JP6449415B2 - X-ray CT system - Google Patents

Description

  Embodiments described herein relate generally to an X-ray CT apparatus capable of setting a plan for sequentially executing a plurality of scans.

  The X-ray CT apparatus rotates an X-ray tube that generates X-rays, an X-ray detector that detects X-rays, a movable top plate on which a subject is placed, an X-ray tube and an X-ray detector And an image processing unit that performs scanning by irradiating the subject placed on the top plate with X-rays, reconstructs projection data collected by the scanning, and generates image data.

  By the way, in the X-ray CT apparatus, the subject is irradiated with X-rays while moving the top plate, and the subject is irradiated with X-rays while the top plate is stopped. There is a scan mode such as a scan that collects projection data, and the scan mode is set according to the inspection. When performing a plurality of scans in an inspection, an expert plan is known in which a plan for executing a plurality of scans is set and each scan is sequentially executed based on the set plan.

JP 2000-116634 A

  However, when the system goes down due to a power failure or the like in the middle of the scan executed based on the expert plan, it is necessary to start again from the first scan, and there is a problem that the exposure dose of the subject increases.

  The embodiment has been made to solve the above problems, and an object thereof is to provide an X-ray CT apparatus capable of reducing the exposure dose of a subject.

In order to solve the above problem, the X-ray CT apparatus of the embodiment rotates an X-ray tube that generates X-rays and an X-ray detector that detects X-rays transmitted through a subject placed on a top plate. A rotating frame that can be supported, a plan storage unit that stores a plan that sequentially executes a plurality of scans that collect a plurality of projection data as the rotating frame rotates, and stores scan information that includes the plurality of projection data comprising a scan information storage unit that, the at least one scan of the plurality of scan is a helical scan for collecting the projection data by X-ray irradiation while the top plate is moving, the the helical scan is stopped halfway during the helical scan execution, and the number of the projection data relating to stored the helical scan to the scan information storage unit beforehand set If the number of glue margins is greater than or equal to the number of glue margins, in the projection data relating to the helical scan, the position of the rotating frame at the time of collection of projection data retroactively counted from the latest projection data and the number of glue margins, and the The helical scan is restarted from the position of the top plate, the helical scan is stopped halfway during the execution of the helical scan, and the number of projection data relating to the helical scan stored in the scan information storage unit is the glue Scan control for determining the position of the rotating frame and the position of the top plate at the start time of the helical scan as the restart position of the helical scan and restarting the helical scan from the restart position when the number is less than the number of charges It further comprises a section.

The figure which shows the structure of the X-ray CT apparatus which concerns on embodiment. The figure which shows an example of the plan setting screen displayed on the display part which concerns on embodiment. The flowchart which shows operation | movement of the X-ray CT apparatus which concerns on embodiment. The flowchart which shows the detail of operation | movement in step S6 of FIG. The figure for demonstrating the 3rd scan which concerns on embodiment. The figure which shows the plan setting screen as which the rest time was set to the 5th scan which concerns on embodiment. The figure for demonstrating the 5th scan by which the idle time which concerns on embodiment was set.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an X-ray CT apparatus according to the embodiment. The X-ray CT apparatus 100 includes a bed unit 10 on which a subject P is movably mounted, and a gantry unit 20 that collects projection data by irradiating the subject P mounted on the bed unit 10 with X-rays. And a scan control unit 30 that controls the bed unit 10 and the gantry unit 20 to execute a scan for collecting projection data.

  In addition, the X-ray CT apparatus 100 sequentially executes the image processing unit 40 that generates image data based on the projection data collected by the gantry unit 20, the image data generated by the image processing unit 40, and a plurality of scans. A display unit 50 for displaying a plan setting screen for setting a plan, an operation unit 60 for performing input for setting a plan, etc., and a plan storage unit 70 for storing a plan set and input by the operation unit 60 It has.

  Further, the X-ray CT apparatus 100 includes a scan information storage unit 80 that stores scan information including projection data obtained by each scan sequentially executed based on the plan stored in the plan storage unit 70, and the scan control unit 30. A system control unit 90 that controls the image processing unit 40, the display unit 50, the plan storage unit 70, and the scan information storage unit 80 in an integrated manner.

  The couch unit 10 is disposed in the vicinity of the front side of the gantry unit 20, and a couchtop 11 on which the subject P is placed, and a couchtop support unit 12 that supports the couchtop 11 so as to be movable in the vertical direction and the longitudinal direction. It has. Then, the top support 12 moves the top 11 in the longitudinal direction and stops it at a position where X-ray irradiation to the affected part of the subject P can be performed by the gantry 20.

  The gantry 20 has a cylindrical opening 20a that passes between the front side and the back side. And the X-ray tube 21 which irradiates X-ray with respect to the subject P sent to the opening part 20a by the movement to the longitudinal direction of the top plate 11 of the bed part 10, and the X-ray tube 21 via the opening part 20a An X-ray detector 22 that detects X-rays that face each other and are transmitted through the subject P, and a data collection unit 23 that collects projection data based on signals detected by the X-ray detector 22 are provided.

  Further, the gantry unit 20 includes a data transmission unit 24 that outputs projection data collected by the data collection unit 23 to the image processing unit 40, a high voltage generation unit 25 that drives the X-ray tube 21 to be irradiated, and an X-ray tube 21. The rotating frame 26 that holds the X-ray detector 22, the data collecting unit 23, the data transmitting unit 24, and the high voltage generating unit 25 so as to be rotatable around the subject P, and rotating the rotating frame 26 in the direction of the arrow R 1 And a rotational drive unit 27 that rotationally drives at a speed.

  The X-ray tube 21 generates X-rays when a high voltage is supplied from the high voltage generator 25. Then, X-rays are irradiated while rotating around the subject P placed on the top 11. The X-ray detector 22 has an arc shape in the rotation direction (channel direction) and converts a plurality of X-rays arranged in a lattice shape in the channel direction and the direction of the rotation axis of the rotation frame 26 (slice direction) into fluorescence. It has an X-ray detection element and a photoelectric conversion element that converts fluorescence into an electrical signal. Then, the X-ray transmitted through the subject P is detected while rotating around the subject P and converted into an electric signal, and the converted signal is output to the data collection unit 23 every time the view angle of the rotating frame 26 is rotated.

  The data collection unit 23 includes an electronic circuit board having an amplifier circuit, an analog / digital conversion circuit, and the like, and is arranged on the outer periphery of the X-ray detector 22. The projection data of one view is collected by amplification of the signal obtained from the X-ray detector 22 and conversion from the analog format to the digital format for each rotation of the rotation angle of the rotation frame 26, for example, 1 °. Data is output to the data transmission unit 24.

  The data transmission part 24 has a pair of transmission / reception part which transmits / receives, for example by an optical communication means. Then, the projection data collected by the data collection unit 23 is output to the scan information storage unit 80. Further, the control signal from the scan control unit 30 is output to each unit held by the rotating frame 26.

  The rotating frame 26 holds the X-ray tube 21, the X-ray detector 22, the data collection unit 23, the data transmission unit 24, and the high voltage generation unit 25, and drives the held units in the R1 direction by driving the rotation driving unit 27. Rotate.

  The scan control unit 30 controls the bed unit 10 and the gantry unit 20 on the basis of the plan stored in the plan storage unit 70, and the X while the rotating frame 26 is rotating at an angle larger than the view angle, for example, X. Each scan for collecting a predetermined number of projection data capable of generating image data by irradiation is sequentially executed. Further, information on each scan executed based on the plan stored in the plan storage unit 70 is stored in the scan information storage unit 80.

  In addition, when the scan is stopped due to a system failure such as a power failure in the middle of each scan executed based on the plan stored in the plan storage unit 70, the plan stored in the plan storage unit 70 and the scan information until the scan is stopped Based on the scan information stored in the storage unit 80, the scan is restarted by starting X-ray irradiation from a position including the stop position of the rotating frame 26 and the top plate 11 when the scan is stopped.

  In the “S & V” mode, two-dimensional image data is generated by X-ray irradiation while the rotating frame 26 of the gantry 20 is rotated once with the top 11 of the bed 10 stopped. An S & V scan for collecting a plurality of projection data to be enabled is executed.

  In the “Helical” mode, the top plate 11 of the bed 10 is moved in the longitudinal direction while the rotating frame 26 is rotating, and a plurality of X-rays are irradiated while the top plate 11 is moving. Helical scanning is performed to collect a plurality of projection data that enables generation of two-dimensional image data or three-dimensional image data.

  Further, in the “RealPrep” mode, the subject is irradiated by X-ray irradiation while the rotating frame 26 is rotating with the top 11 on which the subject P to which the contrast medium is administered is stopped. A RealPrep scan for collecting a plurality of projection data for generating a plurality of two-dimensional image data showing a change in contrast agent concentration in the region of interest of P in time series is executed. In this mode, when the CT value of the region of interest of the image data generated by collecting the projection data reaches the threshold within a preset maximum time, or when the maximum time elapses before the CT value reaches the threshold. End the scan.

  Further, in the “Volume” mode, a plurality of projection data that enables generation of three-dimensional image data is obtained by X-ray irradiation while the rotating frame 26 makes one rotation while the top plate 11 is stopped. Execute the volume scan to be collected.

  The image processing unit 40 reconstructs a plurality of projection data stored in the scan information storage unit 80 to generate two-dimensional or three-dimensional image data. Then, the generated image data is output to the display unit 50.

  The operation unit 60 includes input devices such as a keyboard, a trackball, a joystick, a mouse, a scan start button, and a scan restart button. Then, a scan condition for setting a plan, a scan start for starting a scan, and a start time for starting the next scan are input in response to the scan start input. In addition, input of a pause time that delays the start time of the scan according to the input of the scan start, input of the maximum time for irradiating X-rays according to the input of the scan start, and stop halfway due to the system down after the input of the scan start The input of scan resumption for restarting the performed scan is performed.

  The plan storage unit 70 collects a plurality of projection data set by inputting scanning conditions from the operation unit 60 and capable of generating a plurality of projection data capable of generating image data by X-ray irradiation while the rotating frame 26 of the gantry unit 20 is rotating. Save the plan to execute sequentially.

  The scan information storage unit 80 is obtained from the scan execution information storage unit 81 for storing scan execution information obtained by each scan executed based on the plan stored in the plan storage unit 70, and obtained from the gantry unit 20 by each scan. And a data storage unit 82 for storing projection data.

  The scan execution information storage unit 81 includes a nonvolatile memory such as a flash memory, and is a start input time that is a time when an input for starting a scan is performed from the operation unit 60, and a time when each scan is started. The scan start time and the scan end time, which is the time when each scan ends, are stored. In addition, a skip time that is a time when a scan skip is input to stop the scan in the middle of each scan from the operation unit 60, and a position or top plate indicated by an angle of the rotating frame 26 immediately before the system goes down. 11 position information is saved. In addition, a down time that is a time immediately before the system is down and a restart input time that is a time when an input for resuming scanning is performed from the operation unit 60 are stored.

  The data storage unit 82 includes a large-capacity magnetic disk or optical disk, and scans a plurality of projection data collected by each scan when a view ID and projection data that can identify the projection data in time series are collected. Save it in association with the scan ID to be identified.

  As described above, the collected projection data is stored in the data storage unit 82 in association with the scan ID and the view ID, so that when the system is stopped during the scan due to the system down, the projection data collected until the scan is stopped. And the scan ID and view ID related to the latest projection data of the collected projection data can be retrieved. Thereby, the positions of the top plate 11 and the rotating frame 26 of the gantry 20 when the system stops due to the system down can be calculated.

  The system control unit 90 includes a CPU, and controls the scan control unit 30, the image processing unit 40, the display unit 50, the plan storage unit 70, and the scan information storage unit 80 based on input information input by an operation from the operation unit 60. Control the entire system. Then, the scan is executed. Further, the image processing unit 40 generates and displays image data.

Hereinafter, an example of the operation of the X-ray CT apparatus 100 will be described with reference to FIGS. 1 to 7.
After the plan setting screen is displayed on the display unit 50 by an operation from the operation unit 60, for example, when an input for setting a plan for executing 5 scans is performed in order to inspect the subject P, the system control unit 90. Saves the plan set and input from the operation unit 60 in the plan storage unit 70 and causes the display unit 50 to display a plan setting screen in which five scan plans are set.

FIG. 2 is a diagram showing an example of the plan setting screen displayed on the display unit 50.
The plan setting screen 51 includes “No.”, “Start”, “Start time”, “Pause time”, “Start position”, “End position”, “Mode”, and “Scan number” arranged in the horizontal direction. , “Speed (Total seconds)”, “Slice thickness (mm)”, “kV”, “mA” and the like, and “No.” column corresponding to five scans arranged in the vertical direction. 1, “2”, “3”, “4”, and “5” columns.

  Then, by inputting each scan condition from the operation unit 60, the first scan condition is displayed in each column arranged in the horizontal direction in the “1” column of “No.”, and in the “2” column. The second scan condition is displayed in each column in the horizontal direction. Further, in the column “3”, the third scan condition is displayed in each column in the horizontal direction, and in the column “4”, the fourth scan condition is displayed in each column in the horizontal direction. In the column “5”, the fifth scan condition is displayed in each column in the horizontal direction.

  The “start” column of “1” indicates that the first scan, which is the first scan, is started when a scan start input is performed by pressing the start button from the operation unit 60. “P” is displayed. In addition, since “P” is displayed in the “Start” column, “***” is displayed in the “Start Time” column indicating that setting is not necessary, and the “Pause Time” column is scanned. “0.0” is displayed indicating that the pause time in which the start time of the first scan is delayed according to the start input is 0 second.

  In the “start position” and “end position” fields of “1”, “200.0” indicating the position in the longitudinal direction of the top 11 at the start and end of the scan is displayed, and “mode” is displayed. In the column, “S & V” indicating the S & V scan is displayed. Further, “1” indicating that the number of scans is 1 is displayed in the “scan number” column.

  In the “speed (total seconds)” column of “1”, the rotation speed of the rotating frame 26 is 1 rotation / 0.5 second, and the X-ray irradiation time during the rotation of the rotating frame 26 is 0.5 second. “0.5 (0.5)” indicating that there is a message is displayed. Further, in the column of “imaging slice thickness (mm)”, X-ray detection is performed using 1.0-mm X-ray detection elements arranged in four rows in the slice direction of the X-ray detector 22. “1.0 (4.0)” is displayed.

  Therefore, in the first scan, X-ray irradiation is performed using the initial position of the rotating frame 26 and the position “200.0” of the top plate 11 as the first scan start position according to the input of the scan start from the operation unit 60. Then, X-ray irradiation is performed for 0.5 seconds while the rotating frame 26 makes one rotation from the initial position with the top plate 11 stopped. Then, the S & V scan is executed with the position of the rotating frame 26 rotated once from the start of X-ray irradiation and the position of “200.0” of the top plate 11 as the first scan end position, so that the first number of projections is obtained. Collect data.

  In the “start” column of “2”, “P” indicating that the second scan, which is the second scan, is started when a scan start input is made after the end of the first scan is displayed. Has been. In the “start time” column, “***” indicating that setting is not necessary is displayed. In the “pause time” column, “0.0” indicating that the pause time in which the start time of the second scan is delayed in response to the input of the scan start is 0 second is displayed. .

  Also, “0.0” indicating the longitudinal position of the top plate 11 at the start of scanning is displayed in the “start position” column of “2”, and the top at the end of scanning is displayed in the “end position” column. “200.0” indicating the position in the longitudinal direction of the plate 11 is displayed. In addition, “Helical” indicating that the helicopter scan is displayed in the “Mode” column, and “1” indicating that the number of scans is 1 is displayed in the “Scan Number” column.

  In the “speed (Total seconds)” column of “2”, the rotation speed of the rotating frame 26 is 1 rotation / 0.5 seconds, and the X-ray tube 21 emits X-rays while the rotating frame 26 rotates. “0.5 (5.9)” indicating that the irradiation time is 5.9 seconds is displayed. Further, in the column “Slice Thickness (mm)”, X-ray detection is performed using X-ray detection elements of 0.5 mm size arranged in 64 rows in the slice direction of the X-ray detector 22. “0.5 (32.0)” is displayed.

  Accordingly, in the second scan, X-ray irradiation is started in accordance with the input of the scan start, with the initial position of the rotating frame 26 and the position “0.0” of the top plate 11 as the second scan start position. X-ray irradiation is performed for 5.9 seconds while the frame 26 rotates 11.8 from the initial position, and the top plate 11 is moved from “0.0” to “200.0”. Then, by executing a helical scan to end X-ray irradiation with the position of the rotating frame 26 rotated 11.8 and the position of “200.0” of the top plate 11 as the second scan end position, the second number is obtained. Collect projection data.

  In the “start” column of “3”, “P” indicating that the third scan, which is the third scan, is started when a scan start input is made after the end of the second scan is displayed. Has been. Also, “***” indicating that setting is not necessary is displayed in the “start time” column, and the start time of the third scan is displayed in the “pause time” column in accordance with the input of the scan start. “0.0” indicating that the pause time to be delayed is 0 second is displayed.

  In the “start position” and “end position” fields of “3”, “204.0” indicating the longitudinal position of the top plate 11 at the start of scanning and at the end of scanning is displayed. In the column, “RealPrep” indicating that the RealPrep scan is performed is displayed. In addition, since “RealPrep” is displayed in the “mode” column, “***” indicating that setting is not necessary is displayed in the “number of scans” column.

  In the “Speed (Total seconds)” column of “3”, the rotation speed of the rotating frame 26 is 1 rotation / 0.5 second, and X-rays during rotation of the rotating frame 26 according to the input of scanning start are shown. “0.5 (52)” indicating that the maximum irradiation time is 52 seconds is displayed. Further, in the column of “imaging slice thickness (mm)”, X-ray detection is performed using 1.0-mm X-ray detection elements arranged in four rows in the slice direction of the X-ray detector 22. “1.0 (4.0)” is displayed.

  Therefore, in the third scan, X-ray irradiation is performed with the initial position of the rotating frame 26 and the position “204.0” of the top plate 11 as the third scan start position in response to the input of the scan start from the operation unit 60. Start and generate image data while collecting projection data by X-ray irradiation while the rotating frame 26 is rotating with the top 11 on which the subject P on which the contrast medium is administered is stopped To do. Then, when the CT value of the region of interest of the generated image data reaches a preset threshold value within 52 seconds from the input of the scan start, the X-ray irradiation is terminated with the third scan end position, and the CT value is the threshold value. The RealPrep scan for ending X-ray irradiation is executed with the time when 52 seconds elapse before reaching the third point as the third scan end position. Thus, when X-ray irradiation is terminated when the threshold value is reached, a smaller number of projection data than the third number is collected, and when X-ray irradiation is terminated after 52 seconds, the third number. Collect the number of projection data.

  In the “start” column of “4”, the fourth scan, which is the fourth scan, is started after the end of the third scan in response to the input of the scan start for starting the third scan. “A” is displayed. In the “start time” column, “01: 00.0” indicating that the fourth scan starts one minute later is displayed in response to a scan start input for starting the third scan. . In addition, since “A” is displayed in the “start” column, “***” indicating that setting is not necessary is displayed in the “pause time” column.

  Also, in the “start position” and “end position” columns of “4”, “204.0” indicating the position in the longitudinal direction of the top 11 and one end and the other end of the imaging range in the slice direction of the subject P “204.0” and “364.0” are displayed. In the “Mode” column, “Volume” indicating volume scanning is displayed, and in the “Scan Number” column, “1” indicating that the number of scans is one is displayed.

  In the “speed (total seconds)” column of “4”, the rotation speed of the rotating frame 26 is 1 rotation / 0.5 seconds, and the X-ray irradiation time during the rotation of the rotating frame 26 is 0.5 seconds. “0.5 (0.5)” is displayed. In addition, the column “Slice Thickness (mm)” indicates that X-rays are detected using X-ray detector elements of 0.5 mm size arranged in 320 rows in the slice direction of the X-ray detector 22. .5 (160.0) "is displayed.

  Therefore, in the fourth scan, the initial angle of the rotating frame 26 and the position of “204.0” of the top plate 11 from the time when one minute has elapsed from the input of the scan start for starting the third scan from the operation unit 60. X-ray irradiation is started with the fourth scan start position. Then, with the top plate 11 stopped at the position “204.0”, X-ray irradiation is performed for 0.5 seconds during which the rotating frame 26 rotates once, and the rotating frame 26 rotated once from the start of X-ray irradiation. The fourth number of projection data capable of generating image data is obtained by executing a volume scan that ends X-ray irradiation with the position and the position of “204.0” on the top plate 11 as a fourth scan end position. collect.

  Note that, as in the case of a contrast examination, when the contrast agent concentration of the affected part such as a blood vessel after administration of the contrast agent to the subject P changes over time, the third method is necessary when obtaining image data at an accurate timing. The fourth scan is started after the start time has elapsed from the start of the scan.

  In the “start” column of “5”, “P” indicating that the fifth scan, which is the fifth scan, is started when the scan start is input after the fourth scan is completed is displayed. ing. In addition, “***” indicating that setting is not necessary is displayed in the “start time” column, and the start time of the fifth scan is displayed in the “pause time” column according to the input of the scan start. “0.0” indicating that the pause time to be delayed is 0 second is displayed.

  In the “start position” and “end position” columns of “5”, “204.0” indicating the position of the top plate 11 in the longitudinal direction at the start of scanning and one end and the other end of the imaging range in the slice direction are displayed. “204.0” and “524.0” are displayed. In the “Mode” column, “Volume” indicating volume scanning is displayed, and in the “Scan Number” column, “2” indicating that the number of scans is two is displayed.

  In the “speed (total seconds)” column of “5”, the rotation speed of the rotating frame 26 is 1 rotation / 0.5 second, and the total time of X-ray irradiation during the rotation of the rotating frame 26 is 1. “0.5 (1.0)” indicating zero seconds is displayed. In addition, the column “Slice Thickness (mm)” indicates that X-rays are detected using X-ray detector elements of 0.5 mm size arranged in 320 rows in the slice direction of the X-ray detector 22. .5 (160.0) "is displayed.

  Therefore, in the fifth scan, the initial position of the rotating frame 26 and the position “204.0” of the top plate 11 are set to the first scan start position in accordance with the input of the scan start for starting the scan from the operation unit 60. The first X-ray irradiation is started. Then, with the top plate 11 stopped at the position “204.0”, the rotary frame 26 is rotated for one X-ray irradiation for 0.5 seconds, and the position of the rotary frame 26 rotated once from the start of the X-ray irradiation. And a fourth volume scan capable of generating image data by executing the first volume scan for ending the first X-ray irradiation with the position of “204.0” on the top plate 11 as the first scan end position. Collect a number of projection data.

  After the first volume scan is completed, the top plate 11 is moved in the longitudinal direction and stopped at the position “364.0”, and then the initial position of the rotary frame 26 and the position “364.0” of the top plate 11 are detected. As a second scan start position, the second X-ray irradiation is started. Then, X-ray irradiation is performed for 0.5 second while the rotating frame 26 is rotated once with the top plate 11 stopped, and the position of the rotating frame 26 rotated once from the start of the X-ray irradiation and “364. By executing the second volume scan for ending the second X-ray irradiation with the position of “0” as the second scan end position, a fourth number of projection data capable of generating image data is collected. Thus, the fifth number of projection data, which is twice the fourth number, is collected by combining the first and second scans.

FIG. 3 is a flowchart showing the operation of the X-ray CT apparatus 100.
After the plan for examining the subject P is set, the subject P is placed on the top plate 11. Then, when the top 11 is moved to the position of “0.0” displayed on the plan setting screen 51 of FIG. 2 by the operation from the operation unit 60, and the scan start input is performed, the X-ray CT apparatus 100 starts the operation. Then, after the system goes down in the middle of scanning, when the system is restarted and scanning restart is input from the operation unit 60, the X-ray CT apparatus 100 starts operation (step S1).

  The system control unit 90 controls the scan control unit 30, the image processing unit 40, the display unit 50, the plan storage unit 70, and the scan information storage unit 80 to instruct resumption of scanning. The scan control unit 30 searches projection data related to the nth (n = 1) scan based on the plan stored in the plan storage unit 70 (step S2).

  If projection data related to the nth scan is not stored in the data storage unit 82 (No in step S3), the nth scan is executed from the nth scan start position (step S4). Then, after the nth scan is completed, the process proceeds to step S9. If projection data related to the nth scan is stored in the data storage unit 82 (Yes in step S3), the process proceeds to step S5.

  After the “Yes” in step S3, if projection data smaller than the n-th number is stored in the data storage unit 82 (No in step S5), the system stopped and stopped during the n-th scan. And the process proceeds to step S6. If the nth number of projection data is stored in the data storage unit 82 (Yes in step S5), it is determined that the nth scan is completed, and the process proceeds to step S9.

  If the number of projection data collected by the nth scan is smaller than the nth number, it is searched whether or not the skip time information is stored in the scan execution information storage unit 81. When the skip time information when the scan skip is input from the operation unit 60 during the n-th scan is stored in the scan execution information storage unit 81, the n-th scan is finished. Judge.

  After “No” in step S5, the scan control unit 30 determines whether or not to restart the n-th scan based on the plan stored in the plan storage unit 70 and the scan information stored in the scan information storage unit 80. judge. When the n-th scan is resumed (Yes in step S6), the positions of the rotary frame 26 and the top plate 11 at which the X-ray irradiation is resumed are determined, and the X-ray irradiation is started from the determined position. The scan of n is resumed (step S7). Then, the n-th scan for ending the X-ray irradiation at the n-th scan end position is executed, and after the n-th scan ends, the process proceeds to step S9.

  If the nth scan is to be canceled (No in step S6), the nth scan stop information is displayed and output on the display unit 50 (step S8). Thereafter, the process proceeds to step S9.

  If n is an integer less than 5 when the n-th scan is terminated or stopped (No in step S9), 1 is added to n, and the process returns to step S2. If n is 5 (Yes in step S9), the process proceeds to step 10.

  After “Yes” in step S9, the system control unit 90 instructs the end of the scan by the end of the fifth scan, and the scan control unit 30 stops the top plate 11 and the rotating frame 26 at the home position. The X-ray CT apparatus 100 ends the operation (step S10).

Next, details of the operations in steps S6 to S8 in FIG. 3 will be described.
FIG. 4 is a flowchart showing details of the operation in steps S6 to S8 of FIG. Step S6 includes steps S21 to S33.

  If “n” is 1 after “No” in Step S5 shown in FIG. 3 (Yes in Step S21), the scan control unit 30 proceeds to Step S22. If n is a positive integer other than 1 (No in step S21), the process proceeds to step S23.

  In the first scan when n is 1, no start and pause times are set. Further, this is an S & V scan mode, and the number of scans is one. Accordingly, it is determined that the rotation of the rotating frame 26 is less than 1.0 rotation from the start of the X-ray irradiation, and it is impossible to generate image data. Then, the position of the rotary frame 26 and the top plate 11 for resuming X-ray irradiation is determined as the first scan start position (step S22).

  If n is 2 after “No” in Step S21 (Yes in Step S23), the process proceeds to Step S24. If n is a positive integer other than 2 (NO in step S23), the process proceeds to step S27.

  In the second scan where n is 2, no start and pause times are set. Further, this is a helical scan mode, and the number of scans is one. Therefore, the number of projection data stored in the data storage unit 82 by the helical scan before stopping in the middle of the helical scan is collected while the number of preset margins (for example, while the rotating frame 26 is rotating twice). (Yes in step S24), the position of the rotating frame 26 and the top plate 11 for resuming the X-ray irradiation is updated to the latest projection of the projection data stored in the data storage unit 82 by the helical scan. The number of glue margins counted from the data is determined as the position of the rotating frame 26 and the top plate 11 (the position in the middle of scanning) when projection data retroactive is collected (step S25).

  When the number of projection data stored in the data storage unit 82 by helical scanning is less than the past allowance (No in step S24), the pre-restart paste is added to the projection data collected until the X-ray irradiation is stopped. Since the substitution area cannot be provided, the position of the rotary frame 26 and the top plate 11 at which X-ray irradiation is resumed is determined as the second scan start position (step S26).

  Note that the projection data from the latest projection data stored in the data storage unit 82 until the helical scan is stopped to the projection data retroactive to the past of the number of pastes counted from this projection data is used as the projection data of the paste margin area before restarting, The helical scan is resumed from the middle position of the scan, and the projection data of the number of first margins collected by scanning the same position of the rotation frame 26 and the top plate 11 as that of the margin area before restarting is the projection data of the margin area after the restart. To do. Then, the image processing unit 40 performs data processing for providing continuity to the projection data of the pre-restart paste margin area and the post-restart paste margin area.

  As described above, when stopped in the middle of the helical scan, the helical scan is restarted from the second scan start position when the number of projection data stored in the data storage unit 82 by the helical scan is less than the number of glue margins. As a result, it is not necessary to execute a scan before the helical scan, so that the exposure dose of the subject P can be reduced. Further, when the number of projection data stored in the data storage unit 82 by the helical scan is equal to or greater than the number of margins, the helical scan is resumed from the mid-scan position to the mid-scan position from the second scan start position. Therefore, the exposure dose of the subject P can be reduced.

  If n is 3 after “No” in Step S23 (Yes in Step S27), the process proceeds to Step S28. If n is a positive integer other than 3 (No in step S27), the process proceeds to step S30.

  In the third scan when n is 3, no start and pause times are set. Also, the RealPrep scan mode. Accordingly, when an input for resuming scanning is performed from the operation unit 60 when the operation stops in the middle of the third scan, the scan control unit 30 performs input for resuming the scan stored in the scan execution information storage unit 81. Whether or not the third scan can be restarted is determined based on the scan execution information including the restart input time at that time.

  Then, as shown in FIG. 5, the restart input time is the start input time T30 when the scan start input operation IN30 for starting the third scan before the system goes down is performed from the operation unit 60. Included in the maximum time zone TW31 from the input time T30 to the scheduled end time T31 after 52 seconds, which is the maximum time displayed in the “speed (Total seconds)” column of “3” on the plan setting screen 51 If yes (Yes in step S28), the position of the rotating frame 26 and the top plate 11 at which X-ray irradiation is resumed is determined as the third scan start position (step S29).

  When the third scan start position is determined, when the CT value of the region of interest in the image data generated from the projection data collected by the third scan before the scheduled end time T31 reaches the threshold value, Alternatively, the third scan is ended when the scheduled end time T31 comes before the CT value reaches the threshold value.

  If the restart input time is after the scheduled end time T31 (No in step S28), the restart of the third scan is stopped and the third scan stop information is displayed and output on the display unit 50 (FIG. 3 step S8).

  As described above, in the third scan in which the maximum time for limiting the X-ray irradiation is set, when the restart input time is included in the time zone TW31, the X-ray irradiation is started from the third scan start position. By resuming the third scan, it is not necessary to execute the first and second scans, so that the exposure dose of the subject P can be reduced. Further, when the restart input time is after the scheduled end time T31, the third scan that is unnecessary because it is past the scheduled end time T31 where the third scan needs to be terminated is stopped. The exposure dose of the specimen P can be reduced.

  If n is 4 after “No” in Step S27 (Yes in Step S30), the process proceeds to Step S31. If n is a positive integer other than 4 (No in step S30), the process proceeds to step S33.

  In the fourth scan when n is 4, the start time is set. Accordingly, when an input for restarting scanning is performed from the operation unit 60 when the operation stops in the middle of the fourth scan, the scan control unit 30 has, for example, a constant rotation speed of the rotating frame 26 to restart the fourth scan. The margin time that allows the scan to be restarted is calculated, such as the time required until the top plate 11 is moved to the restart position. Next, the estimated restart time when the margin time has elapsed from the restart input time when the scan restart input is performed is calculated. Then, it is determined whether the fourth scan can be restarted based on the predicted restart time.

  Then, as shown in FIG. 5, the estimated restart time is the time when 1 minute has elapsed from the scheduled end time T31 and the start input time T30 displayed in the “start time” column of “4” on the plan setting screen 51. If it is included in the pause time period TW32 with T32 (Yes in step S31), the position of the rotating frame 26 and the top plate 11 for resuming X-ray irradiation is determined as the fourth scan start position (step S32). ).

  Further, as shown in FIG. 5, when the estimated restart time is included in the time zone TW33 after the time T32 (No in step S31), the time T32 at which the fourth scan needs to be started has passed. Therefore, the restart of the fourth scan is stopped and the fourth scan stop information is displayed on the display unit 50 (step S8 in FIG. 2).

  As described above, in the fourth scan in which the scan needs to be started in response to the scan start input for starting the third scan, when the restart input time is included in the pause time period TW32, the second scan is started at the time T32. By executing the fourth scan from the fourth scan start position, it is not necessary to execute the first to third scans, so that the exposure dose of the subject P can be reduced. In addition, when the restart input time is included in the time zone TW33, the time T32 at which the fourth scan needs to be started has passed. The exposure dose can be reduced.

  After “No” in step S30, the start and pause times are not set in the fifth scan when n is 5. This is a volume scan mode, and the number of scans is two. Accordingly, the stop position of the fifth scan is calculated based on the scan ID and the view ID related to the latest projection data stored in the data storage unit 82 by the fifth scan. When the calculated stop position is a position in the middle of the first scan, the first scan start position is determined, and the position before the second scan is started after the first scan is completed. If the position is in the middle of the second scan, the second scan start position is determined (step S33).

  In this way, when the first scan of the volume scan is stopped in the middle of the first scan, the first to fourth scans for starting the X-ray irradiation from the first scan start position are restarted, whereby the first to fourth scans are performed. Since it is not necessary to execute, the exposure dose of the subject P can be reduced. In addition, when the second scan after the first scan is finished or before stopping the second scan, the second volume scan is restarted from the second scan start position. As a result, it is not necessary to execute the first volume scan, so that the exposure dose of the subject P can be reduced.

Next, an example in which a pause time is set in the “pause time” field of the plan setting screen 51 will be described.
FIG. 6 is a diagram showing a plan setting screen 51a in which a pause time is set for the fifth scan. The plan setting screen 51a is different from the plan setting screen 51 in FIG. 2 in that “15.0” is displayed in the “pause time” column of “5”. Differences from the operation of step S4 shown in FIG. 3 when scanning is performed based on the plan setting screen 51a and stopped in the middle of the fifth scan will be described below.

  When a scan resumption input is made from the operation unit 60 when the operation is stopped in the middle of the fifth scan, the scan control unit 30 until the rotation speed of the rotating frame 26 becomes constant in order to resume the fifth scan, for example. And the estimated restart time when the margin time has elapsed from the restart input time when the scan restart input is performed after calculating the margin time during which the scan can be restarted, such as the time to move the tabletop 11 to the restart position. Calculate Then, based on the estimated restart time and the scan execution information stored in the scan execution information storage unit 81, it is determined whether or not the fifth scan can be restarted.

  Then, as shown in FIG. 7, the estimated restart time is a pause time from the start input time T50 and the start input time T50 when the scan start input operation IN50 for starting the fifth scan is performed before the system goes down. If it is included in the time zone TW51 between the scheduled start time T51 that is the time when 15 seconds have passed, the fifth scan that starts X-ray irradiation from the first scan start position is resumed at the scheduled start time T51 Let

  Further, when it is the time zone TW52 after the scheduled start time T51, the restart of the fifth scan is stopped. Next, in order to ask the operator to determine whether or not to execute the fifth scan, the “execution” and “cancel” buttons are displayed on the display unit 50, and “execution” is executed by the operation from the operation unit 60. When the selection input is made, the fifth scan is resumed from the stopped state, and when the “stop” is selected and inputted, the fifth scan is ended.

  As described above, in a scan that needs to be started after a pause time in accordance with an input for starting the scan, when the restart input time is included in the time zone TW51, the X-ray irradiation starts from the first scan start position. By restarting the fifth scan, it is not necessary to execute the first to fourth scans, so that the exposure dose of the subject P can be reduced. Further, when the restart input time is included in the time zone TW52, the exposure amount of the subject P can be reduced by temporarily stopping the restart of the fifth scan that may be unnecessary.

  According to the embodiment described above, the plan for executing the first to fifth scans is stored in the plan storage unit 70, and each of the first to fifth executions executed based on the plan stored in the plan storage unit 70 is performed. By saving the scan information obtained by the scan in the scan information storage unit 80 and stopping in the middle of each of the first to fifth scans, the plan stored in the plan storage unit 70 and each of the first to fifth scans Based on the scan information stored in the scan information storage unit 80 until the first scan is stopped, X is determined from the position including the stop position of the rotating frame 26 and the top plate 11 when the first to fifth scans are stopped. By stopping the irradiation, the stopped scan can be resumed.

  When the projection is stopped in the middle of the second scan, when the number of projection data stored in the data storage unit 82 by the second scan is less than the number of glue margins, X-ray irradiation is performed from the second scan start position. By resuming the second scan that starts, it is not necessary to execute the first scan, so that the exposure dose of the subject P can be reduced. In addition, when the number of projection data stored in the data storage unit 82 by the second scan is equal to or greater than the number of margins, the second scan that starts X-ray irradiation from the middle position of the scan is resumed. Since it is not necessary to perform X-ray irradiation from the second scan start position to the middle position, the exposure dose of the subject P can be reduced.

  In the third scan in which the maximum time for limiting the X-ray irradiation is set, when the restart input time is included in the maximum time zone TW31 between the start input time T30 and the scheduled end time T31, By restarting the third scan that starts X-ray irradiation from the scan start position, it is not necessary to execute the first and second scans, so that the exposure dose of the subject P can be reduced. In addition, when the restart input time is included in the pause time period TW32 between the scheduled end time T31 and the time T32, it is unnecessary because the scheduled end time T31 that needs to end the third scan has passed. The amount of exposure of the subject P can be reduced by stopping the third scan.

  Further, in the fourth scan in which it is necessary to start the scan after the start time set as the scan condition in accordance with the scan start input for starting the third scan, the resume input time is included in the pause time zone TW32. If it is, it is not necessary to execute the first to third scans by executing the fourth scan from the fourth scan start position at time T32, so that the exposure dose of the subject P can be reduced. .

  When the first volume scan of the fifth scan is stopped, the first to fourth scans need not be executed by resuming the first volume scan from the first scan start position. Therefore, the exposure dose of the subject P can be reduced. In addition, when the second volume scan is started after the first volume scan is completed, or when the second volume scan is stopped in the middle of the second volume scan, the second volume scan from the second scan start position. Since the first volume scan does not need to be executed by restarting, the exposure amount of the subject P can be reduced.

  Also, in a scan that needs to start a scan after a pause time in response to a scan start input for which a pause time is set for the fifth scan, if the restart input time is before the scheduled start time T51, the first scan By restarting the fifth scan from the start position, it is not necessary to execute the first to fourth scans, so that the exposure dose of the subject P can be reduced. Further, when the restart input time is after the scheduled start time T51, the exposure dose of the subject P can be reduced by stopping the restart of the fifth scan that may be unnecessary.

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 novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.
The inventions according to claims 2 to 5 described in the scope of claims of the present application will be appended below.
[2] A rotating frame that rotatably supports an X-ray tube that generates X-rays and an X-ray detector that detects X-rays transmitted through a subject placed on the top plate;
A plan storage unit for storing a plan for sequentially executing a plurality of scans for collecting a plurality of projection data as the rotation frame rotates;
A scan information storage unit that stores scan information including the plurality of projection data, and
The plurality of scans includes a first scan for collecting a plurality of projection data capable of generating image data in a state where the top is stopped, and generation of image data after the first scan is completed. A second scan that collects a plurality of projection data that can be obtained, and based on the projection data stored in the scan information storage unit by the first scan and the second scan, When the stop position of the rotating frame in the first scan is calculated, and the stop position is in the middle of the first scan, the position of the rotating frame related to the first scan to be resumed is determined as the first scan. The first scan is restarted from the start position, and the stop position is the end of the first scan. A scan control unit for restarting the second scan from the start position of the second scan when the second scan is completed and before the start of the second scan or in the middle of the second scan An X-ray CT apparatus provided.
[3] A rotating frame that rotatably supports an X-ray tube that generates X-rays and an X-ray detector that detects X-rays transmitted through a subject placed on the top plate;
A plan storage unit for storing a plan for sequentially executing a plurality of scans for collecting a plurality of projection data as the rotation frame rotates;
A scan information storage unit for storing scan information including the plurality of projection data;
An operation unit that inputs a start of a specific scan among the plurality of scans, a restart of the specific scan after the start of the specific scan, and an X-ray irradiation time in the specific scan;
When the restart input time when the restart of the specific scan is input is included between the scheduled input time after the X-ray irradiation time has elapsed from the start input time when the start of the specific scan is input and the start input time, Resuming the specific scan from the start position of the specific scan, and when the restart input time is after the scheduled end time, a scan control unit for stopping the specific scan;
An X-ray CT apparatus comprising:
[4] A rotating frame that rotatably supports an X-ray tube that generates X-rays and an X-ray detector that detects X-rays transmitted through a subject placed on the top plate;
A plan storage unit for storing a plan for sequentially executing a plurality of scans for collecting a plurality of projection data as the rotation frame rotates;
A scan information storage unit for storing scan information including the plurality of projection data;
An operation unit for inputting a start input time of a specific scan among the plurality of scans, a restart input time of the specific scan, and a pause time for delaying the start of the specific scan;
When the restart input time is input, a margin time at which the specific scan can be restarted is calculated, an estimated restart time that has passed the margin time from the restart input time is calculated, and the predicted restart time is When included between the start input time and the scheduled start time that has passed the pause time from the start input time, the specific scan is resumed at the scheduled start time, and the predicted restart time is the scheduled start time. If later, a scan control unit that stops resumption of the specific scan; and
An X-ray CT apparatus comprising:
[5] A rotating frame that rotatably supports an X-ray tube that generates X-rays and an X-ray detector that detects X-rays transmitted through the subject placed on the top plate;
A plan storage unit for storing a plan for sequentially executing a plurality of scans for collecting a plurality of projection data as the rotation frame rotates;
A scan information storage unit that stores scan information including the plurality of projection data, and the plurality of scans include a specific scan and a post-scan after execution of the specific scan,
An operation unit for inputting a start input time of the specific scan, a start input time of the post scan, and a period between the start input time of the specific scan and the scheduled start time of the post scan,
When the start input time of the post scan is included between the start input time of the specific scan and the scheduled start time, the post scan is resumed at the scheduled start time, and the start input time of the post scan is If it is after the scheduled start time, a scan control unit for stopping the restart of the post scan,
An X-ray CT apparatus further comprising:

P Subject 11 Top plate 20 Base unit 21 X-ray tube 22 X-ray detector 23 Data collection unit 26 Rotating frame 30 Scan control unit 40 Image processing unit 50 Display unit 60 Operation unit 70 Plan storage unit 80 Scan information storage unit 81 Scan Execution information storage unit 82 Data storage unit 90 System control unit 100 X-ray CT apparatus

Claims (1)

A rotating frame that rotatably supports an X-ray tube that generates X-rays and an X-ray detector that detects X-rays transmitted through a subject placed on the top;
A plan storage unit for storing a plan for sequentially executing a plurality of scans for collecting a plurality of projection data as the rotation frame rotates;
A scan information storage unit that stores scan information including the plurality of projection data, and
At least one of the plurality of scans is a helical scan that collects the projection data by X-ray irradiation while the top plate is moving,
When the helical scan stops midway during the execution of the helical scan and the number of the projection data related to the helical scan stored in the scan information storage unit is equal to or greater than a preset number of glue margins, In the projection data related to the helical scan, the helical scan is restarted from the position of the rotating frame and the position of the top plate at the time of collecting projection data retroactively counted from the latest projection data by the number of glue margins, When the helical scan stops midway during execution of the helical scan, and the number of the projection data related to the helical scan stored in the scan information storage unit is less than the number of glue margins, The position of the rotating frame and the position of the top plate at the start time are set to the helical Determined as the restart position of the can, said resuming said helical scan from the resume position, further comprising a scan control unit, X-rays CT device.