JP2020039382A - X-ray ct apparatus - Google Patents

Abstract

To provide an X-ray CT apparatus that presents an appropriate action candidate after suspension of helical scan to an operator.SOLUTION: An X-ray CT apparatus includes an X-ray source 11, an X-ray detector 12, a top plate 33, a scan control function 441, a determination function 445, and a display control function 444. The top plate 33 can be mounted with a subject. The scan control function 441 controls the X-ray source 11, the X-ray detector 12, and the top plate 33, and causes them to execute helical scan. Upon receipt of a helical scan suspension instruction, it causes the helical scan to be suspended. Upon receipt of the helical scan suspension instruction, the determination function 445 determines an action candidate after the suspension according to the time point of the suspension instruction or an elapse of time from a contrast medium injection starting time point. The display control function 444 causes a display unit to display the action candidate.SELECTED DRAWING: Figure 1

Description

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

  There is a medical image diagnostic apparatus that generates medical image data in which a body tissue of a subject is imaged. Examples of the medical image diagnostic apparatus include an X-ray CT apparatus and an MRI (Magnetic Resonance Imaging) apparatus. The X-ray CT apparatus generates raw data by pre-processing detection data detected by an X-ray detector by irradiating the subject with X-rays, and generates an axial tomographic image of the subject based on the raw data. Generate dimensional CT image data.

  In a conventional X-ray CT apparatus, when a patient to be scanned moves during a scan for collecting detection data, or when the patient complains about something, the scan is hindered, The operator needs to confirm safety. Therefore, when the operator performs a scan interrupting operation and checks the patient's condition or the like during the interrupt, and determines that the abnormality has been resolved, the X-ray CT apparatus performs a rescan or a continuous scan.

JP 2017-225605 A

  The problem to be solved by the present invention is to present an appropriate action candidate after the interruption of the helical scan to the operator.

  The X-ray CT apparatus according to the embodiment includes an X-ray irradiator, an X-ray detector, a tabletop, a scan controller, a determiner, and a display controller. The subject can be placed on the top plate. The scan control unit controls the X-ray irradiation unit, the X-ray detection unit, and the tabletop to execute the helical scan, and upon receiving an instruction to interrupt the helical scan, interrupts the helical scan. Upon receiving the instruction to interrupt the helical scan, the determining unit determines an action candidate after the interruption according to the time of the instruction to interrupt or the elapsed time from the start time of the injection of the contrast agent. The display control unit causes the display unit to display the action candidate.

FIG. 1 is a schematic diagram illustrating a configuration of an X-ray CT apparatus according to an embodiment. FIG. 2 is a block diagram showing functions of the X-ray CT apparatus according to the embodiment. FIG. 3 is an exemplary flowchart showing part of the operation of the X-ray CT apparatus according to the embodiment; FIG. 4 is an exemplary flowchart showing a part of the operation of the X-ray CT apparatus according to the embodiment; FIG. 5 is an exemplary view for explaining a method of calculating a backward distance in the X-ray CT apparatus according to the embodiment. FIG. 6 is a view showing an example of a display screen of an action candidate in the X-ray CT apparatus according to the embodiment. FIG. 7 is a diagram illustrating an example of a display screen of an action candidate in the X-ray CT apparatus according to the embodiment, and is a diagram illustrating a change in an elapsed time after the interruption of the helical scan. FIG. 8 is a diagram for explaining action candidates in a scan plan range including a plurality of range elements.

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

  The data collection method using the X-ray CT apparatus includes a rotation / rotation (RR) method in which the X-ray source and the X-ray detector rotate as a unit around the subject, and a ring-shaped method. There are various systems such as a fixed / rotation (SR) system in which a large number of detection elements are arrayed and only an X-ray tube rotates around the subject. The present invention can be applied to any method. Hereinafter, the X-ray CT apparatus according to the embodiment will be described taking as an example a case where a third-generation rotation / rotation method, which is currently dominant, is adopted.

1. Embodiment FIG. 1 is a schematic diagram illustrating a configuration of an X-ray CT apparatus according to an embodiment. FIG. 2 is a block diagram illustrating functions of the X-ray CT apparatus according to the embodiment.

  FIG. 1 shows an X-ray CT apparatus 1 according to the embodiment. The X-ray CT apparatus 1 includes a gantry device 10, a bed device 30, and a console device 40. The gantry device 10 and the bed device 30 are installed in an examination room. The gantry device 10 acquires X-ray detection data (also referred to as “pure raw data”) on the subject (eg, patient) P placed on the bed device 30. In FIG. 1, for convenience of description, a plurality of gantry devices 10 are drawn on the left and right, but as a practical configuration, there is one gantry device 10.

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

  The gantry device 10 includes an X-ray source (for example, an X-ray tube) 11, an X-ray detector 12, a rotating unit (for example, a rotating frame) 13, an X-ray high-voltage device 14, a control device 15, a wedge 16, a collimator 17, A data acquisition circuit (DAS: Data Acquisition System) 18 is provided. The gantry device 10 is an example of a gantry.

  The X-ray tube 11 is provided on a rotating frame 13. The X-ray tube 11 is a vacuum tube that generates X-rays by irradiating thermoelectrons from a cathode (filament) to an anode (target) by applying a high voltage from an X-ray high-voltage device 14. For example, the X-ray tube 11 includes a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermoelectrons.

  In the embodiment, a single-tube X-ray CT apparatus and a so-called multi-tube X-ray CT apparatus in which a plurality of pairs of an X-ray tube and an X-ray detector are mounted on a rotating ring are also used. Applicable. The X-ray source 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 for converging an electron beam generated from an electron gun, a deflection coil for electromagnetic deflection, and a target for generating an X-ray by colliding with a deflected electron beam surrounding a half circumference of the patient P X-rays may be generated by a fifth generation method including a ring. Note that the X-ray tube 11 is an example of an X-ray irradiation unit.

  The X-ray detector 12 is provided on the rotating frame 13 so as to face the X-ray tube 11. The X-ray detector 12 detects X-rays emitted from the X-ray tube 11 and outputs detection data corresponding to the X-ray dose to the DAS 18 as an electric signal. The X-ray detector 12 has, for example, a plurality of X-ray detection element rows in which a plurality of X-ray detection elements are arranged in a channel direction along one arc around the focal point of the X-ray tube. The X-ray detector 12 has, for example, a structure in which a plurality of X-ray detection element rows in which a plurality of X-ray detection elements are arranged in a channel direction are arranged in a slice direction (row direction, row direction).

  The X-ray detector 12 is, for example, an indirect conversion type detector having a grid, a scintillator array, and a photosensor array. The scintillator array has a plurality of scintillators, and the scintillator has a scintillator crystal that outputs light having a photon amount corresponding to an incident X-ray dose. The grid has an X-ray shielding plate disposed on the surface of the scintillator array on the X-ray incident side and having a function of absorbing scattered X-rays. The grid may be called a collimator (one-dimensional collimator or two-dimensional collimator). The optical sensor array has a function of converting an electric signal according to the amount of light from the scintillator, and includes, for example, an optical sensor such as a photomultiplier tube (photomultiplier: 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 an electric signal. The X-ray detector 12 is an example of an X-ray detector.

  The rotating frame 13 supports the X-ray tube 11 and the X-ray detector 12 in opposition. The rotating frame 13 is an annular frame that rotates the X-ray tube 11 and the X-ray detector 12 integrally under the control of the control device 15 described below. The rotating frame 13 may be further provided with an X-ray high-voltage device 14 or a DAS 18 in addition to the X-ray tube 11 and the X-ray detector 12, and may be supported. The rotating frame 13 is an example of a rotating unit.

  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 patient P, so that the multiple views, that is, the patient P Collect 360 ° detection data. Note that the reconstruction method of the CT image data is not limited to the full scan reconstruction method using 360 ° detection data. For example, the X-ray CT apparatus 1 may employ a half reconstruction method of reconstructing CT image data based on detection data for a half circumference (180 °) + fan angle.

  The X-ray high-voltage device 14 is provided on the rotating frame 13 or a non-rotating portion (for example, a fixed frame (not shown)) that rotatably supports the rotating frame 13. The X-ray high-voltage device 14 has an electric circuit such as a transformer (transformer) and a rectifier. The X-ray high-voltage device 14 includes a high-voltage generator (not shown) having a function of generating a high voltage applied to the X-ray tube 11 under the control of a control device 15 described below, and a control by the control device 15 described below. Below, an X-ray control device (not shown) for controlling the output voltage according to the X-ray emitted by the X-ray tube 11 is provided. The high voltage generator may be of a transformer type or an inverter type. In FIG. 1, for convenience of explanation, the X-ray high-voltage device 14 is disposed at a position in the positive direction of the x-axis with respect to the X-ray tube 11. It may be arranged at a position in the direction.

  The control device 15 includes a processing circuit and a memory, and a driving mechanism such as a motor and an actuator. The configuration of the processing circuit and the memory is the same as that of the processing circuit 44 and the memory 41 of the console device 40 described later, and thus the description is omitted.

  The control device 15 has a function of receiving an input signal from an input interface (described later) attached to the console device 40 or the gantry device 10 and controlling the operation of the gantry device 10 and the couch device 30. For example, the control device 15 performs control to rotate the rotating frame 13 in response to an input signal, control to tilt the gantry device 10, and control to operate the bed device 30 and the top board 33. The control to tilt the gantry device 10 is performed by the control device 15 based on the tilt angle (tilt angle) information input by the input interface attached to the gantry device 10. Is realized by rotating. The control device 15 may be provided on the gantry device 10 or on the console device 40. The control device 15 is an example of a control unit.

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

  The wedge 16 is provided on the rotating frame 13 so as to be arranged on the X-ray emission side of the X-ray tube 11. The wedge 16 is a filter for adjusting the X-ray dose emitted from the X-ray tube 11 under the control of the control device 15. Specifically, the wedge 16 is a filter that transmits and attenuates the X-rays emitted from the X-ray tube 11 so that the X-rays emitted to the patient P from the X-ray tube 11 have a predetermined distribution. It is. For example, the wedge 16 (wedge filter, bow-tie filter) is a filter formed by processing aluminum so as to have a predetermined target angle and a predetermined thickness.

  The collimator 17 is also called an X-ray aperture or a slit, and is provided on the rotating frame 13 so as to be arranged on the X-ray emission side of the X-ray tube 11. The collimator 17 is a lead plate or the like for narrowing the irradiation range of the X-ray transmitted through the wedge 16 under the control of the control device 15, and forms an X-ray irradiation opening by a combination of a plurality of lead plates and the like.

  The DAS 18 is provided on the rotating frame 13. The DAS 18 performs an amplification process on an electric signal output from each X-ray detection element of the X-ray detector 12 under the control of the control device 15, and converts the electric signal into a digital signal under the control of the control device 15. An A / D (Analog to Digital) converter that converts the signal into a signal, and generates detection data after amplification and digital conversion. The detection data for a plurality of views generated by the DAS 18 is transferred to the console device 40.

  Here, the detection data generated by the DAS 18 is transmitted from a transmitter having a light emitting diode (LED) provided on the rotating frame 13 to a receiver having a photodiode provided on a fixed frame of the gantry device 10 by optical communication. Then, it is transferred to the console device 40. The method of transmitting the detection data from the rotating frame 13 to the fixed frame of the gantry device 10 is not limited to the above-described optical communication, and any method may be adopted as long as it is a non-contact type data transmission. The rotating frame 13 is an example of a rotating unit.

  The couch device 30 includes a base 31, a couch driving device 32, a top plate 33, and a support frame. The couch device 30 is a device on which a patient P to be scanned can be placed, and which moves the patient P under the control of the control device 15.

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

  The bed 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 the standing CT, a method of moving a patient moving mechanism corresponding to the top plate 33 may be used. Further, in the case of performing an imaging involving a relative change of the positional relationship between the imaging system of the gantry device 10 and the top plate 33, such as a scano imaging for helical scan or positioning, the relative change of the relative position is not performed. It may be performed by driving the top plate 33, may be performed by running the fixed portion of the gantry device 10, or may be performed by a combination thereof.

  In the embodiment, the longitudinal direction of the rotation axis of the rotating frame 13 or the top plate 33 of the bed device 30 in the non-tilt state is perpendicular to the z-axis direction and the z-axis direction, and the axial direction that is horizontal to the floor surface is An axial direction perpendicular to the x-axis direction and the z-axis direction and perpendicular to the floor surface is defined as a y-axis direction.

  The console device 40 includes a memory 41, a display 42, an input interface 43, and a processing circuit 44. Although the console device 40 is described as being separate from the gantry device 10, the gantry device 10 may include the console device 40 or some of the components of the console device 40. 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 console device 40 is an example of a medical image processing device.

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

  The memory 41 stores, for example, detection data before preprocessing, raw data after preprocessing and before reconstruction, and CT image data after reconstruction based on the raw data. The pre-processing means at least one of logarithmic conversion processing, offset correction processing, sensitivity correction processing between channels, beam hardening processing, and the like for the detection data. Further, a cloud server connectable to the X-ray CT apparatus 1 via a communication network such as the Internet receives a storage request from the X-ray CT apparatus 1 and stores detection data, raw data, or CT image data. May be done. Note that the memory 41 is an example of a storage unit.

  The display 42 displays various information. For example, the display 42 outputs CT image data 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 display 42 may be provided on the gantry device 10. Further, the display 42 may be a desktop type, or may be configured by a tablet terminal or the like that can wirelessly communicate with the console device 40 main body. The display 42 is an example of a display unit.

  The input interface 43 includes an input device that can be operated by an operator such as a technician, and an input circuit that inputs a signal from the input device. The input device includes a mouse, a keyboard, a trackball, a switch, a button (for example, a “scan interrupt button” described later), a joystick, a touchpad for performing an input operation by touching an operation surface, and a display screen and a touchpad integrated. A touch screen, a non-contact input circuit using an optical sensor, a voice input circuit, and the like. When the input device receives an input operation from the operator, the input circuit generates an electric signal corresponding to the input operation and outputs the electric signal to the processing circuit 44. The input interface 43 may be provided on the gantry device 10. Further, the input interface 43 may be configured by a tablet terminal or the like that can wirelessly communicate with the console device 40 main body. The input interface 43 is an example of an input unit.

  The processing circuit 44 controls the entire operation of the X-ray CT apparatus 1. The processing circuit 44 means a dedicated or general-purpose CPU (Central Processing Unit), MPU (Micro Processor Unit), or GPU (Graphics Processing Unit), as well as an ASIC, a programmable logic device, and the like. Examples of the programmable logic device include a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). No.

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

  The processing circuit 44 executes a program stored in the memory 41 to realize a scan control function 441, a preprocessing function 442, a reconstruction processing function 443, a display control function 444, a determination function 445, and a calculation function 446. . Note that all or a part of the functions 441 to 446 is not limited to a case where the functions are realized by executing a program of the console device 40, and may be a case where the console device 40 is provided as a circuit such as an ASIC. . Further, all or a part of the functions 441 to 446 may be provided not only in the console device 40 but also in the control device 15.

  The scan control function 441 controls the X-ray tube 11 and the X-ray detector 12 and the like via the control device 15 according to a preset scan condition to execute a helical scan (also referred to as “spiral scan”), and control A function of collecting detection data for a plurality of views from the device 15 is included. For example, the scan conditions are set according to a tube current mA, a tube voltage kV, an X-ray intensity control condition (modulation condition), a rotation speed of the X-ray tube 11 (or the rotating frame 13), and a scan plan relating to the irradiated X-ray. Scan range (hereinafter, referred to as “scan planning range”).

  Here, in the helical scan, the patient P placed on the top 33 is imaged in a spiral (helical) manner. In the helical scan, X-ray irradiation and data collection are performed while moving the table 33 on which the patient P is placed in the z direction with respect to the fixed frame. Alternatively, in the helical scan, X-ray irradiation and data collection are performed on the top plate 33 on which the patient P is placed while moving the fixed frame in the z direction.

  The scan control function 441 includes a function of interrupting the helical scan when receiving an instruction to interrupt the helical scan. For example, the scan control function 441 receives a helical scan interruption instruction when an operator such as a technician presses a scan interruption button as an input device of the input interface 43. The scan control function 441 is an example of a scan control unit.

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

  The reconstruction processing function 443 includes a function of generating CT image data by image reconstruction processing based on the raw data for a plurality of views generated by the preprocessing function 442. As an image reconstruction method, an analytical method represented by a convolution corrected back projection (CBP: Convolution Back Projection) method and a filtered corrected back projection (FBP: Filtered Back Projection) method, and an algebraic method are known. And they are used. The algebraic method is generally called an iterative reconstruction (IR) method because a reconstructed image is obtained using an iterative method.

  The reconstruction processing function 443 may include a function of storing CT image data in the memory 41 and a function of transmitting CT image data to an external device via a network interface (not shown). The reconfiguration processing function 443 is an example of a reconfiguration processing unit.

  The display control function 444 includes a function of displaying the CT image data generated by the reconstruction processing function 443 on the display 42 as a CT image. The display control function 444 is an example of a display control unit.

  The determination function 445 includes a function of determining an action candidate after the interruption according to the elapsed time from the interruption instruction time when the interruption instruction of the helical scan is received. Alternatively, when accepting an instruction to interrupt the helical scan performed in a state where the contrast agent is injected, the determination function 445 determines the action candidate after the interruption according to the elapsed time from the start time of the injection of the contrast agent into the patient P. Including the function to determine. Alternatively, when accepting an instruction to interrupt the helical scan, the determination function 445 determines an action candidate after the interruption according to the elapsed time from the detection time of the abnormality of the patient P by a patient microphone (not shown) or the like. including. For example, the determination function 444 receives an instruction to interrupt the helical scan when an operator such as a technician presses a scan interrupt button as an input device of the input interface 43. Note that the determination function 445 is an example of a determination unit.

  The calculation function 446 includes a function of calculating a parameter corresponding to each action candidate determined by the determination function 445. For example, the calculation function 446 includes a function of calculating a start position of a continuous scan of the interrupted helical scan when receiving an instruction to interrupt the helical scan. Note that the calculation function 446 is an example of a calculation unit.

  The display control function 444 includes a function of causing the display 42 to display the plurality of action candidates determined by the determination function 445 or the start position of the continuous scan calculated by the calculation function 446. In addition, the display control function 444 may include a function of displaying the parameter generated by the calculation function 446 on the display 42 together with the plurality of action candidates. When the display control function 444 is provided in the control device 15, the display control function 444 may be displayed on an operation panel on a fixed frame (not shown) that supports the rotating frame 13.

  The details of the functions 441 to 446 will be described later with reference to FIGS.

  3 and 4 are diagrams showing the operation of the X-ray CT apparatus 1 as a flowchart. In FIGS. 3 and 4, reference numerals with numbers attached to “ST” indicate respective steps in the flowchart.

  First, the operation of the X-ray CT apparatus 1 will be described with reference to FIG.

  The operator operates the input interface 43 while the patient P who is to perform the helical scan is placed on the table 33. The scan control function 441 starts the helical scan by controlling the X-ray tube 11, the X-ray detector 12, and the like via the control device 15 according to a preset scan condition (step ST1). The scan control function 441 can collect detection data for a plurality of views from the control device 15 by helical scan. The description of the pre-scan (also referred to as “scan scan” or “scout scan”) performed prior to the execution of the helical scan in step ST1 is omitted.

  The scan control function 441 determines whether the scan interrupt button has been pressed by an operator such as a technician, that is, whether an instruction to interrupt the helical scan has been received (step ST2). If the determination in step ST2 is NO, that is, if it is determined that the instruction to interrupt the helical scan has not been received, the scan control function 441 determines whether to end the helical scan started in step ST1 (step ST3). If the determination in step ST4 is NO, that is, if it is determined not to end the helical scan, the process returns to step ST2. As described above, if the scan control function 441 does not receive the interruption instruction during the helical scan, the determination in steps ST2 and ST3 is repeated until the helical scan ends (step ST4).

  If the determination in step ST3 is YES, that is, if it is determined to end the helical scan, the scan control function 441 determines whether or not to perform the next helical scan on the same patient as the patient placed on the top 33. (Step ST5). Here, in step ST5, the scan control function 441 performs the following for the patient based on the examination order for the patient transmitted from an external device, for example, an RIS (Radiology Information System) or a MWM (Modality Worklist Management) server. It is determined whether or not the helical scan exists. The examination order includes patient information, examination conditions, and the like.

  If the determination in step ST5 is YES, that is, if it is determined that the next helical scan is to be performed for the same patient as the patient placed on the top 33, the scan control function 441 performs control according to the preset scan conditions. By controlling the X-ray tube 11 and the X-ray detector 12 via the device 15, helical scans such as volume scan and helical scan are started (step ST1).

  On the other hand, if the determination in step ST5 is NO, that is, if it is determined that the next helical scan will not be performed for the same patient as the patient placed on the top 33, the scan control function It is determined that all helical scans for the placed patient have been completed. The patient placed on the table 33 is lowered from the table 33.

  As described above, when no interruption instruction is received at least once in one or more helical scans included in the examination order for one patient, one or more helical scans continue for the patient. Done.

  The pre-processing function 442 performs pre-processing on detection data for a plurality of views collected by the helical scan during the helical scan started in step ST1 or after the end of the helical scan, thereby generating a plurality of views. Generate data. The reconstruction processing function 443 generates CT image data by image reconstruction processing based on raw data for a plurality of views during the helical scan started in step ST1 or after the helical scan ends. The reconstruction processing function 443 stores CT image data in the memory 41 and transmits CT image data to an external device via a network interface (not shown).

  Next, an operation in a case where a scan interruption instruction is received in at least one of one or a plurality of helical scans included in an examination order for one patient will be described.

  When the determination in step ST2 is YES, that is, when it is determined that the instruction to interrupt the helical scan has been received, the scan control function 441 proceeds to FIG. 4 and interrupts the helical scan (step ST11). When it is determined that the instruction to interrupt the helical scan has been received, the determination function 445 determines an action candidate after the interruption (step ST12).

  Here, the action candidate includes at least one of a rescan, a continuous scan, and a skip. Rescanning means restarting the helical scan interrupted in step ST11 from the beginning. The continuous scan means restarting the helical scan interrupted in step ST11. Skip means terminating the helical scan interrupted in step ST11 and starting the next helical scan included in the inspection order. If the next helical scan is not included in the inspection order, skip is not selected as an action candidate. Hereinafter, the case where the determination function 445 determines re-scanning, continuous scanning, and skipping as the action candidates after the interruption in step ST11 will be described.

  The calculation function 446 calculates a parameter corresponding to each action candidate determined in step ST12 (step ST13). The calculation function 446 calculates, as a parameter, a reversing distance for determining a start position of a scan after resuming, for a continuous scan as an action candidate.

  FIG. 5 is a diagram for explaining a method of calculating a backward distance.

  FIG. 5 shows a scan planning range R corresponding to the patient model M when the positive direction of the z-axis is the scan direction of the helical scan. As shown on the left side of FIG. 5, it is assumed that the interruption is performed during the helical scan. In this case, when the continuous scan is selected, the scan control function 441 returns in the negative direction of the z-axis by the interruption position (position in the z direction) or the distance arbitrarily selected by the operator from the interruption position. From the position, a method of restarting the helical scan can be adopted. However, it is difficult and troublesome for the operator to select the optimum distance.

  Therefore, the calculation function 446 calculates the reverse distance D as shown on the right side of FIG. 5, and sets the position returned from the interruption position by the reverse distance D in the negative direction of the z-axis as the start position of the continuous scan. The scan control function 441 restarts the helical scan from the calculated start position of the continuous scan. The calculating function 446 calculates the reversing distance D based on a preset time, distance, and a combination thereof.

  First, the calculation function 446 calculates the reversing distance D based on a preset time. If an event that requires the helical scan to be interrupted halfway occurs (for example, if the operator confirms an abnormality with reference to the displayed CT image or if the patient being scanned utters) This is particularly effective when returning the time required for the determination. For example, it is assumed that the scan is restarted from a position (a position in the z-direction) corresponding to two seconds before the interruption when the operator pressed the scan interruption button. In this case, the calculation function 446 calculates the position two seconds before the interruption as the start position of the continuous scan based on the helical pitch, the imaging slice width, the number of imaging columns, the rotation speed, and the like, and scans from the start position. The scanning condition up to the end position of the range R is determined. Note that if the calculated position calculated by the calculation function 446 and corresponding to two seconds before the interruption is beyond the start position of the scan planning range R, there is no point in executing the continuous scan. In that case, the display control function 444 may control so that “continuous scan” is not displayed as an action candidate in the next step ST14.

  Second, the calculation function 446 calculates the reversing distance D based on a preset distance. For example, it is assumed that the setting has been made so that the scanning is restarted from a position 100 [mm] before the interruption position. In this case, the calculation function 446 calculates a position in the z direction 100 mm before the position in the z direction corresponding to the image position displayed in real time as the start position of the continuous scan, and calculates a scan plan from the start position. The scanning condition up to the end position of the range R is determined. If the position calculated by the calculation function 446 before the interruption 100 [mm] exceeds the start position of the scan planning range R, there is no point in executing the continuous scan. In that case, the display control function 444 may control so that “continuous scan” is not displayed as an action candidate in the next step ST14.

  Third, the calculation function 446 may calculate the reverse distance D based on a preset combination of time and distance. This is because when the backward distance D is calculated based on the distance from the interruption position, the time required for the interruption determination may be significantly shorter depending on the helical pitch, the number of imaging rows, the rotation speed, and the like. In such a case, the calculation function 446 switches the distance reference to a time-based calculation method. On the other hand, when the photographing speed is low, the coverage range may be reduced on the basis of the number of seconds, so that the calculation function 446 can calculate based on the backward distance D. Further, the calculation function 446 may present the operator with the start position of the continuous scan calculated on the basis of the time and the start position of the continuous scan calculated on the basis of the distance, and allow the operator to select one of the start positions. Good.

  Returning to the description of FIG. 4, the display control function 444 causes the display 42 to display “rescan”, “continuous scan”, and “skip” as the action candidates determined in step ST12, and displays the action candidates. The parameters are displayed on the display 42 (step ST14).

  FIG. 6 is a diagram illustrating an example of a display screen of an action candidate.

  As shown in FIG. 6, the display screen includes information indicating that the scan was interrupted during the helical scan due to the operation of interrupting the helical scan, and “Rescan” and “Rescan” as action candidates after the interruption was released. "Continuous scan" and "skip". In addition, the display screen includes parameters corresponding to each action candidate and a “selection button” for each action candidate. That is, the display control function 444 causes the display 42 to display any one of a plurality of action candidates “rescan”, “continuous scan”, and “skip”.

  An example of the parameter of the action candidate “rescan” is a scan execution range (an actually collected data range) from a scan start position to a stop position in a preset scan plan range. The scan execution range is shown as a sparse hatched area on the left side of the display screen shown in FIG. 6 as a part of a scan plan range (broken line) preset on the patient model.

  Here, the action candidate “rescan” is displayed when the determination function 445 determines that the elapsed time from the interruption instruction time or the start time of the injection of the contrast agent into the patient P is within a predetermined time. The control function 444 may not be displayed as an option. This is because if the elapsed time is too short when the contrast helical scan is interrupted, the “continuous scan” is considered to be more suitable in terms of exposure. On the other hand, when it is determined that the elapsed time is within the predetermined time, the display control function 444 may highlight the action candidate “continuous scan”.

  An example of the parameter of the action candidate “continuous scan” is the reversing distance D (shown in FIG. 5) as described with reference to FIG. The return distance D is shown as a hatched area in the center of the display screen shown in FIG. 6 in a part of a scan planning range (broken line) preset on the patient model.

  Here, the action candidate “continuous scan” is set to display control when the determination function 445 determines that the elapsed time from the interruption instruction time or the start time of the injection of the contrast agent into the patient P exceeds a predetermined time. Function 444 may be prevented from being displayed as an option. This is because, when the helical scan of the contrast is interrupted, if the elapsed time is too long, the contrast agent is not stained. In addition, the action candidate “continuous scan” may not be displayed as an option according to the elapsed time from the detection time of the abnormality of the patient P by the patient microphone (not shown) or the like. This is because “rescanning” is more desirable than “continuous scanning” in many cases. On the other hand, when it is determined that the elapsed time exceeds the predetermined time, the display control function 444 may highlight the action candidate “rescan”.

  An example of the parameter of the action candidate “skip” is the elapsed time from the time when the helical scan was interrupted. The elapsed time is shown as character information “10 seconds elapsed” on the right side of the display screen shown in FIG. The parameter of the action candidate “skip” may be an elapsed time from the injection start time of the contrast agent.

  The operator can select the next appropriate action according to the patient and the examination purpose while referring to the action candidate and the parameter, and can easily select the action by operating a button on the screen. In addition, the operator who lacks experience may not be able to manually set the reversing distance (corresponding to the symbol “D” shown in FIG. 5), and even if re-scanning was previously selected, the reversing distance may not be set. By automatically calculating and presenting the distance D, it is easy to select a continuous scan. As a result, the amount of exposure of the patient can be reduced.

  Returning to the description of FIG. 4, the scan control function 444 determines whether an arbitrary action has been selected from the action candidates on the display screen shown in FIG. 6 (step ST15). If the determination in step ST5 is NO, that is, if it is determined that the selection of an arbitrary action from the action candidates has not been received, the determination function 445 calculates the parameter for the parameter that needs to be recalculated (step ST13). ). For example, the determination function 445 recalculates the elapsed time from the interruption of the helical scan for the action candidate “skip”. That is, the display control function 444 can sequentially (real-time) display the elapsed time on the display 42.

  FIG. 7 is a diagram illustrating an example of a display screen of an action candidate, and is a diagram illustrating a change in an elapsed time after the interruption of the helical scan.

  FIG. 7 shows a display screen 20 seconds after the display screen shown in FIG. As shown in FIG. 7, after 20 seconds have elapsed from the display screen shown in FIG. 6, the parameter of the action candidate “skip” has changed from “10 seconds elapsed” in FIG. 6 to “30 seconds elapsed”.

  According to the comparative example of the X-ray CT apparatus, when the scan interrupt button is pressed, the helical scan is interrupted if it is determined that the scan has been executed to the reconfigurable range of the scan plan range, and the next Preparation for helical scan. However, the helical scan is interrupted not only when the scan in the assumed range is completed, but also for the purpose of ensuring safety and adjusting timing due to a change in the situation around the patient. In such a case, the operator does not know whether rescanning or continuous scanning can be performed (whether the data necessary for reconstruction has been collected) or not, and if so, manually again. Since it is necessary to reset the scan range and the like, a large time loss occurs. In addition, when performing a helical scan by contrast, the contrast agent flows, so if it is not possible to select an action that matches the imaging situation that changes from time to time that elapses from the interruption time of the helical scan, There is a problem that an appropriate contrast effect cannot be obtained.

  When the display screens as shown in FIGS. 6 and 7 are displayed, the operator can easily grasp the executable action candidates based on the elapsed time by displaying the action candidates and the parameters. . In particular, the operator can visually recognize the time that has elapsed since the scan interruption time, which is constantly changing, in the helical scan for contrast.

  Returning to the description of FIG. 4, when the determination in step ST5 is YES, that is, when it is determined that the selection of an arbitrary action from the action candidates has been received, the scan control function 441 determines that the received action is “re- It is determined whether it is “scan” or “continuous scan” (step ST17). When the determination in step ST17 is YES, that is, when it is determined that the accepted action is “rescan” or “continuous scan”, the scan control function 441 starts the interrupted helical scan (step S17). ST18), and return to step ST2 shown in FIG.

  More specifically, in the case of “rescanning”, the scan control function 441 performs control via the control circuit 15 via the control circuit 15 to perform a helical scan from the head position of a preset scan planning range R (shown in FIG. 5). The plate 12 is slid in the positive direction of the z-axis. Then, the scan control function 441 adjusts the start position of the scan planning range R to the center position of the X-ray irradiation, and performs the helical scan again (step ST18).

  On the other hand, in the case of the “continuous scan”, the scan control function 441 transmits via the control circuit 15 via the control circuit 15 to perform the helical scan from the position returned from the interrupted position of the helical scan by the reversal distance D determined in step ST13. The top plate 12 is slid in the positive direction of the z axis. Then, the scan control function 441 sets the position returned from the interrupted position of the helical scan by the reversal distance D determined in step ST13 to the center position of the X-ray irradiation, and restarts the helical scan (step ST18). .

  It should be noted that returning from step ST18 to step ST2 shown in FIG. 3, the scan may be interrupted again in the same scan. That is, the interruption of the helical scan can be performed any number of times until the scan reaches the end position of the scan planning range. In this case, the calculation function 446 may calculate the start position of the scan after the second and subsequent interruptions as the start position of the scan after the previous interruption for “continuous scan”, or newly calculate the start position from the reverse return distance D. It may be calculated, or they may be switched.

  If NO in step ST17, that is, if it is determined that the accepted action is “skip”, the process returns to step ST5 shown in FIG.

  Here, it is assumed that after the determination in step ST17 shown in FIG. 4 is NO, the determination in step ST5 shown in FIG. 3 is YES, and the helical scan is started in step ST1. That is, when a plurality of, for example, two helical scans are included in the examination order for a certain patient, the scan is interrupted in the middle of the first helical scan (for example, non-contrast), and the action candidate “skip” is generated. After the determination (step ST17), the case where the second helical scan (for example, contrast imaging) is performed on the same patient is considered.

  First, the calculation function 446 individually calculates the scan execution range of each helical scan. In other words, the calculation function 446 determines that the scan is interrupted in the middle of the scan planned range in the helical scan related to the non-contrast. Is calculated as the scan execution range.

  Second, the calculation function 446 matches the scan execution range of each helical scan. That is, when the scan is interrupted in the middle of the scan planning range in the non-contrast helical scan, the calculation function 446 determines that only the scan execution range executed in the non-contrast is performed for the subsequent helical scan related to the contrast. And

  In the second case, the calculation function 446 adjusts the scan execution range of the second and subsequent helical scans to the scan execution range executed in the previous helical scan in accordance with the operator's selection instruction via the input interface 43. Range.

  Also, consider a reconstruction process when a continuous scan is performed. The reconstruction processing function 443 performs a reconstruction process based on the raw data collected before the interruption of the helical scan to generate first CT image data, and converts the raw data collected by the continuous scan of the helical scan into A second CT image data is generated by performing a reconstruction process based on the second CT image data. Then, the reconstruction processing function 443 generates data excluding the overlapping portion (the range of the symbol “D” illustrated in FIG. 5) of the first and second CT image data.

  As described above, according to the X-ray CT apparatus, a plurality of appropriate action candidates after the interruption are presented to the operator as options in accordance with the interruption instruction time of the helical scan or the elapsed time from the injection start time of the contrast agent. can do. Thus, the operator can refer to the list of the next plurality of possible actions after the interruption, and can easily select an appropriate next action from the list.

2. First Modification The display screen shown in FIG. 6 (or FIG. 7) may display recommended action candidates according to the elapsed time from the interruption time of the helical scan. For example, when the calculation function 446 determines that the elapsed time from the interruption time of the helical scan to the current time is within a preset time, the display control function 444 sets a display that recommends “continuous scan”. I do. If the elapsed time from the time of interruption of the helical scan is within the set time, it is expected that the deviation between the acquired CT images is small, and especially in the case of contrast overtaking in contrast scan or the like, the conditions are reset. This is because it is expected that the photographing will be finely performed by one contrast without performing the operation.

  On the other hand, if the calculation function 446 determines that the elapsed time from the interruption time of the helical scan to the current time has exceeded a preset time, a display that recommends “rescan” is performed. If the elapsed time from the interruption time of the helical scan exceeds the set time, there is a concern that a deviation between CT images due to a time phase difference, a patient's body movement, and the like may increase, so rescanning is considered desirable. .

  As an example of the recommended display, on the display screen shown in FIG. 6 (or FIG. 7), the “selection button” may be highlighted, the elapsed time may be highlighted, “recommended”, etc. May be displayed, or may be displayed as icons or figures. Further, a sound indicating a recommended action candidate may be uttered from a speaker (not shown).

  As described above, according to the first modification of the X-ray CT apparatus 1, in addition to the above-described effects, the operator can instruct the interruption time of the helical scan or the injection start time of the contrast agent regardless of the difference in experience. It is possible to easily refer to the next action recommended according to the elapsed time from.

3. Second Modified Example The scan planning range of the helical scan may be divided into a plurality of range elements. In this case, consider an action candidate related to the interrupted helical scan.

  FIG. 8 is a diagram for explaining action candidates in a scan plan range including a plurality of range elements.

  As shown on the left side of FIG. 8, the scan planning range R includes four elements in the z direction. It is assumed that the scan is interrupted during the scan of the second element among the four elements. Here, when “Skip” is selected from a plurality of action candidates displayed on the display screen, as shown in the upper right part, the calculation function 446 sets the head position of the third element to the next scan Is calculated as the start position. The scan control function 441 starts scanning from the start position.

  On the other hand, when “continuous scan” is selected from a plurality of action candidates displayed on the display screen, as shown in the lower right part, the calculation function 446 starts scanning the head position of the immediately preceding element. Calculate as position. The scan control function 441 starts a continuous scan from the start position.

  The scan control function 441 is an example of a scan control unit. The pre-processing function 442 is an example of a pre-processing unit. The reconstruction processing function 443 is an example of a reconstruction processing unit. The display control function 444 is an example of a display control unit. The determination function 445 is an example of a determination unit. The calculation function 446 is an example of a calculation unit.

  According to at least one embodiment described above, an appropriate action candidate after the interruption of the helical scan can be presented to the operator.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various 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 equivalents thereof.

1 X-ray CT apparatus 11 X-ray source (X-ray tube)
12 X-ray detector 40 Console device (medical image processing device)
44 processing circuit 441 scan control function 442 preprocessing function 443 reconstruction processing function 444 display control function 445 determination function 446 calculation function

Claims (13)

An X-ray irradiator;
An X-ray detector,
A top plate on which the subject can be placed,
The X-ray irradiator, the X-ray detector, and a helical scan that is controlled by controlling the top plate, and a scan controller that suspends the helical scan when receiving an instruction to suspend the helical scan,
When accepting the interruption instruction of the helical scan, the time of the interruption instruction, or, according to the elapsed time from the injection agent injection start time, a determination unit that determines an action candidate after the interruption,
A display control unit for displaying the action candidate on a display unit,
X-ray CT apparatus having: The display control unit is, as the action candidate, a continuous scan of the helical scan interrupted by the scan control unit, a rescan of the helical scan interrupted by the scan control unit, and interrupted by the scan control unit. The skip to the next helical scan of the helical scan is displayed on the display unit so as to be selectable,
The X-ray CT apparatus according to claim 1. When receiving an instruction to interrupt the helical scan, the scan control unit further includes a calculation unit that calculates a start position of a continuous scan of the helical scan interrupted by the scan control unit,
The display control unit causes the display unit to display the start position,
The X-ray CT apparatus according to claim 2. The calculation unit calculates a return distance from an interrupted position based on at least one of a preset distance and time, and calculates a position returned by the return distance from the interrupted position for the continuous scan. Start position,
The X-ray CT apparatus according to claim 3. A first CT image data is generated by performing a reconstruction process based on the raw data collected before the interruption of the helical scan, and a reconstruction is performed based on the raw data collected by the continuous scan of the helical scan. A reconstruction processing unit that performs processing to generate second CT image data and generates data excluding an overlapping portion of the first and second CT image data;
The X-ray CT apparatus according to claim 3. When one inspection includes a plurality of helical scans, when an interruption instruction is given in a predetermined helical scan and the continuous scan is executed, a scan range of a subsequent helical scan is changed to a scan range executed in the predetermined helical scan. Further comprising a calculation unit for calculating as a range according to,
The X-ray CT apparatus according to claim 2. The calculation unit, according to the selection instruction, calculates the scan range of the subsequent helical scan as a range according to the scan range executed in the predetermined helical scan,
The X-ray CT apparatus according to claim 6. When there are a plurality of interruption instructions in one helical scan, the apparatus further includes a calculation unit that calculates a start position of the scan after the second or later interruption as a start position of the scan after the previous interruption.
The X-ray CT apparatus according to claim 2. The determination unit determines whether the elapsed time is within a predetermined time,
The display control unit, when it is determined by the determination unit is within the predetermined time, performs a display recommending the continuous scan,
The X-ray CT apparatus according to claim 2. The determining unit determines whether the elapsed time exceeds a predetermined time,
The display control unit, when it is determined that the predetermined time exceeds the predetermined time, performs a display recommending the re-scan,
The X-ray CT apparatus according to claim 2. The determining unit, when receiving the instruction to interrupt the helical scan, sequentially calculates the elapsed time,
The display control unit causes the display unit to sequentially display the elapsed time,
The X-ray CT apparatus according to claim 2. An X-ray irradiator;
An X-ray detector,
A top plate on which the subject can be placed,
The X-ray irradiator, the X-ray detector, and a helical scan that is controlled by controlling the top plate, and a scan controller that suspends the helical scan when receiving an instruction to suspend the helical scan,
A calculation unit configured to calculate a start position of a continuous scan of the helical scan interrupted by the scan control unit when receiving an instruction to interrupt the helical scan;
A display control unit for displaying the start position on a display unit,
X-ray CT apparatus having: The calculation unit calculates a return distance from an interrupted position based on at least one of a preset distance and time, and calculates a position returned by the return distance from the interrupted position for the continuous scan. Start position,
The X-ray CT apparatus according to claim 12.

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