JP2021016535A - X-ray ct apparatus and x-ray tube device - Google Patents

Abstract

To obtain higher output of an X-ray with a small focal size in a dual energy scan than before.SOLUTION: An X-ray CT apparatus according to an embodiment comprises an X-ray tube, an X-ray detector, a rotation unit, and a control unit. The X-ray tube comprises: a first cathode and a second cathode for radiating thermoelectrons; a toric anode that receives thermoelectrons to generate an X-ray, is provided over the whole circumference of a subject, and is rotatably held; and a drive unit for driving and rotating the anode. The X-ray detector detects an X-ray radiated from the X-ray tube. The rotation unit rotatably holds the X-ray tube and the X-ray detector. The control unit controls the first cathode and the second cathode to make the cathodes generate X-rays having different tube voltages.SELECTED DRAWING: Figure 4

Description

Embodiments of the present invention relate to an X-ray CT (Computed Tomography) device and an X-ray tube device.

There is a medical image diagnostic device that generates medical image data in which the body tissue of a subject is imaged. Examples of the medical image diagnostic apparatus include an X-ray CT apparatus and an MRI (Magnetic Resonance Imaging) apparatus. The X-ray CT apparatus generates an axial cross section of the subject or three-dimensional CT image data based on an electric signal based on the X-ray detected by the X-ray detector by irradiating the subject with X-rays.

The X-ray CT apparatus includes an X-ray tube that generates X-rays. The X-ray tube is a vacuum tube that generates X-rays by irradiating thermoelectrons from the cathode (filament) toward the anode by applying a high voltage. In an X-ray tube, in order to obtain a high output with a small focal point, there is a problem that the focal plane on the anode becomes hot.

Further, as one of the scans by the X-ray CT apparatus, there is a multi-energy scan that acquires X-ray images of different energies. A multi-energy scan is a concept that includes a dual energy scan that acquires X-ray images of two different energies. In order to realize multi-energy scanning, two or more X-ray tubes are required for the X-ray CT device, or control for switching the tube voltage of the cathode of the X-ray tube is required, and the structure of the X-ray CT device. There are upper or functional restrictions.

Japanese Unexamined Patent Publication No. 2013-000233

The problem to be solved by the present invention is to obtain higher output X-rays than before in a dual energy scan with a small focal size.

The X-ray CT apparatus according to the embodiment includes an X-ray tube, an X-ray detector, a rotating unit, and a control unit. The X-ray tube is provided around the entire circumference of the subject to generate X-rays by receiving the thermions and the first cathode and the second cathode that irradiate the thermions, and is held rotatably. It includes an annular anode and a drive unit for rotationally driving the anode. The X-ray detector detects the X-rays emitted from the X-ray tube. The rotating unit rotatably holds the X-ray tube and the X-ray detector. The control unit generates X-rays having different tube voltages by controlling the first cathode and the second cathode.

FIG. 1 is a schematic view showing a configuration of an X-ray CT apparatus according to a first embodiment. FIG. 2 is a schematic view showing a configuration example of an X-ray tube and an X-ray high voltage device and a relationship between two types of tube voltages in the X-ray CT apparatus according to the first embodiment. FIG. 3 is a schematic view of the configuration of the rotating frame provided with the X-ray tube according to the comparative example as viewed from the front. FIG. 4 is a schematic view of a configuration example of a rotating frame provided with an X-ray tube according to the first embodiment as viewed from the front. FIG. 5 is a side view showing a configuration example of the rotating frame shown in FIG. 4 in the X-ray CT apparatus according to the first embodiment. FIG. 6 is a schematic view of the operation of the rotating frame shown in FIG. 4 as viewed from the front in the X-ray CT apparatus according to the first embodiment. FIG. 7 is a schematic view showing the configuration of the X-ray CT apparatus according to the second embodiment. FIG. 8 is a diagram showing the relationship between two types of tube voltages in the X-ray CT apparatus according to the second embodiment. FIG. 9 is a schematic view of a configuration example of the rotating frame provided with the X-ray tube according to the second embodiment as viewed from the front. FIG. 10 is a side view showing a configuration example of the rotating frame shown in FIG. 9 in the X-ray CT apparatus according to the second embodiment.

Hereinafter, embodiments of the X-ray CT apparatus and the X-ray tube apparatus will be described in detail with reference to the drawings.

The data collection method using the X-ray CT device includes a rotation / rotation (RR: Rotate / Rotate) method in which an X-ray tube and an X-ray detector rotate around the subject as one body, or a ring shape. There are various methods such as a fixed / rotating (SR: Stationary / Rotate) method in which a large number of detection elements are arranged in an array and only an X-ray tube rotates around the subject. The present invention can be applied by any method. Hereinafter, in the X-ray CT apparatus according to the embodiment, a case where a third-generation rotation / rotation method, which currently occupies the mainstream, is adopted will be described as an example.

The technical idea of the present invention is applicable not only to perform dual energy scans but also to perform multi-energy scans.

(First Embodiment)
FIG. 1 is a schematic view showing a configuration of an X-ray CT apparatus according to a first embodiment.

FIG. 1 shows an X-ray CT apparatus 1 according to a first embodiment capable of performing a dual energy scan. The X-ray CT device 1 includes a gantry device 10, a sleeper device 30, and a console device 40. The gantry device 10 and the sleeper device 30 are installed in the examination room. The gantry device 10 collects X-ray detection data (also referred to as "pure raw data") for a subject (eg, patient) P placed on the sleeper device 30. In FIG. 1, for convenience of explanation, a plurality of gantry devices 10 are drawn on the upper and lower sides on the left side, but the actual configuration is one gantry device 10.

The console device 40 is installed in a control room adjacent to the examination room. The console device 40 generates raw data by performing preprocessing on the detected data for a plurality of views, and reconstructs and displays the CT image by performing reconstruction processing on the raw data.

The gantry device 10 includes an X-ray tube (synonymous with “X-ray tube device”) 11, a first X-ray detector 121, a second X-ray detector 122, and a rotating unit (for example, a rotating frame) 13. An X-ray high voltage device 14, a control device 15, a first data acquisition circuit (DAS) 181 and a second DAS 182, and a fixed portion (for example, a fixed frame) 19 are provided. The gantry device 10 includes a wedge and a collimator, but the illustration thereof will be omitted for convenience. The gantry device 10 is an example of a gantry unit.

The X-ray tube 11 is provided in the rotating frame 13. The X-ray tube 11 is a vacuum tube including a plurality of cathodes and one annular anode. For example, the X-ray tube 11 includes a first cathode (cathode) 111, a second cathode 112, and an annular anode (anode) 113 (gray portion in FIG. 1). The anode 113 has a structure in which a target is attached to the surface of a copper ingot. Hereinafter, the anode and the target will be described with the same reference numerals 113. By applying a high voltage from the X-ray high voltage device 14, the target 113 generates X-rays of the first energy and the second by irradiating thermions from the first cathode 111 toward the target 113. By irradiating thermions from the cathode 112 of the target 113 toward the target 113, the target 113 generates X-rays of second energy. The detailed configuration of the X-ray tube 11 will be described later with reference to FIGS. 4 to 6. The X-ray tube 11 is an example of an X-ray irradiation unit.

The X-ray detectors 121 and 122 are provided on the rotating frame 13 so as to face each of the two focal positions of the X-ray tube 11. Specifically, the first X-ray detector 121 is provided at a position where X-rays of the first energy generated at the first focal position (focus position F1 shown in FIG. 4) of the target 113 are irradiated. At the same time, the second X-ray detector 122 is provided at a position where X-rays of the second energy generated at the second focal position (fog position F2 shown in FIG. 4) of the target 113 are irradiated. The first X-ray detector 121 detects the X-rays emitted from the first focal position, outputs the detection data corresponding to the X-ray dose to the DAS181 as an electric signal, and the second X-ray detector. The 122 detects the X-rays emitted from the second focal position, and outputs the detection data corresponding to the X-ray dose to the DAS 182 as an electric signal.

For example, the first X-ray detector 121 has a plurality of X-ray detection element sequences in which a plurality of X-ray detection elements are arranged in the channel direction along one arc centering on the first focal position. Similarly, the second X-ray detector 122 has a plurality of X-ray detection element sequences in which a plurality of X-ray detection elements are arranged in the channel direction along one arc centering on the second focal position. Each of the X-ray detectors 121 and 122 has a structure in which a plurality of X-ray detection element rows in which a plurality of X-ray detection elements are arranged in the channel direction are arranged in a slice direction (column direction, low direction), respectively.

Further, the X-ray detectors 121 and 122 are indirect conversion type detectors having, for example, a grid, a scintillator array, and an optical sensor array, respectively. The scintillator array has a plurality of scintillators, and the scintillator has a scintillator crystal that outputs a photon amount of light according to an incident X dose. The grid is arranged on the surface of the scintillator array on the X-ray incident side, and has an X-ray shielding plate having a function of absorbing scattered X-rays. The grid may also be called a collimator (one-dimensional collimator or two-dimensional collimator). The optical sensor array has a function of converting into an electric signal according to the amount of light from the scintillator, and has, for example, an optical sensor such as a photomultiplier tube (PMT).

The X-ray detectors 121 and 122 may be direct conversion type detectors each having a semiconductor element that converts the incident X-ray into an electric signal. Further, the X-ray detectors 121 and 122 are examples of the X-ray detector, respectively.

In the rotating frame 13, the first focal position (focus position F1 shown in FIG. 4) and the first X-ray detector 121 face each other, and the second focal position (focus position F2 shown in FIG. 4) is opposed to each other. ) And the second X-ray detector 122 face each other, and the X-ray tube 11, the first X-ray detector 121, and the second X-ray detector 122 are supported. The rotating frame 13 is an annular frame that integrally rotates the X-ray tube 11, the first X-ray detector 121, and the second X-ray detector 122 under the control of the control device 15 described later. is there. The rotating frame 13 includes an X-ray tube 11, a first X-ray detector 121, a second X-ray detector 122, an X-ray high voltage device 14, a first DAS181, and a first. In some cases, at least one of 2 DAS182 is further provided and supported. The rotating frame 13 is an example of a rotating unit.

In this way, the X-ray CT apparatus 1 rotates the rotation frame 13 around the patient P, and each detector collects a plurality of views, that is, detection data for 360 ° of the patient P. The CT image reconstruction method is not limited to the full scan reconstruction method using the detection data of 360 °. For example, the X-ray CT apparatus 1 may adopt a half reconstruction method in which a CT image is reconstructed based on detection data for half circumference (180 °) + fan angle.

The X-ray high voltage device 14 is provided in the rotating frame 13 or the fixed frame 19 which is a non-rotating portion that rotatably holds the rotating frame 13. The X-ray high voltage device 14 has an electric circuit such as a transformer and a rectifier. The X-ray high voltage device 14 has a function of generating two or more different types of voltages (“HV1” and “HV2” shown in FIG. 2) applied to the X-ray tube 11 under the control of the control device 15 described later. It has a high voltage generator having the above, and an X-ray control device (not shown) that controls the output voltage according to the X-rays emitted by the X-ray tube 11 under the control of the control device 15 described later. The high voltage generator may be a transformer type or an inverter type. In FIG. 1, for convenience of explanation, the X-ray high voltage device 14 is positioned in the positive direction of the x-axis with respect to the first cathode 111 and in the negative direction of the x-axis with respect to the second cathode 112. It is located at a position, but is not limited to that case. The X-ray high-voltage device 14 is an example of an X-ray high-voltage unit.

FIG. 2 is a schematic view showing a configuration example of the X-ray tube 11 and the X-ray high voltage device 14 and the relationship between the two types of tube voltages. FIG. 2A shows a configuration example of the X-ray tube 11 and the X-ray high voltage device 14, and FIG. 2B shows the relationship between the two types of tube voltages.

FIG. 2A shows an X-ray tube 11 and an X-ray high voltage device 14. As shown in FIGS. 2A and 2B, the system control function 441 heats up by controlling the high voltage generator HV1 to apply a voltage of 140 kV to the first cathode 111 of the X-ray tube 11. The thermions are targeted 113 by irradiating the first focal position F1 of the target 113 with electrons and controlling the high voltage generator HV2 to apply a voltage of 80 kV to the second cathode 112 of the X-ray tube 11. The second focal position F2 of the above is irradiated. Then, the system control function 441 simultaneously generates X-rays of two kinds of energies from the two focal points of one X-ray tube 11 and detects them by the two X-ray detectors 121 and 122, respectively. , Run dual energy scans. With such control, dual energy scanning faster than the method of switching the tube voltage for each view at one focal point (so-called Fast_kV method) is possible while ensuring a high dose at a small focal point. Further, it is possible to construct two focal points on one target 113 and control the X-ray output individually.

In addition, in FIG. 2B, a case where a dual energy scan in which X-rays of two kinds of energies are simultaneously generated from two focal points of one X-ray tube 11 is executed has been described, but is limited to that case. It is not something that is done. For example, the system control function 441 may perform control that combines the above-mentioned simultaneous generation of X-rays with the Fast_kV method. Specifically, the system control function 441 controls at least one of the two cathodes 111 and 112 corresponding to the two focal points, and emits X-rays having different energies from the focal point of the cathode at high speed for each view. Switch to. In that case, multi-energy scanning with X-rays of three or more types of energy is possible.

Further, the number of focal points included in one X-ray tube 11 is not limited to two. By downsizing the X-ray high-voltage device 14, it is possible to increase the number of focal points to three or more. In this case, multi-energy scanning with X-rays of three or more types of energy becomes possible.

Returning to the description of FIG. 1, the control device 15 includes a processing circuit and a memory, and a drive mechanism such as a motor and an actuator. The configuration of the processing circuit and the memory is the same as that of the processing circuit 44 and the memory 41 of the console device 40 described later, and thus the description thereof will be omitted.

The control device 15 has a function of receiving an input signal from an input interface (not shown) attached to the console device 40 or the gantry device 10 and controlling the operation of the gantry device 10 and the sleeper device 30. For example, the control device 15 controls to rotate the rotating frame 13 in response to an input signal, controls to tilt the gantry device 10, and controls to operate the sleeper device 30 and the top plate 33. The control for tilting the gantry device 10 is based on the tilt angle (tilt angle) information input by the input interface attached to the gantry device 10, and the control device 15 rotates around an axis parallel to the X-axis direction. It is realized by rotating. The control device 15 may be provided in the gantry device 10 or in the console device 40. The control device 15 is an example of a control unit.

Further, the control device 15 includes a rotation angle of the X-ray tube 11 and a wedge and a collimator described later based on the imaging conditions input from the input interface described later attached to the console device 40 and the gantry device 10 (illustrated). Omitted) Controls the operation.

The wedge (not shown) is provided on the rotating frame 13 so as to be arranged on the exit side of the first focal position (focus position F1 shown in FIG. 4), and the wedge is provided on the rotating frame 13 and the second focal position (focus shown in FIG. 4). The rotating frame 13 is provided so as to be arranged on the exit side of the position F2). The wedge is a filter for adjusting the X-ray dose emitted from each focal position of the X-ray tube 11 under the control of the control device 15. Specifically, the wedge transmits the X-rays emitted from the X-ray tube 11 so that the X-rays emitted to the patient P from each focal position of the X-ray tube 11 have a predetermined distribution. It is a filter that attenuates. For example, a wedge (wedge filter or bow-tie filter) is a filter obtained by processing aluminum so as to have a predetermined target angle and a predetermined thickness.

The collimator (not shown) is provided on the rotating frame 13 so as to be arranged on the exit side of the first focal position (focus position F1 shown in FIG. 4), and the second focal position (focus shown in FIG. 4). The rotating frame 13 is provided so as to be arranged on the exit side of the position F2). The collimator is a lead plate or the like for narrowing the irradiation range of X-rays transmitted through each wedge under the control of the control device 15, and an X-ray irradiation opening is formed by combining a plurality of lead plates or the like. The collimator is also called an X-ray diaphragm or slit.

The DAS 181 and 182 are provided in the rotating frame 13, respectively. The first DAS181 is controlled by an amplifier that amplifies an electric signal output from each X-ray detection element of the first X-ray detector 121 under the control of the control device 15, and a control device 15. Below, it has an A / D (Analog to Digital) converter that converts an electric signal into a digital signal, and generates detection data after amplification and digital conversion. Similarly, the second DAS 182 has an amplifier that amplifies the electric signal output from each X-ray detection element of the second X-ray detector 122, and an A / D converter, and amplifies the electric signal. And generate detection data after digital conversion. The detection data for a plurality of views generated by DAS181 and 182 are transferred to the console device 40, respectively. DAS181 and 182 are examples of data collection units, respectively.

Here, the detection data generated by the first DAS181 has a photodiode provided in the fixed frame 19 of the gantry device 10 by optical communication from a transmitter having a light emitting diode (LED) provided in the rotating frame 13. It is transmitted to the receiver and transferred to the console device 40. Similarly, the detection data generated by the second DAS182 is transferred to the console device 40. The method of transmitting the detection data from the rotating frame 13 to the fixed frame 19 of the gantry device 10 is not limited to the above-mentioned optical communication, and any method may be adopted as long as it is a non-contact type data transmission. The rotating frame 13 is an example of a rotating unit.

The fixed frame 19 forms a bore W for arranging the patient P inside in the radial direction. The fixed frame 19 rotatably supports the rotating frame 13. The fixed frame 19 is an example of a fixed portion.

The sleeper device 30 includes a base 31, a sleeper drive device 32, a top plate 33, and a support frame 34. The sleeper device 30 is a device on which the patient P to be scanned is placed and the patient P is moved under the control of the control device 15.

The base 31 is a housing that movably supports the support frame 34 in the vertical direction (y-axis direction). The sleeper drive device 32 is a motor or actuator that moves the top plate 33 on which the patient P is placed in the long axis direction (z-axis direction) of the top plate 33. The top plate 33 provided on the upper surface of the support frame 34 is a plate having a shape on which the patient P can be placed.

In addition to the top plate 33, the sleeper drive device 32 may move the support frame 34 in the long axis direction (z-axis direction) of the top plate 33. Further, the sleeper drive device 32 may be moved together with the base 31 of the sleeper device 30. When the present invention is applied to standing CT, a method of moving a patient moving mechanism corresponding to a top plate 33 may be used. Further, when performing an imaging involving a relative change in the positional relationship between the imaging system of the gantry device 10 and the top plate 33, such as a helical scan or a scanno imaging for positioning, the relative change in the positional relationship is performed. It may be performed by driving the top plate 33, may be performed by running the fixed frame 19 of the gantry device 10, or may be performed by combining them.

In the embodiment, the rotation axis of the rotation frame 13 in the non-tilt state or the longitudinal direction of the top plate 33 of the sleeper device 30 is orthogonal to the z-axis direction and the z-axis direction, and the axial direction is horizontal to the floor surface. It is assumed that the axial directions orthogonal to the x-axis direction and the z-axis direction and perpendicular to the floor surface are defined as the y-axis directions, respectively.

The console device 40 includes a memory 41, a display 42, an input interface 43, and a processing circuit 44. Although the console device 40 will be described as a separate body from the gantry device 10, the gantry device 10 may include a part of each component of the console device 40 or the console device 40. Further, in the following description, it is assumed that the console device 40 executes all functions on a single console, but these functions may be executed by a plurality of consoles. The console device 40 is an example of a medical image processing device.

The memory 41 is composed of, for example, a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory (Flash Memory), a hard disk, an optical disk, or the like. The memory 41 may be composed of a portable medium such as a USB (Universal Serial Bus) memory and a DVD (Digital Video Disk). The memory 41 stores various processing programs (including an OS (Operating System) and the like in addition to the application program) used in the processing circuit 44 and data necessary for executing the program. In addition, the OS may include a GUI (Graphic User Interface) that makes extensive use of graphics for displaying information on the display 42 to the operator and allows basic operations to be performed by the input interface 43.

The memory 41 stores, for example, the detection data before the preprocessing, the raw data after the preprocessing and before the reconstruction, and the CT image after the reconstruction. The pre-processing means at least one of logarithmic conversion processing, offset correction processing, sensitivity correction processing between channels, beam hardening processing, and the like for the detected data. Further, a cloud server that can be connected to the X-ray CT device 1 via a communication network such as the Internet is configured to store detection data, raw data, and CT images in response to a storage request from the X-ray CT device 1. May be done. The memory 41 is an example of a storage unit.

The display 42 displays various information. For example, the display 42 outputs a CT image generated by the processing circuit 44, a GUI (Graphical User Interface) for receiving various operations from the user, and the like. For example, the display 42 is a liquid crystal display, a CRT (Cathode Ray Tube) display, an OLED (Organic Light Emitting Diode) display, or the like. Further, the display 42 may be provided on the gantry device 10. Further, the display 42 may be a desktop type, or may be composed of a tablet terminal or the like capable of wireless communication with the console device 40 main body. The display 42 is an example of a display unit.

The input interface 43 includes an input device that can be operated by an operator such as an engineer, and an input circuit that inputs a signal from the input device. Input devices include a mouse, keyboard, trackball, switch, button, joystick, a touch pad that performs input operations by touching the operation surface, a touch screen that integrates a display screen and a touch pad, and non-optical sensors. It is realized by a contact input circuit, a voice input circuit, and the like. When the input device receives an input operation from the operator, the input circuit generates an electric signal corresponding to the input operation and outputs it to the processing circuit 44. Further, the input interface 43 may be provided in the gantry device 10. Further, the input interface 43 may be composed of a tablet terminal or the like capable of wireless communication with the console device 40 main body. The input interface 43 is an example of an input unit.

The processing circuit 44 controls the overall operation of the X-ray CT apparatus 1. The processing circuit 44 means a dedicated or general-purpose CPU (Central Processing Unit), MPU (Micro Processor Unit), GPU (Graphics Processing Unit), ASIC, programmable logic device, and the like. Examples of the programmable logic device include a simple programmable logic device (SPLD: Simple Programmable Logic Device), a compound programmable logic device (CPLD: Complex Programmable Logic Device), and a field programmable gate array (FPGA: Field Programmable Gate Array). Can be mentioned. The processing circuit 44 is an example of a processing unit.

Further, the processing circuit 44 may be composed of a single circuit or a combination of a plurality of independent processing circuit elements. In the latter case, the memory may be provided individually for each processing circuit element, or a single memory may store a program corresponding to the functions of the plurality of processing circuit elements.

The processing circuit 44 realizes the system control function 441, the preprocessing function 442, and the reconstruction processing function 443 by executing the program stored in the memory 41. It should be noted that all or a part of the functions 441 to 443 is not limited to the case where it is realized by executing the program of the console device 40, and may be provided in the console device 40 as a circuit such as an ASIC. .. Further, all or a part of the functions 441 to 443 may be provided not only in the console device 40 but also in the control device 15.

The system control function 441 includes a function of generating X-rays having different tube voltages by controlling the first cathode 111 and the second cathode 112 of the X-ray tube 11. Specifically, the system control function 441 includes an X-ray tube 11, a first X-ray detector 121, a second X-ray detector 122, a rotating frame 13, and a rotating frame 13 according to preset scanning conditions. It includes a function of executing a dual energy scan by controlling the operation of the X-ray high voltage device 14 and the like, and acquiring detection data for a plurality of views for each energy. For example, the scanning conditions include a tube current mA, a tube voltage kV, an X-ray intensity control condition (modulation condition), a rotation speed of the X-ray tube 11 (or a rotating frame 13), and the like with respect to the irradiation X-ray. The system control function 441 is an example of a control unit.

In the X-ray CT apparatus 1 according to the first embodiment, the system control function 441 controls X-rays of different tube voltages by controlling the first cathode 111 and the second cathode 112 of the X-ray tube 11. It can be generated simultaneously or alternately. Further, in the X-ray CT apparatus 1A (shown in FIG. 7) according to the second embodiment described later, the system control function 441 controls the first cathode 111 and the second cathode 112 of the X-ray tube 11A. This makes it possible to alternately generate X-rays with different tube voltages.

The preprocessing function 442 includes a function of generating raw data for a plurality of views for each energy by performing preprocessing on the detection data for a plurality of views collected by the system control function 441. The preprocessing function 442 is an example of the preprocessing unit.

The reconstruction processing function 443 includes a function of generating CT image data for each energy by performing image reconstruction processing on raw data of a plurality of views after preprocessing by the preprocessing function 442. Further, the reconstruction processing function 443 has a function of storing CT image data in the memory 41, a function of displaying the CT image data as a CT image on the display 42, and an external CT image data via a network interface (not shown). It may also include the ability to send to the device. The reconstruction processing function 443 is an example of the reconstruction processing unit.

Subsequently, the configuration of the rotating frame provided with the X-ray tube according to the comparative example will be described with reference to FIG. Further, the configuration and operation of the rotating frame 13 including the X-ray tube 11 according to the embodiment will be described with reference to FIGS. 4 to 6.

FIG. 3 is a schematic view of the configuration of the rotating frame provided with the X-ray tube according to the comparative example as viewed from the front.

FIG. 3 shows a rotating frame 13, a first X-ray tube 91 fixed to the rotating frame 13, and a second X-ray tube 92 fixed to the rotating frame 13. The first X-ray tube 91 includes a first cathode 911 and a first target 913. Further, the second X-ray tube 92 includes a second cathode 922 and a second target 923. In FIG. 3, the rotation center axis of the rotation frame 13 is defined as “C”, the rotation center axis of the first target 913 is defined as “E1”, and the rotation center axis of the second target 923 is defined as “E2”. Define.

The cathodes 911 and 922, the targets 913 and 923, and the X-ray detectors 121 and 122 rotate around the rotation center axis C together with the rotation frame 13. The first target 913 further rotates about the rotation center axis E1 with respect to the rotation frame 13. That is, by rotating the first target 913 around the rotation center axis E1, the first X-ray tube 91 is placed on the surface (hereinafter referred to as “focus surface”) T1 on the cathode 911 side of the first target 913. X-rays are generated while shifting the focal position G1. Similarly, the second target 923 further rotates about the rotation center axis E2 with respect to the rotation frame 13. That is, by rotating the second target 923 around the rotation center axis E2, the second X-ray tube 92 X-rays while shifting the focal position G2 on the focal plane T2 on the cathode 922 side of the second target 923. Generate a line.

The X-rays generated by the first target 913 pass through the patient arranged in the bore W and are detected by the first X-ray detector 121 held by the rotating frame 13. In this way, on the rotation frame 13 rotated around the rotation center axis C, the first target 913 further rotated around the rotation center axis E1 generates X-rays at each focal position G1 of the focal plane T1. Then one of the dual energy scans is performed. Similarly, the X-rays generated by the second target 923 pass through the patient placed in the bore W and are detected by the second X-ray detector 122 held in the rotating frame 13. In this way, on the rotation frame 13 rotated around the rotation center axis C, the second target 923 further rotated around the rotation center axis E2 generates X-rays at each focal position G2 of the focal plane T2. Then the other scan of the dual energy scan is performed.

In such a dual energy scan, if high output is to be obtained with a small focal point in the X-ray tubes 91 and 92, the areas of the focal planes T1 and T2 of the targets 913 and 923 are small, so that the focal planes T1 of the targets 913 and 923 are small. , T2 becomes hot. Further, it is also conceivable to adopt a method of expanding the area of the focal planes T1 and T2 of the targets 913 and 923 in order to overcome the high temperature by maintaining the positions of the rotation center axes E1 and E2 of the targets 913 and 923. .. However, it is difficult to adopt this method due to the influence of the installation space of the targets 913 and 923 and the centrifugal force of the rotation of the rotating frame 13. Therefore, while shifting the position of the rotation center axis E1 of the first target 913 and the position of the rotation center axis E2 of the second target 923 to the vicinity of the rotation center axis C, the focal planes T1 and T2 of the targets 913 and 923 Consider expanding the area of (Condition 1).

On the other hand, it is preferable that the axial cross section of the CT image is parallel to the xy plane, and the X-ray detectors 121 and 122 are used in order to divert the third generation X-ray detectors 121 and 122. It is preferable not to change the size (Condition 2).

Therefore, consider a case where both of the above conditions 1 and 2 are satisfied. That is, assuming that the axial cross section of the CT image is parallel to the xy plane and the size of the X-ray detectors 121 and 122 is not changed, the positions of the rotation center axes E1 and E2 are moved to the vicinity of the rotation center axis C. Consider expanding the area of the focal planes T1 and T2 while shifting.

Assuming that the axial cross section of the CT image is parallel to the xy plane and the size of the X-ray detectors 121 and 122 is not changed, the positions of the rotation center axes E1 and E2 are shifted to the vicinity of the rotation center axis C. In this case, the rotation center axis E1 of the first target 913 and the rotation center axis E2 of the second target 923 adopt a configuration having a predetermined inclination angle from the rotation center axis C, so that the focal planes T1 and T2 The area can be expanded.

FIG. 4 is a schematic view of a configuration example of the rotating frame 13 provided with the X-ray tube 11 as viewed from the front. FIG. 5 is a side view showing a configuration example of the rotating frame 13 shown in FIG.

The X-ray CT apparatus 1 includes one X-ray tube 11 and two X-ray detectors 121 and 122 in the rotating frame 13. One X-ray tube 11 includes a plurality of, for example, two cathodes 111 and 112 for irradiating thermions, and one annular target 113 (gray portions in FIGS. 4 and 5). Further, the rotation frame 13 and the target 113 are arranged so that the rotation center axes are different from each other. On the left side of FIG. 5, the first cathode 111 is located on the inner side of the second cathode 112 (the side in the negative direction of the X-axis), and the first focal position F1 is the second focal position F2. The second X-ray detector 122 is located on the back side of the first X-ray detector 121, and is therefore not shown. Similarly, on the right side of FIG. 5, the second cathode 112 is located behind the first cathode 111, and the second focal position F2 is located behind the first focal position F1. Since the X-ray detector 121 of 1 is located behind the second X-ray detector 122, it is not shown.

In FIG. 5, the rotation center axis of the rotation frame 13 is defined as “C”, and the rotation center axis of the target 113 with respect to the rotation frame 13 is defined as “D”. Further, in FIGS. 4 and 5, the intersection of the rotation center axis C and the rotation center axis D is defined as the imaging center, that is, the rotation center I.

The X-ray tube 11 will be described with reference to FIG. The target 113 is provided in an annular shape so as to extend around the rotation center axis D including the rotation center I, that is, the entire circumference of the patient P.

The cathodes 111 and 112, the targets 113, and the X-ray detectors 121 and 122 rotate together with the rotation frame 13 around the rotation center axis C including the rotation center I. The target 113 further rotates about the rotation center axis D including the rotation center I with respect to the rotation frame 13. That is, by further rotating the target 113 with respect to the rotating frame 13, the X-ray tube 11 generates X-rays from the focal position F1 while shifting the irradiation position of thermions on the focal plane U of the target 113. , X-rays are generated from the focal position F2 while shifting the irradiation position of thermions on the focal plane U of the target 113.

The X-rays generated at the focal position F1 of the target 113 and passed through the wedge and the collimator (not shown) pass through the patient arranged in the bore W and are held by the rotating frame 13. The first X-ray detector 121 Is detected by. In this way, on the rotation frame 13 rotated around the rotation center axis C, the targets 113 further rotated around the rotation center axis D generate X-rays at each focal position F1 of the focal plane U, whereby a plurality of targets 113 are generated. One of the dual energy scans is performed to collect the view data. Similarly, the X-rays generated at the focal position F2 of the target 113 and passed through the wedge and the collimator (not shown) pass through the patient placed in the bore W and are held by the rotating frame 13. It is detected by the detector 122. In this way, on the rotation frame 13 rotated around the rotation center axis C, the targets 113 further rotated around the rotation center axis D generate X-rays at each focal position F2 of the focal plane U, whereby a plurality of targets 113 are generated. The other scan of the dual energy scan is performed to collect the view data.

Compared with the targets 913 and 923 shown in FIG. 3, in the X-ray tube 11 shown in FIG. 4, the area of the focal planes T1 and T2 shown in FIG. 3 can be expanded to the focal plane U, so that in the dual energy scan, It has the effect of being able to obtain high output with a small focus. Further, in the target 113, it is possible to suppress the temperature rise of the focal plane U in the dual energy scan. Further, the target 113 has an effect that the centrifugal force resistance of the target 113 due to the rotation of the rotating frame 13 is improved in the dual energy scan.

A configuration example of the rotating frame 13 shown in FIG. 4 will be described with reference to FIG. The left side of FIG. 5 shows the configuration of the X-ray tube 11 and the like when the cathodes 111 and 112 of the X-ray tube 11 are located on the upper side. On the other hand, the right side of FIG. 5 shows the configuration of the X-ray tube 11 and the like when the cathodes 111 and 112 of the X-ray tube 11 are located on the lower side. That is, the right side of FIG. 5 shows the configuration of the X-ray tube 11 and the like when the rotation angle of the rotating frame 13 differs from the left side by 180 degrees.

The rotating frame 13 holds the vacuum vessel V, the first X-ray detector 121, and the second X-ray detector 122. As the rotating frame 13 rotates around the rotating center axis C, the vacuum vessel V, the first X-ray detector 121, and the second X-ray detector 122 are integrated with the rotating frame 13 to form the rotating center axis. Rotate around C.

Further, the vacuum vessel V includes a support portion B, a drive unit (for example, a rotation drive frame) R for rotationally driving the target 113 around the rotation center axis D, and an X-ray tube 11 inside. The support portion B is fixed to the inner wall of the vacuum vessel V and rotates together with the vacuum vessel V. The rotation drive frame R is held by the support portion B so as to be rotatable in the circumferential direction with respect to the support portion B via a plurality of ball bearings L arranged in the circumferential direction of the support portion B. The target 113 of the X-ray tube 11 is fixed to the rotation drive frame R and rotates together with the rotation drive frame R. Further, the support portion B, the rotation drive frame R, and the target 113 of the X-ray tube 11 are arranged along the circumference centered on the rotation center axis D. On the other hand, the cathode 111 of the X-ray tube 11 is fixed to the inner wall of the vacuum vessel V at the convex portion V1 of the vacuum vessel V, while the cathode 112 of the X-ray tube 11 is vacuumed at the convex portion V2 of the vacuum vessel V. It is fixed to the inner wall of the container V. That is, the cathodes 111 and 112 of the X-ray tube 11 rotate together with the vacuum vessel V.

The rotary frame 13 supports a drive means for rotationally driving the rotary drive frame R. As the driving means, for example, a direct drive type motor (not shown) provided along the ring of the target 113, that is, a DD motor is used. By the operation of the DD motor, the rotation drive frame R rotates around the rotation center axis D with respect to the support portion B via the plurality of ball bearings L, so that the target 113 fixed to the rotation drive frame R has a rotation center. Rotate around axis D. That is, the vacuum vessel V, the first X-ray detector 121, and the second X-ray detector 122 can rotate together with the rotating frame 13, and the target 113 inside the vacuum vessel V is the rotation drive frame R. At the same time, it can be further rotated inside the vacuum vessel V independently of the rotation of the rotating frame 13.

Here, the target 113 is arranged so that its rotation center axis D overlaps with the rotation center axis C at the rotation center I. Further, the target 113 has a second focal point so that the straight line connecting the first focal position F1 and the central position of the detection surface of the first X-ray detector 121 is vertical (parallel to the y-axis). The straight line connecting the position F2 and the center position of the detection surface of the second X-ray detector 122 is arranged so as to be vertical. Further, the target angle of the target 113 is formed so that X-rays are irradiated around the linear direction connecting the first focal position F1 and the center position of the detection surface of the first X-ray detector 121. Further, the target angle is formed so that X-rays are irradiated around the linear direction connecting the second focal position F2 and the center position of the detection surface of the second X-ray detector 122. As a result, the axial cross section of the obtained CT image becomes parallel to the xy plane.

As shown in FIG. 5, the rotation center axis D of the rotation drive frame R is inclined with respect to the rotation center axis C of the rotation frame 13. The rotation angle position of the rotation frame 13 when the most protruding portion in the negative direction of the z-axis is located at the uppermost portion of the inclined rotation drive frame R is defined as the home position. The left side of FIGS. 4 and 5 shows the arrangement of the rotating frame 13 at the home position. At the home position of the rotating frame 13, the rotation center axis D of the rotation drive frame R has a predetermined inclination angle α in the yz plane with respect to the rotation center axis C of the rotation frame 13. The predetermined tilt angle α is appropriately determined according to the number of rows of detection elements (the number in the parallel direction of the z-axis) of the X-ray detectors 121 and 122.

Further, in the first cathode 111 and the second cathode 112, the first focal position F1 on the target 113 and the second focal position F2 on the target 113 are in the direction of the rotation center axis C of the rotation frame 13. It is preferable that the rotating frame 13 is held so as to substantially match the above. This is because the first X-ray detector 121 corresponding to the first focal position F1 and the second X-ray detector 122 corresponding to the second focal position F2 obtain a tomographic image of the same axial cross section. Is. For example, in the home position of the rotation frame 13, the convex portions V1 and V2, that is, the cathode 111, are arranged so that the focal positions F1 and F2 are arranged at positions symmetrical with respect to the yz plane including the rotation center I. 112 is arranged. In particular, at the home position of the rotation frame 13, the focal positions F1 and F2 are arranged at positions symmetrical with respect to the yz plane including the rotation center I, and the first focal position F1 and the rotation center I It is preferable that the straight line connecting the two and the straight line connecting the second focal position F2 and the rotation center I are arranged so as to be orthogonal to each other (shown in FIG. 4).

In addition, as compared with the comparative example shown in FIG. 3, in FIG. 5, since the target 113 and the like are arranged at a constant inclination angle α, it seems that the gantry device 10 is enlarged in the z-axis direction. However, in the X-ray tube 11, it is not necessary to configure a mechanism (rotor, stator, etc.) for rotating the conventional target 913,923 (shown in FIG. 3) according to the comparative example in the z-axis direction, and the vacuum tube Since it is not necessary to install a large cooling device due to the large surface area of the frame device 10, it is possible to minimize the increase in size of the gantry device 10.

Subsequently, the rotation speed and the rotation direction of the rotation frame 13 and the target 113 will be described with reference to FIG. FIG. 6 is a schematic view of the operation of the rotating frame 13 shown in FIG. 4 as viewed from the front. The target 113 is configured to rotate at a speed exceeding "0" with respect to the rotation frame 13. That is, the target 113 is configured to rotate in the same direction as the rotation direction of the rotation frame 13 at a speed exceeding "0" with respect to the rotation frame 13, or is opposite to the rotation direction of the rotation frame 13. It is configured to rotate in the direction at a speed exceeding "0" with respect to the rotating frame 13.

As shown in FIG. 6, the rotation of the rotating frame 13 causes the cathodes 111 and 112 to rotate clockwise at a speed J1. On the other hand, the target 113 rotates clockwise with respect to the rotation frame 13 at a relative speed J2 due to the rotation of the rotation drive frame R. The relative velocity J2 is not "0". When the relative speed J2 is "0", the rotation of the rotating frame 13 causes the first cathode 111, the second cathode 112, and the target 113 to rotate in the same direction at the same speed, and the target 113 This is because the irradiation positions of thermions in the above are not dispersed.

The rotation direction of the rotating frame 13 and the like (rotation direction at the speed J1) and the rotation direction of the target 113 and the like with respect to the rotation frame 13 (rotation direction at the relative speed J2) are limited to the same direction. It's not a thing. The same effect can be obtained even if the rotation direction of the rotating frame 13 or the like and the rotation direction of the target 113 or the like with respect to the rotating frame 13 are opposite to each other.

Although the case of the target 113 rotating with respect to the rotating frame 13 has been described with reference to FIGS. 4 to 6, it is also conceivable to adopt a configuration in which an annular target fixed to the fixed frame 19 is adopted. However, in that case, it is necessary to install an X-ray detector having channels for the entire circumference or half. According to the target 113 shown in FIGS. 4 to 6 that rotates with respect to the rotating frame 13, the X-ray detector, the data processing method, the X-ray high voltage device, and the high voltage provided in the third generation X-ray CT device are provided. The cable can be diverted.

As described above, according to the X-ray tubes 11 shown in FIGS. 1, 2, 4 to 6, in the dual energy scan, the gantry device 10 is suppressed from being enlarged, and the focal size is small and the output is higher than before. X-rays can be obtained. Further, according to the X-ray tube 11, it is possible to suppress the temperature rise of the focal plane U in the dual energy scan, so that it is not necessary to install a cooling device, and the centrifugal force resistance of the target 113 due to the rotation of the rotating frame 13 is not required. Has the effect of dramatically improving. Further, according to the X-ray tube 11, one X-ray tube 11 can also perform a dual energy scan by simultaneously generating X-rays of different energies.

(Second Embodiment)
The X-ray CT apparatus according to the second embodiment is different from the X-ray CT apparatus according to the first embodiment in that one X-ray detection is performed for two cathodes contained in one X-ray tube. It is equipped with a device (for example, an X-ray detector 121).

FIG. 7 is a schematic view showing the configuration of the X-ray CT apparatus according to the second embodiment.

FIG. 7 shows an X-ray CT apparatus 1A according to a second embodiment capable of performing a dual energy scan. The X-ray CT device 1A includes a gantry device 10A, a sleeper device 30, and a console device 40. The gantry device 10A and the sleeper device 30 are installed in the examination room. The gantry device 10A collects X-ray detection data (also referred to as "pure raw data") for a subject (eg, patient) P placed on the bed device 30. In FIG. 7, for convenience of explanation, a plurality of gantry devices 10A are drawn on the upper and lower sides on the left side, but as an actual configuration, there is only one gantry device 10A.

The gantry device 10A includes an X-ray tube 11A, one X-ray detector 121, a rotating frame 13, an X-ray high voltage device 14, a control device 15, a DAS181, and a fixed frame 19. The gantry device 10A includes a wedge and a collimator, but the illustration thereof will be omitted for convenience. The gantry device 10A is an example of the gantry portion.

The X-ray detector 121 is provided on the rotating frame 13 so as to face a set of two focal positions of the X-ray tube 11A. Specifically, the X-ray detector 121 includes X-rays of the first energy generated at the focal position of the target 113 (focus position F1 shown in FIG. 9) and the focal position of the target 113 (focus shown in FIG. 9). It is provided at a position where X-rays of the second energy generated at the position F2) are irradiated. The X-ray detector 121 has a first X-ray generated based on the thermions emitted from the first cathode 111 and a second X generated based on the thermions emitted from the second cathode 112. Detect lines and. In FIG. 7, the same members as those of the X-ray CT apparatus 1 shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 8 is a diagram showing the relationship between two types of tube voltages.

The system control function 441 controls the high voltage generator HV1 (shown in FIG. 2A) to apply a voltage of 140 kV to the first cathode 111 of the X-ray tube 11A, thereby targeting thermoelectrons. Heat is generated by irradiating the first focal position F1 and controlling the high voltage generator HV2 (shown in FIG. 2A) to apply a voltage of 80 kV to the second cathode 112 of the X-ray tube 11A. The second focal position F2 of the target 113 is irradiated with electrons. Then, the system control function 441 alternately generates X-rays of two kinds of energies from two focal points of one X-ray tube 11A and detects them by one X-ray detector 121, thereby performing dual. Have an energy scan run. Such control enables dual energy scanning at a higher speed than the method of switching the tube voltage for each view at one focal point while ensuring a high dose at a small focal point. Further, it is possible to construct two focal points on one target 113 and control the X-ray output individually.

In FIG. 8, a case where a dual energy scan in which X-rays of two kinds of energies are alternately generated from two focal points of one X-ray tube 11A is executed has been described, but is limited to that case. It's not a thing. For example, the system control function 441 may perform control that combines the above-mentioned alternating generation of X-rays with the Fast_kV method. Specifically, the system control function 441 controls at least one of the two cathodes 111 and 112 corresponding to the two focal points, and emits X-rays having different energies from the focal point of the cathode at high speed for each view. Switch to. In that case, multi-energy scanning with X-rays of three or more types of energy is possible.

FIG. 9 is a schematic view of a configuration example of the rotating frame 13 as viewed from the front. FIG. 10 is a side view showing a configuration example of the rotating frame 13 shown in FIG.

The X-ray CT apparatus 1A includes one X-ray tube 11A and one X-ray detector 121 in the rotating frame 13. One X-ray tube 11A includes a plurality of, for example, two cathodes 111 and 112, and one annular target 113 (gray portion in FIGS. 9 and 10). Further, the rotation frame 13 and the target 113 are arranged so that the rotation center axes are different from each other. In addition, on the left side of FIG. 10, the first cathode 111 is located on the back side of the second cathode 112 (the side in the negative direction of the X axis), and the first focal position F1 is the second focal position F2. Since it is located on the back side of, each is not shown. Similarly, on the right side of FIG. 10, the second cathode 112 is located behind the first cathode 111, and the second focal position F2 is located behind the first focal position F1. Each is not shown.

Further, in the first cathode 111 and the second cathode 112, the first focal position F1 on the target 113 and the second focal position F2 on the target 113 are in the direction of the rotation center axis C of the rotation frame 13. It is preferable that the rotating frame 13 is held so as to substantially match the above. This is to obtain a tomographic image of the same axial cross section with one X-ray detector 121. For example, in the home position of the rotation frame 13, the convex portions V1, that is, the cathodes 111 and 112 are arranged so that the focal positions F1 and F2 are arranged at positions symmetrical with respect to the yz plane including the rotation center I. Be placed. In particular, in the home position of the rotation frame 13, the focal positions F1 and F2 are arranged at positions symmetrical with respect to the yz plane including the rotation center I, and in consideration of the mutually intermittent data areas. It is preferable that they are arranged close to each other (shown in FIG. 9).

In FIGS. 9 and 10, the same members as the fixed frame 19 shown in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted. Further, the rotation speed and the rotation direction of the rotation frame 13 and the target 113 are the same as those described with reference to FIG.

As described above, according to the X-ray tube 11A shown in FIGS. 7 to 10, the same effect as that of the above-mentioned X-ray tube 11 can be obtained. Further, according to the X-ray tube 11A, by performing the reconstruction by the reconstruction processing function 443, it is possible to reconstruct different images based on X-rays having different energies by one X-ray detector 121. ..

The system control function 441 is an example of a control unit. The preprocessing function 442 is an example of a preprocessing unit. The reconstruction processing function 443 is an example of the reconstruction processing unit.

According to at least one embodiment described above, it is possible to obtain higher output X-rays than before with a small focal size in the dual energy scan.

Although some embodiments of the present invention 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, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1,1A X-ray CT device 11,11A X-ray tube 111 First cathode 112 Second cathode 113 Target 121 First X-ray detector 122 Second X-ray detector 13 Rotating frame 19 Fixed frame 441 System control Function 442 Pretreatment function 443 Reconstruction processing function V Vacuum vessel B Support part R Rotation drive frame L Multiple ball bearings

Claims (12)

A first cathode and a second cathode that irradiate thermions, and an annular anode that receives the thermions to generate X-rays, is provided over the entire circumference of the subject, and is held rotatably. An X-ray tube including a drive unit for rotationally driving the anode, and
An X-ray detector that detects X-rays emitted from the X-ray tube,
A rotating unit that rotatably holds the X-ray tube and the X-ray detector,
A control unit that generates X-rays with different tube voltages by controlling the first cathode and the second cathode.
An X-ray CT apparatus comprising. The rotation center axis of the rotating portion has a predetermined inclination angle with respect to the rotation center axis of the driving unit.
The X-ray CT apparatus according to claim 1. The first one so that the focal position on the anode corresponding to the first cathode and the focal position on the anode corresponding to the second cathode substantially coincide with each other in the rotation axis direction of the rotating portion. The cathode and the second cathode are held by the rotating portion.
The X-ray CT apparatus according to claim 2. The drive unit is configured to rotate in the same direction as or in the direction opposite to the rotation direction of the rotating unit.
The X-ray CT apparatus according to any one of claims 1 to 3. The drive unit is configured to rotate at a speed exceeding "0" with respect to the rotating unit.
The X-ray CT apparatus according to any one of claims 1 to 4. The target angle of the anode is formed so that the X-ray is irradiated around the linear direction connecting the focal position and the center position of the detection surface of the X-ray detector.
The X-ray CT apparatus according to any one of claims 1 to 5. The rotating part holds the vacuum vessel and
The vacuum container is internally held by the support portion fixed to the vacuum vessel, the first cathode, the second cathode, and the support portion rotatably with respect to the support portion. A drive unit and the anode fixed to the drive unit are provided.
The X-ray CT apparatus according to any one of claims 1 to 6. The drive unit is held by the support portion so as to be rotatable in the circumferential direction with respect to the support portion via a plurality of ball bearings arranged in the circumferential direction of the support portion.
The X-ray CT apparatus according to claim 7. The X-ray detector
A first X-ray detector that detects first X-rays generated based on thermions emitted from the first cathode, and
A second X-ray detector that detects a second X-ray generated based on thermions emitted from the second cathode, and
Including
By controlling the first cathode and the second cathode, the control unit simultaneously generates X-rays having different tube voltages.
The X-ray CT apparatus according to any one of claims 1 to 8. The X-ray detector has a first X-ray generated based on the thermions emitted from the first cathode and a second X-ray generated based on the thermions emitted from the second cathode. Detects lines and
The control unit alternately generates X-rays having different tube voltages by controlling the first cathode and the second cathode.
The X-ray CT apparatus according to any one of claims 1 to 8. The control unit controls the first cathode and the second cathode to generate X-rays having different tube voltages, and at least one of the first cathode and the second cathode. By controlling the cathode, X-rays with different tube voltages are generated by switching between views.
The X-ray CT apparatus according to claim 9 or 10. The first cathode and the second cathode that irradiate thermions,
An annular anode that receives the thermions, generates X-rays, and is rotatably held around the subject.
A drive unit that rotationally drives the anode,
X-ray tube device.

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