JP2019030410A - X-ray CT apparatus and X-ray CT system - Google Patents

Abstract

To provide an X-ray CT apparatus and an X-ray CT system, capable of executing a wide volume scan under the condition of respiration synchronization, the wide volume scan having been executed under the condition of breath holding, by shortening a waiting time between scan operation and bed driving operation.SOLUTION: An X-ray CT apparatus, according to an embodiment, capable of executing a wide volume scan in which a subject is not moved during a scan and the subject's position is moved during an inter-scan pause time, the X-ray CT apparatus comprising: a console to which a scan condition is input; an imaging unit for executing the scan; a drive unit for moving the subject's position; and a control unit that when receiving input of scan start from the console, directly controls the imaging unit and the drive unit without using the console to control execution of the wide volume scan.SELECTED DRAWING: Figure 5

Description

  Embodiments described herein relate generally to an X-ray CT apparatus and an X-ray CT system.

  An X-ray CT (Computed Tomography) apparatus is a modality capable of collecting a three-dimensional image of a subject by rotating imaging in which an X-ray source is rotated around the subject at high speed.

  There are various scanning methods for imaging in an X-ray CT apparatus. For example, the helical scan is an imaging method in which a bed on which a subject is placed is moved simultaneously with rotational imaging (scanning). In contrast to this helical scan, there is a non-helical scan that does not move the subject during the scan and moves the subject within the inter-scan pause time.

  The non-helical scan is an imaging method conventionally performed in the X-ray CT apparatus, and thus is called a conventional scan. The conventional scan includes a wide volume scan and a step & shoot scan.

  The wide volume scan is also an imaging method for imaging a wide range like the helical scan. In the helical scan, since the subject is continuously imaged, artifacts due to body movement become a problem, and various interpolation processes are required in the image reconstruction process. On the other hand, wide volume scans can be executed in a short time, and are therefore less affected by body movements.

  The wide volume scan is used for imaging in a range in which images cannot be collectively captured by one rotation imaging (180 ° + α angle or 360 °). In the wide volume scan, an imaging range that cannot be captured by one rotation imaging can be captured by overlapping a part of the imaging area in one rotation imaging and shifting the position of the subject for each rotation imaging. .

  The shape of an organ such as the lung periodically changes due to respiration. Therefore, in imaging with the X-ray CT apparatus, the scan is executed in a state where the subject stops breathing and the organ is not deformed or moved by breathing.

  However, since such a breath-hold scan places a heavy burden on the subject, imaging by a breath-synchronized scan that can be performed under free breathing is required. The respiratory synchronization scan is an imaging method in which imaging is performed during a period when the respiratory cycle of the subject is stable. The period in which the respiration is stable is, for example, a period from the end of expiration of the subject to the start of inspiration for starting the next respiration. In the following description, a period in which respiration is stable is referred to as a respiration stable period.

  When the wide volume scan is executed under respiratory synchronization, the bed must be moved by the next stable respiratory period after performing one rotation imaging in the stable respiratory period. However, in the conventional X-ray CT apparatus, there is a waiting time between the scanning operation and the bed driving operation, and there is a case where the wide volume scan cannot be executed under respiratory synchronization.

JP 2013-153832 A

  The problem to be solved by the present invention is to reduce the waiting time between the scanning operation and the bed driving operation, so that a wide volume scan that has been executed by breath holding can be executed under respiratory synchronization. An apparatus and an X-ray CT system are provided.

  An X-ray CT apparatus according to an embodiment is an X-ray CT apparatus capable of performing a wide volume scan that moves a position of the subject within a pause time between scans without moving the subject during the scan. A console to which conditions are input, an imaging unit that executes the scan, a drive unit that moves the position of the subject, and an input of scan start from the console, the imaging unit and the drive unit are A control unit that directly controls without using a console and controls execution of the wide volume scan.

1 is a conceptual configuration diagram illustrating an example of an X-ray CT system according to an embodiment. The sequence diagram explaining the control of the conventional wide volume scan with a breath hold. The timing chart explaining the conventional wide volume scan with breath holding. The flowchart which shows an example of operation | movement of the X-ray CT system which concerns on embodiment. The timing chart explaining the wide volume scan by breath synchronization in the X-ray CT system concerning an embodiment. The sequence diagram explaining control of the wide volume scan by breath synchronization in the X-ray CT system concerning an embodiment. The timing chart explaining the wide volume scan with breath holding in the X-ray CT system concerning an embodiment. The sequence diagram explaining control of the wide volume scan with breath holding in the X-ray CT system which concerns on embodiment. The timing chart explaining the 1st modification in the case of performing the wide volume scan by breath synchronization in the X-ray CT system concerning an embodiment. The timing chart explaining the 2nd modification in the case of performing the wide volume scan by respiratory synchronization in the X-ray CT system which concerns on embodiment.

  Hereinafter, an X-ray CT apparatus and an X-ray CT system of an embodiment will be described with reference to the drawings.

(1) Configuration FIG. 1 is a conceptual configuration diagram illustrating an example of an X-ray CT system according to an embodiment. The X-ray CT system 100 in FIG. 1 includes an X-ray CT apparatus 1 and a respiration sensor 20.

  The respiratory sensor 20 is a biological sensor that collects the respiratory cycle of the subject P. The respiration sensor 20 may be a pressure sensor that is wound around the chest abdomen of the subject P and collects pressure changes in the chest according to the respiration motion of the subject P. Further, the respiration sensor 20 may be a non-contact sensor that collects the respiration cycle of the subject P by measuring the displacement amount of the body surface of the subject P using infrared rays or a camera.

  The respiration sensor 20 is not limited to a pressure sensor or a non-contact sensor. For example, it may be a flow sensor that is mounted so as to cover the mouth and nose of the subject P and measures the flow rate and volume of the subject in exhalation and inspiration.

  The X-ray CT apparatus 1 includes a Rotate / Rotate-Type (third generation CT) in which an X-ray tube and an X-ray detector are integrally rotated around a subject, and a large number of X-rays arrayed in a ring shape. There are various types such as Stationary / Rotate-Type (fourth generation CT) in which the line detection element is fixed and only the X-ray tube rotates around the subject, and any type is applicable to the present embodiment. In the following description, an example in which the third generation Rotate / Rotate-Type is adopted as the X-ray CT apparatus 1 according to the present embodiment will be shown.

  The X-ray CT apparatus 1 includes a gantry device 10, a couch device 30, and a console device 40. The gantry device 10 and the couch device 30 are installed in an examination room. The gantry device 10 generates X-ray detection data (transmission data) related to the subject P placed on the couch device 30. On the other hand, the console apparatus 40 is installed in a control room adjacent to the examination room, and generates and displays a reconstructed image by generating projection data based on the detection data.

  The gantry device 10 includes an X-ray tube 11, an X-ray detector 12, a rotating frame 13 having an opening 19 in which an imaging region is inherent, an X-ray high voltage device 14, a control device 15, a wedge 16, a collimator 17, and a data collection circuit. (DAS: Data Acquisition System) 18 is provided.

  The X-ray tube 11 is a vacuum tube that irradiates thermionic electrons from a cathode (filament) to an anode (target) when a high voltage is applied from the X-ray high voltage device 14. In the present embodiment, the single tube X-ray CT apparatus is a so-called multi-tube X-ray CT apparatus in which a plurality of pairs of X-ray tubes and X-ray detectors are mounted on a rotating ring. Is also applicable.

  Note that hardware that generates X-rays is not limited to the X-ray tube 11. For example, instead of the X-ray tube 11, a focus coil that converges an electron beam generated from an electron gun, a deflection coil that electromagnetically deflects, and an electron beam that surrounds the half circumference of the subject P collides to generate X-rays. X-rays may be generated by a fifth generation method including a target ring.

  The X-ray detector 12 detects X-rays irradiated from the X-ray tube 11 and passed through the subject P, and outputs an electrical signal corresponding to the X-ray dose to the DAS 18. The X-ray detector 12 includes, for example, a plurality of X-ray detection element arrays in which a plurality of X-ray detection elements are arranged in the channel direction along one arc around the focal point of the X-ray tube. For example, the X-ray detector 12 has a structure in which a plurality of X-ray detection element arrays in which a plurality of X-ray detection elements are arrayed in the channel direction are arrayed in the slice direction (column direction, row direction).

  The X-ray detector 12 is an indirect conversion type detector having a grid, a scintillator array, and an optical sensor array, for example. The scintillator array has a plurality of scintillators, and the scintillator has a scintillator crystal that outputs a photon amount of light corresponding to the incident X-ray dose. The grid has an X-ray shielding plate that is disposed on the surface of the scintillator array on the X-ray incident side and has a function of absorbing scattered X-rays. The optical sensor array has a function of converting into an electrical signal corresponding to the amount of light from the scintillator, and includes, for example, an optical sensor such as a photomultiplier tube (PMT).

  Note that the X-ray detector 12 may be a direct conversion type detector having a semiconductor element that converts incident X-rays into electrical signals.

  The rotating frame 13 is an annular frame that supports the X-ray tube 11 and the X-ray detector 12 opposite to each other and rotates the X-ray tube 11 and the X-ray detector 12 by a control device 15 described later. In addition to the X-ray tube 11 and the X-ray detector 12, the rotating frame 13 further includes and supports an X-ray high voltage device 14 and a DAS 18.

  The detection data generated by the DAS 18 is obtained by transmitting a photodiode provided on a non-rotating portion of the gantry 10, for example, a fixed frame (not shown) by optical communication from a transmitter having a light emitting diode (LED) provided on the rotating frame 13. And transmitted to the console device 40. The detection data transmission method from the rotating frame 13 to the non-rotating portion of the gantry device 10 is not limited to the optical communication described above, and any method may be adopted as long as it is a non-contact type data transmission. A fixed frame (not shown) is a frame that rotatably supports the rotating frame 13.

  As described above, the X-ray CT apparatus 1 rotates the rotating frame 13 that supports the X-ray tube 11 and the X-ray detector 12 so as to face each other around the subject P, so that the entire circumference of the subject P can be obtained. That is, 360 ° detection data of the subject P is collected. The CT image reconstruction method is not limited to the full scan reconstruction method using 360 ° detection data. For example, a half reconstruction method in which a CT image is reconstructed based on detection data corresponding to a half circumference (180 °) + fan angle may be used.

  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 controls the output voltage in accordance with the X-ray irradiated by the X-ray tube 11 and the high-voltage generator having a function of generating a high voltage to be applied to the X-ray tube 11. It has a control device. The high voltage generator may be a transformer system or an inverter system. The X-ray high voltage device 14 may be provided on the rotating frame 13 described later, or may be provided on the fixed frame side of the gantry device 10.

  The control device 15 includes a processing circuit 151 and a driving mechanism such as a memory (not shown), a motor, and an actuator.

  The processing circuit 151 of the control device 15 may be configured by dedicated hardware, or may be configured to realize various functions described later by software processing by a built-in processor. Here, as an example, a case where the processing circuit 151 realizes various functions by software processing by a processor will be described.

  The processor in the above description is a dedicated or general-purpose CPU (Central Processing Unit), GPU (Graphics Processing Unit), application specific integrated circuit (ASIC), programmable logic device, and field programmable gate array. It means a circuit such as (FPGA: Field Programmable Gate Array). Examples of the programmable logic device include a simple programmable logic device (SPLD) and a complex programmable logic device (CPLD). The processing circuit 151 reads out a program stored in a memory (not shown) or a program directly incorporated in the processor of the processing circuit 151, and implements each function by executing the program.

  The processing circuit 151 may be configured by a single processor or a combination of a plurality of independent processors. In the latter case, a plurality of memories respectively corresponding to a plurality of processors may be provided, and a program executed by each processor may be stored in a memory corresponding to the processor. As another example, a configuration in which one memory collectively stores programs corresponding to functions of a plurality of processors may be employed.

  The control device 15 comprehensively controls the entire scanning operation. For example, control for tilting the gantry device 10 is performed. The tilt control of the gantry device 10 is controlled by the control device 15 about the axis parallel to the X-axis direction based on the tilt angle (tilt angle) information input by the input interface attached to the gantry device 10. It is realized by rotating.

  Here, as an example, the apparatus coordinate system of the X-ray CT apparatus 1 is defined as follows. The rotation axis of the rotating frame 13 in the non-tilt state or the direction parallel to the longitudinal direction of the top plate 33 of the bed apparatus 30 is parallel to the z-axis direction and the short direction of the top plate 33 and is orthogonal to the z-axis direction. An axial direction perpendicular to the vertical direction is orthogonal to the x-axis direction, the z-axis direction, and the x-axis direction, and an axial direction horizontal to the vertical direction is a y-axis direction.

  Further, the control device 15 controls the angle of the X-ray tube 11, the wedge 16 and the collimator 17 described later, based on the imaging conditions input from the console device 40 and the input interface attached to the gantry device 10.

  Further, the processing circuit 151 of the control device 15 realizes the direct control function 152. The direct control function 152 is a function realized by executing a program stored in the memory of the control device 15 by the processor of the processing circuit 151.

  The direct control function 152 directly controls the operation of the gantry device 10 and the couch device 30 in the wide volume scan without using the console device 40. That is, the direct control function 152 executes control for rotating the rotating frame 13 in response to an input signal and control for operating the bed apparatus 30 and the top board 33 without waiting for an instruction from the console apparatus 40. Control of the gantry device 10 and the couch device 30 by the direct control function 152 will be described in detail with reference to FIGS.

  The wedge 16 is a filter for adjusting the X-ray dose irradiated from the X-ray tube 11. Specifically, the wedge 16 transmits and attenuates the X-rays irradiated from the X-ray tube 11 so that the X-rays irradiated from the X-ray tube 11 to the subject P have a predetermined distribution. It is a filter. For example, the wedge 16 (wedge filter, bow-tie filter) is a filter obtained by processing aluminum so as to have a predetermined target angle and a predetermined thickness.

  The collimator 17 is a lead plate or the like for narrowing the irradiation range of X-rays transmitted through the wedge 16, and forms a slit by a combination of a plurality of lead plates or the like.

  The DAS 18 (Data Acquisition System) includes an amplifier that performs amplification processing on an electric signal output from each X-ray detection element of the X-ray detector 12 and an A / D converter that converts the electric signal into a digital signal. And generate detection data. The detection data generated by the DAS 18 is transferred to the console device 40.

  The couch device 30 is a device that places and moves the subject P to be scanned, and includes a base 31, a couch driving device 32, a top plate 33, and a support frame 34.

  The base 31 is a housing that supports the support frame 34 so as to be movable in the vertical direction (y-axis direction). The couch driving device 32 is a motor or actuator that moves the top plate 33 on which the subject 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 on which the subject P is placed.

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

  The console device 40 includes a memory 41, a display 42, an input interface 43, and a processing circuit 44. In the following description, it is assumed that the console device 40 executes all functions with a single console, but these functions may be executed by a plurality of consoles.

  The memory 41 includes a recording medium that can be read by a processor, such as a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, and an optical disk.

  Projection data and reconstructed image data generated by the X-ray CT apparatus 1 may be stored in the memory 41. The projection data and reconstructed image data generated by the X-ray CT apparatus 1 are stored in an external storage device such as an image server that can be connected to the X-ray CT apparatus 1 via a network such as a LAN (Local Area Network). May be. Similarly, some or all of the programs and data in the recording medium of the memory 41 may be downloaded by communication via a network, or may be given to the memory 41 via a portable storage medium such as an optical disk. Good.

  The display 42 displays various information. For example, the display 42 outputs a medical image (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.

  The input interface 43 receives various input operations from the user, converts the received input operations into electrical signals, and outputs them to the processing circuit 44. For example, the input interface 43 receives setting information such as a collection condition when collecting projection data, a reconstruction condition when reconstructing a CT image, and an image processing condition when image processing a CT image from the user. For example, the input interface 43 is realized by an input device such as a mouse, a keyboard, a trackball, a switch, a button, or a joystick.

  The processing circuit 44 controls the overall operation of the X-ray CT apparatus 1. In addition, the processing circuit 44 implements an image generation function 441 and a determination function 442. The processing circuit 44 of the console device 40 has the same configuration as the processing circuit 151 of the control device 15.

  Each function executed by the processing circuit 44 may be executed by an integrated server other than the console device 40. An integrated server is a computer that collectively processes detection data acquired in a plurality of modalities. Here, the server is a computer having a memory and a processor and providing its own functions and data to a client computer via a network. The server may be configured from a plurality of physical servers as virtual servers, or may be a cloud server provided outside the facility and connectable to the console device 40 via a wide area network.

  The image generation function 411 of the processing circuit 44 performs preprocessing such as correction processing on the detection data output from the data collection circuit 14, and reconstructs the detection data after the preprocessing to generate CT image data. Execute. Further, the image generation function 411 executes image processing for generating CT image data tomographic image data or three-dimensional image data of an arbitrary cross section by a known method.

  The determination function 442 determines whether to execute the wide volume scan with breath holding or under respiratory synchronization based on the respiratory cycle of the subject P collected in advance by the respiratory sensor 20. A method for determining whether the wide volume scan in the determination function 442 is executed with breath holding or with respiratory synchronization will be described in detail with reference to FIG.

(2) Operation First, a waiting time between a scanning operation and a bed driving operation in a conventional wide volume scan will be described with reference to FIGS.

  FIG. 2 is a sequence diagram for explaining control of a conventional wide volume scan with breath holding. The conventional wide volume scan with breath holding is an imaging method in which rotating imaging (scanning) is performed without moving the subject, and the operation of moving the bed during non-scanning is executed a plurality of times during the breath holding period of the subject. For example, when three rotation imaging is performed during the breath-holding period, the gantry device is in the order of the first scan operation, the first bed operation, the second scan operation, the second bed operation, and the third scan operation. And the control of the bed apparatus is executed.

  FIG. 2 shows a console device of a conventional X-ray CT apparatus, a CPU of a control device, a gantry device, and a bed device from the left. Hereinafter, with reference to FIG. 2, the operation of each apparatus in a conventional wide volume scan with breath holding will be described.

  When the user inputs imaging conditions from the input interface of the console apparatus and it is determined that scanning is performed with the input imaging conditions, the console apparatus transmits setup information to the CPU of the control apparatus. The setup information includes the angle of the X-ray tube included in the imaging conditions, settings of wedges and collimators, and the like.

  When the setup information is received from the console device, the CPU of the control device operates devices in the gantry such as an X-ray tube, a wedge and a collimator to set up the gantry device. Setup refers to preparation for scan execution. Here, preparation for scan execution refers to the position of each device related to scan execution in the state immediately before X-ray exposure so that the operation at the time of scan execution is only rotation of the rotating frame and X-ray exposure. It is to prepare the setting.

  When the setup of the gantry device is completed, the CPU of the control device transmits a setup completion notification to the console device. When the console receives a setup completion notification from the CPU of the control device, the console notifies the user that scanning can be started. For example, the console device notifies the user that scanning can be started by turning on a scan start button or controlling the button so that it can be pressed.

  The user instructs the subject to hold his / her breath, and when the breath holding is started, presses the scan start button. When the scan start button is pressed, a scan start notification signal is transmitted from the console device to the CPU of the control device. When receiving the scan start notification signal from the console device, the CPU of the control device transmits a scan instruction notification signal to the gantry device. When the gantry device receives the scan instruction notification signal from the CPU of the control device, the gantry device executes the first scan.

  The CPU of the control device transmits a scan end notification to the console device at the timing when the first scan is completed. Note that the CPU of the control device determines the timing for completing the scan based on the time required for the scan. The time required for scanning may be included in setup information from the console device, or may be included in a scan start notification signal from the console. Further, the scan required time may be stored in advance in the memory of the control device.

  When the console device receives the scan completion notification from the CPU of the control device, the console device transmits the bed operation information and a notification signal of the start of the bed operation to the CPU of the control device. The couch motion information includes top plate movement information such as the position and movement speed at which the top plate on which the subject is placed is moved.

  Thus, since the exchange of signals occurs between the CPU of the control device and the console device between the completion of the first scan S1 and the start of the bed operation B1, the first scan S1 is completed. A waiting time occurs before the start of the bed operation B1. Hereinafter, the time from the completion of the scan to the start of the bed operation is referred to as a bed operation waiting time W1.

  When the CPU of the control device receives the bed operation information and the bed operation start notification signal, the CPU executes the bed operation according to the bed operation information. The CPU of the control device controls the bed driving device of the bed apparatus to move the position of the top plate on which the subject is placed to the position specified in the bed movement information.

  When the couch operation is completed, the couch device transmits a couch status notification to the CPU of the control device. The bed status notification includes operation log information at the time of the bed movement such as the position information of the top board after the bed movement.

  When receiving the couch status information from the couch device, the CPU of the control device transmits a couch operation end notification to the console device. The console device transmits a scan start notification signal of the second scan S2 to the CPU of the control device.

  Thus, after the bed operation B1 is completed, the CPU of the bed device and the control device, the CPU of the control device, and the console device exchange signals, so that a waiting time is generated before the second scan S2 starts. Hereinafter, the time from the completion of the bed operation to the start of scanning is referred to as a scanning operation waiting time W2.

  FIG. 3 is a timing chart illustrating a conventional wide volume scan with breath holding. FIG. 3 shows a timing chart of the scanning operation and the bed operation when performing the three rotation imaging and the two bed movements while holding the breath.

  The uppermost part of FIG. 3 shows the respiratory signal of the subject. In the respiration signal, the period from the start of breath holding to the end of breath holding indicates the breath holding period. The middle part of FIG. 3 shows a scanning operation. The graph showing the scan operation shows an example in which the scan is executed at the timing indicated by the rectangular wave and three scans are executed during the breath holding period. The lower part of FIG. 3 shows the bed operation. In the bed operation, an example is shown in which the bed movement is executed twice during the breath holding period.

  Note that the slope of the graph in the bed operation indicates the bed moving speed. That is, in the graph showing the bed operation, an upward slope indicates a bed acceleration, and a downward slope indicates a bed deceleration. Note that the bed operations B1 and B2 are executed between the first scan S1 and the second scan S2 and between the second scan S1 and the third scan S3, respectively.

  When breath holding is started by the subject, the first scan S1 is executed. Thereafter, the bed operation B1 is started after the bed operation waiting time W1. When the bed operation B1 is completed, the second scan S2 is started after the scan operation waiting time W2. Similarly, when the second scan S2 is completed, the bed operation B2 starts after the bed operation waiting time W1, and when the bed operation B2 is completed, the third scan S2 is started after the scan operation waiting time W2. .

  As described above, in the conventional wide volume scan, signals are exchanged between the CPU of the control device and the console device immediately before the bed operation and immediately before the scan operation, so that waiting is performed before each operation is executed. Time occurs. The waiting time includes signal processing time such as generation time and reading time of bed operation information in the console device in addition to signal communication time between devices. Therefore, if a signal is exchanged a plurality of times between apparatuses before one operation is executed, the waiting time is increased accordingly.

  As shown in FIG. 3, when a plurality of scans are executed during the breath holding period, the time required for the entire wide volume scan becomes longer due to the generation of the bed operation waiting time W1 and the scanning operation waiting time W2. Also gets longer.

  Thus, since breath-hold imaging places a heavy burden on the subject, imaging under free breathing is required. As shown in FIG. 2 and FIG. 3, conventionally, there is a case where the breath synchronization scan cannot be selected due to the waiting time between the scan operation and the bed operation.

  Specifically, in order to execute the conventional wide volume scan by the respiratory synchronization scan, the first scan and the bed operation B1 must be completed at least by the next respiratory stable period. However, in the control via the conventional console device, the time from the start of the first scan to the end of the bed operation B1 is increased by the waiting time between the scan operation and the bed operation. Therefore, depending on the respiratory cycle of the subject and the length of the stable breathing period, the respiratory synchronization scan may not be selected.

  Therefore, the present inventor has come up with the idea of the X-ray CT apparatus 1 and the X-ray CT system 100 in which the CPU of the control device executes the bed operation and the scanning operation without using the console device. In the X-ray CT apparatus 1 and the X-ray CT system 100 according to the present embodiment, when the first scan S <b> 1 is completed, the CPU 15 of the control apparatus transmits a notification signal of the bed operation instruction directly to the bed apparatus 30, and the bed is set. Operation B1 is executed. Thereby, the waiting time between the scanning operation and the bed operation can be minimized. Hereinafter, a method of controlling the scanning operation and the bed operation without using the console device is referred to as direct control.

  By using this direct control, the number of cases in which a respiratory synchronization scan can be applied is increased. First, the operation of the determination method of the breath synchronization scan or the breath holding scan in the wide volume scan according to the present embodiment will be described using the flowchart of FIG. Thereafter, the operation of wide volume scanning by direct control according to the present embodiment will be described with reference to FIGS.

  FIG. 4 is a flowchart illustrating an example of the operation of the X-ray CT system 100 according to the embodiment. Hereinafter, according to the step number of the flowchart of FIG. 4, the operation | movement of the determination method of the respiration synchronous scan or the breath holding scan in the X-ray CT system 100 which concerns on embodiment is demonstrated.

  In step S <b> 101, the determination function 442 of the console device 40 acquires a respiratory signal of the subject P collected in advance. Here, “preliminarily” means before the start of the wide volume scan.

  In step S102, the determination function 422 of the console device 40 analyzes the respiratory cycle obtained from the respiratory signal of the subject P, and specifies the respiratory stable period T2. The stable respiratory period is determined based on a plurality of parameters such as whether the waveform indicating the respiratory cycle of the subject P matches an arbitrary waveform or whether the amplitude is within a predetermined threshold.

  Further, the respiratory stable period may be determined by the respiratory sensor 20. In that case, the determination function 422 may specify the respiratory stabilization period T <b> 2 based on the length of the gate signal from the respiratory sensor 20. Note that the gate signal output from the respiration sensor 20 may be a pulse signal for notifying the start of the respiration stable period. In this case, the determination function 422 may specify a predetermined time between the pulse signals as the respiratory stable period. In addition, since the prior art should just use the identification method of a respiratory stable period, detailed description is abbreviate | omitted.

  The determination function 422 further calculates a total time T1 of the scan time and bed movement time in the direct control. The total time T1 is the time from the start of scanning to the completion of bed movement. In the direct control, since the next operation is executed immediately after the scan is completed or the bed operation is completed by the direct control function 152 of the control circuit 15, the total time T1 is the time required for the scan operation and the time required for the bed operation. Is equal to the total time.

  If the respiratory stabilization period T2 is shorter than the total time T1, the process branches to NO in step S102, and in step S103, the determination function 422 determines to execute the wide volume scan by the breath holding scan.

  On the other hand, if the respiratory stabilization period T2 is equal to or greater than the total time T1, the process branches to YES in step S102. In step S104, the determination function 422 determines that the wide volume scan is to be executed in the respiratory synchronization scan.

  FIG. 5 is a timing chart for explaining a wide volume scan in breath synchronization in the X-ray CT system 100 according to the embodiment. The timing chart of FIG. 5 shows a respiratory signal, a gate signal, a scanning operation, and a bed operation from the top. FIG. 5 shows a timing chart of a wide volume scan including three scans and two bed movements, as in FIG.

  In the gate signal graph, the first scan S1 is executed simultaneously with the rise of the first gate signal from the left. Further, the bed operation B1 is performed immediately after the first scan S1 is completed. In the example of FIG. 5, the total time T1 of the first scan S1 and the bed operation B1 coincides with the respiratory stabilization period T2 indicated by the length of the gate signal.

  In the next respiratory stability period, the second scan S2 and the bed operation B2 are executed, and in the rightmost respiratory stability period, the third scan is executed, and the wide volume scan is completed.

  FIG. 6 is a sequence diagram for explaining the control of the wide volume scan in the respiratory synchronization in the X-ray CT system according to the embodiment. FIG. 6 shows the console device 40, the CPU of the control device 15, the gantry device 10, and the couch device 30 from the left.

  First, the console device 40 transmits scan information and bed operation information to the CPU of the gantry device 15. The scan information includes setup information and setting information in the wide volume scan. The setting information in the wide volume scan includes, for example, control information in the wide volume scan such as the number of scans and the number of bed movements. The couch movement information includes table top movement information such as a position to move the table top 33 on which the subject P is placed and a table top movement speed.

  The CPU of the gantry device 15 sets up the gantry device 10 when receiving the scan information and the bed operation information. The setup here is the same as described above. When the setup is completed, the CPU of the gantry device 15 transmits a setup completion notification to the console device 40.

  When the console device 40 receives the setup completion notification, the user can press the scan start button. When the user presses the scan start button, a scan start notification signal is transmitted from the console device 40 to the CPU of the control device 15.

  When receiving the scan start notification signal, the CPU of the control device 15 enters a gate signal waiting state. When receiving the gate signal from the respiration sensor 20, the CPU of the control device 15 transmits a scan instruction notification signal to the gantry device 10. When the gantry device 10 receives a scan instruction from the CPU of the control device 15, the gantry device 10 executes the first scan S1.

  The CPU of the control device 15 determines the completion of the first scan S1, and transmits a notification signal for the couch operation instruction to the couch device 30 at the timing when the first scan S1 is completed. Note that the operation of transmitting a bed operation instruction notification signal to the bed apparatus 30 without using the console apparatus 40 after the completion of the first scan S1 is realized by the direct control function 151 of the control apparatus 15.

  When the bed apparatus 30 receives the bed operation instruction notification signal, the bed apparatus 30 executes the bed operation B1. When the bed operation B <b> 1 is completed, the bed apparatus 30 transmits a bed status notification to the CPU of the control apparatus 15.

  When receiving the couch status notification, the CPU of the control device 15 enters a gate signal waiting state. The operation of causing the CPU of the control device 15 to immediately shift to the gate signal waiting state after the bed operation B1 is completed is realized by the direct control function 151.

  Thus, in the direct control, the operation shown in the sequence L2 is repeatedly executed. Specifically, the direct control function 151 repeats scanning and couch movement for the number of scans and couch movements included in the scan information. If the number of scans is N, the number of bed movements is N-1 times. That is, the direct control function 151 alternately performs scanning N times and bed movement N-1 times alternately.

  When a scan operation for the number of scans included in the scan information and a bed operation for the number of bed movements are executed, the CPU of the control device 15 transmits a couch operation end notification to the console device 40. That is, after the N-th scan is completed, a bed operation end notification is transmitted to the console device 40.

  The above is the explanation of the direct control of the wide volume scan under the respiratory synchronization. Hereinafter, direct control in the wide volume scan in the breath holding scan will be described.

  FIG. 7 is a timing chart illustrating a wide volume scan with breath holding in the X-ray CT system 100 according to the embodiment. FIG. 7 shows an example of a wide volume scan in which three scans and two bed operations are executed during the breath holding period, as in FIG. 3 showing a timing chart of a conventional wide volume scan. 7 is different from FIG. 3 in that there is no bed operation waiting time W1 and scan operation waiting time W2 by direct control.

  Specifically, the bed operation B1 is executed immediately after the completion of the first scan S1. Similarly, the second scan S2 is started immediately after completion of the bed operation B1. Thus, in direct control, the waiting time between operations can be shortened, so that the breath holding period can be shortened as compared with the prior art.

  FIG. 8 is a sequence diagram for explaining the control of the wide volume scan with breath holding in the X-ray CT system 100 according to the embodiment. FIG. 8 shows the console device 40, the CPU of the control device 15, the gantry device 10, and the couch device 30 from the left, similarly to FIG. 6 showing a sequence diagram of a wide volume scan under respiratory synchronization. Hereinafter, only a different part from FIG. 6 is demonstrated and description of the overlapping operation | movement is abbreviate | omitted.

  When a notification signal for starting scanning is transmitted from the console device 40 to the CPU of the control device 15, the CPU of the control device 15 waits for a breath holding start instruction. When the user issues a breath holding start instruction to the subject P and the breath holding is started, the CPU of the control device 15 transmits a scan instruction notification signal to the gantry device 10.

  Note that the breath holding start timing of the subject P may be determined by the user based on the breathing cycle and may be input via the input interface of the console device 40. The breath holding start timing may be determined by the respiration sensor 20, and each unit of the X-ray CT system 100 may be configured so that the CPU of the control device 15 receives a breath holding start notification signal from the respiration sensor 20.

  When breath holding is started, the CPU of the control device 15 transmits a scan instruction notification signal to the gantry device 10. Similar to the sequence L2 in FIG. 6, the direct control function 152 repeats the scan and the couch movement by the number of scans and the couch movement included in the scan information. When the Nth scan is completed, the user issues a breath holding end instruction to the subject P, and the wide volume scan with the breath holding ends.

  As described above, according to the X-ray CT system 100 according to the present embodiment, since the scanning operation and the bed operation can be directly executed without using the console device 40, the scanning operation and the bed operation can be completed in a shorter time than before. . Therefore, the case where a wide volume can be performed under free breathing increases. In addition, even with a wide volume under breath hold, the breath hold period can be shorter than with a conventional wide volume scan by non-direct control, so the burden on the subject can be reduced.

  The case where the respiratory synchronization scan is executed when the total time T1 of the time required for the scan operation and the time required for the bed operation is equal to or less than the time T2 in the respiratory stability period has been described above. However, the execution of the respiratory synchronization scan is not limited to the case where the total time T1 of the time required for the scan operation and the time required for the bed operation is equal to or less than the time T2 of the respiratory stable period. For example, the bed operation may be executed in a period other than the respiratory stable period.

  FIG. 9 is a timing chart for explaining a first modification in the case where a wide volume scan is performed in respiratory synchronization in the X-ray CT system 100 according to the embodiment. FIG. 9 shows an example of a timing chart of a wide volume scan in breath synchronization as in the timing chart of FIG. In FIG. 9, the major difference from FIG. 5 is that the scan start timing is not immediately after the start of the respiratory stable period.

  The respiratory stable period may include periods before and after the period when the respiratory is most stable. For example, if the period during which breathing is most stable is the middle period of the gate signal, performing a scan during the middle period has a greater effect on breathing than performing a scan immediately after the start of the breathing stabilization period. Less image data can be obtained.

  On the other hand, the bed operation need only be completed before the start of the next scan, and thus may not be completed within the respiratory stability period. For example, the bed operation may be executed in a period other than the respiratory stable period. In the following description, a period other than the respiratory stable period is referred to as a non-respiratory stable period.

  FIG. 9 shows an example in which a scan is executed in the middle period of the respiratory stability period, and then the bed movement is executed from the second half of the respiratory stability period to the first half of the non-respiratory stability period. As described above, when only the scanning operation is completed within the respiratory stable period and the bed operation is completed by the next scanning, the number of cases where the wide volume scanning can be performed under the respiratory synchronization is further increased.

  In the above, an example in which the bed operation is started immediately after the completion of scanning has been described, but the bed operation may be executed after a predetermined time has elapsed after the completion of scanning. For example, a predetermined waiting time may be provided after the scan is completed.

  Moreover, you may comprise each part of the X-ray CT apparatus 1 so that a predetermined waiting time may be provided and scanning may be started after the bed operation is completed. The tabletop 33 may be shaken by the bed operation. When scanning is performed in a state where the top plate 33 on which the subject P is placed is shaken, the acquired image data is affected by the shake of the top plate 33. Therefore, a scan may be started with a predetermined waiting time after completion of the bed operation so that the influence of the shaking of the top board 33 can be ignored. Therefore, the “predetermined waiting time” here is a time until the shaking of the top board 33 is settled to such an extent that the scanning is not affected.

  In the above description, a case has been described in which scanning is started with a predetermined waiting time after completion of the bed operation so that the influence of shaking of the top board 33 does not appear in the image data. However, the method of reducing the shaking of the top plate 33 is not limited to a method of providing a predetermined waiting time. For example, the shaking of the couchtop 33 can be reduced by reducing the speed at which the couch is moved during the couch operation.

  FIG. 10 is a timing chart for explaining a second modification in the case where a wide volume scan is performed in respiratory synchronization in the X-ray CT system according to the embodiment. A difference from FIG. 9 is the moving speed of the bed. FIG. 10 shows an example in which the speed at the start of bed movement and the speed at the time of deceleration is slower than that in FIG. 9 and a period for moving at a constant speed is provided.

  As described above, by slowing down the bed moving speed, the bed moving time becomes longer, but the influence of the shaking of the top board 33 accompanying the bed operation can be minimized. In addition, when the time obtained by subtracting the total time T1 of the time required for the scanning operation and the time required for the bed operation from the time T2 in the respiratory stabilization period is longer than a predetermined time, the X-ray CT apparatus is configured to reduce the moving speed of the bed. Each part of 1 may be constituted.

  Note that the modification examples described with reference to FIGS. 9 and 10 can also be applied to a conventional respiratory synchronization scan that does not apply direct control.

  According to the X-ray CT apparatus 1 and the X-ray CT system 100 of at least one of the embodiments described above, the waiting time between the scanning operation and the bed driving operation is shortened, so that the wide area that has been executed with the breath-holding function. Volume scan can be executed under respiratory synchronization.

  The correspondence relationship between the terms in the claims and the embodiments is, for example, as follows. In addition, the correspondence shown below is one interpretation shown for reference, and does not limit the present invention.

  The gantry device 10 is an example of an imaging unit described in the claims. The bed driving device 32 is an example of a driving unit described in the claims. The console device 40 is an example of a console recited in the claims. The direct control function 152 of the processing circuit 151 of the control device 15 is an example of a control unit described in the claims. The determination function 442 of the processing circuit 44 is an example of a determination unit described in the claims.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example 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 spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 100 ... X-ray CT system 1 ... X-ray CT apparatus 20 ... Respiration sensor 15 ... Control apparatus 152 ... Direct control function 442 ... Determination function

Claims (10)

An X-ray CT apparatus capable of performing a wide volume scan that moves the position of the subject within a pause between scans without moving the subject during the scan,
A console where scan conditions are entered,
An imaging unit that performs the scan;
A drive unit for moving the position of the subject;
When receiving a scan start input from the console, the control unit directly controls the imaging unit and the drive unit without going through the console, and controls the execution of the wide volume scan;
An X-ray CT apparatus comprising: It further includes a determination unit that determines whether the wide volume scan can be executed under breath synchronization or whether it can be executed with breath holding based on the respiratory cycle of the subject acquired in advance.
The control unit executes the wide volume scan based on a determination result in the determination unit.
The X-ray CT apparatus according to claim 1. The determination unit breathes the wide volume scan when the time of the respiratory stable period in the respiratory cycle of the subject is shorter than the total time of the time required for one scan and the time required for one position movement. If the time of the respiratory stabilization period in the respiratory cycle of the subject is equal to or longer than the total time of the time required for one scan and the time required for one position movement, the wide volume scan is performed. It is determined to execute under respiratory synchronization,
The X-ray CT apparatus according to claim 2. When executing the wide-volume scan under the respiratory synchronization, the control unit completes one scan and one position movement within the time of the respiratory stable period in the respiratory cycle of the subject. Controlling the imaging unit and the driving unit;
The X-ray CT apparatus according to claim 3. The determination unit determines that the wide volume scan is to be executed by holding the breath when the time of the respiratory stabilization period in the respiratory cycle of the subject is shorter than the time required for one scan, and in the respiratory cycle of the subject If the time of the respiratory stabilization period is longer than the time required for one scan, it is determined that the wide volume scan is performed under respiratory synchronization.
The X-ray CT apparatus according to claim 2. The control unit controls the drive unit so that the position movement of the subject is completed before the next scan is started when the wide volume scan is performed under respiratory synchronization.
The X-ray CT apparatus according to any one of claims 2 to 5. The controller, when executing the wide volume scan under respiratory synchronization, a time obtained by subtracting the time required to move the position of the subject from the time from the completion of the previous scan to the start of the next scan Is greater than a predetermined threshold, the bed moving speed is made slower than the predetermined speed.
The X-ray CT apparatus according to any one of claims 2 to 6. The control unit executes the scan in a period in which the breathing of the subject is most stable in the respiratory stable period.
The X-ray CT apparatus according to any one of claims 4 to 7. When executing the wide volume scan with breath holding, the control unit alternately executes the scan and the position movement of the subject within the breath holding period, and performs a predetermined number of scans within the breath holding period. Control to complete,
The X-ray CT apparatus according to any one of claims 3 to 5. A respiratory sensor that collects the respiratory cycle of the subject and notifies the respiratory stability period of the subject to another device;
A console where scan conditions are entered,
An imaging unit for performing a scan;
A drive unit for moving the position of the subject;
After receiving a scan start input from the console and receiving a notification indicating the respiratory stability period from the respiratory sensor, the imaging unit and the drive unit are directly controlled without going through the console. A control unit for controlling the execution of the scan;
X-ray CT system.

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