JP2021023662A - X-ray ct apparatus - Google Patents

Abstract

To prevent deterioration of image quality of a scan image due to noise with power supply.SOLUTION: An X-ray CT apparatus includes an X-ray tube, an X-ray detector, a data processing section, a power source, a battery, a rotor, and a control section. The X-ray detector detects an X-ray to be output by the X-ray tube. The data processing section processes a signal to be output by the X-ray detector. The power source supplies power to the data processing section. The battery supplies power to the data processing section. The rotor rotatably supports the X-ray tube and the X-ray detector by facing and also rotatably supports the data processing section and the battery. The control section performs changeover control between the power source and the battery based on prior information of scan, so as to control power supply to the data processing section.SELECTED DRAWING: Figure 3

Description

Embodiments of the present invention relate to an X-ray CT apparatus.

Conventionally, in an X-ray CT (Computed Tomography) device, a data acquisition system (hereinafter, DAS: Data Acquisition System) is used to collect and process data obtained by irradiating a subject with X-rays. It's being used. Since this DAS requires a large-capacity power supply, for example, a switching power supply that converts a commercial 200V AC voltage into a DC voltage is used as the power supply.

However, since the switching power supply generates high-frequency noise during operation, the influence of noise becomes dominant especially in shooting in a low count region, which may lead to deterioration of image quality and an increase in radiation exposure of the subject. .. In order to avoid the influence of such noise, it is conceivable to use a high-performance switching power supply capable of reducing noise, a linear regulator (LDO: Low Dropout), a noise filter, etc., but the circuit configuration becomes complicated. At the same time, there was concern that the cost would increase. In addition, there is an option of a noiseless power supply typified by a battery, but a battery having a capacity that can withstand clinical practice does not yet exist.

JP-A-2010-284221 U.S. Patent Application Publication No. 2013/0386877

An object to be solved by the present invention is to prevent deterioration of the image quality of the scanned image due to noise caused by power supply.

The X-ray CT apparatus of the embodiment includes an X-ray tube, an X-ray detector, a data processing unit, a power supply, a battery, a rotating body, and a control unit. The X-ray detector detects the X-rays output by the X-ray tube. The data processing unit processes the signal output by the X-ray detector. The power supply supplies electric power to the data processing unit. The battery supplies electric power to the data processing unit. The rotating body rotatably supports the X-ray tube and the X-ray detector so as to face each other, and further rotatably supports the data processing unit and the battery. The control unit executes switching control between the power supply and the battery based on the prior information of the scan, and controls the power supply to the data processing unit.

The block diagram of the X-ray CT apparatus 1 which concerns on 1st Embodiment. The figure which shows how the X-ray detector 15 and DAS 16 are supported by the rotating frame 17 which concerns on 1st Embodiment. The figure explaining an example of the power supply system for DAS16 which concerns on 1st Embodiment. The flowchart which shows an example of the processing of the processing circuit 50 of the console device 40 which concerns on 1st Embodiment. FIG. 5 is a flowchart showing another example of processing of the processing circuit 50 of the console device 40 according to the first embodiment. The figure explaining the power supply switching control by the power supply switching function 57 of the processing circuit 50 which concerns on 1st Embodiment. The figure explaining an example of the power feeding system for DAS16A which concerns on 2nd Embodiment. The figure explaining an example of the power feeding system for DAS16B which concerns on 2nd Embodiment.

Hereinafter, the X-ray CT apparatus of the embodiment will be described with reference to the drawings. In the X-ray CT apparatus of the embodiment, the DAS that processes the X-ray data is switched between power supply by the DAS power supply and power supply by the battery. When there is concern about the influence of noise generated during power supply, it is possible to prevent deterioration of the image quality of the scanned image due to noise by using battery power supply.

(First Embodiment)
[overall structure]
FIG. 1 is a block diagram of the X-ray CT apparatus 1 according to the first embodiment. The X-ray CT device 1 includes, for example, a gantry device 10, a bed device 30, and a console device 40. In FIG. 1, for convenience of explanation, both a view of the gantry device 10 from the Z-axis direction and a view from the X-axis direction are shown, but in reality, the gantry device 10 is one. In the present embodiment, the rotation axis of the rotation frame 17 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 axis horizontal to the floor surface is X. The directions orthogonal to the axial direction and the Z-axis direction and perpendicular to the floor surface are defined as the Y-axis directions, respectively.

The gantry device 10 includes, for example, an X-ray tube 11, a wedge 12, a collimator 13, an X-ray high voltage device 14, an X-ray detector 15, a DAS 16 (an example of a data processing unit), and a rotating frame 17 (an example of a data processing unit). An example of a rotating body) and a control device 18 (an example of a control unit) are provided.

The X-ray tube 11 generates X-rays by irradiating thermoelectrons from the cathode (filament) toward the anode (target) by applying a high voltage from the X-ray high voltage device 14. The X-ray tube 11 includes a vacuum tube. For example, the X-ray tube 11 is a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermoelectrons.

The wedge 12 is a filter for adjusting the X-ray dose applied to the subject P from the X-ray tube 11. The wedge 12 attenuates the X-rays that pass through itself so that the distribution of the X-ray dose radiated from the X-ray tube 11 to the subject P becomes a predetermined distribution. The wedge 12 is also called a wedge filter or a bow-tie filter. The wedge 12 is, for example, a product obtained by processing aluminum so as to have a predetermined target angle and a predetermined thickness.

The collimator 13 is a mechanism for narrowing down the irradiation range of X-rays transmitted through the wedge 12. The collimator 13 narrows down the X-ray irradiation range (FOV: Field of View) by forming a slit, for example, by combining a plurality of lead plates. The collimator 13 is sometimes called an X-ray diaphragm.

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

The X-ray detector 15 detects the intensity of X-rays generated by the X-ray tube 11 and passed through the subject P to be incident. The X-ray detector 15 outputs an electric signal (or an optical signal or the like) corresponding to the intensity of the detected X-ray to the DAS 16. The X-ray detector 15 has, for example, a plurality of X-ray detection element sequences. Each of the plurality of X-ray detection element sequences is an array of a plurality of X-ray detection elements in the channel direction along an arc centered on the focal point of the X-ray tube 11. The plurality of X-ray detection element sequences are arranged in the slice direction (column direction, row direction).

The X-ray detector 15 is, for example, an indirect detector having a grid, a scintillator array, and an optical sensor array. The scintillator array has a plurality of scintillators. Each scintillator has a scintillator crystal. The scintillator crystal emits an amount of light according to the intensity of the incident X-rays. The grid is arranged on the surface of the scintillator array where X-rays are incident, 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 includes, for example, an optical sensor such as a photomultiplier tube (PMT). The optical sensor array outputs an electric signal according to the amount of light emitted by the scintillator. The X-ray detector 15 may be a direct conversion type detector having a semiconductor element that converts incident X-rays into an electric signal.

The DAS 16 has, for example, an amplifier, an integrator, and an A / D converter. The amplifier performs amplification processing on the electric signal output by each X-ray detection element of the X-ray detector 15. The integrator integrates the amplified electrical signal over the view period. The A / D converter converts an electric signal indicating the integration result into a digital signal. The DAS 16 outputs the detection data based on the digital signal to the console device 40. The detection data is a digital value of the X-ray intensity identified by the channel number, the column number, and the view number indicating the collected view of the X-ray detection element of the generation source. The view number is a number that changes according to the rotation of the rotation frame 17, for example, a number that is incremented according to the rotation of the rotation frame 17. Therefore, the view number is information indicating the rotation angle of the X-ray tube 11. The view period is a period within a period from the rotation angle corresponding to a certain view number to the rotation angle corresponding to the next view number. The DAS 16 may detect the change of view by a timing signal input from the control device 18, an internal timer, or a signal acquired from a sensor (not shown). .. When X-rays are continuously exposed by the X-ray tube 11 in the case of performing a full scan, the DAS 16 collects a detection data group for the entire circumference (360 degrees). When X-rays are continuously exposed by the X-ray tube 11 in the case of performing a half scan, the DAS 16 collects detection data for a half circumference (180 degrees).

The rotating frame 17 is an annular member that rotatably supports the X-ray tube 11, the wedge 12, the collimator 13, and the X-ray detector 15 so as to face each other. The rotating frame 17 is rotatably supported by the fixed frame around the subject P introduced inside. The rotating frame 17 further rotatably supports the DAS 16. The detection data output by the DAS 16 has a photodiode provided in a non-rotating portion (for example, a fixed frame) of the gantry device 10 by optical communication from a transmitter having a light emitting diode (LED) provided in the rotating frame 17. It is transmitted to the receiver and transferred to the console device 40 by the receiver. The method of transmitting the detection data from the rotating frame 17 to the non-rotating portion is not limited to the method using the above-mentioned optical communication, and any non-contact type transmitting method may be adopted. The rotating frame 17 is not limited to an annular member as long as it can support and rotate the X-ray tube 11 and the like, and may be a member such as an arm.

The X-ray CT apparatus 1 is, for example, a Rotate / Rotate-Type X-ray CT apparatus (third) in which both the X-ray tube 11 and the X-ray detector 15 are supported by the rotating frame 17 and rotate around the subject P. Generation CT), but not limited to this, in Stationary / Rotate-Type in which a plurality of X-ray detection elements arranged in an annular shape are fixed to a fixed frame and the X-ray tube 11 rotates around the subject P. It may be an X-ray CT apparatus (4th generation CT).

FIG. 2 is a diagram showing how the X-ray detector 15 and the DAS 16 are supported by the rotating frame 17. As shown in FIG. 2, the X-ray detector 15 includes a plurality of X-ray detection elements 20-1 to 20-5. The DAS 16 includes a plurality of DAS substrates 21-1 to 21-5 (an example of the substrate). The X-ray detection elements 20-1 to 20-5 detect X-rays that are output by the X-ray tube 11 and have passed through the subject P. Each of the DAS substrates 21-1 to 21-5 includes an amplifier, an integrator, and an A / D converter as described above. Each of the DAS boards 21-1 to 21-5 processes the electric signals output from each of the X-ray detection elements 20-1 to 20-5, and outputs the detection data as the processing result to the console device 40. .. The DAS substrates 21-1 to 21-5 are supported by being inserted into a slot provided in the rotating frame 17. In FIG. 5, five X-ray detection elements 20-1 to 20-5 and five DAS substrates 21-1 to 21-5 are shown, but the number of these elements is arbitrary. Further, in the following, when the X-ray detection elements 20-1 to 20-5 are not distinguished from each other, they are simply referred to as "X-ray detection element 20". Further, in the following, when the DAS substrates 21-1 to 21-5 are not distinguished from each other, they are simply referred to as "DAS substrate 21".

Returning to FIG. 1, the control device 18 includes, for example, a processing circuit having a processor such as a CPU (Central Processing Unit) and a drive mechanism including a motor, an actuator, and the like. The control device 18 receives an input signal from the input interface 43 attached to the console device 40 or the gantry device 10 and controls the operation of the gantry device 10 and the bed device 30.

The control device 18 rotates, for example, the rotating frame 17, tilts the gantry device 10, and moves the top plate 33 of the bed device 30. When tilting the gantry device 10, the control device 18 rotates the rotating frame 17 around an axis parallel to the Z-axis direction based on the tilt angle (tilt angle) input to the input interface 43. The control device 18 grasps the rotation angle of the rotation frame 17 by the output of a sensor (not shown) or the like. Further, the control device 18 provides the rotation angle of the rotation frame 17 to the processing circuit 50 (an example of the control unit) at any time. The control device 18 may be provided in the gantry device 10 or in the console device 40.

The bed device 30 is a device on which the subject P to be scanned is placed, moved, and introduced into the rotating frame 17 of the gantry device 10. The bed device 30 has, for example, a base 31, a bed drive device 32, a top plate 33, and a support frame 34. The base 31 includes a housing that movably supports the support frame 34 in the vertical direction (Y-axis direction). The bed drive device 32 includes a motor and an actuator. The bed driving device 32 moves the top plate 33 on which the subject P is placed in the longitudinal direction (Z-axis direction) of the top plate 33 along the support frame 34. The top plate 33 is a plate-shaped member on which the subject P is placed.

The bed drive 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 device 10 may be movable in the Z-axis direction, and the rotation frame 17 may be controlled to come around the subject P by the movement of the gantry device 10. Further, both the gantry device 10 and the top plate 33 may be movable. Further, the X-ray CT device 1 may be a device in which the subject P is scanned in a standing or sitting position. In this case, the X-ray CT device 1 has a subject support mechanism instead of the bed device 30, and the gantry device 10 rotates the rotating frame 17 about an axial direction perpendicular to the floor surface.

The console device 40 has, for example, a memory 41, a display 42, an input interface 43, a network connection circuit 44, and a processing circuit 50. In the first embodiment, the console device 40 will be described as a separate body from the gantry device 10, but the gantry device 10 may include a part or all of each component of the console device 40.

The memory 41 is realized by, for example, a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, an optical disk, or the like. The memory 41 stores, for example, detection data, projection data, a reconstructed image (CT image), a scan plan, a scanno image, and the like. These data may be stored in an external memory with which the X-ray CT apparatus 1 can communicate, instead of the memory 41 (or in addition to the memory 41). The external memory is controlled by the cloud server, for example, when the cloud server that manages the external memory receives a read / write request. The external memory is realized by, for example, a system called PACS (Picture Archiving and Communication Systems). PACS is a system that systematically stores images and the like taken by various diagnostic imaging devices.

The display 42 displays various information. For example, the display 42 displays a medical image (CT image) generated by the processing circuit 50, a GUI (Graphical User Interface) image that accepts various operations by the operator, and the like. The display 42 is, for example, a liquid crystal display, a CRT (Cathode Ray Tube), an organic EL (Electroluminescence) display, or the like. The display 42 may be provided on the gantry device 10. The display 42 may be a desktop type or a display device (for example, a tablet terminal) capable of wirelessly communicating with the main body of the console device 40.

The input interface 43 accepts various input operations by the operator and outputs an electric signal indicating the contents of the received input operations to the processing circuit 50. For example, the input interface 43 is an input operation such as a collection condition when collecting detection data or projection data, a reconstruction condition when reconstructing a CT image, and an image processing condition when generating a post-processed image from a CT image. Accept. For example, the input interface 43 is realized by a mouse, a keyboard, a touch panel, a trackball, a switch, a button, a joystick, a camera, an infrared sensor, a microphone, and the like. The input interface 43 may be provided on the gantry device 10. Further, the input interface 43 may be realized by a display device (for example, a tablet terminal) capable of wireless communication with the main body of the console device 40.

The network connection circuit 44 includes, for example, a network card having a printed circuit board, a wireless communication module, and the like. The network connection circuit 44 implements an information communication protocol according to the form of the network to be connected. The network includes, for example, a LAN (Local Area Network), a WAN (Wide Area Network), the Internet, a cellular network, a dedicated line, and the like.

The processing circuit 50 controls the overall operation of the X-ray CT apparatus 1. The processing circuit 50 executes, for example, a system control function 51, a preprocessing function 52, a reconstruction processing function 53, an image processing function 54, a scan control function 55, a display control function 56, a power supply switching function 57, and the like. The processing circuit 50 realizes these functions by, for example, the hardware processor executing a program stored in the memory 41.

The hardware processor is, for example, a CPU, GPU (Graphics Processing Unit), application specific integrated circuit (ASIC), programmable logic device (for example, Simple Programmable Logic Device (SPLD)) or It means a circuit (circuitry) such as a complex programmable logic device (CPLD) and a field programmable gate array (FPGA). Instead of storing the program in the memory 41, the program may be configured to be directly embedded in the circuit of the hardware processor. In this case, the hardware processor realizes the function by reading and executing the program embedded in the circuit. The hardware processor is not limited to one configured as a single circuit, and a plurality of independent circuits may be combined to be configured as one hardware processor to realize each function. Further, a plurality of components may be integrated into one hardware processor to realize each function.

Each component of the console device 40 or the processing circuit 50 may be distributed and implemented by a plurality of hardware. The processing circuit 50 may be realized not by the configuration of the console device 40 but by a processing device capable of communicating with the console device 40. The processing device is, for example, a workstation connected to one X-ray CT device, or a device connected to a plurality of X-ray CT devices and collectively executing processing equivalent to the processing circuit 50 described below (for example,). , Cloud server). That is, it is also possible to realize the configuration of the present embodiment as an X-ray CT system (medical diagnostic system) in which an X-ray CT apparatus and another processing apparatus are connected via a network.

The system control function 51 controls various functions of the processing circuit 50, for example, based on the input operation received by the input interface 43.

The preprocessing function 52 performs preprocessing such as logarithmic conversion processing, offset correction processing, sensitivity correction processing between channels, beam hardening correction, and correction processing using calibration data for the detection data output by DAS16. Projection data is generated, and the generated projection data is stored in the memory 41. The correction process using the calibration data may be performed by the reconstruction process function 53.

The reconstruction processing function 53 performs reconstruction processing by a filter correction back projection method, a successive approximation reconstruction method, or the like on the projection data generated by the preprocessing function 52 to generate a reconstruction image, and the generated reconstruction. The configuration image is stored in the memory 41.

The image processing function 54 converts the reconstructed image into a three-dimensional image or cross-sectional image data of an arbitrary cross section by a known method based on the input operation received by the input interface 43. The conversion to a three-dimensional image may be performed by the preprocessing function 52.

The scan control function 55 controls the collection process of the detection data in the gantry device 10 by instructing the X-ray high voltage device 14, the DAS 16, the control device 18, and the bed drive device 32. The scan control function 55 controls the operation of each part at the time of capturing the alignment data, the main captured image, and the image used for diagnosis, and collecting the calibration data.

The display control function 56 controls the display mode of the display 42. For example, the display control function 56 controls the display 42 to display a CT image generated by the processing circuit 50, a GUI image that accepts various operations by the operator, and the like.

The power switching function 57 controls the power supply to the DAS 16. The power supply switching function 57 controls the DAS 16 to switch between two power supply methods, that is, power supply by a power supply (DAS power supply) supplied from a commercial power source or the like and power supply by a battery. The power switching function 57 executes switching control between the DAS power supply and the battery based on the advance information of the scan, and controls the power supply to the DAS 16. Details of the power switching function 57 will be described later.

With the above configuration, the X-ray CT apparatus 1 scans the subject P in a manner such as a helical scan, a conventional scan, and a step-and-shoot. The helical scan is a mode in which the rotating frame 17 is rotated while the top plate 33 is moved to spirally scan the subject P. The conventional scan is a mode in which the rotating frame 17 is rotated while the top plate 33 is stationary to scan the subject P in a circular orbit. Perform a conventional scan. The step-and-shoot is a mode in which the position of the top plate 33 is moved at regular intervals to perform a conventional scan in a plurality of scan areas.

[Power supply method to DAS]
FIG. 3 is a diagram illustrating an example of a power feeding method for the DAS 16. The DAS 16 includes, for example, a plurality of DAS boards 21, a changeover switch 22, a DAS power supply 23 (an example of a power supply), and a battery 25. Each of the plurality of DAS substrates 21 is connected to each of the plurality of X-ray detection elements 20, and processes the electric signals output from each of the X-ray detection elements 20-1 to 20-5.

The DAS power supply 23 is, for example, a switching power supply. The DAS power supply 23 includes, for example, an AC / DC converter 24. The DAS power supply 23 converts the AC power supplied from the commercial power supply E into DC power by the AC / DC converter 24 and supplies it to the DAS substrate 21.

The battery 25 is a large-capacity battery such as a lithium ion battery or an all-solid-state battery. The battery 25 supplies the electric power stored inside to the DAS substrate 21. Under the control of the power switching function 57, the battery 25 is charged by receiving power supplied from the DAS power supply 23 while not performing a scan such as when the X-ray CT device 1 is idling. The battery 25 may be charged by receiving power supplied from the commercial power source E instead of the DAS power source 23 when the X-ray CT device 1 is idling. Further, the battery 25 may be charged by receiving power supply via the slip ring. Further, the battery 25 may be charged by using the regenerative energy when the rotation of the rotating frame 17 is stopped.

The changeover switch 22 switches the power supply to the DAS board 21 (the drive source of the DAS board 21) between the DAS power supply 23 and the battery 25. The changeover switch 22 controls the continuity / cutoff state between the DAS board 21 and the DAS power supply 23 and the continuity / cutoff state between the DAS board 21 and the battery 25. The changeover switch 22 is, for example, a semiconductor switch such as a MOSFET or a bipolar transistor, a MEMS switch, or another switch. The changeover switch 22 performs changeover control based on the changeover signal transmitted by the console device 40.

[Processing flow (power switching before scanning starts)]
Hereinafter, the processing flow of the processing circuit 50 of the console device 40 will be described. FIG. 4 is a flowchart showing an example of processing of the processing circuit 50 of the console device 40. When the X-ray CT apparatus 1 scans the subject P, the operator of the X-ray CT apparatus 1 creates a scan plan (scan plan, an example of prior information) to be executed. The scan plan includes scan protocol information regarding the dose information of the X-rays applied to the subject P. The scan plan is created by the operator inputting physical information such as the weight and height of the subject P and the scan site via the input interface 43. The scan plan may be created by using a reference table or the like in which the relationship between the information of the subject P and the dose of X-rays irradiated to the subject P is defined. In the following, it is assumed that this scan plan is created and stored in the memory 41.

First, the power switching function 57 of the processing circuit 50 reads out the scan plan stored in the memory 41 (step S101). Next, the power switching function 57 determines whether or not the read scan plan is a scan plan having a small X-ray dose (mAs) (step S103). The power switching function 57 executes switching control based on the X-ray dose information included in the scan protocol, which is prior information.

When the power switching function 57 determines that the read scan plan is a scan plan with a small X-ray dose, the power switching function 57 instructs DAS 16 to use the battery 25 as a drive source (battery drive signal). ) Is output (S105). The changeover switch 22 of the DAS 16 that has received the battery drive signal switches between the DAS board 21 and the DAS power supply 23 so as to be in a cutoff state and between the DAS board 21 and the battery 25 in a conductive state. Next, the scan control function 55 executes scan control (step S109). As a result, the gantry device 10 executes a scan using the battery 25 as a drive source. When the battery 25 is used as the drive source, noise due to power supply does not occur. Therefore, even when the dose of X-rays irradiated to the subject P is small and the count value detected by the X-ray detector 15 is small (when the count is low), deterioration of the image quality of the scanned image is prevented. be able to. When the power switching function 57 determines that the read scan plan is a scan plan having a short scan time, the power switching function 57 sends a battery drive signal instructing the DAS 16 to use the battery 25 as a drive source. It may be output.

Noise may occur when switching the power supply. Therefore, in the subsequent reconstruction process in the reconstruction process function 53, the data detected immediately after the power supply switching may not be used for generating the scanned image. Further, the power supply switching function 57 monitors the remaining capacity of the battery 25, and when the remaining capacity becomes less than a predetermined threshold value, the power supply by the battery 25 may be switched to the power supply by the DAS power supply 23.

On the other hand, when the power switching function 57 determines that the read scan plan is not a scan plan with a small X-ray dose, the power switching function 57 instructs DAS 16 to use the DAS power supply 23 as a drive source (DAS). Power supply drive signal) is output (S107). The changeover switch 22 of the DAS 16 that has received the DAS power supply drive signal switches so that the DAS board 21 and the DAS power supply 23 are in a conductive state and the DAS board 21 and the battery 25 are in a cutoff state. Next, the scan control function 55 executes scan control (step S109). As a result, the gantry device 10 executes a scan using the DAS power supply 23 as a drive source. When the DAS power supply 23 is used as the drive source, noise due to power supply is generated. However, when the dose of X-rays applied to the subject P is large and the count value detected by the X-ray detector 15 is large, the influence of noise does not become dominant, so that the image quality of the scanned image is maintained. be able to.

That is, the power supply switching function 57 increases the frequency of power supply by the DAS power supply 23 as the dose of X-rays indicated by the dose information increases, and increases the frequency of power supply by the battery 25 as the dose of X-rays decreases. In addition, switching control is executed.

[Processing flow (power switching during scan execution)]
FIG. 5 is a flowchart showing another example of processing of the processing circuit 50 of the console device 40. When the X-ray CT apparatus 1 scans the subject P, the adjustment image used for positioning before the main imaging, etc., prior to the imaging of the main captured image (scanned image) used for diagnosis. (Hereinafter, "scano image") is taken.

In general, the higher the attenuation rate of the part where X-rays pass through the subject P (the lower the transmission rate), the greater the magnitude of the X-ray output that passes through the subject P and is detected by the X-ray detector 15. (Count value) becomes smaller, while the lower the attenuation rate of the part where X-rays pass through the subject P (the higher the transmission rate), the more the X-rays pass through the subject P and are detected by the X-ray detector 15. The magnitude of the X-ray output tends to be large. For example, the head and legs have low attenuation (high transmittance), so the magnitude of X-ray output increases, and the shoulders and abdomen have high attenuation (low transmittance). , The magnitude of the X-ray output tends to decrease. In the following processing, information on such a scan site is acquired in advance from the scanno image and used for switching control.

In the following, it is assumed that such a scanno image is taken and stored in the memory 41. Further, it is assumed that the changeover switch 22 is set so that the DAS board 21 and the DAS power supply 23 are in a conductive state and the DAS board 21 and the battery 25 are in a cutoff state at the start of scanning. To do.

First, the power switching function 57 of the processing circuit 50 reads out the scanno image stored in the memory 41 (step S201). The power switching function 57 acquires information about the scan target portion based on the scanno image. Next, the scan control function 55 starts scan control (step S203). As a result, the gantry device 10 starts scanning with the DAS power supply 23 as the drive source. The power switching function 57 may acquire information about the scan target portion based on the optical image obtained by photographing the subject P in place of or in addition to the scanno image.

Next, the power switching function 57 is a portion where the body portion of the subject P to be scanned thereafter becomes a low count while referring to the information regarding the scan target portion acquired from the read scanno image. Whether or not it is determined (step S205). For example, the power switching function 57 acquires the progress of one scan for the subject P based on the detection data received from the DAS 16. Subsequently, the power switching function 57 counts the body part of the subject P to be subsequently scanned based on the acquired progress status and the information about the scan target part acquired from the scanno image. Determine if it is a site.

When the power switching function 57 determines that the body part of the subject P to be scanned thereafter is a part having a low count, the battery drive instructing the DAS 16 to use the DAS power supply 23 as a drive source. A signal is output (S207). The changeover switch 22 of the DAS 16 that has received the battery drive signal switches between the DAS board 21 and the DAS power supply 23 so as to be in a cutoff state and between the DAS board 21 and the battery 25 in a conductive state. Next, the scan control function 55 executes scan control (step S211). As a result, the gantry device 10 executes a scan using the battery 25 as a drive source. When the battery 25 is used as the drive source, noise due to power supply does not occur. Therefore, even when the count is low, it is possible to prevent deterioration of the image quality of the scanned image.

On the other hand, the power switching function 57 instructs the DAS 16 to use the DAS power supply 23 as the drive source when it is determined that the body part of the subject P to be scanned thereafter is not a part having a low count. The DAS power supply drive signal is output (S209). The changeover switch 22 of the DAS 16 that has received the DAS power supply drive signal switches so that the DAS board 21 and the DAS power supply 23 are in a conductive state and the DAS board 21 and the battery 25 are in a cutoff state. Next, the scan control function 55 executes scan control (step S211). As a result, the gantry device 10 executes a scan using the DAS power supply 23 as a drive source. When the DAS power supply 23 is used as the drive source, noise due to power supply is generated. However, if the count is not low, the influence of noise is not dominant, so that the image quality of the scanned image can be maintained.

FIG. 6 is a diagram illustrating power switching control by the power switching function 57 of the processing circuit 50. FIG. 6 shows a case where a whole body scan is performed on the subject P. In this whole body scan, the scan is performed in the order of head, shoulders, abdomen, and legs. In this example, the head scan is executed after the start of the scan at time t0, but it can be determined from the scanno image that the head is not a low-count portion. Therefore, at time t0, the power switching function 57 determines that the body part of the subject P to be scanned thereafter is not a part where the count is low, and outputs a DAS power supply drive signal to the DAS 16. The changeover switch 22 of the DAS 16 that has received the DAS power supply drive signal switches so that the DAS board 21 and the DAS power supply 23 are in a conductive state and the DAS board 21 and the battery 25 are in a cutoff state. As a result, the gantry device 10 executes a scan using the DAS power supply 23 as a drive source.

Next, the shoulder scan is executed from time t1, and it can be determined from the scanno image that the shoulder is a low-count portion. Therefore, at time t1, the power switching function 57 determines that the body part of the subject P to be scanned thereafter is a part having a low count, and outputs a battery drive signal to the DAS 16. The changeover switch 22 of the DAS 16 that has received the battery drive signal switches between the DAS board 21 and the DAS power supply 23 so as to be in a cutoff state and between the DAS board 21 and the battery 25 in a conductive state. As a result, the gantry device 10 executes a scan using the battery 25 as a drive source. After that, at the time t2 when the scan of the abdomen is started and the time t3 when the scan of the legs is started, the switching determination is performed by the power switching function 57, and the power switching control is executed.

That is, the switching control is executed based on the information regarding the power supply switching function 57 and the scan target portion. The power switching function 57 increases the frequency of power supply by the battery 25 as the X-ray attenuation rate at the scan target site increases, and increases the frequency of power supply by the DAS power supply 23 as the X-ray attenuation rate at the scan target site decreases. The switching control is executed so as to increase.

According to the X-ray CT apparatus 1 of the first embodiment described above, it is possible to prevent deterioration of the image quality of the scanned image due to noise generated during power supply and reduce the exposure dose of the subject. When a scan is executed in which the dose of X-rays irradiated to the subject P is small or a portion where a low count is expected is executed, the battery 25 is used as a drive source to prevent the generation of noise. This makes it possible to prevent deterioration of the image quality of the scanned image even when the X-ray dose is small or the count is low.

On the other hand, the DAS power supply 23 is used as a drive source when executing a scan in which the dose of X-rays irradiated to the subject P is large or when scanning a portion where a low count is not expected. In this case, noise is generated, but the influence of the noise is not dominant, so that the image quality of the scanned image can be maintained. Further, by limiting the use of a battery having a limited capacity and switching between the DAS power supply 23 and the battery 25, a stable power supply can be realized.

In addition, it is not necessary to use a high-performance switching power supply, a linear regulator, a noise filter, or the like capable of reducing noise, which reduces the difficulty of circuit design and the manufacturing cost.

In the above embodiment, the case where the processing circuit 50 of the console device 40 performs power supply switching control has been described as an example, but the present invention is not limited to this. For example, the power switching control may be performed by the control device 18 provided on the gantry device 10 or by the control unit provided on the DAS board 21 of the DAS 16.

(Second Embodiment)
Hereinafter, the second embodiment will be described. The second embodiment is different from the first embodiment in that each of the DAS substrates 21 includes a battery 25 and a changeover switch. Therefore, for the configuration and the like, the drawings and related descriptions described in the first embodiment will be referred to, and detailed description will be omitted.

FIG. 7 is a diagram illustrating an example of a power feeding method for the DAS 16A according to the second embodiment. The DAS 16A includes, for example, a plurality of DAS substrates 21 and a DAS power supply 23. Each of the plurality of DAS substrates 21 includes, for example, a first changeover switch 22-1, a second changeover switch 22-2, and a battery 25.

The first changeover switch 22-1 and the second changeover switch 22-2 switch the power supply to the DAS board 21 (the drive source of the DAS board 21) between the DAS power supply 23 and the battery 25. The first changeover switch 22-1 and the second changeover switch 22-2 determine the continuity / cutoff state between the DAS board 21 and the DAS power supply 23 and the continuity / cutoff state between the DAS board 21 and the battery 25. Control. The first changeover switch 22-1 and the second changeover switch 22-2 are, for example, semiconductor switches such as MOSFETs and bipolar transistors, MEMS switches, and other switches. The changeover switch 22 switches based on the changeover signal transmitted by the console device 40.

In the DAS 16A, switching control of the power supply is performed on each of the DAS boards 21. Since the switching control process is the same as the process described in the first embodiment (“power supply switching before the start of scanning” and “power switching during scanning execution”), detailed description thereof will be omitted.

According to the X-ray CT apparatus 1 of the second embodiment described above, it is possible to prevent deterioration of the image quality of the scanned image due to noise generated during power supply and reduce the exposure dose of the subject. Further, by providing the battery 25 on the DAS substrate 21, the GND path is simplified and common mode noise can be suppressed.

In the above embodiment, the case where the processing circuit 50 of the console device 40 performs power supply switching control has been described as an example, but the present invention is not limited to this. FIG. 8 is a diagram illustrating an example of a power feeding method for the DAS 16B. In the example shown in FIG. 8, each of the plurality of DAS boards 21 has a DAS control unit 26 (an example of a control unit) in addition to the first changeover switch 22-1, the second changeover switch 22-2, and the battery 25. To be equipped. The DAS control unit 26 acquires scan plan information, scanno images, and the like from the console device 40, and performs power supply switching control similar to that of the processing circuit 50. The power supply switching control may be performed by the control device 18 provided in the gantry device 10.

In the above embodiment, the case where the power supply switching control is performed based on the scan plan or the scanno image has been described as an example, but the present invention is not limited to this. When the X-ray CT apparatus is a high-definition CT apparatus, noise does not occur during imaging that requires high spatial resolution (for example, when each of a plurality of pixels is controlled to generate a scanned image). When shooting using a battery as the drive source and not requiring high spatial resolution (for example, when dividing multiple pixels into several groups and bundling them into groups to generate a scanned image), the power supply is driven. It may be used as a source. That is, the power switching function 57 of the processing circuit 50 may execute the switching control based on the unit of the bundle of detection data in the X-ray detector 15.

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 embodiments, and various mitigations, replacements, and modifications 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 ... X-ray CT device, 10 ... gantry device, 11 ... X-ray tube, 12 ... wedge, 13 ... collimeter, 14 ... X-ray high voltage device, 15 ... X-ray detector, 16 ... data acquisition system, 17 ... rotation Frame, 18 ... Control device, 30 ... Sleep device, 31 ... Base, 32 ... Sleep drive device, 33 ... Top plate, 34 ... Support frame, 40 ... Console device, 50 ... Processing circuit, 51 ... System control function, 52 ... pre-processing function, 53 ... reconstruction processing function, 54 ... image processing function, 55 ... scan control function, 56 ... display control function, 57 ... power switching function

Claims (11)

X-ray tube and
An X-ray detector that detects the X-rays output by the X-ray tube, and
A data processing unit that processes the signal output by the X-ray detector,
A power supply that supplies power to the data processing unit and
A battery that supplies power to the data processing unit
A rotating body that rotatably supports the X-ray tube and the X-ray detector so as to face each other and further rotatably supports the data processing unit and the battery.
A control unit that executes switching control between the power supply and the battery based on prior information of scanning and controls power supply to the data processing unit.
An X-ray CT apparatus. The control unit executes the switching control based on the X-ray dose information included in the scan protocol which is the prior information.
The X-ray CT apparatus according to claim 1. The control unit
The switching control is performed so that the frequency of power supply by the battery increases as the dose of the X-ray indicated by the dose information decreases, and the frequency of power supply by the power supply increases as the dose of the X-ray increases. Execute,
The X-ray CT apparatus according to claim 2. The control unit executes the switching control based on the information regarding the scan target portion.
The X-ray CT apparatus according to any one of claims 1 to 3. The control unit increases the frequency of power supply by the battery as the attenuation rate of the X-rays at the scan target site increases, and supplies power from the power supply as the attenuation rate of the X-rays at the scan target site decreases. The switching control is executed so as to increase the frequency.
The X-ray CT apparatus according to claim 4. The control unit executes the switching control during scan execution.
The X-ray CT apparatus according to claim 4 or 5. The control unit acquires information about the scan target site based on a scanno image of the subject.
The X-ray CT apparatus according to any one of claims 4 to 6. The control unit acquires information about the scan target site based on an optical image of the subject.
The X-ray CT apparatus according to any one of claims 4 to 6. At least one of the battery and the control unit is provided on the substrate of the data processing unit.
The X-ray CT apparatus according to any one of claims 1 to 8. The control unit controls to supply the power of the power source to the battery to charge the battery while the scan is not being executed.
The X-ray CT apparatus according to any one of claims 1 to 9. The control unit executes the switching control based on the unit of the bundle of detection data in the X-ray detector.
The X-ray CT apparatus according to any one of claims 1 to 10.

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