JP2014138910A - X-ray computer tomography apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in positioning and shape fitting of a heart in an X-ray CT apparatus that scans the heart at multiple timings with different contrast effects.SOLUTION: A scan mechanism 10 supports an X-ray tube 16 and an X-ray detector 18 rotatably around a subject P in order to scan the subject P with an X-ray. A storage part 52 stores a target breathing level at the breath-holding time of the subject P. A breathing instruction part 40 uses the target breathing level to instruct the subject P to breathe. The storage part 52 stores a target heart rate or target breath-holding elapsed time at the start timing of scanning by the scan mechanism 10. A scan control part 44 controls the start timing of scanning in accordance with the target heart rate and a real-time heart rate value of the subject P or in accordance with the target breath-holding elapsed time and real-time breath-holding elapsed time of the subject P.

Description

  Embodiments described herein relate generally to an X-ray computed tomography apparatus that scans a heart with X-rays.

  A heart scan is performed by an X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT apparatus). For image diagnosis of the heart, a difference image between a CT image related to the heart in the contrast phase and a CT image related to the heart in the non-contrast phase is often used.

  The position and shape of the heart in the scan region become intense with pulsation and respiratory motion. Therefore, it is difficult to align the position and shape of the heart in the scan region during the contrast phase scan and the non-contrast phase scan, and are included in the CT image related to the contrast phase and the CT image related to the non-contrast phase, respectively. The position and shape of the heart region will be different. Therefore, the extraction accuracy of the blood vessel region due to the difference between these CT images is poor, and improvement in the image quality of the difference image is desired.

  An object is to realize improvement in accuracy of heart position and shape alignment in an X-ray CT apparatus that scans the heart at a plurality of timings with different contrast effects.

  The X-ray computed tomography apparatus according to this embodiment includes a scan mechanism that rotatably supports an X-ray tube and an X-ray detector around the subject in order to scan the subject with X-rays, and the subject A first storage unit that stores a target value of the breathing level at the time of breath holding, a breathing instruction unit that executes a breathing instruction to the subject using the target value of the breathing level, and a scan mechanism A second storage unit that stores a target value of a heart rate at a start timing or a target value of an elapsed time of breath holding; and a target value of the heart rate and a measured value of a real-time heart rate of the subject, or the target A control unit that controls the start timing in accordance with a breath holding elapsed time and a measured value of the subject's real-time breath holding elapsed time.

The figure which shows an example of the system configuration | structure of the X-ray CT apparatus which concerns on embodiment of this invention. The figure which shows the other example of the system configuration | structure of the X-ray CT apparatus which concerns on embodiment of this invention. The figure which shows the structure of the X-ray CT apparatus which concerns on embodiment of this invention. The figure which shows an example of the test | inspection sequence performed under control of the system control part of FIG. The figure which shows the example of a display of the target respiration level displayed on the monitor of FIG. The figure which shows the 1st pattern of the 2nd target breath holding level of FIG. The figure which shows the 2nd pattern of the 2nd target breath holding level of FIG. The figure which shows the typical flow of the control processing of the start timing of the 2nd heart scan performed under control of the system control part of FIG. The figure which shows an example of the test | inspection sequence which concerns on the modification 1 performed under control of the system control part which concerns on the modification 1 of this embodiment. The figure which shows an example of the test | inspection sequence which concerns on the modification 2 performed under control of the system control part which concerns on the modification 2 of this embodiment.

  Hereinafter, an X-ray CT apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  In the X-ray CT apparatus, an X-ray tube and an X-ray detector are combined into one body, and the ROTATE / ROTATE type that rotates around the subject, and a large number of detection elements are arranged in a ring shape, and the X-ray tube There are various types such as a STATIONARY / ROTATE type that rotates around the subject, but the present embodiment can be applied to any type. Here, the ROTATE / ROTATE type will be described.

  Image reconstruction methods used by the X-ray computed tomography apparatus include a full scan method and a half scan method. In the full scan method, in order to reconstruct the data of one volume of CT image, projection data for one round around the subject, that is, about 2π [rad] is required. Further, in the half scan method, projection data for π + α [rad] (α: fan angle) is required to reconstruct the data of one volume of CT image. In this embodiment, any of the full scan method and the half scan method can be applied. However, in the following description, it is assumed that the present embodiment employs the full scan method for specific description.

  The X-ray CT apparatus according to the present embodiment scans the heart of a subject, and executes a heart scan at each of two timings at which the contrast effect of the diagnostic region in the heart region is different. The cardiac scan includes the following two scanning methods. The first method is to collect projection data by irradiating only a specific electrocardiographic phase with X-rays in synchronization with the electrocardiogram waveform. In this case, CT image data is reconstructed based on the collected projection data. The second method is to collect projection data for a plurality of rounds while continuously irradiating X-rays (so-called dynamic scan). In this case, CT image data is reconstructed based on the projection data of a specific electrocardiographic phase in the collected projection data. In the present embodiment, the above-described two types of heart scans can be applied, but for the sake of simplicity of the following description, the second heart scan is executed.

  In this embodiment, it is assumed that the heart scan is executed twice. The heart scan that is performed first will be referred to as the first heart scan, and the heart scan that is performed after the first heart scan is referred to as the second heart scan.

  1 and 2 are diagrams showing a schematic system configuration of the X-ray CT apparatus according to the present embodiment. In the system configuration shown in FIG. 1, an X-ray CT apparatus, an electrocardiograph, and a respiration sensor are connected via a cable. In the system shown in FIG. 1, the subject and the operator can use a monitor mounted on the X-ray CT apparatus and a monitor mounted on the respiration sensor. On the other hand, in the system configuration shown in FIG. 2, an X-ray CT apparatus incorporating a respiration sensor and an electrocardiograph are connected via a cable. In the system of FIG. 2, the subject and the operator use only the monitor mounted on the X-ray CT apparatus. In order to specifically carry out the following description, it is assumed that the X-ray CT apparatus according to the present embodiment is under the system configuration of FIG.

  FIG. 3 is a diagram showing a configuration of the X-ray CT apparatus according to the present embodiment. As shown in FIG. 1, a scanning mechanism (gantry) 10 and an image processing apparatus 30 are mounted.

  The scanning mechanism 10 has various mechanisms for scanning the subject P with X-rays. Specifically, the scanning mechanism 10 is mounted with an annular or disk-shaped rotating frame 12. On the inner peripheral side of the rotating frame 12, a scan region into which the subject P placed on the top 14 is inserted is formed. The top plate 14 is supported by a bed (not shown) so as to be slidable along the longitudinal direction and the vertical direction.

  The rotating frame 12 supports the X-ray tube 16 and the X-ray detector 18 so as to face each other with the subject P placed on the top plate 14 interposed therebetween. The rotating frame 12 rotates the X-ray tube 16 and the X-ray detector 18 around the rotation axis Z in response to the driving signal supplied from the rotation driving unit 20. The rotation axis Z of the rotary frame 12 is typically arranged in parallel with the long axis of the top plate 14. The rotation driving unit 20 rotates the rotating frame 12 according to control by the scan control unit 44 in the image processing apparatus 30.

  The X-ray tube 16 receives an application of a high voltage from the high voltage generator 22 and generates X-rays. The high voltage generator 22 applies a high voltage to the X-ray tube 16 according to control by the scan controller 44 in the image processing apparatus 30.

  The X-ray detector 18 detects X-rays generated from the X-ray tube 16 and transmitted through the subject P, and generates a current signal corresponding to the detected X-ray intensity. A data acquisition circuit (DAS) 24 is connected to the X-ray detector 18.

  The data acquisition circuit 24 reads a current signal from the X-ray detector 18 according to control by the scan control unit 44. The data acquisition circuit 24 amplifies the read current signal and digitally converts the amplified current signal to generate projection data that is a digital signal. The generated projection data is supplied to the image processing apparatus 30 via a non-contact data transmission unit (not shown). A set of projection data related to one view (X-ray irradiation angle) is referred to as a projection data set.

  The electrocardiograph 100 and the respiration sensor 200 are connected to the image processing apparatus 30 via a cable or the like.

  The electrocardiograph 100 electrically detects an electrical signal (electrocardiogram signal) generated from the heart of the subject P, and generates an electrocardiogram waveform based on the detected electrocardiogram signal. The generated electrocardiogram waveform data is supplied to the image processing device 30. The electrocardiograph 100 measures the heart rate related to the subject P. Specifically, the electrocardiograph 100 measures the heart rate per minute from the generated electrocardiogram waveform. A heart rate measurement value (hereinafter referred to as a heart rate value) is supplied to the image processing apparatus 30. Thus, the electrocardiograph 100 functions as an electrocardiogram waveform generation unit and a heart rate measurement unit.

  The respiration sensor 200 measures a respiration level related to the subject P. The respiratory level is a measured value that periodically changes with the respiratory motion of the subject P. As the respiration sensor 200, any existing type can be used. For example, a laser wavelength device that measures the movement of the abdomen of the subject P can be used. In this case, typically, the breathing level corresponds to the position of the abdominal surface of the subject P that changes with breathing motion. A measured value of the respiration level (hereinafter referred to as a respiration level value) is supplied to the image processing device 30. Further, the respiration sensor 200 measures the breath holding elapsed time of the subject P in real time based on the respiration level value. The breath holding elapsed time is an elapsed time from the time when the subject P starts to hold the breath to the measurement time. The breath holding elapsed time is ideally defined as a period during which the respiration level value is maintained at a constant value, and in practice, a period during which the respiration level value remains within the predetermined range. A measured value of the breath holding elapsed time (hereinafter referred to as a breath holding elapsed time value) is supplied to the image processing apparatus 30. Thus, the respiration sensor 200 functions as a respiration level measurement unit and a breath holding elapsed time measurement unit.

  The image processing apparatus 30 includes an interface unit 32, a preprocessing unit 34, a reconstruction unit 36, a subtraction unit 38, a breathing instruction unit 40, a recording unit 42, a scan control unit 44, a monitor 46, a speaker 48, an operation unit 50, and a storage unit. 52 and a system control unit 54.

  The interface unit 32 transmits and receives data between the scanning mechanism 10, the electrocardiograph 100, and the respiration sensor 200 and the image processing apparatus 30.

  The preprocessing unit 34 performs preprocessing such as logarithmic conversion and sensitivity correction on the projection data supplied from the data collection circuit 24. By performing the preprocessing, projection data used for image reconstruction is generated. The projection data set is managed in association with the electrocardiographic phase on the electrocardiogram waveform from the electrocardiograph 100.

  The reconstruction unit 36 reconstructs CT image data related to the heart of the subject P based on the projection data that has been preprocessed. Specifically, the reconstruction unit 34 generates CT image data related to a specific electrocardiographic phase based on a plurality of projection data sets related to the specific electrocardiographic phase. As described above, in the present embodiment, the first heart scan and the second heart scan are executed. The CT image data based on the projection data collected by the first cardiac scan is the first CT image data, and the CT image data based on the projection data collected by the second cardiac scan is the second CT image. We will call it data.

  The subtracting unit 38 subtracts the first CT image data and the second CT image data, and generates difference image data based on the first CT image data and the second CT image data. To do. For example, the subtraction unit 38 subtracts the data of the second CT image from the data of the first CT image in order to generate the data of the difference image.

  The breathing instruction unit 40 executes a breath holding start instruction and a breath holding end instruction via the monitor 46 and the speaker 48. In the breath holding start instruction, the breathing instruction unit 40 instructs the subject P to breathe using the target breath holding level. For example, the breathing instruction unit 40 notifies the subject P of the target breath holding level by displaying the target breath holding level on the monitor 46. This prompts the subject P to hold his / her breath at the target breath holding level. The target breath-hold level is a target value of the breath level targeted by the subject P for holding the breath, and is used to prompt the subject P to hold the breath at a uniform breath level over different timing scans. It becomes a landmark. The subject P holds his / her breath so that the real-time measurement value of the breathing level matches the target breath-holding level when holding his / her breath.

  The recording unit 42 monitors the heart rate value from the electrocardiograph 100 and records the heart rate value during the heart scan. The recorded heart rate value can be used as a target value of the heart rate at the start timing of the subsequent heart scan (hereinafter referred to as a target heart rate). Further, the recording unit 42 monitors the breath holding elapsed time value from the breathing sensor 200 and records the breath holding elapsed time value at the time of the heart scan. The recorded breath holding elapsed time value can be used as a target value of the breath holding elapsed time at the start timing of the subsequent heart scan (referred to as a target breath holding elapsed time). In addition, the recording unit 42 monitors the respiration level value from the respiration sensor 200, and the respiration level value at the time of heart scanning (that is, when the subject P is holding his / her breath) (hereinafter, referred to as a breath holding level). Record. The recorded breath hold level can be used as a target breath hold level in subsequent cardiac scans.

  The scan control unit 44 controls the scan mechanism 10 to scan the subject P with X-rays. Specifically, first, the scan control unit 44 determines whether or not the real-time heart rate value from the electrocardiograph 100 satisfies a scan start condition based on the target heart rate (hereinafter referred to as a heart rate condition). judge. When it is determined that the heart rate condition is satisfied, the scan control unit 44 controls the scan mechanism 10 and starts a heart scan. On the other hand, when it is determined that the heart rate condition is not satisfied, the scan control unit 44 waits for the start of the heart scan. As an alternative to the determination based on the heart rate value, the scan control unit 44 may use the breath holding elapsed time value. In this case, specifically, first, the scan control unit 44 refers to a scan start condition (hereinafter referred to as a breath hold elapsed time condition) in which the real-time breath hold elapsed time value from the breath sensor 200 is based on the target breath hold elapsed time. It is determined whether or not the above is satisfied. When it is determined that the breath-hold elapsed time condition is satisfied, the scan control unit 44 controls the scan mechanism 10 and starts a cardiac scan. On the other hand, when it is determined that the breath holding elapsed time condition is not satisfied, the scan control unit 44 waits for the start of the cardiac scan. As described above, the scan control unit 44 performs the subject by the scan mechanism 10 according to the target heart rate and the real-time heart rate value of the subject P, or according to the target breath-hold elapsed time and the real-time breath-hold elapsed time value of the subject P. The start timing of the heart scan of the specimen P is controlled.

  The monitor 46 is installed at a position where it can be visually recognized by the subject P during the cardiac scan. The monitor 46 displays the waveform of the respiratory level value from the respiratory sensor 200 and the target breath holding level in a predetermined display layout. The monitor 46 may display various CT images.

  The speaker 48 outputs sound for breathing instructions. For example, the speaker 48 outputs a sound such as “Please start breath holding” or “Please end breath holding”.

  The operation unit 50 receives various commands and information input from the operator. As an input device, a keyboard, a mouse, a switch, or the like can be used.

  The storage unit 52 stores projection data and various CT image data. In addition, the storage unit 52 stores a target breath holding level, a target heart rate, and a target breath holding elapsed time. The storage unit 52 stores a control program for the X-ray CT apparatus. This control program is for causing the system control unit 54 to execute a control function of the start timing of the cardiac scan described later.

  The system control unit 52 functions as the center of the X-ray CT apparatus. Specifically, the system control unit 52 reads out a control program stored in the storage unit 50 and expands it on the memory, and controls each unit according to the expanded control program.

  Next, an operation example of the X-ray CT apparatus according to the present embodiment will be described using a specific inspection sequence as an example. In the following examination sequence, it is assumed that the first heart scan is a contrast scan and the second heart scan is a non-contrast scan. The contrast scan means a scan executed in a contrast phase having a relatively high contrast effect, such as a contrast agent injection period. An example of the contrast scan is CTA (CT Angiography). In contrast, a non-contrast scan means a scan performed in a non-contrast phase where the contrast effect is relatively low, such as after the end of the injection of contrast agent. In the present embodiment, it is assumed that the non-contrast phase includes a period corresponding to a scan for delayed contrast enhancement (Late Enhance).

  FIG. 4 is a diagram illustrating an example of an inspection sequence according to the present embodiment, which is performed under the control of the system control unit 54. As shown in FIG. 4, a monitoring scan for monitoring the contrast effect is performed before the first cardiac scan. First, a contrast agent is injected into the subject P by an operator such as a technician. Then, after the start of the injection of the contrast agent, the operator inputs a monitoring scan start instruction via the operation unit 50. When the start instruction is input via the operation unit 50, the scan control unit 44 starts the monitoring scan. During the monitoring scan, the scan control unit 44 continuously irradiates the X-ray tube 16 with X-rays having a lower X-ray dose than the first heart scan while rotating the rotating frame 12, and the data collection unit 24. To collect projection data. The reconstruction unit 36 generates CT image data related to a predetermined cross section in time series based on the collected projection data. The predetermined cross section is set so as to include, for example, an examination site. The scan control unit 44 monitors a contrast agent concentration index value (for example, an average CT value) in a predetermined ROI on a CT image generated in time series. Average CT values and time-series CT images are displayed on the monitor 46.

  In response to the average CT value monitored by the scan control unit 44 reaching a predetermined threshold, the breathing instruction unit 40 executes a breath holding start instruction. The breathing instruction unit 40 may execute the breath holding start instruction when the user inputs a breath holding start instruction via the operation unit 50. In the breath holding start instruction, the breathing instruction unit 40 notifies the subject P of a message to start breathing via the monitor 46 and the speaker 48. At this time, as shown in FIG. 5, the breathing instruction unit 40 superimposes a line indicating the target breath-holding level TL on the waveform of the breathing level value of the subject P and displays it on the monitor 46. The subject P observes the monitor 46 and tries to hold his / her breath at a timing when his / her breathing level matches the target breath-holding level.

  When breath holding is performed, the recording unit 42 monitors the breathing level from the breathing sensor 200 and records the breath holding level. The recording unit 42 records, for example, the breathing level value at the time when the recording instruction is given as a breath holding level, triggered by the recording instruction made by the user via the operation unit 50. As another recording method, the recording unit 50 records the breath level value at the timing when the breath hold level determination condition is satisfied as the breath hold level. The determination condition of the breath holding level is defined according to a typical change pattern of the breath holding level with time. For example, the determination condition of the breath holding level is that the respiration level value is within a predetermined range for a predetermined period (for example, 1 second). The predetermined range can be arbitrarily set by the operator via the operation unit 50. The recorded breath holding level is stored in the storage unit 52.

  When the contrast effect reaches a desired level, the scan control unit 44 stops the monitoring scan and starts the first heart scan. When the first heart scan is started, the recording unit 42 records the heart rate value and the breath-hold elapsed time value at the time of the first heart scan. Note that the first heart scan is executed in a certain time width. Therefore, “at the time of contrast scan” refers to every time point in the contrast scan period such as the start time, the intermediate time, and the end time of the contrast scan. That is, “the heart rate and the breath holding elapsed time during the contrast scan” indicate the heart rate and the breath holding elapsed time at an arbitrary time during the contrast scanning. Further, “the heart rate and the elapsed time of breath holding during contrast scanning” may be an average value, an intermediate value, a maximum value, a minimum value, a mode value, etc. of the heart rate value and the elapsed time of breath holding during the cardiac scan period.

  When the first cardiac scan is completed by the scan control unit 44, the breathing instruction unit 40 executes a breath holding end instruction to the subject P via the monitor 46 and the speaker 48. When the breath holding end instruction is executed, the subject P resumes breathing.

  When the contrast effect at the examination site is sufficiently reduced and the scanning mechanism 10 is set in a standby state in preparation for the second heart scan (non-contrast scan), the operator can take a breath for the second heart scan. A stop start instruction (second breath hold start instruction) is input via the operation unit 50. In response to the input of the start instruction, the breathing instruction unit 40 executes a second breath holding start instruction. Note that the second heart scan is executed in response to the start instruction from the operator. However, this embodiment is not limited to this. For example, it may be automatically executed by a preset inspection program.

  In the second breath holding start instruction, the breathing instruction unit 40 sets the target breathing level waveform of the subject P in the same manner as the breath holding start instruction for the first heart scan (first breath holding start instruction). The breath holding level is superimposed and displayed on the monitor 46. There are two possible target breath-hold levels in the second breath-hold start instruction. The two patterns of target breath holding levels will be described below.

  FIG. 6 is a diagram showing a first pattern of the second target breath holding level TL2. In the case of FIG. 6, the first target breath-hold level TL1 and the second target breath-hold level TL2 are the same value. FIG. 7 is a diagram showing a second pattern of the second target breath holding level TL2. In the case of FIG. 7, the second target breath holding level TL2 is equal to the first actual breath holding level HL recorded by the recording unit 42. Note that the second target breath-holding level TL2 can be arbitrarily selected from the above-described first pattern and second pattern according to the subject P and the preference of the operator. When the target breath-hold level is displayed, the subject P tries to hold his / her breath at a timing when his / her breath level matches the target breath-hold level.

  At this time, the breathing instruction unit 40 issues a breathing instruction according to the magnitude relationship between the actual breath holding level of the subject P and the target breath holding level so as to guide the breathing level of the subject P to the target breath holding level. May be executed. For example, when the actual breath-hold level of the subject P is higher than the target breath-hold level, the breathing instruction unit 40 causes the speaker 48 to “breathe shallower and breathe more shallowly” in order to reduce the amplitude of the breath level of the subject P. Please output "etc." When the actual breath-hold level of the subject P is smaller than the target breath-hold level, the breathing instruction unit 40 increases the amplitude of the breath level of the subject P from the speaker 48 to “breath deeper”. Please output "etc." By giving a breathing instruction according to the magnitude relationship between the actual breath holding level and the target breath holding level, the subject P can be held at a breathing level closer to the target breath holding level.

  Further, the breathing instruction unit 40 may execute a breathing instruction according to whether or not the difference between the actual breath holding level of the subject P and the target breath holding level is within an allowable range. For example, when the difference is out of the allowable range, the breathing instruction unit 40 may notify the re-execution of breath holding via the monitor 46 and the speaker 48. When the difference is outside the allowable range, the scan control unit 44 may interrupt the second heart scan (turn off the standby state).

  Further, when an instruction to start breath holding is executed, the system control unit 54 executes a control process for the start timing of the second heart scan (non-contrast scan). FIG. 8 is a diagram showing a typical flow of the control processing of the start timing of the second heart scan performed under the control of the system control unit 54.

  In step S1, the system control unit 54 causes the electrocardiograph 100 to perform measurement processing (step S1). In step S1, the electrocardiograph 100 measures the heart rate of the subject P at the time of breath holding. The heart rate value is supplied to the image processing device 30.

  When step S1 is executed, the system control unit 54 causes the scan control unit 44 to execute determination processing (step S2). In step S2, the scan control unit 44 determines whether or not the heart rate value from the electrocardiograph 100 satisfies a heart rate condition based on the target heart rate. The heart rate condition is, for example, that the heart rate matches a threshold value based on the target heart rate, or that the heart rate value is included in a threshold range based on the target heart rate. For example, the threshold value is set to a value equal to the target heart rate, a value obtained by adding or subtracting a predetermined value to the target heart rate, or the like. The threshold range is set to a range between, for example, the sum of the target heart rate and a predetermined value (upper limit heart rate) and the difference between the target heart rate and the predetermined value (lower limit heart rate). Thus, in step S, the scan control unit 44 determines whether or not the heart rate value substantially matches the target heart rate.

  When it is determined in step S2 that the scan control unit 44 does not satisfy the heart rate condition (the heart rate value from the electrocardiograph 100 does not substantially match the target heart rate) (step S2: NO), the system control unit 54 again Proceed to step S1. Then, step S1 and step S2 are repeated until the heart rate condition is satisfied in step S2.

  When the scan control unit 44 determines in step S2 that the determination condition is satisfied (the heart rate value from the electrocardiograph 100 substantially matches the target heart rate) (step S2: YES), the system control unit 54 performs scan control. The unit 44 is caused to execute the second heart scan (step S3). In step S3, the scan control unit 44 controls the scan mechanism 10 similarly to the first heart scan, and executes the second heart scan.

  Thus, the control processing of the start timing of the second heart scan by the system control unit 54 is completed. In the above description of FIG. 8, the case where the start timing of the second heart scan is controlled according to the heart rate has been described. However, the start timing control process is not limited to this. For example, instead of the heart rate value, the start timing may be controlled according to the breath holding elapsed time value from the respiration sensor 200. The control process of the start timing in this case can be realized by the same process as when using the heart rate value. That is, it can be executed by replacing “heart rate value” in the description of the control processing of the start timing of the second heart scan with “breath holding elapsed time value”. Therefore, description of the start timing control process using the breath-hold elapsed time is omitted.

  As described above, the X-ray CT apparatus according to the present embodiment uses the first target breath-hold level or the first actual breath-hold level in the breath-hold instruction in the second heart scan. As a result, the respiratory phases during the first heart scan and the second heart scan can be made relatively uniform. Furthermore, when the X-ray CT apparatus according to the present embodiment performs the second heart scan, the heart rate (or breath-hold elapsed time) of the subject P is the heart rate (or breath-hold progress) during the first heart scan. The second heart scan is started at a timing substantially coincident with (time). Accordingly, the X-ray CT apparatus can relatively align the electrocardiographic phases of the subject P during the first heart scan and the second heart scan.

  With these two ideas, the X-ray CT apparatus according to the present embodiment can relatively align the position and shape of the heart in the scan region during the contrast scan and the non-contrast scan. Accordingly, the positions and shapes of the heart regions included in the CT image related to the contrast phase and the CT image related to the non-contrast phase are relatively aligned. Therefore, the extraction accuracy of the blood vessel region based on the difference between the CT image related to the contrast phase and the CT image related to the non-contrast phase is improved as compared with the conventional case, and the image quality of the difference image between the CT image related to the contrast phase and the CT image related to the non-contrast phase is improved. Is improved as compared with the prior art.

  Thus, the X-ray CT apparatus according to the present embodiment can improve the accuracy of heart position and shape alignment by scanning the heart at a plurality of timings with different contrast effects.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.

(Modification 1)
FIG. 9 is a diagram illustrating an example of an inspection sequence according to the first modification. As shown in FIG. 9, in the examination sequence according to the first modification, the breath holding start instruction is not performed during the monitoring scan as shown in FIG. 8, but is performed after the monitoring scan. For this reason, the X-ray CT apparatus according to the modified example 1 has the respiratory phase of the subject P during the first heart scan and the second scan even when the time interval between the monitoring scan and the contrast scan is relatively long. Easy to align.

(Modification 2)
FIG. 10 is a diagram illustrating an example of an inspection sequence according to the second modification. As illustrated in FIG. 10, in the examination sequence according to the second modification, the first heart scan is a non-contrast scan, and the second heart scan is a contrast scan. An example of the non-contrast scan according to Modification 2 is a scan for Ca Score (calcium score). The contrast scan according to Modification 2 corresponds to CTA. The scan control unit 44 according to the modification 2 controls the start timing of the contrast scan using the breath holding elapsed time recorded during the non-contrast scan.

(Modification 3)
In the present embodiment, an electrocardiogram waveform generation unit and a heart rate measurement unit are mounted on the electrocardiograph 100, and a respiration level measurement unit and a breath holding elapsed time measurement unit are mounted on the respiration sensor 200. did. In the third modification, the electrocardiograph 100 is not provided with a heart rate measurement unit, and the respiration sensor 200 is not provided with a breath holding elapsed time measurement unit. Alternatively, the X-ray CT apparatus according to the modified example 3 further includes a heart rate measuring unit and a breath holding elapsed time measuring unit.

  Thereby, the measurement of the heart rate and the measurement of the breath holding elapsed time can be executed in the X-ray CT apparatus.

  In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  As described above, according to the present invention, in the X-ray CT apparatus that scans the heart at a plurality of timings with different contrast effects, it is possible to improve the accuracy of heart position and shape alignment.

  DESCRIPTION OF SYMBOLS 10 ... Scanning mechanism, 12 ... Rotary frame, 14 ... Top plate, 16 ... X-ray tube, 18 ... X-ray detector, 20 ... Rotation drive part, 22 ... High voltage generation part, 24 ... Data collection part (DAS), DESCRIPTION OF SYMBOLS 30 ... Image processing apparatus, 32 ... Interface part, 34 ... Pre-processing part, 36 ... Reconstruction part, 38 ... Subtraction part, 40 ... Respiration instruction part, 42 ... Recording part, 44 ... Scan control part, 46 ... Monitor, 48 DESCRIPTION OF SYMBOLS ... Speaker, 50 ... Operation part, 52 ... Memory | storage part, 54 ... System control part, 100 ... Electrocardiograph, 2000 ... Respiration sensor.

The X-ray computed tomography apparatus according to the present embodiment uses an X-ray tube to execute a first X-ray scan and a second scan temporally after the first scan for a subject. an X-ray detector a supporting and scanning mechanism for lifting, the subject of breath holding SL you stores a target value of the respiratory level during憶部a target value of the respiratory level, the scan of the 1 The first storage unit, which is a target value of the respiratory level in the first scan, or a measured value of the respiratory level at the time of breathing of the subject in the first scan, and the subject using the target value of the respiratory level A breathing instruction unit that executes a breathing instruction; a second storage unit that stores a target value of a heart rate or a target value of an elapsed breath-holding time at the start timing of the second scan by the scan mechanism; Goal And a control unit for controlling the start timing according to the measured value of the subject's real-time heart rate or according to the target breath-hold elapsed time and the measured value of the subject's real-time breath-hold elapsed time. It has.

Claims (5)

A scanning mechanism for rotatably supporting an X-ray tube and an X-ray detector around the subject in order to scan the subject with X-rays;
A first storage unit for storing a target value of a respiration level at the time of breath holding of the subject;
A breathing instruction unit that executes a breathing instruction to the subject using the target value of the breathing level;
A second storage unit that stores a target value of a heart rate or a target value of an elapsed time of breath holding at a scan start timing by the scan mechanism;
Control the start timing according to the target value of the heart rate and the measured value of the subject's real-time heart rate, or according to the target breath-hold elapsed time and the measured value of the subject's real-time elapsed breath-hold time. A control unit,
An X-ray computed tomography apparatus comprising:   The X-ray computed tomography apparatus according to claim 1, further comprising a measurement unit that measures a heart rate of the subject or an elapsed time of breath holding of the subject.   The X-ray computed tomography apparatus according to claim 1, wherein the control unit determines whether a real-time measurement value of the heart rate substantially matches the target heart rate, and controls the start timing according to the determination result. .   2. The X-ray according to claim 1, wherein the respiration instruction unit executes the respiration instruction according to at least one of a magnitude relationship and a difference between a measurement value of a real-time respiration level of the subject and a target value of the respiration level. Computer tomography equipment.   The said control part determines whether the measured value of the real-time respiration level of the said subject substantially corresponds to the target value of the said respiration level, and controls the said start timing according to a determination result. X-ray computed tomography apparatus.

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