JP6762774B2 - X-ray CT device - Google Patents

Description

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

Conventionally, in an examination using an X-ray CT apparatus (CT: Computed Tomography), there is a possibility that motion artifacts or the like may occur in a CT image obtained by the influence of the movement of an organ such as the heart or the respiratory movement of a subject. For this reason, in the X-ray CT apparatus, in order to eliminate the effects of pulsatile movement and respiratory movement of the organ, the electrocardiographic waveform and respiratory waveform of the subject measured in parallel with the collection of projection data. Electrocardiographic synchronous reconstruction and respiratory synchronous reconstruction are performed in which image data is collected and CT images are reconstructed based on the above.

Japanese Unexamined Patent Publication No. 2013-198747

An object to be solved by the present invention is to provide an X-ray CT apparatus capable of reducing radiation exposure in synchronous reconstruction.

The X-ray CT apparatus of the embodiment includes a pedestal, a sleeper, a control unit, and a reconstruction unit. The gantry has a rotating portion for rotating and moving the X-ray tube. The sleeper has a top plate on which the subject is placed. When the control unit performs a positioning scan while relatively moving the subject and the gantry placed on the top plate, the control unit moves the dynamics of the subject based on biological information related to the dynamics of the subject. Controls to perform a synchronous scan synchronized with. The reconstructing unit reconstructs the image data from the data collected by executing the main scan under the conditions determined based on the result of the synchronous scan.

FIG. 1 is a diagram showing an example of the configuration of the X-ray CT apparatus according to the first embodiment. FIG. 2 is a diagram for explaining an example of a general electrocardiographic synchronous scan. FIG. 3 is a diagram for explaining an example of a general respiratory synchronization scan. FIG. 4 is a flowchart showing a processing procedure by the X-ray CT apparatus according to the first embodiment. FIG. 5 is a flowchart showing a processing procedure of the target range start determination process by the control function according to the first embodiment. FIG. 6 is a diagram (1) for explaining the first embodiment. FIG. 7 is a flowchart showing a processing procedure of the target range end determination process by the control function according to the first embodiment. FIG. 8 is a diagram (2) for explaining the first embodiment. FIG. 9 is a diagram (3) for explaining the first embodiment. FIG. 10 is a diagram for explaining other embodiments.

Hereinafter, embodiments of an X-ray CT (Computed Tomography) apparatus will be described in detail with reference to the accompanying drawings.

(First Embodiment)
FIG. 1 is a diagram showing an example of the configuration of the X-ray CT apparatus 1 according to the first embodiment. As shown in FIG. 1, the X-ray CT apparatus 1 according to the first embodiment includes a pedestal 10, a sleeper apparatus, and a console 30. Further, the X-ray CT device 1 is connected to the electrocardiograph 40 and the respiration detection device 50 as shown in FIG.

The gantry 10 is a device that irradiates the subject P (patient) with X-rays, detects the X-rays transmitted through the subject P, and outputs the X-rays to the console 30. The X-ray irradiation control circuit 11 and the X-ray generator are generated. It has a device 12, a detector 13, a data acquisition circuit (DAS: Data Acquisition System) 14, a rotating frame 15, and a gantry drive circuit 16. Further, in the gantry 10, as shown in FIG. 1, an orthogonal coordinate system including an X-axis, a Y-axis, and a Z-axis is defined. That is, the X-axis indicates the horizontal direction, the Y-axis indicates the vertical direction, and the Z-axis indicates the rotation center axis direction of the rotating frame 15 when the gantry 10 is not tilted.

The rotating frame 15 supports the X-ray generator 12 and the detector 13 so as to face each other with the subject P in between, and rotates at high speed in a circular orbit centered on the subject P by a gantry drive circuit 16 described later. It is an annular frame.

The X-ray irradiation control circuit 11 is a device that supplies a high voltage to the X-ray tube 12a as a high voltage generating unit, and the X-ray tube 12a uses the high voltage supplied from the X-ray irradiation control circuit 11 to X. Generate a line. The X-ray irradiation control circuit 11 adjusts the X-ray dose to be irradiated to the subject P by adjusting the tube voltage and the tube current supplied to the X-ray tube 12a under the control of the scan control circuit 33 described later. ..

Further, the X-ray irradiation control circuit 11 switches the wedge 12b. Further, the X-ray irradiation control circuit 11 adjusts the X-ray irradiation range (fan angle and cone angle) by adjusting the opening degree of the collimator 12c. In this embodiment, the operator may manually switch between a plurality of types of wedges.

The X-ray generator 12 is a device that generates X-rays and irradiates the subject P with the generated X-rays, and has an X-ray tube 12a, a wedge 12b, and a collimator 12c.

The X-ray tube 12a is a vacuum tube that irradiates the subject P with an X-ray beam by a high voltage supplied by a high voltage generator (not shown), and the X-ray beam is sent to the subject P as the rotating frame 15 rotates. Irradiate against. The X-ray tube 12a generates an X-ray beam that spreads with a fan angle and a cone angle. For example, under the control of the X-ray irradiation control circuit 11, the X-ray tube 12a is continuously exposed to X-rays all around the subject P for full reconstruction, or half-reconstructable for half-reconstruction. It is possible to continuously expose X-rays within the range (180 degrees + fan angle). Further, by controlling the X-ray irradiation control circuit 11, the X-ray tube 12a can intermittently emit X-rays (pulse X-rays) at a preset position (tube position). The X-ray irradiation control circuit 11 can also modulate the intensity of X-rays exposed from the X-ray tube 12a. For example, the X-ray irradiation control circuit 11 increases the intensity of X-rays emitted from the X-ray tube 12a at a specific tube position, and exposes the X-ray tube 12a to a range other than the specific tube position. Decreases the intensity of the emitted X-rays.

The wedge 12b is an X-ray filter for adjusting the X-ray dose of X-rays exposed from the X-ray tube 12a. Specifically, the wedge 12b transmits the X-rays exposed from the X-ray tube 12a so that the X-rays radiated from the X-ray tube 12a to the subject P have a predetermined distribution. It is a filter that attenuates. For example, the wedge 12b is a filter made of aluminum so as to have a predetermined target angle and a predetermined thickness. The wedge is also called a wedge filter or a bow-tie filter.

The collimator 12c is a slit for narrowing down the X-ray irradiation range in which the X-ray dose is adjusted by the wedge 12b under the control of the X-ray irradiation control circuit 11 described later.

The gantry drive circuit 16 rotates the rotating frame 15 to rotate the X-ray generator 12 and the detector 13 on a circular orbit centered on the subject P.

The detector 13 is a two-dimensional array type detector (surface detector) that detects X-rays that have passed through the subject P, and the detection element sequence formed by arranging X-ray detection elements for a plurality of channels is the subject P. A plurality of rows are arranged along the body axis direction (Z-axis direction shown in FIG. 1). Specifically, the detector 13 in the first embodiment has X-ray detection elements arranged in multiple rows such as 320 rows along the body axis direction of the subject P, for example, the lungs of the subject P. It is possible to detect X-rays that have passed through the subject P over a wide range, such as in the range including the heart and the heart.

The data collection circuit 14 is a DAS and collects projection data from the X-ray detection data detected by the detector 13. For example, the data acquisition circuit 14 generates projection data by performing amplification processing, A / D conversion processing, sensitivity correction processing between channels, and the like on the X-ray intensity distribution data detected by the detector 13. The projected projection data is transmitted to the console 30 described later. For example, when X-rays are continuously exposed from the X-ray tube 12a during the rotation of the rotating frame 15, the data acquisition circuit 14 collects the projection data group for the entire circumference (360 degrees). Further, the data collection circuit 14 associates the tube position with each of the collected projection data and transmits the data to the console 30 described later. The tube position is information indicating the projection direction of the projection data. The sensitivity correction processing between channels may be performed by the preprocessing circuit 34, which will be described later.

The sleeper device is a device on which the subject P is placed, and has a sleeper drive device 21 and a top plate 22 as shown in FIG. The sleeper drive device 21 moves the top plate 22 in the Z-axis direction to move the subject P into the rotating frame 15. The top plate 22 is a plate on which the subject P is placed.

The gantry 10 executes, for example, a helical scan in which the rotating frame 15 is rotated while the top plate 22 is moved to spirally scan the subject P. Alternatively, the gantry 10 executes a conventional scan in which the rotating frame 15 is rotated while the position of the subject P is fixed after the top plate 22 is moved to scan the subject P in a circular orbit. Alternatively, the gantry 10 executes a step-and-shoot method in which the position of the top plate 22 is moved at regular intervals to perform a conventional scan in a plurality of scan areas.

The console 30 is a device that accepts the operation of the X-ray CT device 1 by the operator and reconstructs the X-ray CT image data using the projection data collected by the gantry 10. As shown in FIG. 1, the console 30 includes an input circuit 31, a display 32, a scan control circuit 33, a preprocessing circuit 34, a storage circuit 35, an image reconstruction circuit 36, and a processing circuit 37. ..

The input circuit 31 has a mouse, keyboard, trackball, switch, button, joystick, etc. used by the operator of the X-ray CT apparatus 1 to input various instructions and various settings, and information on the instructions and settings received from the operator. Is transferred to the processing circuit 37. For example, the input circuit 31 receives from the operator the imaging conditions for the X-ray CT image data, the reconstruction conditions for reconstructing the X-ray CT image data, the image processing conditions for the X-ray CT image data, and the like. Further, the input circuit 31 accepts an operation for selecting a test for the subject P. Further, the input circuit 31 accepts a designation operation for designating a portion on the image.

The display 32 is a monitor referred to by the operator, and under the control of the processing circuit 37, the display 32 displays the image data generated from the X-ray CT image data to the operator, or the operator via the input circuit 31. Displays a GUI (Graphical User Interface) for receiving various instructions and various settings from. In addition, the display 32 displays a plan screen for a scan plan, a screen during scanning, and the like. In addition, the display 32 displays a virtual patient image including exposure information, image data, and the like. The virtual patient image displayed by the display 32 will be described in detail later.

The scan control circuit 33 controls the operations of the X-ray irradiation control circuit 11, the gantry drive circuit 16, the data acquisition circuit 14, and the sleeper drive device 21 under the control of the processing circuit 37, so that the projection data on the gantry 10 is displayed. Control the collection process. Specifically, the scan control circuit 33 controls the collection process of projection data in the imaging for collecting the positioning image (scano image) and the main imaging (scan) for collecting the image used for diagnosis. Here, in the X-ray CT apparatus 1 according to the first embodiment, a two-dimensional scanno image and a three-dimensional scanno image can be taken.

For example, the scan control circuit 33 fixes the X-ray tube 12a at a position of 0 degrees (a position in the front direction with respect to the subject P), and continuously shoots while moving the top plate 22 at a constant speed. Take a two-dimensional scano image with. Alternatively, the scan control circuit 33 fixes the X-ray tube 12a at a position of 0 degrees, moves the top plate 22 intermittently, and intermittently repeats shooting in synchronization with the movement of the top plate, thereby causing two dimensions. Take a scanno image of. Here, the scan control circuit 33 can capture a positioning image from the subject P not only from the front direction but also from an arbitrary direction (for example, the side direction).

In addition, the scan control circuit 33 can capture a three-dimensional scanno image by collecting projection data for the entire circumference of the subject P when capturing the scanno image. For example, the scan control circuit 33 can collect projection data for the entire circumference of the subject P by helical scan or non-helical scan. Here, the scan control circuit 33 can perform a helical scan or a non-helical scan on a wide area such as the entire chest, abdomen, upper body, and whole body of the subject P at a lower dose than the main imaging. .. As the non-helical scan, for example, the above-mentioned step-and-shoot method scan is executed.

In this way, the scan control circuit 33 collects the projection data for the entire circumference of the subject P, and the image reconstruction circuit 36 described later reconstructs the three-dimensional X-ray CT image data (volume data). This makes it possible to generate a positioning image from any direction using the reconstructed volume data. Here, whether to capture the positioning image in two dimensions or in three dimensions may be arbitrarily set by the operator, or may be preset according to the inspection content.

The preprocessing circuit 34 performs logarithmic conversion processing and correction processing such as offset correction, sensitivity correction, and beam hardening correction on the projection data generated by the data acquisition circuit 14, and obtains the corrected projection data. Generate. Specifically, the preprocessing circuit 34 generates corrected projection data for each of the projection data of the positioning image generated by the data acquisition circuit 14 and the projection data collected by the main shooting, and the storage circuit 35. Store in.

The storage circuit 35 stores the projection data generated by the preprocessing circuit 34. Specifically, the storage circuit 35 stores the projection data of the positioning image generated by the preprocessing circuit 34 and the projection data for diagnosis collected by the main imaging. In addition, the storage circuit 35 stores image data and a virtual patient image generated by the image reconstruction circuit 36 described later. Further, the storage circuit 35 appropriately stores the processing result by the processing circuit 37 described later. The virtual patient image and the processing result by the processing circuit 37 will be described later.

The image reconstruction circuit 36 reconstructs the X-ray CT image data using the projection data stored in the storage circuit 35. Specifically, the image reconstruction circuit 36 reconstructs the X-ray CT image data from the projection data of the positioning image and the projection data of the image used for diagnosis. Here, as the reconstruction method, there are various methods, and examples thereof include a back projection process. Further, as the back projection process, for example, a back projection process by the FBP (Filtered Back Projection) method can be mentioned. Alternatively, the image reconstruction circuit 36 can reconstruct the X-ray CT image data by using the successive approximation method.

Further, the image reconstruction circuit 36 generates image data by performing various image processing on the X-ray CT image data. Then, the image reconstruction circuit 36 stores the reconstructed X-ray CT image data and the image data generated by various image processes in the storage circuit 35.

The processing circuit 37 controls the operation of the gantry 10, the sleeper device, and the console 30 to control the entire X-ray CT device 1. Specifically, the processing circuit 37 controls the CT scan performed on the gantry 10 by controlling the scan control circuit 33. Further, the processing circuit 37 controls the image reconstruction processing and the image generation processing in the console 30 by controlling the image reconstruction circuit 36. Further, the processing circuit 37 controls the display 32 to display various image data stored in the storage circuit 35.

Further, as shown in FIG. 1, the processing circuit 37 executes the control function 37a, the display control function 37b, the condition reception function 37c, and the change reception function 37d. Here, for example, each processing function executed by the control function 37a, the display control function 37b, the condition acceptance function 37c, and the change acceptance function 37d, which are the components of the processing circuit 37 shown in FIG. 1, is a program that can be executed by a computer. It is recorded in the storage circuit 35 in the form. The processing circuit 37 is a processor that realizes a function corresponding to each program by reading each program from the storage circuit 35 and executing the program. In other words, the processing circuit 37 in the state where each program is read has each function shown in the processing circuit 37 of FIG. The control function 37a is also referred to as a control unit, the display control function 37b is also referred to as a display control unit, the condition reception function 37c is also referred to as a condition reception unit, and the change reception function 37d is also referred to as a change reception unit. To tell. The details of each function executed by the processing circuit 37 will be described later.

The electrocardiograph 40 is attached to the subject P and acquires the electrocardiographic waveform of the subject P. The electrocardiographic waveform acquired by the electrocardiograph 40 is transmitted to the console 30. The electrocardiographic waveform transmitted to the console device 30 is stored in the storage circuit 35. In other words, the storage circuit 35 stores the electrocardiographic waveform. The period of one cycle of the electrocardiographic waveform is standardized from 0 to 100%, and each position in this period is expressed in%, which is called the cardiac phase. For example, in the cardiac phase, the indefinite period from one R wave to the next R wave is normalized by 0 to 100%.

The respiration detection device 50 has a respiration sensor and acquires the respiration waveform of the subject P. For example, the breath sensor has a laser generator and a receiver, and processes the signal of the reflected light from the abdominal surface of the subject P to change the time from the laser irradiation to the reception of the reflected light or the phase change of the reflected light signal. Based on this, the distance between the laser generator and the abdominal surface of the subject is repeatedly calculated in real time. Although the case where the respiration sensor has a laser generator and a light receiver as the respiration detection device 50 has been described, the embodiment is not limited to this. For example, the respiration sensor may be attached with a pressure sensor between the band attached to the abdomen of the subject P and the abdomen, and the state of respiration may be observed by the change in pressure. Alternatively, an object to which the light reflector is attached may be placed on the abdomen, photographed by a camera, and the movement of the portion of the light reflector may be tracked to observe the state of respiration. The electrocardiograph 40 and the respiratory detection device 50 will be described as being external devices as non-components of the X-ray CT device 1, but the X-ray CT device 1 will be used as a component of the X-ray CT device 1. It may be incorporated. The respiration waveform acquired by the respiration detector 50 is transmitted to the console 30. The respiratory waveform transmitted to the console device 30 is stored in the storage circuit 35. In other words, the storage circuit 35 stores the respiratory waveform. The period of one cycle of the respiratory waveform is standardized from 0 to 100%, and each position in this period is expressed in%, which is called the respiratory phase. For example, in the respiratory phase, the period from the maximum inspiration to the next maximum inspiration is normalized by 0 to 100%.

The configuration of the X-ray CT apparatus 1 according to the first embodiment has been described above. Under such a configuration, the X-ray CT apparatus 1 according to the first embodiment may execute an electrocardiographic synchronous scan or a respiratory synchronous scan in a diagnostic scan.

By the way, in the X-ray CT apparatus 1, a positioning scan is performed before the diagnostic scan. In the positioning scan, a two-dimensional positioning scan in which the top plate 22 is moved without moving the X-ray tube 12a and a three-dimensional positioning scan such as a helical scan is executed. Here, in the conventional positioning scan, which timing of the cardiac phase or the respiratory phase is not considered. For this reason, the operator could not grasp the amount of movement of the heartbeat or the movement of the patient's organs under natural respiration from the scanno image generated by the conventional positioning scan. Then, when the operator determines the conditions of the main scan using such a scanno image and executes the electrocardiographic synchronous scan or the respiratory synchronous scan, the operator sets a margin in the phase width for irradiating X-rays. ..

FIG. 2 is a diagram for explaining an example of a general electrocardiographic synchronous scan. FIG. 2 shows an example of the electrocardiographic waveform of the subject P. As shown in FIG. 2, in the electrocardiographic waveform, P wave, Q wave, R wave, S wave, T wave, and U wave appear during one heartbeat cycle. The R wave appears during the period when the heart is moving the most, and the U wave appears during the period when the movement is relatively slow. Therefore, in general, the scan (electrocardiographic synchronous scan) is performed during a period in which the movement is relatively slow, avoiding the period in which the R wave is generated.

In the example shown in FIG. 2, Sc1 and Sc2 are set as the target period of the electrocardiographic synchronous scan. However, since the operator cannot grasp the movement amount of the heartbeat and the movement of the patient's organs under natural respiration in the positioning scan, a predetermined margin is set in the target period. For example, the margins of M1 and M2 are set before and after Sc1, and the margins of M3 and M4 are set before and after Sc2.

As a result, the irradiation period of X-rays including the margin for the target period Sc1 becomes Ex1, and the irradiation period of X-rays including the margin for the target period Sc2 becomes Ex2. That is, extra X-rays are irradiated for the set margin period. As a result, the exposure dose of the subject in the electrocardiographic synchronous reconstruction increases.

FIG. 3 is a diagram for explaining an example of a general respiratory synchronization scan. FIG. 3 shows an example of the respiratory waveform of the subject P. As shown in FIG. 3, in the respiratory waveform, maximum inspiration and maximum expiration appear during one respiratory cycle. Maximum inspiration is the peak of the respiratory waveform and maximum expiration is the bottom of the respiratory waveform. In general, the scan (respiratory synchronous scan) is performed during the period of maximum inspiration and maximum expiration.

In the example shown in FIG. 3, Sc1 and Sc2, which are the maximum exhalations, are set as the target period of the respiratory synchronous scan. However, since the operator cannot grasp the movement of the patient's organs under natural respiration in the positioning scan, a predetermined margin is set in the target period. For example, the margins of M1 and M2 are set before and after Sc1, and the margins of M3 and M4 are set before and after Sc2.

As a result, the irradiation period of X-rays including the margin for the target period Sc1 becomes Ex1, and the irradiation period of X-rays including the margin for the target period Sc2 becomes Ex2. That is, extra X-rays are irradiated for the set margin period. As a result, the exposure dose of the subject in the respiratory-gated reconstruction is increased.

For this reason, the X-ray CT apparatus 1 according to the first embodiment reduces the exposure in the synchronous reconstruction by making it possible to determine the conditions of the main scan without setting a predetermined margin. Hereinafter, the details of the processing by the X-ray CT apparatus 1 according to the first embodiment will be described.

FIG. 4 is a flowchart showing a processing procedure by the X-ray CT apparatus 1 according to the first embodiment. FIG. 4 shows a flowchart explaining the operation of the entire X-ray CT apparatus 1, and describes which step of the flowchart each component corresponds to. In the example shown in FIG. 4, a case where a diagnostic scan is performed in electrocardiographic synchronization and respiratory synchronization will be described. Further, when performing electrocardiographic synchronization and respiratory synchronization, for example, the subject P is held in a state of maximum exhalation, and when the electrocardiographic waveform becomes an R wave, the subject P is made to resume breathing.

Step S1 is a step realized by the input circuit 31. In step S1, the input circuit 31 receives the input of patient information. For example, the input circuit 31 accepts inputs such as name, height, weight, gender, positioning scan type, and body position as patient information. More specifically, in the input circuit 31, the "name" is "○○○○", the "height" is "1700 mm", the "weight" is "63.0 kg", and the "gender" is Accepts the input of "male".

Further, the input circuit 31 accepts the "positioning scan type" and the "position". Here, the "type of positioning scan" includes, for example, a two-dimensional positioning scan and a three-dimensional positioning scan. Here, the three-dimensional positioning scan further includes a helical scan, a non-helical scan, an electrocardiographic synchronous scan, and a respiratory synchronous scan. In the following, it is assumed that the selection of the electrocardiographic synchronous scan and the respiratory synchronous scan is accepted in step S1.

Further, the "position" indicates the direction in which the subject P is placed on the top plate 22. The body positions include, for example, the supine position in which the subject P lies on the top plate 22 and the prone position in which the subject P lies on the top plate 22. The information related to the "position" includes information indicating whether the subject P is in a lying posture with the head facing the gantry 10 or a lying posture with the lower limbs facing the gantry 10. In the following description, it is assumed that the selection of the supine position and the lying posture with the head facing the gantry 10 is accepted in step S1.

Step S2 is a step realized by the processing circuit 37. In step S2, the processing circuit 37 determines the scanning conditions. For example, the processing circuit 37 determines scanning conditions such as X-ray irradiation conditions, imaging target range and imaging direction, and moving speed of the top plate 22 based on the patient information received in step S1, scan type, and body position. To do.

The X-ray irradiation condition referred to here is a condition relating to an X-ray irradiation amount such as a tube current and a tube voltage. The X-ray CT apparatus 1 has an irradiation condition table set in advance according to the scan type and the body type of the subject. Further, the imaging target range is a target range including an object for acquiring biological information such as an electrocardiographic waveform and a respiratory waveform. Further, the imaging direction indicates whether to photograph from the head toward the lower limbs or from the lower limbs toward the head. The moving speed of the top plate 22 is the moving speed of the top plate 22 in the positioning scan. The X-ray CT apparatus 1 has a moving speed table set in advance according to the scan type.

As an example, in the processing circuit 37, since the electrocardiographic synchronous scan is selected as the scan type in step S1, the imaging target range is determined as the chest. Further, since the respiration synchronous scan is selected as the scan type in step S1, the processing circuit 37 determines the imaging target range as the abdomen. That is, in step S2, the processing circuit 37 determines the imaging target range as the chest and abdomen. Further, the processing circuit 37 determines the photographing direction from the information related to the "position". For example, in step S1, the processing circuit 37 accepts the selection of the posture in which the head is facing the gantry 10 and is in a lying position. Therefore, it is determined that the imaging direction is from the head to the lower limbs. In addition, the processing circuit 37 determines the X-ray irradiation conditions according to the electrocardiographic synchronous scan, the respiratory synchronous scan, and the body shape of the subject from the irradiation condition table. Further, the processing circuit 37 determines the moving speed of the top plate 22 according to the electrocardiographic synchronous scan and the respiratory synchronous scan from the moving speed table. In the moving speed table, the moving speed of the initial setting value and the moving speed after the change are set as the moving speed of the top plate 22, and the processing circuit 37 is initially set as the moving speed of the top plate 22. Determine the moving speed of the value and the moving speed after the change.

Step S3 is a step realized by the processing circuit 37. In step S3, the processing circuit 37 controls the scan control circuit 33 to execute the positioning scan by the helical scan. As a result, the console 30 collects projection data from the gantry 10. The projection data of the positioning image collected from the gantry 10 is stored in the storage circuit 35. Then, when the positioning scan by the helical scan is started, the image reconstruction circuit 36 starts the process of reconstructing the image data in real time from the projection data of the positioning image collected by the positioning scan by the helical scan. That is, when the image reconstruction circuit 36 starts the reconstruction process, the image data is sequentially reconstructed in real time from the projection data collected by the positioning scan by the helical scan. The image data sequentially reconstructed in real time by the image reconstructing circuit 36 after the positioning scan in the helical scan is started is referred to as a "real-time image".

Steps S4 to S8 are steps corresponding to the control function 37a. This is a step in which the control function 37a is realized by the processing circuit 37 calling and executing a predetermined program corresponding to the control function 37a from the storage circuit 35. In step S4, the control function 37a executes the target range start determination process. The target range start determination process will be described with reference to FIG.

FIG. 5 is a flowchart showing a processing procedure of the target range start determination process by the control function 37a according to the first embodiment. Steps S101 to S111 are steps corresponding to the control function 37a. In step S101, the control function 37a acquires a real-time image. Here, the control function 37a acquires the latest real-time image.

In step S102, the control function 37a executes a filtering process on the real-time image. For example, the control function 37a divides air, water, and bone into regions using CT values in a real-time image. Then, the control function 37a applies a smoothing filter to the real-time image as needed.

In step S103, the control function 37a reads out the reference image. For example, the control function 37a acquires the patient information received in step S1 and the reference image corresponding to the scan condition determined in step S2 from the storage circuit 35.

In step S104, the control function 37a executes a filtering process on the reference image. For example, the control function 37a divides the air, water, and bone into regions using the CT value in the reference image, as in step S102. Then, the control function 37a applies a smoothing filter to the reference image as needed. The processes of steps S101 and S102 and the processes of steps S103 and S104 may be executed in parallel. Further, the processes of steps S103 and S104 may be executed before the processes of steps S101 and S102.

In step S105, the control function 37a determines whether or not the real-time image and the reference image match. For example, the control function 37a recognizes the structure and converts it by using an alignment technique such as affine transformation in order to match the structure of the region-divided reference image with the structure of the real-time image. Further, the control function 37a takes the difference between the converted reference image and the real-time image, and calculates how much the edge positions are different. The control function 37a determines that the real-time image and the reference image match when the difference in the edge positions is equal to or less than a predetermined threshold value. On the other hand, the control function 37a determines that the real-time image and the reference image do not match when the difference in the edge positions is larger than a predetermined threshold value.

Here, when the control function 37a does not determine that the real-time image and the reference image match (step S105, No), the reference image is postponed by one slice (step S106), and the determination process of step S105 is repeated. Here, the control function 37a advances the reference image by one slice based on the shooting direction. For example, the control function 37a postpones the reference image by one slice from the head side to the lower limb side when the imaging direction is from the head to the lower limb portion. On the other hand, when the imaging direction is from the lower limbs to the head, the control function 37a advances the reference image by one slice from the lower limbs to the head.

On the other hand, when the control function 37a determines that the real-time image and the reference image match (step S105, Yes), the control function 37a calculates the anatomical position (step S107). For example, the control function 37a identifies an anatomically identifiable structure such as a bone and calculates an anatomical position.

Subsequently, in step S108, the control function 37a calculates the time to the start position of the target range based on the calculated anatomical position. For example, the control function 37a calculates the time required to change the moving speed of the top plate 22 from the calculated distance from the anatomical position to the start position of the target range and the moving speed of the top plate 22.

In step S109, the control function 37a determines whether or not the calculated time is equal to or less than a predetermined threshold value. Here, when the control function 37a does not determine that the calculated time is equal to or less than a predetermined threshold value (steps S109, No), it determines that the synchronous scan is not prepared to start (step S110). On the other hand, when it is determined that the calculated time is equal to or less than a predetermined threshold value (step S109, Yes), the control function 37a determines that the synchronous scan is prepared to start (step S111). After the end of step S110 or step S111, the control function 37a shifts to step S5 shown in FIG.

Return to FIG. In step S5, the control function 37a determines whether or not to start the synchronous scan. For example, the control function 37a determines whether or not to start the synchronous scan based on the result of the determination process in step S109. For example, when the control function 37a determines in step S110 that the synchronous scan is not prepared to start, it determines that the synchronous scan is not started, and in step S111, it determines that the synchronous scan is prepared to start. , Determines to start a synchronous scan. Here, when it is determined that the synchronous scan is not started (step S5, No), the control function 37a proceeds to step S4 and executes the target range start determination process. On the other hand, when the control function 37a determines that the synchronous scan is to be started (step S5, Yes), the control function 37a executes the scan in consideration of the electrocardiographic synchronization and the respiratory synchronization (step S6). For example, the control function 37a controls the moving speed of the top plate 22 so that biometric information for at least one cycle can be acquired in each image data reconstructed from the data collected by the synchronous scan. FIG. 6 is a diagram for explaining the first embodiment.

The horizontal axis of FIG. 6 indicates the body axis direction, and the vertical axis of FIG. 6 indicates the moving speed of the top plate 22. Further, in FIG. 6, the subject P is placed on the top plate 22 in the supine position with the head facing the gantry 10, and the positioning scan is started from the head side to the lower limb side of the subject P. Show the case. Further, in FIG. 6, the chest and abdomen are determined as the target range, and the range indicated by the positions P1 to P2 in the body axis direction corresponds to the target range. In the example of FIG. 6, the case where the moving speed of the top plate 22 at the start of the positioning scan is the default value V1 is shown. The moving speed V1 of the top plate 22 is determined in step S2.

Here, the control function 37a calculates the anatomical position by comparing the real-time image reconstructed in real time from the data collected by the synchronous scan with the reference image, and obtains the calculated anatomical position. The timing of performing a synchronous scan in the target range is estimated based on the start position of the target range. For example, when the control function 37a reaches the position P3 in the body axis direction shown in FIG. 6, it determines that the time to the position P1 is equal to or less than a predetermined threshold value, and executes a scan considering electrocardiographic synchronization and respiratory synchronization. To do. More specifically, the control function 37a changes the moving speed of the top plate 22 from V1 so that the moving speed of the top plate 22 becomes V2 in the target range. Here, when the moving speed of the top plate 22 is V2, it is possible to acquire biometric information for at least one cycle in each image data reconstructed from the data collected by the synchronous scan. In this way, the control function 37a controls to perform synchronous scanning at least in the target range including the target for which biological information is acquired. Further, the control function 37a may reduce the dose irradiated from the X-ray tube 12a in the target range.

Return to FIG. In step S7, the control function 37a executes the same target range end determination process as in step S4. FIG. 7 is a flowchart showing a processing procedure of the target range end determination process by the control function 37a according to the first embodiment. The processing of steps S201 to S207 of the target range end determination processing shown in FIG. 7 is the same as the processing of steps S101 to S107 of the target range start determination processing shown in FIG. Therefore, in FIG. 7, the description of the processes from steps S201 to S207 is omitted, and the processes of steps S208 and subsequent steps will be described.

More specifically, in step S208 of the target range end determination process in step S7, the control function 37a determines whether or not the end position of the target range has been reached based on the calculated anatomical position. Here, when the control function 37a does not determine that the end position of the target range has been reached (step S208, No), the control function 37a determines that preparation for the end of the synchronous scan is not performed (step S209). On the other hand, when it is determined that the end position of the target range has been reached (step S209, Yes), the control function 37a determines that the synchronous scan is ready to end (step S210). After the end of step S209 or step S210, the control function 37a shifts to step S8 shown in FIG.

Return to FIG. In step S8, the control function 37a determines whether or not to end the synchronous scan. For example, the control function 37a determines whether or not the current real-time image is in the synchronization target range based on the result of the determination process in step S209. For example, when the control function 37a determines in step S209 that the synchronous scan is not prepared to end, it determines that the synchronous scan is not completed, and in step S210, it determines that the synchronous scan is prepared to end. , Judge that the synchronous scan is finished. Here, when the control function 37a determines that the synchronous scan is not completed (steps S8 and No), the control function 37a proceeds to step S7 and executes the target range end determination process. On the other hand, when the control function 37a determines that the synchronous scan is completed (step S8, Yes), the control function 37a proceeds to step S9.

Here, the process of step S8 will be described again with reference to FIG. The control function 37a calculates the anatomical position by comparing the real-time image reconstructed in real time from the data collected by the synchronous scan with the reference image, and the calculated anatomical position and the target range. Estimate the timing of synchronous scanning in the target range based on the end position. For example, when the control function 37a reaches the position P2 in the body axis direction shown in FIG. 6, it determines that the end position of the target range has been reached, and ends the scan in consideration of electrocardiographic synchronization and respiratory synchronization. More specifically, the control function 37a changes the moving speed of the top plate 22 from V2 to V1, which is the moving speed of the top plate 22 of the initial setting value. As a result, for example, at the position P4 in the body axis direction shown in FIG. 6, the moving speed of the top plate 22 returns to the initial set value V1.

Step S9 is a step realized by the image reconstruction circuit 36. In step S9, the image reconstruction circuit 36 executes the synchronous reconstruction process of the target range. For example, the image reconstruction circuit 36 reconstructs image data from the data collected by the synchronous scan in units obtained by dividing the time phase of biological information into a predetermined number. More specifically, the image reconstruction circuit 36 performs synchronous reconstruction for one cycle of the cardiac phase and the respiratory phase for the chest and abdomen.

FIG. 8 is a diagram for explaining the first embodiment. FIG. 8 shows a case where the subject P is held in the state of maximum exhalation, and when the electrocardiographic waveform becomes an R wave, the subject P is restarted to breathe and the electrocardiographic synchronization and the respiratory synchronization scan are performed. Shown. In FIG. 8, the period between the maximum inspiration and the next maximum inspiration in the respiratory waveform is defined as one cycle of the respiratory waveform, and the period of this one cycle is standardized by 0 to 100% to be expressed as the respiratory phase. Further, in FIG. 8, the period from the R wave of the electrocardiographic waveform to the next R wave is defined as one cycle of the electrocardiographic waveform, and the period of this one cycle is expressed as the cardiac phase by normalizing from 0 to 100%. .. Then, when the image reconstruction circuit 36 reconstructs the image using the projection data collected by the electrocardiographic synchronization and the respiratory synchronization scan, for example, the image reconstruction circuit 36 performs synchronous reconstruction for one cycle in 1% increments of the cardiac phase. , Synchronous reconstruction for one cycle is performed in 1% increments of the respiratory phase.

Here, one cycle of the respiratory waveform is longer than one cycle of the electrocardiographic waveform. In the example shown in FIG. 8, the respiratory waveform for one cycle corresponds to the electrocardiographic waveform for about three cycles. For example, in FIG. 8, the maximum exhalation occurs at times t1 and t4. Further, the cardiac phase corresponding to the maximum expiratory respiratory phase of 50% has an electrocardiographic waveform of 100% (0%) R wave. Further, in FIG. 8, the electrocardiographic waveform becomes an R wave at times t1, t2, t3, t4, t5 and t6. Further, the respiratory phase corresponding to 100% (0%) of the cardiac phase in which the electrocardiographic waveform is an R wave is 50%, which is the maximum expiratory phase when the times are t1 and t4, and the time is t2. And t5, the respiratory phase is 70%, and when the times are t3 and t6, the respiratory phase is 30%. As shown in FIG. 8, a unique cardiac phase corresponds to the respiratory phase, but a plurality of respiratory phases correspond to the cardiac phase.

For this reason, the image reconstruction circuit 36 synchronously reconstructs the respiratory phase in 1% increments for the respiratory phase, but the cardiac phase is associated with the respiratory phase in 1% increments. Perform synchronous reconfiguration. For example, the image reconstruction circuit 36 provides incidental information such as (cardiac phase 100% (0%), respiratory phase 50%), (cardiac phase 100% (0%), respiratory phase 70%) to the reconstructed image. By giving, it is possible to distinguish which phase the respiratory phase is. The image reconstruction circuit 36 stores the reconstructed image data in the storage circuit 35. The image reconstruction circuit 35 generates volume data from the data collected by the synchronous scan, performs a cross-section reconstruction method (MPR: Multi Planar Reconstruction), and performs an MPR image (axial image, coronal image, and sagittal image) from the volume data. Image) may be generated.

Return to FIG. Step S10 is a step realized by the display control function 37b. In step S10, the display control function 37b causes the display 32 to display the image data reconstructed from the data collected by the synchronous scan. FIG. 9 is a diagram for explaining the first embodiment.

FIG. 9 describes a case where the display area of the display 32 is divided into four parts and used. For example, the display control function 37b displays information indicating the time phase of biological information corresponding to the axial image, the coronal image, the sagittal image, and the image data to be displayed. More specifically, the display control function 37b displays an axial image in the upper left of the display area of the display 32 divided into four, a coronal image in the upper right, and a sagittal image in the lower left.

Here, the display control function 37b shows the target range in which the synchronous scan is performed so that it can be visually recognized. For example, the display control function 37b displays the information 90a indicating the target range in the upper right area for displaying the coronal image and the information 90b indicating the coping range in the lower left area for displaying the sagittal image.

Further, the display control function 37b displays information indicating the time phase of biometric information in the lower right of the display area of the display 32 divided into four. For example, the display control function 37b displays information indicating the respiratory phase and information indicating the cardiac phase corresponding to the currently displayed axial image, coronal image, and sagittal image, respectively. More specifically, as shown in FIG. 9, the display control function 37b displays a setting bar 90c indicating the phase of the cardiac phase and a setting bar 90d indicating the phase of the respiratory phase. The setting bar 90c can be moved to an arbitrary position of the information indicating the cardiac phase, and the setting bar 90d can be moved to an arbitrary position of the information indicating the respiratory phase.

For example, the operator moves either the setting bar 90c or the setting bar 90d to a position of an arbitrary phase. In such a case, the change acceptance function 37d accepts the change of the time phase in the information indicating the time phase of the biological information. Then, the display control function 37b displays the image data corresponding to the changed time phase. That is, the display control function 37b reads out the synchronously reconstructed image corresponding to the changed phase from the storage circuit 35 and displays it. This allows the operator to grasp the amount of movement of the heartbeat and the movement of the patient's organs under natural respiration. By moving the respiratory phase setting bar 90d, the cardiac phase setting bar 90c corresponding to the respiratory phase also moves in conjunction with the movement. Further, by moving the cardiac phase setting bar 90c, the respiratory phase setting bar 90d corresponding to the cardiac phase also moves in conjunction with the movement. By observing the axial image, the coronal image, and the sagittal image while arbitrarily moving the setting bar 90c and the setting bar 90d, the operator can visually determine and find the phase with less movement.

Return to FIG. Step S11 is a step corresponding to the condition reception function 37c. In step S11, the condition reception function 37c accepts the setting of scan conditions for the diagnostic scan as a scan plan. For example, the condition acceptance function 37c accepts the setting of this scan condition from an operator who refers to the image data reconstructed from the data collected by the synchronous scan. For example, the condition reception function 37c receives from the operator the designation of the cardiac phase and the respiratory phase to be synchronously reconstructed.

Step S12 is a step realized by the processing circuit 37. In step S12, the processing circuit 37 controls the scan control circuit 33 to execute a diagnostic scan by a helical scan. Here, the processing circuit 37 controls the scan control circuit 33 to execute the diagnostic scan under the diagnostic scan conditions received from the operator in step S11. That is, the processing circuit 37 controls the scan control circuit 33 to execute the synchronous scan in the cardiac phase and the respiratory phase received from the operator. In addition, when performing electrocardiographic synchronization and respiratory synchronization in step S12, in order to associate the phase determined by the scanogram with the phase in the diagnostic scan, for example, the subject P is held in the state of maximum exhalation, and the heart is held. When the radio wave becomes an R wave, the subject P resumes breathing and then performs a diagnostic scan. As a result, the image reconstruction circuit 36 reconstructs the image data from the collected data by executing the main scan under the conditions determined based on the result of the synchronous scan. For example, the image reconstruction circuit 36 reconstructs the image data from the collected data by executing the present scan condition that has received the setting.

As described above, in the first embodiment, the positioning scan is executed by the helical scan, and the biological information for at least one cycle can be acquired in each image data reconstructed from the data collected by the synchronous scan in the target range. In addition, the moving speed of the top plate 22 is controlled. That is, by acquiring the biological information for one cycle in each cross-sectional image of the target range, the operator can grasp the amount of movement of the heartbeat and the movement of the patient's organs under natural respiration. .. This allows the operator to determine the conditions for the main scan without setting a predetermined margin. As a result, according to the first embodiment, it is possible to reduce the exposure in the synchronous reconstruction. As a result, according to the first embodiment, it is possible to reduce the burden on the patient.

(Second Embodiment)
In the first embodiment, a case where the scan conditions of the diagnostic scan are determined and the diagnostic scan is executed is described using the scanno image which is the image data generated by the positioning scan. By the way, the use of the scanno image generated by the positioning scan is not limited to determining the scan conditions of the diagnostic scan. Therefore, in the second embodiment, a case where the scanno image generated by the positioning scan is used for purposes other than determining the scan conditions of the diagnostic scan will be described.

The configuration of the X-ray CT apparatus 1 according to the second embodiment is the same as the configuration of the X-ray CT apparatus 1 according to the first embodiment. Therefore, the description of the configuration of the X-ray CT apparatus 1 according to the second embodiment will be omitted.

In the X-ray CT apparatus 1 according to the second embodiment, the processes of steps S1 to S10 shown in FIG. 4 are executed. Then, in step S10, the operator refers to the scanno image displayed on the display 32. Here, the operator can visually judge and find the phase with less movement by observing the axial image, the coronal image, and the sagittal image while arbitrarily moving the setting bar 90c and the setting bar 90d. ..

As a result, the operator can perform, for example, a simulation of a surgical operation under fluoroscopy, a simulation of respiratory synchronous irradiation in radiotherapy, a simulation of setting a region of interest of a contrast medium monitoring scanno, and the like using a scanno image. It will be possible. As a result, according to the second embodiment, the operator can determine the optimum conditions in surgery, radiotherapy, contrast agent monitoring, and the like. In the second embodiment, the X-ray CT apparatus 1 does not have to execute the diagnostic scan in step S12.

In the above-described embodiment, the X-ray CT apparatus 1 has been described as displaying a scanno image on the display 32 of the console 30, but the embodiment is not limited to this. For example, the X-ray CT apparatus 1 according to the second embodiment and other apparatus such as an image processing apparatus and a medical image diagnostic apparatus are directly or indirectly connected to each other by an in-hospital LAN (Local Area Network) installed in the hospital. May be in a state where they can communicate with each other. In such a case, the X-ray CT apparatus 1 according to the second embodiment may display image data other than the display 32 of the console 30. In such a case, the processing circuit 37 of the X-ray CT apparatus 1 executes the transmission function.

For example, the X-ray CT device 1 according to the second embodiment transmits image data to other devices such as an image processing device and a medical image diagnostic device by executing a transmission function. That is, the transmission function transmits the image data reconstructed from the data collected by the synchronous scan to another device. As a result, other devices such as an image processing device and a medical image diagnostic device display the image data received from the X-ray CT device 1 on their own display. For example, a processing circuit included in another device such as an image processing device or a medical diagnostic imaging device executes a display control function similar to the display control function 37b described above. As an example, the display control function visually shows the target range in which the synchronous scan is performed. In addition, the display control function displays information indicating the respiratory phase and information indicating the cardiac phase corresponding to the currently displayed axial image, coronal image, and sagittal image, respectively. Further, the processing circuit of another device such as the image processing device and the medical image diagnosis device executes the same change reception function as the change reception function 37d described above. As an example, the change reception function accepts a change in the time phase in the information indicating the time phase of the biological information. Then, the display control function displays the image data corresponding to the changed time phase. As a result, the operator who refers to the image processing device or the medical diagnostic imaging device refers to the scanno image and observes the movement of the organ in each phase, which is optimal in surgery, radiotherapy, contrast agent monitoring, and the like. It becomes possible to determine the conditions. When PACS (Picture Archiving and Communication System) is installed in the facility where the X-ray CT device 1 is installed, the X-ray CT device 1 and each device are DICOM (Digital Imaging and Communications in Medicine) standards. In accordance with the above, medical images and the like may be transmitted and received to and from each other.

(Other embodiments)
By the way, the first embodiment to the second embodiment have been described so far, but in addition to the above-mentioned first embodiment to the second embodiment, various different embodiments may be implemented. ..

In the above-described embodiment, the input circuit 31 has been described as accepting the input of patient information in step S1, but the embodiment is not limited to this. For example, in a facility where an X-ray CT device 1 is installed, for example, when HIS (Hospital Information System) or RIS (Radiology Information System) is introduced and various information is managed, the X-ray CT device 1 is a step. Patient information may be acquired from HIS or RIS in S1.

In the above-described embodiment, the processing circuit 37 controls the scan control circuit 33 to collect projection data of the whole body from the head to the lower limbs of the subject P by a helical scan in taking a scanno image. However, the embodiment is not limited to this. For example, when performing a synchronized scan of the chest and abdomen, it is not always necessary to take a scanno of the whole body. More specifically, when performing a synchronous scan of the chest and abdomen, the processing circuit 37 does not have to perform a positioning scan on a portion or region other than the target range such as the head or lower limbs.

Further, the processing circuit 37 may perform a positioning scan of only the target range. FIG. 10 is a diagram for explaining other embodiments. The horizontal axis of FIG. 10 indicates the body axis direction, and the vertical axis of FIG. 10 indicates the moving speed of the top plate 22. Further, in FIG. 10, the subject P is placed on the top plate 22 in the supine position with the head facing the gantry 10, and the positioning scan is started from the head side to the lower limb side of the subject P. Show the case. Further, in FIG. 10, the chest and abdomen are determined as the target range, and the range indicated by the positions P1 to P2 in the body axis direction corresponds to the target range.

In such a case, the processing circuit 37 moves the top plate 22 to the position P1 in the body axis direction shown in FIG. 10 by controlling the scan control circuit 33. Then, the processing circuit 37 starts the positioning scan in the helical scan from the position P1. In such a case, the control function 37a controls the moving speed of the top plate 22 so that biometric information for at least one cycle can be acquired in each image data reconstructed from the data collected by the synchronous scan. In the example of FIG. 10, the control function 37a controls the moving speed of the top plate 22 to V2. After starting the positioning scan by the helical scan, the control function 37a executes the target range end determination process in the same manner as in step S7 shown in FIG. Then, the control function 37a executes a positioning scan by a helical scan, for example, until it is determined that the end position P2 of the target range has been reached.

Further, in the above-described embodiment, the conditions for this scan have been described as being accepted from the operator, but the embodiment is not limited to this. For example, the control function 37a may automatically set the scan conditions. In such a case, the control function 37a, for example, compares the reconstructed images in each phase to identify the cardiac phase and the respiratory phase with less movement. Then, the processing circuit 37 controls the scan control circuit 33 to execute the synchronous scan in the cardiac phase and the respiratory phase specified by the control function 37a.

Further, in the above-described embodiment, the movement speed of the top plate 22 has been described as being changed in the target range, but the embodiment is not limited to this. For example, the rotation speed of the rotation frame 15 may be changed. Further, for example, when the gantry 10 can be moved without moving the top plate 22, the moving speed of the gantry 10 may be changed in the target range. That is, the control function 37a can acquire biometric information for at least one cycle in each image data reconstructed from the data collected by the synchronous scan, and can acquire the moving speed of the top plate 22, the rotating speed of the rotating frame 15, and the gantry 10. By controlling at least one of the moving speeds of the above, synchronous scanning is controlled. In such a case, the control function 37a can acquire biometric information for at least one cycle in each image data reconstructed from the data collected by the synchronous scan, so that the rotation speed of the rotation frame 15 and the movement speed of the gantry 10 can be acquired. To change.

Further, in the target range start determination process in the above-described embodiment, the process of determining whether or not the image matches the reference image each time a real-time image is generated is described as being repeated until the start position of the target range is reached. The embodiment is not limited to this. For example, when the reference image and the real-time image match, the time to the start position of the target range is calculated based on the anatomical position of the structure drawn in the reference image, and the calculated time elapses before synchronous scanning. May be done. In such a case, the number of reference images used for the target range start determination process may be a predetermined number set in advance, for example, one image.

Similarly, in the target range end determination process in the above-described embodiment, for example, when the reference image and the real-time image match, the target range ends based on the anatomical position of the structure drawn in the reference image. The time to the position may be calculated, and the synchronous scan may be terminated after the calculated time has elapsed. Even in such a case, the number of reference images used for the target range end determination process may be a predetermined number set in advance, for example, one image. Further, it is not necessary to execute the target range end determination process. In such a case, the end time of the synchronous scan may be calculated at the start of the synchronous scan, and the synchronous scan may be terminated after the calculated time has elapsed.

Further, in the above-described embodiment, when electrocardiographic synchronization and respiratory synchronization are performed, for example, the subject P is held in a state of maximum exhalation, and when the electrocardiographic waveform becomes an R wave, the subject P is subjected to. Although it has been described that the positioning scan and the diagnostic scan are performed after resuming breathing, the embodiment is not limited to this. For example, the subject P may be allowed to resume breathing when the electrocardiographic waveform becomes an R wave by holding the breath in the state of maximum inspiration. Alternatively, the subject P may resume breathing when the electrocardiographic waveform becomes a P wave from the state of holding the breath.

Further, in the above-described embodiment, the case of monitoring the cardiac phase and the respiratory phase has been described, but the embodiment is not limited to this. For example, either the cardiac phase or the respiratory phase may be monitored. Further, when monitoring only the cardiac phase, the image reconstruction circuit 36 performs synchronous reconstruction of the cardiac phase in 1% increments without associating the cardiac phase with the respiratory phase.

The word "processor" used in the above description means, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), or a programmable logic device (for example, a programmable logic device). It means a circuit such as a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). The processor realizes the function by reading and executing the program stored in the storage circuit. Instead of storing the program in the storage circuit, the program may be directly embedded in the circuit of the processor. In this case, the processor realizes the function by reading and executing the program embedded in the circuit. It should be noted that each processor of the present embodiment is not limited to the case where each processor is configured as a single circuit, and a plurality of independent circuits may be combined to form one processor to realize its function. Good. Further, the plurality of components in FIG. 1 may be integrated into one processor to realize the function.

Further, each component of each device shown in the above-described embodiment is a functional concept, and does not necessarily have to be physically configured as shown in the figure. That is, the specific form of distribution / integration of each device is not limited to the one shown in the figure, and all or part of the device is functionally or physically distributed / physically in arbitrary units according to various loads and usage conditions. It can be integrated and configured. For example, the image reconstruction circuit 36 may be distributed into a scanno image reconstruction circuit and an image reconstruction circuit. In such a case, the scanno image reconstruction circuit reconstructs the image data from the data collected by the synchronous scan in units obtained by dividing the time phase of the biological information into a predetermined number. In addition, the image reconstruction circuit reconstructs image data from the data collected by executing the main scan under the conditions determined based on the result of the synchronous scan. Further, each processing function performed by each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

Further, the control method described in the above-described embodiment can be realized by executing a control program prepared in advance on a computer such as a personal computer or a workstation. This control program can be distributed via a network such as the Internet. Further, this control program can also be executed by being recorded on a computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, or DVD, and being read from the recording medium by the computer.

As described above, according to each embodiment, it is possible to reduce the exposure in the synchronous reconstruction.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention as well as the invention described in the claims and the equivalent scope thereof.

1 X-ray CT device 36 Image reconstruction circuit 37 Processing circuit 37a Control function 37b Display control function 37c Condition reception function 37d Change reception function

Claims (16)

A pedestal having a rotating part for rotating the X-ray tube, and
A sleeper with a top plate on which the subject is placed,
When a positioning scan is performed while relatively moving the subject and the gantry placed on the top plate, synchronization synchronized with the dynamics of the subject based on biological information related to the dynamics of the subject. A control unit that controls scanning
A reconstruction unit that reconstructs image data from the data collected by executing the main scan under the conditions determined based on the result of the synchronous scan, and
A display control unit that displays image data reconstructed from the data collected by the synchronous scan on a predetermined display unit, and
A scanno image reconstruction unit that reconstructs image data in units obtained by dividing the time phase of the biometric information into a predetermined number from the data collected by the synchronous scan.
Equipped with a,
The display control unit displays information indicating the time phase of the biometric information corresponding to the image data to be displayed.
X-ray CT device. The X-ray CT apparatus according to claim 1 , wherein the display control unit displays information indicating a target range including an object for which the biological information is acquired. In the information indicating the time phase of the biometric information, a change reception unit that accepts the change of the time phase is further provided.
The X-ray CT apparatus according to claim 1 or 2 , wherein the display control unit displays image data corresponding to the changed time phase. Further provided with a condition reception unit that accepts the setting of this scan condition from an operator who refers to the image data reconstructed from the data collected by the synchronous scan.
The X-ray CT apparatus according to any one of claims 1 to 3 , wherein the reconstructing unit reconstructs image data from the data collected by executing the present scan condition for which the setting has been accepted. A pedestal having a rotating part for rotating the X-ray tube, and
A sleeper with a top plate on which the subject is placed,
When a positioning scan is performed while relatively moving the subject and the gantry placed on the top plate, synchronization synchronized with the dynamics of the subject based on biological information related to the dynamics of the subject. A control unit that controls scanning
A transmitter that transmits image data reconstructed from the data collected by the synchronous scan to another device, and a transmitter.
A scanno image reconstruction unit that reconstructs image data from the data collected by the synchronous scan, and
Equipped with a,
The other device includes a display control unit that displays image data reconstructed from the data collected by the synchronous scan on a predetermined display unit.
The scanno image reconstructing unit reconstructs image data from the data collected by the synchronous scan in units obtained by dividing the time phase of the biometric information into a predetermined number.
The display control unit displays information indicating the time phase of the biometric information corresponding to the image data to be displayed.
The other device further includes a change receiving unit that accepts a change in the time phase in the information indicating the time phase of the biometric information.
The display control unit displays image data corresponding to the changed time phase.
X-ray CT device. The X-ray CT apparatus according to claim 5 , wherein the display control unit displays information indicating a target range including an object for which the biological information is acquired. The X-ray CT apparatus according to claim 5 or 6 , further comprising a reconstructing unit that reconstructs image data from data collected by executing the main scan under conditions determined based on the result of the synchronous scan. The control unit can acquire biometric information for at least one cycle in each image data reconstructed from the data collected by the synchronous scan, and the moving speed of the top plate, the rotating speed of the rotating unit, and the gantry. The X-ray CT apparatus according to any one of claims 1 to 7 , wherein the synchronous scan is controlled by controlling at least one of the moving speeds of the above. A pedestal having a rotating part for rotating the X-ray tube, and
A sleeper with a top plate on which the subject is placed,
When a positioning scan is performed while relatively moving the subject and the gantry placed on the top plate, synchronization synchronized with the dynamics of the subject based on biological information related to the dynamics of the subject. A control unit that controls scanning
A reconstruction unit that reconstructs image data from the data collected by executing the main scan under the conditions determined based on the result of the synchronous scan, and
With
The control unit can acquire biometric information for at least one cycle in each image data reconstructed from the data collected by the synchronous scan, and the moving speed of the top plate, the rotating speed of the rotating unit, and the gantry. By controlling at least one of the moving speeds of the above, the synchronous scan is controlled to be performed.
The real-time image reconstructed in real time from the data collected by the synchronous scan is compared with the reference image to calculate the anatomical position, and the calculated anatomical position and the start position of the target range are used. The timing of performing the synchronous scan in the target range is estimated based on the above.
X-ray CT device. A pedestal having a rotating part for rotating the X-ray tube, and
A sleeper with a top plate on which the subject is placed,
When a positioning scan is performed while relatively moving the subject and the gantry placed on the top plate, synchronization synchronized with the dynamics of the subject based on biological information related to the dynamics of the subject. A control unit that controls scanning
A transmitter that transmits image data reconstructed from the data collected by the synchronous scan to another device, and a transmitter.
With
The control unit
Of the moving speed of the top plate, the rotating speed of the rotating portion, and the moving speed of the gantry, it is possible to acquire biometric information for at least one cycle in each image data reconstructed from the data collected by the synchronous scan. By controlling at least one of them, the synchronous scan is controlled to be performed.
The real-time image reconstructed in real time from the data collected by the synchronous scan is compared with the reference image to calculate the anatomical position, and the calculated anatomical position and the start position of the target range are used. The timing of performing the synchronous scan in the target range is estimated based on the above.
X-ray CT device. The X-ray CT apparatus according to any one of claims 1 to 10 , wherein the control unit controls to perform the synchronous scan in a target range including at least the object for which the biological information is acquired. A pedestal having a rotating part for rotating the X-ray tube, and
A sleeper with a top plate on which the subject is placed,
When a positioning scan is performed while relatively moving the subject and the gantry placed on the top plate, synchronization synchronized with the dynamics of the subject based on biological information related to the dynamics of the subject. A control unit that controls scanning
A reconstruction unit that reconstructs image data from the data collected by executing the main scan under the conditions determined based on the result of the synchronous scan, and
With
The control unit
Controlled to perform the synchronous scan at least in the target range including the target for which the biological information is acquired,
The anatomical position is calculated by comparing the real-time image reconstructed in real time from the data collected by the synchronous scan with the reference image, and the calculated anatomical position and the start position of the target range are obtained. Based on the above, the timing of performing the synchronous scan in the target range is estimated .
X-ray CT device. A pedestal having a rotating part for rotating the X-ray tube, and
A sleeper with a top plate on which the subject is placed,
When a positioning scan is performed while relatively moving the subject and the gantry placed on the top plate, synchronization synchronized with the dynamics of the subject based on biological information related to the dynamics of the subject. A control unit that controls scanning
A transmitter that transmits image data reconstructed from the data collected by the synchronous scan to another device, and a transmitter.
With
The control unit
Controlled to perform the synchronous scan at least in the target range including the target for which the biological information is acquired,
The anatomical position is calculated by comparing the real-time image reconstructed in real time from the data collected by the synchronous scan with the reference image, and the calculated anatomical position and the start position of the target range are obtained. Based on the above, the timing of performing the synchronous scan in the target range is estimated.
X-ray CT device. The reconstruction unit according to any one of claims 1 to 4, 7, 9, and 12, wherein the reconstruction unit reconstructs image data from the data collected by executing the main scan under the conditions determined by the user. X-ray CT device. The X-ray CT apparatus according to any one of claims 2, 6, 9 to 13, wherein the control unit reduces the dose emitted from the X-ray tube in the target range. The X-ray CT apparatus according to any one of claims 1 to 15, wherein the biological information is at least one of a respiratory phase and a cardiac phase.

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