendicular to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction.

[0011] The gantry device 10 has, for example, an X-ray tube 11, a wedge 12, a collimator 13, an X-ray high voltage device 14, an X-ray detector 15, a data acquisition system (hereinafter referred to as DAS: Data Acquisition System) 16, a rotating frame 17, a control device 18, and a camera 20.

[0012] X-ray tube 11 generates X-rays by irradiating thermoelectrons from a cathode (filament) to an anode (target) when a high voltage is applied from X-ray high voltage device 14. X-ray tube 11 includes a vacuum tube. For example, X-ray tube 11 is a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermoelectrons.

[0013] The wedge 12 is a filter for adjusting the amount of X-rays irradiated from the X-ray tube 11 to the subject P. The wedge 12 attenuates the X-rays passing through it so that the distribution of the amount of X-rays irradiated from the X-ray tube 11 to the subject P becomes a predetermined distribution. The wedge 12 is also called a wedge filter or a bow-tie filter. The wedge 12 is, for example, made by processing aluminum so as to have a predetermined target angle and a predetermined thickness.

[0014] The collimator 13 is a mechanism for narrowing down the irradiation range of the X-rays transmitted through the wedge 12. The collimator 13 narrows down the irradiation range of the X-rays, for example, by forming a slit by combining multiple lead plates. The collimator 13 may also be called an X-ray aperture. The narrowing range of the collimator 13 may be mechanically drivable.

[0015] The X-ray high voltage device 14 has, for example, a high voltage generator (not shown) and an X-ray control device (not shown). The high voltage generator has an electric circuit including a transformer and a rectifier, etc., and generates a high voltage to be applied to the X-ray tube 11. The X-ray control device controls the output voltage of the high voltage generator according to the amount of X-rays to be generated by the X-ray tube 11. The high voltage generator may be one that boosts the voltage using the above-mentioned transformer, or one that boosts the voltage using an inverter. The X-ray high voltage device 14 may be provided on the rotating frame 17, or may be provided on the side of the fixed frame (not shown) of the gantry device 10.

[0016] The X-ray detector 15 detects the intensity of X-rays generated by the X-ray tube 11 and incident on the subject P. The X-ray detector 15 outputs an electrical signal (which may be an optical signal, etc.) corresponding to the intensity of the detected X-rays to the DAS 16. The X-ray detector 15 has, for example, multiple detection element rows. Each of the multiple detection element rows has multiple detection elements arranged in the channel direction along an arc centered on the focal point of the X-ray tube 11. The multiple detection element rows are arranged in the slice direction (column direction, row direction).

[0017] The X-ray detector 15 is, for example, a direct detection type detector. For example, a semiconductor diode with electrodes attached to both ends of a semiconductor can be used as the X-ray detector 15. An X-ray photon incident on the semiconductor is converted into an electron-hole pair. The number of electron-hole pairs generated by the incidence of one X-ray photon depends on the energy of the incident X-ray photon. The electrons and holes are respectively attracted to a pair of electrodes formed on both ends of the semiconductor. The pair of electrodes generates an electric pulse having a pulse height value according to the charge of the electron-hole pair. One electric pulse has a pulse height value according to the energy of the incident X-ray photon.

[0018] FIG. 2A is a diagram for explaining the position of the center of gravity of the X-ray irradiated region (light receiving region) when one detection element is arranged for one grid of the ASG in the X-ray detector according to the conventional technology. In the X-ray CT device 1, a CT image is reconstructed by back-projecting a signal dependent on the X-ray flux to the position of the center of gravity of the range irradiated by the X-ray among the detection elements. FIG. 2A shows an indirect conversion type X-ray detector 15A. In this X-ray detector 15A, a plurality of detection elements 151 are arranged in the channel direction (X-axis direction in FIG. 2A), and one detection element 151 is arranged between adjacent ASG153-1 and ASG153-2, which correspond to one grid of the ASG153. In such a 1-grid-1 detection element configuration, the area between the adjacent ASG153-1 and ASG153-2 becomes the X-ray irradiated region, and the position of the center of gravity between them is defined as the irradiation position PP (projection position). In this 1-grid-1 detection element configuration, a case is assumed in which the detection element 151 is misaligned with respect to the ASG153. In this example, the solid line indicates the assumed position of the designed detector element 151, the dotted line indicates the actual position of the detector element 151 when a positional deviation occurs, and the amount of positional deviation is m. In this case, since the center of gravity position between ASG 153-1 and ASG 153-2 is defined as the irradiated position PP, even if a positional deviation occurs, as long as the partition between the detector elements 151 is hidden by the shadow of ASG 153 (as long as the partition is located below ASG 153 in the Y-axis direction in FIG. 2A), the irradiated position is not affected.

[0019] On the other hand, FIG. 2B is a diagram for explaining the position of the center of gravity of the X-ray irradiated region when a plurality of detection elements are arranged for one grid of the ASG in the X-ray detector according to the first embodiment. FIG. 2B shows a direct conversion type X-ray detector 15B. In this X-ray detector 15B, a plurality of detection elements 151 are arranged in the channel direction (X-axis direction in FIG. 2B), and a plurality of detection elements 151 (detection elements 151-1 to 151-3) are arranged between adjacent ASG153-1 and ASG153-2, which correspond to one grid of the ASG153. In such a configuration of one grid and multiple detection elements, the region between adjacent ASG153-1 and ASG153-2 becomes the X-ray irradiated region. Note that a plurality of detection elements 151 are also arranged in the slice direction (Z-axis direction in FIG. 2B). That is, the multiple ASGs 153 (scattered radiation elimination plates) are arranged in parallel along the channel direction at intervals such that two or more of the multiple detection elements 151 are provided between adjacent ASGs 153 (scattered radiation elimination plates).

[0020] In such a one-grid-multiple-detector-element configuration, for the detector element 151-1 close to the ASG 153-1, the center of gravity between the right end of the ASG 153-1 and the right end of the designed detector element 151-1 is defined as the designed irradiated position PP-1d. The distances along the X-axis from the right end of the ASG 153-1 and the right end of the designed detector element 151-1 to the irradiated position PP-1d are both distances D-1d. For the central detector element 151-2, the center of gravity between the left end and right end of the designed detector element 151-2 is defined as the designed irradiated position PP-2d. The distances along the X-axis from the left end and right end of the designed detector element 151-2 to the irradiated position PP-2d are both distances D-2d. For the detector element 151-3 close to the ASG 153-2, the center of gravity between the designed left end of the detector element 151-3 and the designed left end of the ASG 153-2 is defined as the designed irradiated position PP-3d. The distances along the X axis from the designed left ends of the detector element 151-3 and ASG 153-2 to the designed irradiated position PP-3d are both distances D-3d.

[0021] In such a one-grid-multiple detector element configuration, assume that the detector element 151 is misaligned with respect to the ASG 153. In this example, the solid line indicates the assumed position of the detector element 151 in design, and the dotted line indicates the actual position of the detector element 151 in which the position is misaligned in the channel direction (X-axis direction in FIG. 2B), with the amount of misalignment being m. When the position is misaligned in this configuration, the irradiated position is affected. That is, for the detector element 151-1, the designed irradiated position is PP-1d, but the actual irradiated position PP-1r is the center of gravity between the right end of the ASG 153-1 and the right end of the actual detector element 151-1 in which the position is misaligned. The distances along the X-axis from each of the right end of the ASG 153-1 and the right end of the actual detector element 151-1 to the irradiated position PP-1r are both distances D-1r. In addition, for the detection element 151-2, the designed irradiated position is PP-2d, but the actual irradiated position PP-2r is the center of gravity between the left end and the right end of the actual detection element 151-2 where the position shift occurs. The distances along the X-axis from each of the left end and the right end of the actual detection element 151-2 to the irradiated position PP-2r are both distances D-2r. In addition, for the detection element 151-3, the designed irradiated position is PP-3d, but the actual irradiated position PP-3r is the center of gravity between the left end of the actual detection element 151-3 where the position shift occurs and the left end of the ASG 153-2. The distances along the X-axis from each of the left end of the actual detection element 151-3 and the left end of the ASG 153-2 to the irradiated position PP-3r are both distances D-3r.

[0022] The above-described positional deviation of the detection elements 151 also occurs in the detection elements 151 arranged in the slice direction (the Z-axis direction in FIG. 2B), affecting the irradiated position. That is, deviation may occur between the designed irradiated position and the actual irradiated position.

[0023] In the X-ray image diagnostic system of this embodiment, even if the above-mentioned positional deviation occurs in the detection element 151 in the configuration of one grid-multiple detection elements, the image quality of the generated CT image can be improved by accurately grasping the center of gravity of the region receiving X-rays and performing projection processing based on the center of gravity. Note that this embodiment can also be applied to a sparse channel grid. This makes it possible to simplify the structure of the X-ray detector and reduce costs.

[0024] Returning to FIG. 1, the DAS 16 collects count data (count data) indicating the number of counts of X-ray photons detected by the X-ray detector 15 for a plurality of energy bins, for example, according to a control signal from the control device 18. The count data for a plurality of energy bins corresponds to an energy spectrum for X-rays incident on the X-ray detector 15, which is modified according to the response characteristics of the X-ray detector 15. The DAS 16 outputs detection data based on a digital signal to the console device 40. The detection data is a digital value of count data identified by the channel number and row number of the detection element from which the data was generated, and a view number indicating the collected view. The view number is a number that changes according to the rotation of the rotating frame 17, for example, a number that is incremented according to the rotation of the rotating frame 17. Therefore, the view number is information indicating the rotation angle of the X-ray tube 11. The view period is a period that falls within the period from a rotation angle corresponding to a certain view number to a rotation angle corresponding to the next view number. The DAS 16 collects signals output by each of the plurality of detection elements 151. The DAS 16 is an example of a "collection unit."

[0025] The DAS 16 may detect the view switching by a timing signal input from the control device 18, by an internal timer, or by a signal obtained from a sensor (not shown). When performing a full scan and X-rays are continuously irradiated by the X-ray tube 11, the DAS 16 collects a group of detection data for the entire circumference (360 degrees). When performing a half scan and X-rays are continuously irradiated by the X-ray tube 11, the DAS 16 collects detection data for half the circumference (180 degrees).

[0026] The rotating frame 17 is an annular member that supports the X-ray tube 11, the wedge 12, the collimator 13, and the X-ray detector 15 in opposing relation to each other. The rotating frame 17 is supported by a fixed frame so as to be rotatable about the subject P introduced inside. The rotating frame 17 also supports the DAS 16. Detection data output by the DAS 16 is transmitted by optical communication from a transmitter having a light-emitting diode (LED) provided on the rotating frame 17 to a receiver having a photodiode provided on a non-rotating part (e.g., the fixed frame) of the gantry device 10, and is transferred to the console device 40 by the receiver. Note that the method of transmitting detection data from the rotating frame 17 to the non-rotating part is not limited to the above-mentioned method using optical communication, and any non-contact type transmission method may be adopted. The rotating frame 17 is not limited to an annular member, and may be an arm-like member as long as it can support and rotate the X-ray tube 11, etc.

[0027] The control device 18 has a processing circuit having a processor such as a CPU (Central Processing Unit). The control device 18 receives an input signal from an input interface attached to the console device 40 or the gantry device 10, and controls the operations of the gantry device 10, the bed device 30, the DAS 16, and the camera 20. For example, the control device 18 rotates the rotating frame 17 and tilts the gantry device 10. When tilting the gantry device 10, the control device 18 rotates the rotating frame 17 around an axis parallel to the Z-axis direction based on an inclination angle (tilt angle) input to the input interface. The control device 18 grasps the rotation angle of the rotating frame 17 based on the output of a sensor (not shown) or the like. The control device 18 may be provided in the gantry device 10 or in the console device 40.

[0028] The X-ray CT device 1 is, for example, a Rotate / Rotate-type X-ray CT device (third generation CT) in which both the X-ray tube 11 and the X-ray detector 15 are supported by a rotating frame 17 and rotate around the subject P, but is not limited to this and may be a Stationary / Rotate-type X-ray CT device (fourth generation CT) in which multiple detection elements arranged in a circular ring are fixed to a fixed frame and the X-ray tube 11 rotates around the subject P.

[0029] The camera 20 captures each detection element included in the X-ray detector 15. The camera 20 is, for example, an infrared camera. The camera 20 irradiates the detection element with infrared light, detects the reflected light (light reflected by the electrode provided at the bottom of the detection element and the ASG 153) and converts it into an electric signal. The camera 20 is provided at an arbitrary position where it can capture the detection element inside the X-ray detector 15 or the like. For example, the camera 20 captures the detection element inside the X-ray detector 15 or the like from a position in a direction substantially normal to the first surface at a timing when the X-ray CT device 1 is not capturing images. The camera 20 may be detachable from the X-ray CT device 1. For example, the camera 20 may be attached to the bed device 30 and stored when not in use.

[0030] FIG. 3 is a diagram for explaining how infrared light (reflected light) reflected by a detection element according to the first embodiment is acquired. As shown in FIG. 3, a plurality of detection elements 151 are arranged in the channel direction (X-axis direction in FIG. 3) in the X-ray detector 15C. In addition, ASGs 153 are similarly arranged in the channel direction (X-axis direction in FIG. 3) on the first surface side (X-ray irradiation side) of the row of the detection elements 151. The X-ray detector 15C has a one-grid-multiple detection element configuration. An anode 155 is arranged on the second surface side facing the first surface of each detection element 151. The camera 20 is provided on the first surface side and irradiates infrared light onto the first surface of the detection element 151. In general, materials such as cadmium telluride (CdTe), CZT (CdZnTe), and silicon (Silicon) used in the detection element 151 transmit infrared light. On the other hand, materials such as tungsten (W) and molybdenum (Mo) used for the ASG 153 and materials such as gold (Au) and platinum (Pt) used for the anode 155 do not transmit infrared light but reflect it. Therefore, images of the anode 155 and the ASG 153 are captured by the reflected light of the infrared light irradiated by the camera 20. Since the ASG 153 is in the shadow of the infrared light, the detection element 151 (the same area as the X-ray irradiation field) paired with each anode 155 can be imaged by using the reflected light by the anode 155. Note that when the detection elements 151 are arranged extending in the body axis direction (column direction, Z-axis direction in FIG. 3), the camera 20 (light source and sensor) is extended in the body axis direction to capture an image of the infrared camera.

[0031] Fig. 4 is a diagram showing an example of a detector image generated based on infrared light (reflected light) in the first embodiment. As shown in Fig. 4, the detector image shows the actual X-ray irradiation range of each of the multiple detector elements 151 (151-1 to 151-9) arranged in the channel direction (X-axis direction in Fig. 4) and slice direction (Z-axis direction in Fig. 4). Using this detector image, it is possible to obtain the center of gravity C of the actual X-ray irradiation range of each detector element 151.

[0032] Returning to FIG. 1, the bed device 30 is a device that places and moves the subject P to be scanned and introduces the subject P into the rotating frame 17 of the gantry device 10. The bed device 30 includes, for example, a base 31, a bed driving device 32, a top plate 33, and a support frame 34. The base 31 includes a housing that supports the support frame 34 so that the support frame 34 can move in the vertical direction (Y-axis direction). The bed driving device 32 includes a motor and an actuator. The bed driving device 32 moves the top plate 33 in the longitudinal direction (Z-axis direction) of the top plate 33 along the support frame 34. The bed driving device 32 also moves the top plate 33 in the vertical direction (Y-axis direction). The top plate 33 is a plate-shaped member on which the subject P is placed.

[0033] The bed driving device 32 may move not only the tabletop 33 but also the support frame 34 in the longitudinal direction of the tabletop 33. Conversely to the above, the gantry device 10 may be movable in the Z-axis direction, and the rotation frame 17 may be controlled to come to the periphery of the subject P by the movement of the gantry device 10. Also, a configuration in which both the gantry device 10 and the tabletop 33 are movable may be used. The X-ray CT device 1 may be an apparatus in which the subject P is scanned in a standing or sitting position. In this case, the X-ray CT device 1 has a subject support mechanism instead of the bed device 30, and the gantry device 10 rotates the rotation frame 17 around an axial direction perpendicular to the floor surface.

[0034] The console device 40 includes, for example, a memory 41, a display 42, an input interface 43, a network connection circuit 44, and a processing circuit 50. In this embodiment, the console device 40 is described as being separate from the gantry device 10, but the gantry device 10 may include some or all of the components of the console device 40.

[0035] The memory 41 is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory), a flash memory, a hard disk, an optical disk, etc. The memory 41 stores, for example, design data DD, center of gravity data CD (correction parameters), detection data, projection data, reconstructed image data, information on the subject P, imaging conditions, etc. These data may be stored in an external memory with which the X-ray CT apparatus 1 can communicate, instead of the memory 41 (or in addition to the memory 41). The external memory is controlled by a cloud server that manages the external memory, for example, by the cloud server accepting a read / write request.

[0036] The display 42 displays various types of information. For example, the display 42 displays medical images (CT images) generated by a processing circuit, GUI (Graphical User Interface) images that accept various operations by an operator such as a doctor or an engineer, and the like. The display 42 is, for example, a liquid crystal display, a CRT (Cathode Ray Tube), an organic EL (Electroluminescence) display, or the like. The display 42 may be provided on the gantry device 10. The display 42 may be a desktop type, or may be a display device (for example, a tablet terminal) that can wirelessly communicate with the main body of the console device 40.

[0037] The input interface 43 accepts various input operations by an operator and outputs an electrical signal indicating the contents of the accepted input operation to the processing circuitry 50. For example, the input interface 43 accepts input operations such as collection conditions when collecting detection data or projection data, reconstruction conditions when reconstructing a CT image, etc. For example, the input interface 43 is realized by a mouse, a keyboard, a touch panel, a drag ball, a switch, a button, a joystick, a camera, an infrared sensor, a microphone, etc.

[0038] The input interface 43 may be provided in the gantry device 10. The input interface 43 may also be realized by a display device (e.g., a tablet terminal) capable of wireless communication with the main body of the console device 40. In this specification, the input interface is not limited to an input interface having physical operation parts such as a mouse and a keyboard. For example, an example of the input interface also includes an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs the electrical signal to a control circuit.

[0039] The network connection circuit 44 includes, for example, a network card having a printed circuit board, a wireless communication module, etc. The network connection circuit 44 implements an information communication protocol according to the type of the network to be connected.

[0040] The processing circuit 50 controls the overall operation of the X-ray CT apparatus 1, the operation of the gantry device 10, the operation of the bed device 30, the operation of the camera 20, etc. The processing circuit 50 executes, for example, a system control function 51, a pre-processing function 52, a reconstruction function 53, an image processing function 54, an acquisition function 55, a scan control function 56, a generation function 57, a display control function 58, etc. These components are realized, for example, by a hardware processor (computer) executing a program (software) stored in the memory 41. The hardware processor means, for example, a circuit such as a CPU, a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), a programmable logic device (for example, a Simple Programmable Logic Device (SPLD) or a Complex Programmable Logic Device (CPLD), a Field Programmable Gate Array (FPGA)), etc.

[0041] Instead of storing the program in memory 41, the program may be directly built into the circuit of the hardware processor. In this case, the hardware processor realizes the function by reading and executing the program built into the circuit. The hardware processor is not limited to being configured as a single circuit, and may be configured as one hardware processor by combining multiple independent circuits to realize each function. Also, multiple components may be integrated into one hardware processor to realize each function.

[0042] Each component of the console device 40 or the processing circuit 50 may be distributed and realized by multiple pieces of hardware. The processing circuit 50 may be realized by a processing device capable of communicating with the console device 40, rather than being a component of the console device 40. The processing device is, for example, a workstation connected to one X-ray CT device, or a device (for example, a cloud server) connected to multiple X-ray CT devices and collectively executing processing equivalent to that of the processing circuit 50 described below.

[0043] The system control function 51 controls various functions of the processing circuit 50 based on the input operation received by the input interface 43 .

[0044] A pre-processing function 52 performs pre-processing such as offset correction, inter-channel sensitivity correction, and beam hardening correction on the detection data output by the DAS 16 .

[0045] The reconstruction function 53 generates a reconstructed image (CT image) of the subject P based on the detection data (signal) and data on the irradiated region. The reconstruction function 53 has, for example, a correction function 531. The correction function 531 corrects the irradiated position of the detection data based on the data on the irradiated region of each of the detection elements generated by the generation function 57. The reconstruction function 53 is an example of a "reconstruction section." The reconstruction function 53 generates a reconstructed image by taking the center of gravity position of the actual irradiated region of each of the multiple detection elements 151 included in the data on the irradiated region as the irradiated position.

[0046] The image processing function 54 converts the CT image data into three-dimensional image data or CT image data of an arbitrary cross section by a known method based on the input operation received by the input interface 43. The conversion into three-dimensional image data may be performed by the pre-processing function 52.

[0047] The acquisition function 55 acquires an image (detector element image) of a plurality of detector elements 151 that output signals according to incident X-rays, and a plurality of ASGs 153 (scattered radiation removal plates) arranged at least in the channel direction on the first surface side of the plurality of detector elements 151 on which X-rays are incident, captured from a direction approximately normal to the first surface. The acquisition function 55 acquires a detector element image generated based on reflected light data transmitted from the camera 20. The acquisition function 55 includes, for example, an image generation function 551. The image generation function 551 generates a detector element image based on the reflected light data. The acquisition function 55 is an example of an "acquisition unit".

[0048] The scan control function 56 issues instructions to the X-ray high voltage device 14, the DAS 16, the control device 18, and the bed driving device 32 to control the collection process of detection data in the gantry device 10. The scan control function 56 performs control for the monitoring scan and the main scan. The scan control function 56 also controls the operation of each part when capturing images for collecting positioning images and when capturing images used for diagnosis.

[0049] The generating function 57 generates data (center of gravity data) on the irradiated region of each of the multiple detecting elements based on the detecting element image acquired by the acquiring function 55. The generating function 57 generates data in which the information on the center of gravity position of the actual irradiated region of each of the multiple detecting elements is set as the irradiated position among the regions of the multiple detecting elements included in the detecting element image. The generating function 57 is an example of a "generating unit". That is, the acquiring function 55 acquires an infrared light image based on output data corresponding to infrared light irradiated from a light source provided on the first surface side and reflected by electrodes corresponding to each of the multiple detecting elements and the multiple scattered radiation removing plates, and the generating function 57 generates data on the irradiated region based on the infrared light image.

[0050] The display control function 58 causes the display 42 to display CT images generated by the processing circuit, GUI images that accept various operations by operators such as doctors and engineers, detection element images, images showing data regarding the irradiated area, and the like.

[0051] With the above configuration, the X-ray CT device 1 scans the subject P in a scan mode such as a helical scan, a conventional scan, or a step-and-shoot. A helical scan is a mode in which the subject P is scanned in a spiral manner by rotating the rotating frame 17 while moving the top plate 33. A conventional scan is a mode in which the subject P is scanned in a circular orbit by rotating the rotating frame 17 while keeping the top plate 33 stationary. A step-and-shoot is a mode in which the position of the top plate 33 is moved at regular intervals and conventional scans are performed in multiple scan areas.

[0052] [Processing flow] <Calculation process of center of gravity data> Next, an example of calculation processing of center of gravity data will be described. Fig. 5 is a flowchart showing an example of calculation processing of center of gravity data of detection elements in the X-ray CT apparatus according to the first embodiment. The processing shown in Fig. 5 is started when, for example, an operator of the X-ray CT apparatus 1 issues an instruction to start calculation processing of center of gravity data via the input interface 43 during apparatus maintenance (when assembling or replacing the X-ray detector), etc.

[0053] First, the acquisition function 55 transmits an infrared light irradiation signal to the camera 20, and causes the camera 20 to irradiate the infrared light to the detection element 151 (step S101). The infrared light passes through the detection element 151, is reflected by the anode 155 paired with the detection element 151, and is detected by the camera 20.

[0054] Next, the image generating function 551 performs imaging processing based on the reflected light data detected by the camera 20 (step S103). As a result, a detection element image showing the actual irradiated area of ​​each of the detection elements 151 is generated.

[0055] Next, the generating function 57 performs image analysis on the generated detection element image to calculate the center of gravity (coordinates) of each irradiation area of ​​the detection element 151 (step S105). Next, the generating function generates center of gravity data CD that summarizes the calculated data of the center of gravity of each irradiation area of ​​the detection element 151, and stores it in the memory 41 (step S107). With this, the processing of this flowchart is completed.

[0056] <Reconstruction process> Next, an example of the reconstruction process will be described. Fig. 6 is a flowchart showing an example of the reconstruction process of the CT image in the X-ray CT device according to the first embodiment. The process shown in Fig. 6 is started when, for example, the operator of the X-ray CT device 1 issues an instruction to start the imaging process of the subject P.

[0057] First, the reconstruction function 53 acquires detection data collected by the DAS 16 by irradiating the subject P with X-rays (step S201).

[0058] Next, the correction function 531 corrects the center of gravity positions defined in advance in the design data DD using data on the center of gravity positions of the respective detector elements 151 included in the center of gravity data CD (step S203).

[0059] Next, the reconstruction function 53 reconstructs a CT image of the subject P based on the corrected center of gravity position data (step S205). The reconstructed CT image is displayed, for example, on the display 42, so that the operator can check the CT image. With the above, the processing of this flowchart is completed.

[0060] According to the first embodiment described above, the image quality of the X-ray image can be improved by grasping the X-ray irradiated area (actual irradiation range) and the exact irradiated position in the detection element. Since the irradiated position can be grasped accurately, the spatial resolution of the X-ray diagnostic device can be improved. Also, artifacts in the X-ray image can be reduced.

[0061] In the above, a configuration in which one grid is surrounded by four ASGs 153 has been described as an example, but this embodiment is not limited to this. This embodiment can also be applied to a configuration in which the ASGs 153 are arranged only in one dimension (for example, the Z-axis direction in FIG. 7) as shown in FIG.

[0062] <Second embodiment> Next, a second embodiment will be described. Compared to the first embodiment, the second embodiment is different in that it targets an indirect conversion type X-ray detector and obtains data on the irradiated area of ​​the detection element using transmitted X-ray light. Hereinafter, the X-ray CT device 1 of the second embodiment will be described, focusing on the differences from the first embodiment.

[0063] FIG. 8 is a diagram for explaining a configuration in which data on an irradiated region of a detection element is acquired using transmitted light of an X-ray according to the second embodiment. As shown in FIG. 8, a plurality of detection elements 151 are arranged along the channel direction (X-axis direction in FIG. 8) in the X-ray detector 15D. In addition, ASGs 153 are similarly arranged along the channel direction (X-axis direction in FIG. 8) on the first surface side (X-ray irradiation side) of the row of the detection elements 151. The X-ray detector 15D has a one-grid-multiple detection element configuration. A partition 157 is arranged between each detection element 151. The X-ray tube 11 is provided on the first surface side and irradiates X-rays to the first surface of the detection element 151. In general, materials such as GOS, LYSO, CWO, and BGO contained in the scintillator used in the indirect conversion type detection element 151 have high absorption for X-rays. In addition, materials such as tungsten (W) and molybdenum (Mo) used in the ASG 153 also have high absorption for X-rays. On the other hand, materials such as epoxy resin and alumina (Al2O3) used for the partition 157 have low absorption of X-rays.

[0064] The X-rays irradiated from the X-ray tube 11 to the first surface of the detection element 151 are absorbed by the detection element 151 and the ASG 153, but are not absorbed by the partition 157 and are transmitted through. When an image is generated using detection data obtained by detecting such transmitted X-ray light by the transmission X-ray detector 22, an image of the partition 157 that is not hidden by the ASG 153 is captured. In this image, the shadowed area corresponds to the ASG 153 and the area of ​​the detection element 151. Therefore, the image generation function 551 can generate a detection element image of the range of the detection element 151, i.e., the area of ​​each detection element 151 irradiated with X-rays, by excluding the area corresponding to the ASG 153 from the shadowed area in this image.

[0065] That is, the acquisition function 55 acquires a transmission image based on output data corresponding to X-rays irradiated from the X-ray tube 11 provided on the first surface side and transmitted through the partitions 157 of the multiple detection elements 151, and the generation function 57 generates data on the irradiated region based on the transmission image. The generation function 57 generates data on the irradiated region by excluding a region corresponding to the ASG 153 (scattered radiation removal plate) from the shadowed region in the transmission image.

[0066] According to the second embodiment described above, the image quality of the X-ray image can be improved by grasping the X-ray irradiated area (actual irradiated area) and the exact irradiated position in the detection element. Since the irradiated position can be grasped accurately, the spatial resolution of the X-ray diagnostic device can be improved. Also, artifacts in the X-ray image can be reduced.

[0067] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0068] 1...X-ray CT device, 10...mounting device, 11...X-ray tube, 12...wedge, 13...collimator, 14...X-ray high voltage device, 15...X-ray detector, 16...data acquisition system (DAS), 17...rotating frame, 18...control device, 20...camera, 22...transmission X-ray detector, 30...bed device, 31...base, 32...bed drive device, 33...top plate, 34...support frame, 40...console device, 41...memory, 42...data Display, 43... input interface, 44... network connection circuit, 50... processing circuit, 51... system control function, 52... pre-processing function, 53... reconstruction function, 531... correction function, 54... image processing function, 55... acquisition function, 551... image generation function, 56... scan control function, 57... generation function, 58... display control function, 151... detection element, 153... ASG (scattered radiation removal plate), 155... anode, 157... partition

Claims

1. an acquisition unit that acquires an image of a plurality of detection elements that output signals corresponding to incident X-rays and a plurality of scattered radiation removal plates that are arranged at least in a channel direction on a first surface side of the plurality of detection elements on which the X-rays are incident, taken in a direction substantially normal to the first surface; A generating unit that generates data regarding an irradiated region of each of the plurality of detection elements based on the image; An X-ray imaging diagnostic system comprising:

2. The generation unit generates the data in which a center of gravity position of an actual irradiated area of ​​each of the plurality of detection elements is set as an irradiated position within the area of ​​the plurality of detection elements included in the image. The X-ray imaging diagnostic system according to claim 1 .

3. the plurality of anti-scatter plates are arranged in parallel along the channel direction at intervals such that two or more of the plurality of detection elements are provided between adjacent anti-scatter plates; The X-ray imaging diagnostic system according to claim 1 .

4. The plurality of detection elements; The plurality of scattered radiation elimination plates; A collection unit that collects signals output by each of the plurality of detection elements; a reconstruction unit that generates a reconstructed image based on the signal and the data; Further comprising: The X-ray imaging diagnostic system according to claim 1 .

5. the reconstruction unit generates the reconstructed image by taking the center of gravity of the actual irradiated region of each of the plurality of detection elements included in the data as an irradiated position. The X-ray imaging diagnostic system according to claim 4.

6. the acquisition unit acquires an infrared light image based on output data corresponding to infrared light irradiated from a light source provided on the first surface side and reflected by electrodes corresponding to each of the plurality of detection elements and the plurality of scattered radiation removal plates; The generation unit generates the data based on the infrared light image. The X-ray imaging diagnostic system according to claim 1 .

7. the acquisition unit acquires a transmission image based on output data corresponding to X-rays that are irradiated from an X-ray tube provided on the first surface side and transmitted through partitions of the plurality of detection elements; The generation unit generates the data based on the transmission image. The X-ray imaging diagnostic system according to claim 1 .

8. the generating unit generates the data by excluding an area corresponding to the scattered radiation removal plate from an area that is in shadow in the transmission image. The X-ray imaging diagnostic system according to claim 7.

9. The computer acquiring an image of a plurality of detection elements that output signals according to incident X-rays and a plurality of scattered radiation removal plates arranged at least in a channel direction on a first surface side of the plurality of detection elements on which the X-rays are incident, from a direction substantially normal to the first surface; generating data relating to an illuminated area of ​​each of the plurality of detector elements based on the image; X-ray imaging diagnostic methods.

10. On the computer, acquiring an image of a plurality of detection elements that output signals according to incident X-rays and a plurality of scattered radiation removal plates arranged at least in a channel direction on a first surface side of the plurality of detection elements on which the X-rays are incident, in a direction substantially normal to the first surface; generating data relating to an illuminated area of ​​each of the plurality of detection elements based on the image; program.

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