18 ascertains the rotation angle of the rotary frame 17 according to the output of a sensor that is not shown, or the like. The control device 18 may be provided on the gantry 10 or may be provided on the console device 40.

The X-ray CT apparatus 1 is, for example, a rotate/rotate-type X-ray CT apparatus (a third generation CT) in which both the X-ray tube 11 and the X-ray detector 15 are supported by the rotary frame 17 and rotate around the subject P, but is not limited thereto and may be a stationary/rotate-type X-ray CT apparatus (a fourth generation CT) in which a plurality of detection elements arranged in an annular shape are fixed to a fixed frame and the X-ray tube 11 rotates around the subject P.

The camera 20 images each detection element included in the X-ray detector 15. The camera 20 is, for example, an infrared camera. The camera 20 radiates infrared light to detection elements, detects the reflected light (reflected light reflected by electrodes provided below the detection elements and the ASG 153), and converts the same into electrical signals. The camera 20 is provided at any position where it can image the detection elements, such as inside the X-ray detector 15. For example, the camera 20 images detection elements inside the X-ray detector 15 from a position substantially normal to a first surface at a time when the X-ray CT apparatus 1 is not performing imaging. The camera 20 may be attachable/detachable to/from the X-ray CT apparatus 1. For example, when the camera 20 is not in use, it may be attached to the bed device 30 and stored.

FIG. 3 is a diagram showing a state in which 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 X-ray detector 15C in the channel direction (X-axis direction in FIG. 3). Furthermore, ASGs 153 are similarly arranged in the channel direction (X-axis direction in FIG. 3) on the side of a first surface (X-ray radiation side) of this row of detection elements 151. The X-ray detector 15C has a configuration of one grid and a plurality of detection elements. Anodes 155 are disposed on the side of a second surface of each detection element 151 opposite to the first surface. The camera 20 is provided on side of the first surface and radiates infrared light to the first surface of the detection elements 151. Generally, materials such as cadmium telluride (CdTe), CZT (CdZnTe), and silicon used for the detection elements 151 transmit infrared light. On the other hand, materials such as tungsten (W) and molybdenum (Mo) used for the ASGs 153 and materials such as gold (Au) and platinum (Pt) used for the anodes 155 do not transmit infrared light but reflect it. Therefore, reflected infrared light radiated by the camera 20 captures an image of the anodes 155 and the ASGs 153. Since the ASGs 153 form shadows with respect to infrared light, it is possible to image the detection element 151 (the same area as a field irradiated with X-rays) that is paired with each anode 155 by using the reflected light due to the anode 155. When the detection elements 151 are arranged extending in the body axis direction (row 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.

FIG. 4 is a diagram showing an example of a detection element image generated on the basis of infrared light (reflected light) in the first embodiment. As shown in FIG. 4, the detection element image shows an actual X-ray irradiation range of each of a plurality of detection elements 151 (151-1 to 151-9) disposed in the channel direction (X-axis direction in FIG. 4) and the slice direction (Z-axis direction in FIG. 4). By using this detection element image, it is possible to determine the center of gravity C of the actual X-ray irradiation range of each detection element 151.

Referring back to FIG. 1, the bed device 30 is a device on which the subject P to be scanned is placed and moved, and introduced into the rotary frame 17 of the gantry 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 such 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 along the support frame 34 in the longitudinal direction of the top plate 33 (Z-axis direction). Further, the bed driving device 32 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.

The bed driving device 32 may move not only the top plate 33 but also the support frame 34 in the longitudinal direction of the top plate 33. Further, contrary to the above, the gantry 10 may be movable in the Z-axis direction, and the rotary frame 17 may be controlled to come around the subject P by moving the gantry 10. Further, both the gantry 10 and the top plate 33 may be movable. Further, the X-ray CT apparatus 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 apparatus 1 includes a subject support mechanism instead of the bed device 30, and the gantry 10 rotates the rotary frame 17 about an axial direction perpendicular to the floor surface.

The console device 40 includes, for example, a memory 41, a display 42, an input interface 43, a network connection circuit 44, and processing circuitry 50. Although the console device 40 will be described as being separate from the gantry 10 in the present embodiment, the gantry 10 may include some or all of the components of the console device 40.

The memory 41 is realized by, for example, a semiconductor memory element such as a random access memory (RAM) or a flash memory, a hard disk, an optical disc, or the like. The memory 41 stores, for example, design data DD, center of gravity data CD (correction parameters), detection data, projection data, reconstructed image data, information regarding the subject P, imaging conditions, and the like. Such 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, when the cloud server receives read/write requests.

The display 42 displays various types of information. For example, the display 42 displays a medical image (CT image) generated by the processing circuitry, a graphical user interface (GUI) image for receiving various operations by an operator such as a doctor or a technician, and the like. The display 42 is, for example, a liquid crystal display, a cathode ray tube (CRT), an organic electroluminescence (EL) display, or the like. The display 42 may be provided on the gantry 10. The display 42 may be of a desktop type, or may be a display device (for example, a tablet terminal) that can communicate wirelessly with the main body of the console device 40.

The input interface 43 receives various input operations of an operator, and outputs electrical signals indicating the content of the received input operations to the processing circuitry 50. For example, the input interface 43 receives input operations such as collection conditions at the time of collecting detection data or projection data and reconstruction conditions at the time of reconstructing a CT image. For example, the input interface 43 is realized by a mouse, a keyboard, a touch panel, a track ball, a switch, a button, a joystick, a camera, an infrared sensor, a microphone, etc.

The input interface 43 may be provided in the gantry 10. Further, the input interface 43 may be realized by a display device (for example, a tablet terminal) that can communicate wirelessly with the main body of the console device 40. In this specification, the input interface is not limited to one that includes physical operation parts such as a mouse and a keyboard. For example, examples of the input interface include electrical signal processing circuitry that receives an electrical signal corresponding to an input operation from external input equipment provided separately from the device and outputs this electrical signal to a control circuit.

The network connection circuit 44 includes, for example, a network card having a printed circuit board, a wireless communication module, or the like. The network connection circuit 44 implements an information communication protocol depending on the type of network to be connected.

The processing circuitry 50 controls the overall operation of the X-ray CT apparatus 1, the operation of the gantry 10, the operation of the bed device 30, and the operation of the camera 20. The processing circuitry 50 executes, for example, a system control function 51, a preprocessing 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, and the like. These components are realized, for example, by a hardware processor (computer) executing a program (software) stored in the memory 41. The hardware processor is, for example, circuitry such as a CPU, a graphics processing unit (GPU), 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), and a field programmable gate array (FPGA)), etc.

The program may be directly incorporated into the circuit of the hardware processor instead of being stored in the memory 41. In this case, the hardware processor realizes the functions by reading and executing the program incorporated into the circuit. The hardware processor is not limited to being configured as a single circuit, but may be configured as one hardware processor by combining a plurality of independent circuits to realize each function. Further, a plurality of components may be integrated into one hardware processor to realize each function.

The components included in the console device 40 or the processing circuitry 50 may be distributed and realized by a plurality of pieces of hardware. The processing circuitry 50 may be realized by a processing device that can communicate with the console device 40 instead of being a component included in the console device 40. The processing device is, for example, a workstation connected to one X-ray CT apparatus, or a device (e.g., a cloud server) that is connected to a plurality of X-ray CT apparatuses and collectively executes the same processing as that performed by the processing circuitry 50 described below.

The system control function 51 controls various functions of the processing circuitry 50 on the basis of input operations received by the input interface 43.

The preprocessing function 52 performs preprocessing such as offset correction processing, inter-channel sensitivity correction processing, and beam hardening correction on detection data output by the DAS 16.

The reconstruction function 53 generates a reconstructed image (CT image) regarding the subject P on the basis of detection data (signal) and data regarding an irradiated area. The reconstruction function 53 includes, for example, a correction function 531. The correction function 531 corrects an irradiated position of detection data on the basis of the data regarding an irradiated area of each detection element generated by the generation function 57. The reconstruction function 53 is an example of a “reconstructor.” The reconstruction function 53 generates a reconstructed image by setting the position of the center of gravity of the actual irradiated area of each of the plurality of detection elements 151 included in the data regarding the irradiated area as an irradiated position.

The image processing function 54 converts CT image data into three-dimensional image data or CT image data of an arbitrary cross section using a known method on the basis of an input operation received by the input interface 43. Conversion into three-dimensional image data may be performed by the preprocessing function 52.

The acquisition function 55 acquires an image (detection element image) obtained by imaging the plurality of detection elements 151 that output signals in response to incident X-rays, and a plurality of ASGs 153 (scattered radiation removal plates) arranged at least in the channel direction on the side of the first surface on which X-rays of the plurality of detection elements 151 are incident in a direction substantially normal to the first surface. The acquisition function 55 acquires a detection element image generated on the basis of 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 detection element image on the basis of reflected light data. The acquisition function 55 is an example of an “acquirer.”

The scan control function 56 controls detection data collection processing in the gantry 10 by instructing the X-ray high voltage device 14, the DAS 16, the control device 18, and the bed driving device 32. The scan control function 56 performs control for monitoring scanning and main scanning. Further, the scan control function 56 controls the operation of each part at the time of capturing for collecting positioning images and capturing images used for diagnosis.

The generation function 57 generates data (center of gravity data) regarding an irradiated area of each of the plurality of detection elements on the basis of the detection element image acquired by the acquisition function 55. The generation function 57 generates data in which information on the position of the center of gravity of the actual irradiated area of each of the plurality of detection elements among the areas of the plurality of detection elements included in the detection element image is set as an irradiated position. The generation function