Direct conversion X-ray detector and X-ray computed tomography device

Abstract

To improve maintainability in a direct conversion type X-ray detector.SOLUTION: A direct conversion type X-ray detector according to an embodiment includes a plurality of detector modules, a single bias voltage generator, a common electrode and a conductor. The detector modules are arranged in a channel direction and include semiconductor crystal. The single bias voltage generator generates a bias voltage to be applied between a cathode electrode provided on the semiconductor crystal and an anode electrode provided on the semiconductor crystal. The common electrode is electrically connected to the bias voltage generator and extends in the channel direction. The conductor electrically connects the common electrode and the cathode electrode of the semiconductor crystal in each of the detector modules.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The embodiments disclosed in this specification and the drawings relate to a direct conversion type X-ray detector and an X-ray computed tomography apparatus. [Background technology]

[0002] Conventionally, direct conversion X-ray detectors have been used in X-ray computed tomography systems. Direct conversion X-ray detectors collect ion pairs generated by the interaction of X-rays with a semiconductor or high-pressure gas from electrodes using high voltage. This allows direct conversion X-ray detectors to obtain a charge output proportional to the intensity of the incident X-rays. Therefore, direct conversion X-ray detectors require a higher-voltage power supply than indirect conversion X-ray detectors. That is, a high voltage must be applied to each of the multiple detector modules in a direct conversion X-ray detector. Examples of configurations for applying a high voltage to each of the multiple detector modules include providing a high-voltage power supply to each of the multiple detector modules and supplying the high voltage to each detector module via a high-voltage cable (or high-voltage wiring), or providing a large external power supply and distributing the high voltage to each of the multiple detector modules via a high-voltage cable.

[0003] In either case, when the detector module is replaced during maintenance of the X-ray detector, the number of steps may increase due to wiring and routing of high-voltage cables, etc. For this reason, the maintainability of direct conversion type X-ray detectors may be low for service personnel and the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special publication 2006-509198 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the maintainability of a direct conversion X-ray detector. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0006] The direct conversion X-ray detector according to this embodiment includes a plurality of detector modules, a single bias voltage generator, a common electrode, and a conductor. The plurality of detector modules are arranged in the channel direction and include semiconductor crystals. The single bias voltage generator generates a bias voltage to be applied between a cathode electrode provided in the semiconductor crystal and an anode electrode provided in the semiconductor crystal. The common electrode is electrically connected to the bias voltage generator and extends in the channel direction. The conductor electrically connects the common electrode to the cathode electrode of the semiconductor crystal in each of the plurality of detector modules. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of the arrangement of an X-ray CT apparatus according to an embodiment. [Figure 2] FIG. 2 is a diagram showing an example of an outline of the X-ray detector 12 as viewed along the long axis direction (Z-axis direction) of the tabletop according to the embodiment. [Figure 3] 3 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2 according to the embodiment. [Figure 4] 4 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2 according to the embodiment, which is different from FIG. 3. FIG. [Figure 5] 5 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2 according to the embodiment, which is different from FIGS. 3 and 4. FIG. [Figure 6]6 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2 according to the embodiment, and is different from FIGS. 3 to 5. FIG. [Figure 7] 7 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2 according to the embodiment, and is different from FIGS. 3 to 6. FIG. [Figure 8] 8 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2, different from FIG. 5, according to a modified example of the embodiment. [Figure 9] 9 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2, different from FIG. 8, according to a modified example of the embodiment. [Figure 10] 10 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2 according to a modified example of the embodiment, which is different from FIGS. 8 and 9. FIG. [Figure 11] 11 is a cross-sectional view taken along the dashed dotted line AA′ in FIG. 2 according to the embodiment, and is different from FIGS. 8 to 10. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, with reference to the drawings, embodiments of a direct conversion type X-ray detector and an X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT (computed tomography) apparatus) equipped with the X-ray detector will be described in detail. Note that the X-ray detector may be realized as a radiation detector that detects gamma rays and the like. A radiation detector that detects gamma rays may be called a gamma ray detector. In this case, a radiation diagnostic apparatus equipped with the radiation detector is realized as, for example, a nuclear medicine diagnostic apparatus. In the following embodiments, parts with the same reference symbols perform similar operations, and duplicated explanations will be omitted as appropriate.

[0009] For the sake of specificity, the X-ray CT apparatus described in the following embodiments is assumed to be an apparatus capable of performing photon-counting CT. In other words, the X-ray CT apparatus is an apparatus capable of reconstructing X-ray CT image data with a high S / N ratio by counting X-rays transmitted through a subject using a photon-counting detector, rather than a conventional integral (current-mode measurement) detector. Furthermore, the photon-counting detector in this embodiment is a direct conversion detector (hereinafter referred to as a direct conversion detector) having a crystal that converts incident X-rays into electrons, i.e., electrical signals. In other words, the radiation detector installed in a radiological diagnostic apparatus corresponds to a direct conversion detector having a semiconductor crystal that directly converts radiation incident on the radiation detector into an electrical signal.

[0010] (Embodiment) FIG. 1 is a diagram showing an example of the configuration of an X-ray CT apparatus 1 according to this embodiment. As shown in FIG. 1, the X-ray CT apparatus 1 includes, for example, a gantry apparatus 10, a bed apparatus 30, and a console apparatus 40. In this embodiment, the rotation axis of the rotating frame 13 in a non-tilted state or the longitudinal direction of the tabletop 33 of the bed apparatus 30 is defined as the Z-axis direction, the axial direction perpendicular to the Z-axis direction and horizontal to the floor surface is defined as the X-axis direction, and the axial direction perpendicular to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction. For convenience of explanation, multiple gantry apparatuses 10 are depicted in FIG. 1, but the actual configuration of the X-ray CT apparatus 1 includes only one gantry apparatus 10.

[0011] The gantry 10 and the bed 30 operate based on a user's operation via the console 40 or an operation unit provided on the gantry 10 or the bed 30. The gantry 10, the bed 30, and the console 40 are connected to each other by wire or wirelessly so as to be able to communicate with each other.

[0012] The gantry device 10 is an apparatus having an imaging system that irradiates an object P with X-rays and collects projection data from detection data of the X-rays that have passed through the object P. The gantry device 10 has an X-ray tube 11 (X-ray generation unit), a direct conversion type X-ray detector 12, a rotating frame 13, a wedge 16, an X-ray high voltage device 17, a control device 18, a source side collimator 19, and a DAS (Data Acquisition System) 21.

[0013] The X-ray tube 11 is a vacuum tube that generates X-rays by irradiating thermoelectrons from a cathode (filament) toward an anode (target) when a high voltage is applied from the X-ray high voltage device 17 and a filament current is supplied. X-rays are generated when the thermoelectrons collide with the target. The X-rays generated at the tube focus of the X-ray tube 11 are shaped into a cone beam via a collimator 20, for example, and irradiated onto the subject P. For example, the X-ray tube 11 may be a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermoelectrons. Note that this embodiment can be applied to both a single-tube X-ray CT device and a so-called multi-tube X-ray CT device in which multiple pairs of X-ray tubes 11 and X-ray detectors 12 are mounted on a rotating frame 13.

[0014] The direct conversion type X-ray detector 12 detects X-rays emitted from the X-ray tube 11 and passing through the subject P. The X-ray detector 12 outputs an electrical signal corresponding to the X-ray dose to the DAS 21. The X-ray detector 12 may also be referred to as a direct conversion type detector. The X-ray detector 12 includes, for example, a plurality of detector modules, a collimator module, a single bias voltage generator, a common electrode, a conductor, and a first elastic body. The plurality of detector modules are arranged in the channel direction along an arc centered on the focal point of the X-ray tube 11, for example.

[0015] In each of the multiple detector modules, electrodes are provided on opposing surfaces of a semiconductor crystal such as CdTe (cadmium telluride) or CdZnTe (cadmium zinc telluride: CZT), and an electric field is generated by applying a bias voltage. In the X-ray detector 12, when radiation is absorbed by the crystal, electron-hole pairs are generated, and the electrons move to the anode side (anode electrode (pixel electrode) side) and the holes move to the cathode side (cathode electrode side), thereby outputting a signal.

[0016] Each of the plurality of detector modules is provided with a plurality of anode electrodes and a plurality of cathode electrodes. In each of the plurality of detector modules, a surface formed by the plurality of anode electrodes corresponds to an anode surface. In each of the plurality of detector modules, a surface formed by the plurality of cathode electrodes corresponds to a cathode surface.

[0017] The single bias voltage generating unit generates a bias voltage to be applied between a cathode electrode provided on the semiconductor crystal and an anode electrode provided on the semiconductor crystal. The single bias voltage generating unit is realized as hardware, for example, by a single high-voltage power supply (bias power supply). The common electrode is electrically connected to the single bias voltage generating unit and is provided extending in the channel direction. The common electrode is realized, for example, by a bus bar, which is a metal conductor rod. For the sake of concreteness, the common electrode will be referred to as a bus bar hereinafter.

[0018] The conductor electrically connects the bus bar to the cathode electrode of the semiconductor crystal in each of the detector modules. Note that the outputs from the multiple anode electrodes may be combined as needed based on the imaging conditions for the subject P or a user instruction via the input interface 43. For the sake of concreteness, the following description will be given assuming that the outputs from the multiple anode electrodes are each processed independently as outputs corresponding to a pixel.

[0019] Each of the multiple anode electrodes (hereinafter referred to as a detection element) outputs one pulse of an electrical signal (analog signal) each time an X-ray photon is incident on it. By counting the number of electrical signals (pulses), it is possible to count the number of X-ray photons incident on each detection element. In addition, by performing various calculations on this signal, it is possible to measure the energy value of the X-ray photon that caused the output of that signal.

[0020] In addition to the above-described detecting elements, the X-ray detector 12 includes, for example, a plurality of application specific integrated circuits (hereinafter referred to as ASICs (Application Specific Integrated Circuits)) connected to the detecting elements and counting the X-ray photons detected by the detecting elements. The ASIC counts the number of X-ray photons incident on the detecting elements by measuring the "number of pulses" output by the detecting elements. The ASIC also measures the energy of the counted X-ray photons by performing arithmetic processing based on the "magnitude of each pulse (amount of charge)." Furthermore, the ASIC outputs the X-ray photon counting results to the DAS 21 as digital data.

[0021] The collimator module has a collimator plate and a collimator frame. A conductor is attached to the surface of the collimator module facing the semiconductor crystal. The collimator plate is provided on the radiation incident surface side of the semiconductor crystal. The collimator plate is provided between two anode electrodes and arranged at least in the channel direction. Specifically, the collimator plate is arranged on the X-ray incident side of the cathode electrode. More specifically, a plurality of collimator plates are arranged along the channel direction at positions facing each other between two adjacent anode electrodes among the plurality of anode electrodes, with the semiconductor crystal interposed therebetween.

[0022] The collimator plate may further have a plurality of scattered radiation removal portions arranged along a row direction (slice direction) perpendicular to the channel direction. The collimator plate is, for example, composed of an X-ray shielding plate having the function of absorbing scattered X-rays, and is also called an anti-scatter grid (hereinafter referred to as ASG). The ASG may be called a one-dimensional collimator, a two-dimensional collimator, or simply a grid depending on the dimension in which it is arranged.

[0023] The collimator frame supports the plurality of collimator plates. The collimator frame supports the collimator plates while avoiding the radiation incidence surfaces of the semiconductor crystals. Bus bars may be provided at both ends of the collimator frame in the column direction. The bus bars may be disposed between the collimator frame and the plurality of detector modules. The bus bars may also be disposed at both ends of the semiconductor crystals in the column direction without contacting the semiconductor crystals.

[0024] The first elastic body is conductive. The first elastic body is provided, for example, between the conductor and the cathode surface. The material of the first elastic body desirably has low stopping power for X-rays in order to reduce the blocking of X-rays incident on the semiconductor crystal. The first elastic body is realized, for example, by conductive rubber. The detailed structure of the X-ray detector 12 according to this embodiment will be described later.

[0025] The X-ray CT apparatus 1 is available in a rotate / rotate type (third generation CT) in which the X-ray tube 11 and the X-ray detector 12 rotate together around the subject P, and a stationary / rotate type (fourth generation CT) in which a large number of X-ray detection elements arranged in a ring shape are fixed and only the X-ray tube 11 rotates around the subject P, and either type can be applied to this embodiment. For the sake of specificity, the X-ray CT apparatus 1 of this embodiment will be described below using a third generation CT as an example.

[0026] The rotating frame 13 has a bore, and an X-ray tube 11 that generates X-rays is attached to the rotating frame 13. Specifically, the rotating frame 13 is an annular frame that supports the X-ray tube 11 and the X-ray detector 12 so that they face each other, and rotates the X-ray tube 11 and the X-ray detector 12 using a control device 18 (described later). The rotating frame 13 is rotatably supported on a fixed frame made of metal such as aluminum. More specifically, the rotating frame 13 is connected to the edge of the fixed frame via bearings. The rotating frame 13 receives power from a drive mechanism of the control device 15 and rotates at a constant angular velocity around a rotation axis Z.

[0027] The rotating frame 13 is equipped with and supports an X-ray high-voltage generator 17 and a DAS 21 in addition to the X-ray tube 11 and the X-ray detector 12. The rotating frame 13 is housed in a substantially cylindrical housing with an opening (bore) that forms the imaging space. The opening substantially coincides with the FOV. The central axis of the opening coincides with the rotation axis Z of the rotating frame 13. The detection data generated by the DAS 21 is transmitted by optical communication from a transmitter having, for example, a light-emitting diode (LED) to a receiver having a photodiode provided in a non-rotating part of the gantry 10 (for example, a fixed frame), and then transferred to the console device 40. The method of transmitting the detection data from the rotating frame 13 to the non-rotating part of the gantry 10 is not limited to the optical communication described above, and any method of non-contact data transmission may be used.

[0028] The wedge 16 is a filter for adjusting the amount of X-rays irradiated from the X-ray tube 11. Specifically, the wedge 16 is a filter that transmits and attenuates the X-rays irradiated from the X-ray tube 11 so that the X-rays irradiated from the X-ray tube 11 to the subject P have a predetermined distribution. The wedge 16 is, for example, a wedge filter or a bow-tie filter, and is a filter made of processed aluminum so as to have a predetermined target angle and a predetermined thickness.

[0029] The X-ray high voltage device 17 has electrical circuits such as a transformer and a rectifier, and includes a high voltage generator having the function of generating a high voltage to be applied to the X-ray tube 11 and a filament current to be supplied to the X-ray tube 11, and an X-ray control device that controls the output voltage according to the X-rays irradiated by the X-ray tube 11. The high voltage generator may be of a transformer type or an inverter type. The X-ray high voltage device 17 may be provided on the rotating frame 13, or on the fixed frame (not shown) side of the gantry device 10.

[0030] The control device 18 includes a processing circuit having a CPU (Central Processing Unit) and other components, and a drive mechanism for motors, actuators, and other components. The processing circuit includes hardware resources such as a processor, such as a CPU or an MPU (Micro Processing Unit), and memories, such as a ROM (Read Only Memory) or RAM (Random Access Memory). The control device 15 may also be implemented using an ASIC, a Field Programmable Gate Array (FPGA), other Complex Programmable Logic Devices (CPLDs), or Simple Programmable Logic Devices (SPLDs). The control device 18 controls the X-ray high-voltage generator 17, the DAS 21, and other components in accordance with commands from the console device 40. The processor reads and executes programs stored in the memory to achieve the above control.

[0031] The control device 18 also has a function of receiving input signals from the console device 40 or an input interface attached to the gantry 10 and controlling the operation of the gantry 10 and the bed 30. For example, the control device 18 receives input signals and controls the rotation of the rotating frame 13, the tilt of the gantry 10, and the operation of the bed 30 and the tabletop 33. Note that the control of tilting the gantry 10 may be realized by the control device 18 rotating the rotating frame 13 around an axis parallel to the X-axis direction based on inclination angle (tilt angle) information input via an input interface attached to the gantry 10.

[0032] The control device 18 may be provided in the gantry device 10 or in the console device 40. The control device 18 may be configured so that the program is directly incorporated into the circuitry of the processor, instead of storing the program in the memory. In this case, the processor realizes the above control by reading and executing the program incorporated into the circuitry.

[0033] The source-side collimator 19 is a lead plate or the like for constricting the X-rays transmitted through the wedge 16 to an X-ray irradiation range, and a slit is formed by combining a plurality of lead plates or the like.

[0034] The DAS 21 has a plurality of counting circuits. Each of the plurality of counting circuits has an amplifier that performs an amplification process on the electrical signals output from each detection element of the X-ray detector 12 and an A / D converter that converts the amplified electrical signals into digital signals, and generates detection data that is the result of a counting process using the detection signals of the X-ray detector 12. The result of the counting process is data that assigns the number of X-ray photons to each energy bin. For example, the DAS 21 counts photons (X-ray photons) derived from X-rays that have been irradiated from the X-ray tube 11 and transmitted through the subject P, and discriminates the energy of the counted photons to obtain the result of the counting process.

[0035] The detection data generated by the DAS 21 is transferred to the console device 40. The detection data is a set of data including the channel number of the detector pixel that generated the detection data, the column number, the view number indicating the acquired view (also called the projection angle), and a value indicating the detected X-ray dose. The view number may be the order in which the view was acquired (acquisition time), or a number indicating the rotation angle of the X-ray tube 11 (e.g., 1 to 1000). Each of the multiple counting circuits in the DAS 21 is realized, for example, by a group of circuits equipped with circuit elements capable of generating detection data.

[0036] The bed device 30 is a device on which the subject P to be scanned is placed and moved, and includes a base 31, a bed driving device 32, a top 33, and a top support frame 34. The base 31 is a housing that supports the top support frame 34 so that it can move vertically. The bed driving device 32 is a motor or actuator that moves the top 33, on which the subject P is placed, in the longitudinal direction of the top 33. The bed driving device 32 moves the top 33 under the control of the console device 40 or the control device 15. The top 33, which is provided on the upper surface of the top support frame 34, is a plate on which the subject P is placed. Note that the bed driving device 32 may move the top support frame 34 in addition to the top 33 in the longitudinal direction of the top 33.

[0037] The console device 40 has a memory 41 (storage unit), a display 42 (display unit), an input interface 43 (input unit), and a processing circuit 44 (processing unit). Data communication between the memory 41, the display 42, the input interface 43, and the processing circuit 44 is performed via a bus (BUS).

[0038] The memory 41 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or an integrated circuit storage device that stores various types of information. The memory 41 stores, for example, projection data and reconstructed image data. In addition to an HDD or an SSD, the memory 41 may be a portable storage medium such as a CD (Compact Disc), a DVD (Digital Versatile Disc), or a flash memory, or a drive that reads and writes various types of information from and to a semiconductor memory element such as a RAM (Random Access Memory). The storage area of ​​the memory 41 may be located within the X-ray CT apparatus 1 or in an external storage device connected via a network. The memory 41 also stores a control program according to this embodiment.

[0039] The display 42 displays various types of information. For example, the display 42 outputs medical images (CT images) generated by the processing circuitry 44, a GUI (Graphical User Interface) for receiving various operations from the operator, and the like. For example, the display 42 may be a liquid crystal display (LCD), a cathode ray tube (CRT), an organic electroluminescence display (OLED), a plasma display, or any other display, as appropriate. The display 42 may also be provided on the gantry device 10. The display 42 may also be a desktop type, or may be configured as a tablet terminal or the like capable of wireless communication with the console device 40 main body.

[0040] The input interface 43 accepts various input operations from the operator, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuitry 44. For example, the input interface 43 accepts from the operator acquisition conditions for acquiring projection data, reconstruction conditions for reconstructing CT images, image processing conditions for generating post-processed images from CT images, etc. As the input interface 43, for example, a mouse, keyboard, trackball, switch, button, joystick, touchpad, touch panel display, etc. can be used as appropriate.

[0041] In this embodiment, the input interface 43 is not limited to one having physical operation components such as a mouse, keyboard, trackball, switch, button, joystick, touchpad, and touch panel display. For example, an example of the input interface 43 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 the processing circuit 44. The input interface 43 is also an example of an input unit. The input interface 43 may also be provided in the gantry device 10. The input interface 43 may also be configured as a tablet terminal or the like that is capable of wireless communication with the console device 40 main body.

[0042] The processing circuitry 44 controls the overall operation of the X-ray CT apparatus 1 in response to electrical signals of input operations output from the input interface 43. For example, the processing circuitry 44 has, as hardware resources, processors such as a CPU, MPU, or GPU (Graphics Processing Unit), and memories such as ROM and RAM. The processing circuitry 44 executes a system control function 441 (system control unit), a preprocessing function 442, and a reconstruction processing function 443 (reconstruction unit) by a processor that executes a program loaded in the memory. Note that each of the functions 441 to 443 is not limited to being realized by a single processing circuit. A processing circuit may be configured by combining multiple independent processors, and each processor may execute a program to realize each of the functions 441 to 443.

[0043] The system control function 441 controls each function of the processing circuitry 44 based on an input operation received from an operator via the input interface 43. Specifically, the system control function 441 reads out a control program stored in the memory 41, expands it on the memory in the processing circuitry 44, and controls each part of the X-ray CT apparatus 1 in accordance with the expanded control program. For example, the processing circuitry 44 controls each function of the processing circuitry 44 based on an input operation received from the operator via the input interface 43.

[0044] The preprocessing function 442 generates data by performing preprocessing such as logarithmic conversion, offset correction, inter-channel sensitivity correction, and beam hardening correction on the detection data output from the DAS 21. Note that data before preprocessing is called raw data, and data after preprocessing is called projection data.

[0045] The reconstruction processing function 443 performs reconstruction processing using a filtered back projection (FBP) method, an iterative reconstruction method, or the like on the projection data generated by the preprocessing function 442 to generate CT image data. The reconstruction processing function 443 stores the reconstructed CT image data in the memory 41. The projection data generated from the counting results obtained by the photon counting CT contains information on the energy of X-rays attenuated by passing through the subject P. Therefore, the reconstruction processing function 443 can reconstruct X-ray CT image data of, for example, a specific energy component. Furthermore, the reconstruction processing function 443 can reconstruct X-ray CT image data of, for example, each of a plurality of energy components.

[0046] Furthermore, the reconstruction processing function 443 can, for example, assign a color tone corresponding to the energy component to each pixel of the X-ray CT image data of each energy component, and generate image data in which multiple X-ray CT image data colored according to the energy component are superimposed. Furthermore, the reconstruction processing function 343 can, for example, generate image data that enables identification of a substance by utilizing a K-absorption edge specific to the substance. Other image data generated by the reconstruction processing function 443 include monochromatic X-ray image data, density image data, effective atomic number image data, etc. The processing circuitry 44 that realizes the preprocessing function 442 and the reconstruction processing function 443 corresponds to an image generation unit that generates a medical image based on electrons output from the anode electrode in the X-ray detector 12.

[0047] The configuration of the X-ray CT system 1 according to the embodiment has been described above. With this configuration, the X-ray detector 12 in the X-ray CT system 1 has a configuration that can improve the maintainability of the X-ray detector 12. The X-ray detector 12 according to the embodiment will be described below.

[0048] 2 is a diagram showing an example of an overview of the X-ray detector 12 viewed along the long axis direction (Z-axis direction) of the tabletop 33. As shown in FIG. 2, the multiple detector modules 121 are arranged in the channel direction. The collimator module 123 is disposed in front of the multiple detector modules 121 on the X-ray tube 11 side. A collimator frame that forms the outer frame of the collimator module 123 is provided with a bus bar 125.

[0049] Fig. 3 is a cross-sectional view taken along dashed dotted line AA' in Fig. 2. As shown in Fig. 3, detector module 121 has a plurality of semiconductor crystals 1211, a plurality of anode electrodes 1213 provided on each of the plurality of semiconductor crystals 1211, and a plurality of cathode electrodes 1215 provided opposite the plurality of anode electrodes 1213 across the plurality of semiconductor crystals 1211. Between two adjacent semiconductor crystals in the plurality of semiconductor crystals 1211, an insulator is provided that can block the movement of electrons between the two adjacent semiconductor crystals.

[0050] As shown in FIG. 3 , the detector module 121 has a plurality of semiconductor modules (hereinafter referred to as small modules) each having a semiconductor crystal 1211 with a cathode electrode 1215 and an anode electrode 1213. The small module includes, for example, the semiconductor crystal 1211, the anode electrode 1213, the cathode electrode 1215, and various circuits downstream of the anode electrode 1213. The small modules are arranged in the column direction (Z direction). Each of the small modules is detachable from each of the detector modules. That is, the detector module 121 is composed of a plurality of small modules arranged in the column direction. Each of the small modules is detachable from the detector module 121, for example, when a user performs maintenance on the X-ray detector 12. A known structure can be used for the detachable structure, and therefore a description thereof will be omitted. The anode electrode 1213 in the small module may be composed of a plurality of small electrodes each having a width smaller than that of the semiconductor crystal 1211.

[0051] As shown in FIG. 3, the collimator module 123 includes a collimator plate 1231 that blocks scattered radiation and a collimator frame 1232 that supports the collimator plate 1231. The collimator frame 1232 is provided with a collimator plate holding plate 1233 that holds the lower end (the side facing the semiconductor crystal 1211) of the collimator plate 1231. Also, as shown in FIG. 3, a thread is formed by tapping on the outer frame of the collimator frame 1232, avoiding the radiation incidence surface of the semiconductor crystal 1211. Also, as shown in FIG. 3, a bus bar 125 is installed on the outer frame of the collimator frame 1232. The collimator frame 1232 is made of, for example, an insulating material. Note that, if the collimator frame 1232 is conductive, insulators (not shown) are arranged between the collimator frame 1232 and the bus bar 125 and between the collimator frame 1232 and the conductor 129. The insulators are, for example, insulating films. In this case, since the insulating film may be located on the radiation incident surface of the semiconductor crystal 1211, it is desirable that the material of the insulating film has low stopping power for X-rays.

[0052] As shown in FIG. 3, the bus bar 125 is electrically connected to a single bias voltage generator 127. The bus bar 125 is provided in the collimator module 123 as a separate unit. Regarding the application of bias voltages to the anode surface 1213 and the cathode surface 1215, an electrical readout circuit 1271 connecting the single bias voltage generator 127 is realized, for example, by a readout circuit as shown in FIG. 3, but is not limited to this. A conductor 129 is electrically connected to the bus bar 125. The conductor 129 is installed in the collimator module 123. The conductor 129 extends from the bus bar 125 to a collimator plate 1231 facing the semiconductor crystal 1211. At this time, the conductor 129 contacts a collimator plate holding plate 1233. In other words, the conductor 129 directly below the collimator plate holding plate 1233 is attached to the collimator plate holding plate 1233. The conductor 129 is realized by, for example, a conductive film or a metal foil. Since the conductor 129 is located on the radiation incident surface of the semiconductor crystal 1211, it is desirable that the material of the conductor 129 has low stopping power for X-rays. An insulator 131 is provided between the conductor 129 and the detector module 121. The insulator 131 is provided on the conductor 129. Note that the insulator 131 may also be provided on the detector module 121. Furthermore, an insulator (not shown) may be provided on the side surface of the semiconductor crystal 1211.

[0053] A conductive first elastic body 133 is provided between the conductor 129 and the cathode surface 1215. The first elastic body 133 and the conductor 129 are provided in the collimator module 123 for each of the multiple detector modules. At least one of the first elastic body 133 and the conductor 129 may be uniformly provided in the collimator module 123 across the multiple detector modules. The first elastic body 133 has a thickness that reduces the positional tolerance between the collimator module 123 and the detector module 121. When the detector module 121 is attached to the collimator module 123 by tightening with the screws 135, the positional tolerance is reduced due to elastic deformation of the first elastic body 133. As a result, the cathode surface 1215 and the first elastic body 133 contact each other over a surface rather than at a point. Therefore, contact between cathode surface 1215 and first elastic body 133 is improved, and electrical continuity between bus bar 125 and cathode surface 1215 is ensured.

[0054] 4 is a cross-sectional view taken along dashed line AA' in FIG. 2, taken along the arrows different from those in FIG. 3. In FIG. 4, the single bias voltage generating unit 127 and the readout circuit 1271 are omitted for the sake of convenience. The difference between FIG. 4 and FIG. 3 is that the bus bars 125 are disposed at both ends of the collimator frame 1232 in the column direction. As a result, the detector module 121 shown in FIG. 4 improves the uniformity of the bias voltage applied from the bus bars 125 between the anode surface 1213 and the cathode surface 1215. The other configurations in FIG. 4 are the same as those in FIG. 3.

[0055] 5 is a cross-sectional view taken along dashed dotted line AA' in FIG. 2, taken along a line different from FIGS. 3 and 4. In FIG. 5, the single bias voltage generating unit 127 and the readout circuit 1271 are omitted for the sake of convenience. The difference between FIG. 5 and FIG. 3 is that a second elastic body 137 is provided between the bus bar 125 and the conductor 129. As shown in FIG. 5, the second elastic body 137 is conductive and is provided between the bus bar 125 and the conductor 129. Other configurations in FIG. 5 are the same as those in FIG. 3.

[0056] The second elastic body 137 has a thickness that reduces the positional tolerance between the bus bar 125 and the conductor 129. When the detector module 121 is attached to the collimator module 123 by fastening with the screws 135, the positional tolerance between the bus bar 125 and the conductor 129 is reduced due to elastic deformation of the second elastic body 137. As a result, the bus bar 125 and the conductor 129 contact each other at a surface rather than at a point. This improves the contact between the bus bar 125 and the conductor 129, ensuring electrical continuity between the bus bar 125 and the conductor 129. The second elastic body 137 is realized by, for example, conductive rubber or a conductive spring. Note that a conductive lead wire may be used instead of the second elastic body 137.

[0057] FIG. 6 is a cross-sectional view taken along dashed line AA′ in FIG. 2, taken along the arrow different from those in FIGS. 3 to 5. In FIG. 6, the single bias voltage generating unit 127 and the readout circuit 1271 are omitted for the sake of convenience. The difference between FIG. 5 and FIG. 3 is that a bus bar 125 is provided between the collimator frame 1232 and the detector module 121. As shown in FIG. 6, the bus bar 125 is installed on the collimator frame 1232 on the radiation incident surface side of the bus bar 125. That is, as shown in FIG. 6, the bus bar 125 is incorporated into the collimator module 123, and is configured as, for example, a component of the collimator module 123. Other configurations in FIG. 6 are the same as those in FIG. 3.

[0058] FIG. 7 is a cross-sectional view taken along dashed line AA′ in FIG. 2, taken along the arrows different from those in FIGS. 3 to 6. In FIG. 7, the single bias voltage generating unit 127 and the readout circuit 1271 are omitted for the sake of convenience. The difference from FIG. 6 is that the bus bars 125 are disposed at both ends of the collimator frame 1232 in the column direction. As a result, the detector module 121 shown in FIG. 7 improves the uniformity of the bias voltage applied from the bus bars 125 between the anode surface 1213 and the cathode surface 1215. The other configurations in FIG. 7 are the same as those in FIG. 6.

[0059] The direct conversion type X-ray detector 12 according to the embodiment described above includes a plurality of detector modules 121 arranged in the channel direction and each having a semiconductor crystal 1211; a single bias voltage generating unit 127 that generates a bias voltage to be applied between a cathode electrode 1215 provided on the semiconductor crystal 1211 and an anode electrode 1213 provided on the semiconductor crystal 1211; a common electrode (bus bar) 125 that is electrically connected to the bias voltage generating unit 127 and extends in the channel direction; and a conductor 129 that electrically connects the common electrode 125 to the cathode surface 1215 of the semiconductor crystal 1211 in each of the plurality of detector modules 121.

[0060] The X-ray detector 12 according to the embodiment further includes a collimator module 123 having a collimator plate 1231 provided on the radiation incident surface side of the semiconductor crystal 1211, and the conductor 129 is attached to the surface of the collimator module 123 facing the semiconductor crystal 1211. Note that in the X-ray detector 12 according to the embodiment, the collimator module 123 may further include a collimator frame 1232 that supports the collimator plate 1231 away from the radiation incident surface of the semiconductor crystal 1211, and in this case, the common electrode (bus bar) 125 is disposed between the collimator frame 1232 and the plurality of detector modules 121.

[0061] The X-ray detector 12 according to the embodiment further includes a first elastic body 133 having conductivity and provided between the conductor 129 and the cathode surface 1215. In the X-ray detector 12 according to the embodiment, each of the plurality of detector modules 121 includes a plurality of semiconductor modules having semiconductor crystals 1211 provided with a cathode electrode 1215 and an anode electrode 1213, the plurality of semiconductor modules are arranged along the column direction, and each of the plurality of semiconductor modules is detachable from each of the plurality of detector modules.

[0062] For these reasons, the X-ray detector 12 according to this embodiment uses a single bus bar 125 and a single bias voltage generator (bias power supply) 127 in the channel direction, thereby reducing the number of high-voltage cables connected to each detector module or each small module and reducing the complexity of the high-voltage cable routing. Additionally, because the detector module 121 is electrically connected to the conductor 129 via the first elastic body 133, it is not necessary to remove the conductor 129 from the detector module 121 when replacing the detector module 121. That is, when replacing the detector module 121 during maintenance of the X-ray detector 12, it is not necessary to wire the high-voltage cables within the housing of the X-ray detector 12, route the high-voltage cables, or remove the conductor 129, which significantly reduces the number of steps required. Therefore, the X-ray detector 12 allows the detector module 121 or small module to be easily replaced as needed.

[0063] For example, when the detector module 121 is divided into small modules, the X-ray detector 12 eliminates the need for wiring related to bias voltage across the small modules, and since the cathode electrode 1215 is separated for each small module, the small modules can be easily replaced.

[0064] As described above, according to the present X-ray detector 12, the maintainability of the direct conversion type X-ray detector 12 and the serviceability during maintenance of the X-ray detector 12 can be improved.

[0065] In addition, the configuration of the X-ray detector 12 according to the embodiment eliminates the need to wire and route high-voltage cables within the housing of the X-ray detector 12, making it possible to easily ensure airflow as a heat countermeasure within the housing of the X-ray detector 12. Furthermore, the configuration of the X-ray detector 12 simplifies (e.g., eliminates) the wiring and routing of high-voltage cables within the housing of the X-ray detector 12 compared to a method of supplying power to each detector module via a cable, a flexible board, or the like, making it possible to easily manufacture the X-ray detector 12. Furthermore, the configuration of the X-ray detector 12 according to the embodiment uses a single bias voltage generating unit (bias power supply) 127, making it unnecessary to provide redundancy against failures of each of the high-voltage power supplies when multiple detector modules are provided with multiple high-voltage power supplies, respectively. For these reasons, the configuration of the present X-ray detector 12 makes it easier to ensure airflow within the housing of the X-ray detector 12, improves the manufacturability of the X-ray detector 12, improves the maintainability of the X-ray detector 12 (improves maintenance throughput), and eliminates the need for redundancy, thereby reducing the costs of manufacturing and maintaining the X-ray detector 12.

[0066] Furthermore, with the configuration of the present X-ray detector 12, it is possible to avoid the risk of breakdown due to discharge between detector modules and between small modules, since a high voltage is applied to all of the plurality of small modules and the plurality of detector modules 121 from a single bias voltage generating unit (bias power supply) 127. Therefore, with the present X-ray detector 12, it is possible to simplify the voltage resistance structure between two adjacent detector modules and between two adjacent small modules, and it is possible to reduce the cost of manufacturing the present X-ray detector 12.

[0067] In addition, the present X-ray detector 12 uses a single bias voltage generator (bias power supply) 127, which facilitates the design of control for increasing and decreasing the bias voltage, thereby enabling the increase and decrease of the bias voltage to be achieved at low cost and in a short time. Therefore, the present X-ray detector 12 can improve the workflow for controlling the bias voltage.

[0068] Furthermore, the X-ray detector 12 can be equipped with a bias power supply according to the intensity (dose rate) of X-rays because it uses a single bias voltage generating unit (bias power supply) 127. Therefore, the X-ray detector 12 can acquire a signal according to the detection of X-rays regardless of the maximum dose rate or the rotation speed of the rotating frame 13, thereby reducing unnecessary exposure of the subject P and deterioration of image quality due to noise.

[0069] Furthermore, since the X-ray detector 12 according to the embodiment does not use a high-voltage cable, it is possible to eliminate variations in bias voltage due to individual differences in the voltage resistance design and impedance of the high-voltage cables connected to the detector modules, compared to the case where multiple high-voltage power supplies are provided for multiple detector modules. As a result, when the X-ray detector 12 is used in the X-ray CT device 1, it is possible to improve the image quality of X-ray CT images.

[0070] In the X-ray detector 12 according to the embodiment, the collimator module 123 further includes a collimator frame 1232 that supports the collimator plates 1231 while avoiding the radiation incident surface of the semiconductor crystals 1211, and the common electrodes (bus bars) 125 are arranged at both ends in the column direction of the collimator frame 1232. In the X-ray detector 12 according to the embodiment, the collimator module 123 further includes a collimator frame 1232 that supports the collimator plates 1231 while avoiding the radiation incident surface of the semiconductor crystals 1211, and the common electrodes (bus bars) 125 are arranged between the collimator frame 1232 and the plurality of detector modules 121, at both ends in the column direction of the semiconductor crystals 1211 without contacting the semiconductor crystals 1211.

[0071] As a result, the X-ray detector 12 according to the embodiment can further improve the contact quality between the bus bar 125 and the conductor 129, and can also improve the uniformity of the bias voltage applied to the semiconductor crystal 1211. Therefore, when the X-ray detector 12 is used in the X-ray CT device 1, the image quality of the X-ray CT image can be further improved.

[0072] (Variation) In this modification, the detector module 121 has a single cathode electrode as the conductor 129, and a second elastic body 137 is provided between the bus bar 125 and the conductor 129. For the sake of concrete explanation, it is assumed below that the first elastic body 133 is not mounted in this modification, and the conductor 129 extends along the column direction relative to the plurality of semiconductor crystals 1211.

[0073] FIG. 8 is a cross-sectional view of this modified example taken along dashed line AA′ in FIG. 2, taken along a line different from FIG. 5. In FIG. 8, the single bias voltage generating unit 127 and the readout circuit 1271 are omitted for ease of explanation. The differences between FIG. 8 and FIG. 5 are that a second elastic body 137 is provided between the bus bar 125 and the conductor 129, the conductor 129 is provided instead of the multiple cathode electrodes, and the first elastic body 133 is omitted. As shown in FIG. 8, the insulator 131 is provided in the detector module 121. Also, as shown in FIG. 8, the conductor 129 is provided on the radiation incident surface side of the semiconductor crystal 1211 and on the insulator 131. Although FIG. 8 depicts the semiconductor crystal 1211 as an integrated structure, it may be formed of multiple semiconductor crystals, as in FIG. 5.

[0074] As shown in Fig. 8, the second elastic body 137 is provided to the collimator module 123 via the bus bar 125. The conductor 129 is not limited to being provided to each of the plurality of detector modules, and may be provided across the plurality of detector modules. The second elastic body 137 may also be provided to the detector module via the conductor 129 and the insulator 131. Other configurations in Fig. 8 are the same as those in Fig. 3.

[0075] When the detector module 121 and the collimator module 123 are fastened together with the screws 135, the elastic deformation of the second elastic body 137 reduces the positional tolerance between the bus bar 125 and the conductor 129. This improves the contact between the bus bar 125 and the conductor 129, ensuring electrical continuity between the bus bar 125 and the conductor 129. The second elastic body 137 is realized by, for example, conductive rubber or a conductive spring. Note that a conductive lead wire may be used instead of the second elastic body 137.

[0076] FIG. 9 is a cross-sectional view of this modified example taken along dashed line AA′ in FIG. 2, taken along a line different from FIG. 8. In FIG. 9, the single bias voltage generating unit 127 and the readout circuit 1271 are omitted for ease of explanation. The difference between FIG. 9 and FIG. 8 is that the bus bars 125 are disposed at both ends of the collimator frame 1232 in the column direction. As a result, the detector module 121 shown in FIG. 9 improves the uniformity of the bias voltage applied from the bus bars 125 between the anode surface 1213 and the cathode surface of the conductor 129. The other configurations in FIG. 9 are the same as those in FIG. 8.

[0077] FIG. 10 is a cross-sectional view of this modified example taken along dashed line AA′ in FIG. 2, different from FIGS. 8 and 9. In FIG. 10, the single bias voltage generating unit 127 and the readout circuit 1271 are omitted for convenience of explanation. The difference between FIG. 10 and FIG. 8 is that a bus bar 125 is provided between the collimator frame 1232 and the detector module 121. As shown in FIG. 10, the bus bar 125 is installed on the collimator frame 1232 on the radiation incident surface side of the bus bar 125. Other configurations in FIG. 10 are the same as those in FIG. 8.

[0078] FIG. 11 is a cross-sectional view of this modified example taken along dashed line AA′ in FIG. 2, taken along an arrow different from that shown in FIGS. 8 to 10. In FIG. 11, the single bias voltage generating unit 127 and the readout circuit 1271 are omitted for convenience of explanation. The difference from FIG. 10 is that the bus bars 125 are disposed at both ends of the collimator frame 1232 in the column direction. As a result, the detector module 121 shown in FIG. 11 improves the uniformity of the bias voltage applied from the bus bars 125 between the anode surface 1213 and the cathode surface formed by the conductor 129. The other configurations in FIG. 11 are the same as those in FIG. 10.

[0079] The effects of this modification are similar to those of the embodiment, and therefore a description thereof will be omitted.

[0080] When the technical ideas of the embodiments and the like are realized in an X-ray CT device 1, the X-ray CT device 1 includes an X-ray tube 11 that generates X-rays and a direct conversion type X-ray detector 12 that detects X-rays, and the X-ray detector 12 includes a plurality of detector modules 121 arranged in the channel direction and each including a semiconductor crystal 1211, a single bias voltage generator 127 that generates a bias voltage to be applied between a cathode electrode 1215 provided in the semiconductor crystal 1211 and an anode electrode 1213 provided in the semiconductor crystal 1211, a common electrode (bus bar) 125 that is electrically connected to the bias voltage generator 127 and extends in the channel direction, and a conductor 129 that electrically connects the common electrode (bus bar) 125 to the cathode surface 1215 of the semiconductor crystal 1211 in each of the plurality of detector modules 121. The effects of the X-ray CT device 1 are similar to those of the embodiments and the like, so a description thereof will be omitted.

[0081] According to at least the embodiment and modifications described above, the maintainability of the direct conversion type X-ray detector 12 can be improved.

[0082] Although several 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, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0083] 1 X-ray CT device 10 Mounting device 11 X-ray tube 12 X-ray detector 13 Rotating Frame 16 Wedge 17. X-ray high voltage device 18 Control Device 19 Source side collimator 21 DAS (Data Acquisition System) 30 Bed Device 31 Foundation 32 Bed drive unit 33 Top plate 34 Top plate support frame 40 Console device 41 memory 42 Display 43 Input Interface 44 Processing circuit 121 Detector Module 123 Collimator Module 125 Common electrode (bus bar) 127 Single bias voltage generator 129 Conductors 131 Insulator 133 First Elastic Body 135 screws 137 Second Elastic Body 441 System Control Functions 442 Pre-processing function 443 Reconstruction Processing Function 1211 Semiconductor crystals 1213 Anode electrode, anode surface 1215 Cathode electrode, cathode surface 1231 Collimator plate 1232 Collimator Frame 1233 Collimator plate holder 1271 Readout circuit

Claims

1. A plurality of detector modules each having a semiconductor crystal, arranged in a channel direction along a single arc centered on the focal point of an X-ray tube; a single bias voltage generating unit that generates a bias voltage to be applied between a cathode electrode provided on the semiconductor crystal and an anode electrode provided on the semiconductor crystal; a common electrode electrically connected to the bias voltage generating unit and extending in the channel direction; a conductor electrically connecting the common electrode and the cathode electrode of the semiconductor crystal in each of the plurality of detector modules; A direct conversion type X-ray detector comprising:

2. a collimator module having a collimator plate provided on the radiation incident surface side of the semiconductor crystal, the conductor is attached to a surface of the collimator module facing the semiconductor crystal; 2. The direct conversion type X-ray detector according to claim 1.

3. the collimator module further includes a collimator frame that supports the collimator plates while avoiding the radiation incident surface of the semiconductor crystal; the common electrodes are disposed on both ends of the collimator frame in the column direction; 3. The direct conversion type X-ray detector according to claim 2.

4. the collimator module further includes a collimator frame that supports the collimator plates while avoiding the radiation incident surface of the semiconductor crystal; the common electrode is disposed between the collimator frame and the plurality of detector modules.

3. The direct conversion type X-ray detector according to claim 2.

5. the common electrodes are disposed on both ends of the semiconductor crystal in the column direction without contacting the semiconductor crystal; 5. The direct conversion type X-ray detector according to claim 4.

6. a first elastic body that is provided between the conductor and the cathode electrode and has electrical conductivity; 6. A direct conversion type X-ray detector according to claim 1.

7. each of the plurality of detector modules includes a plurality of semiconductor modules having the semiconductor crystal on which the cathode electrode and the anode electrode are provided; The plurality of semiconductor modules are arranged in a column direction, each of the plurality of semiconductor modules is detachable from each of the plurality of detector modules; 7. A direct conversion type X-ray detector according to claim 1.

8. a second elastic body having conductivity between the common electrode and the conductor; 8. A direct conversion type X-ray detector according to claim 1.

9. an X-ray tube that generates X-rays; a direct conversion X-ray detector for detecting the X-rays, The X-ray detector includes: a plurality of detector modules each including a semiconductor crystal, the detector modules being arranged in a channel direction along an arc centered on the focal point of the X-ray tube; a single bias voltage generating unit that generates a bias voltage to be applied between a cathode electrode provided on the semiconductor crystal and an anode electrode provided on the semiconductor crystal; a common electrode electrically connected to the bias voltage generating unit and extending in the channel direction; a conductor electrically connecting the common electrode and the cathode electrode of the semiconductor crystal in each of the plurality of detector modules; An X-ray computed tomography apparatus having:

Images