JP2007275360A - X-ray computerized tomography diagnosis apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray computerized tomography diagnosis apparatus, where both of its optimum tomography timing function and complicated inspection process have been improved by optimizing tomography conditions based on contrast medium conditions. <P>SOLUTION: In the X-ray computerized tomography diagnosis apparatus where bolus tracking is done prior to the main scanning with a contrast medium to obtain diagnostic tomogram, a gantry controller 31 in a computer system 3 measures the time from the start of contrast medium injection to the end of bolus tracking and according to the measured time, changes the timing of start of tomography for main scanning. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bolus tracking assist function for capturing optimal imaging timing when used for contrast examination in clinical practice, and in particular, medical X-ray that irradiates a living body with X-rays and obtains information inside the body as an image. The present invention relates to a computer tomography diagnostic apparatus.

  In contrast medium imaging with an X-ray computed tomography diagnostic apparatus, it is important to perform a scan (main scan) for capturing a diagnostic image at the timing when the contrast medium administered to the subject flows into the imaging region. . Therefore, a preliminary scan (prep scan) is performed before the main scan, the inflow of contrast medium is detected based on the change in CT value measured by the prep scan, and the main scan is automatically performed in accordance with this. The technique which starts is known (for example, refer the following patent document 1).

In general, the prep scan is performed on a part different from the part to be subjected to the main scan. For example, when the liver is imaged by the main scan, the prep scan is performed on the abdominal aorta. For this reason, after the CT value measured by the prep scan exceeds the threshold value, the main scan is started at a timing when a certain time has passed. This is to wait for the contrast agent to sufficiently flow into the imaging region.
JP 2003-245275 A

  By the way, in recent years, multi-slice CT (hereinafter referred to as MSCT) has become multi-rowed, and wide-range imaging using thin slices has become possible in a short time. As a result, the imaging timing of the contrast agent that did not occur in the single slice CT era has become difficult.

  FIG. 8 is a schematic cross-sectional view of a subject by conventional general bolus tracking.

  In CT contrast examination, an agent that makes an X-ray absorption difference called a contrast agent is used, and blood flow information is imaged as shown in FIG. Thus, on the cross-sectional image of the subject 100, the contrast medium 101 sets the ROI in the artery, and the CT value in the blood is measured in the low-dose mode with low exposure.

FIG. 9 is a graph in which the measured values are expressed as time on the horizontal axis and the change in CT value over time on the vertical axis. In this graph, when the CT value exceeds the threshold value (HU) at which the lumen of the blood vessel is sufficiently stained with the contrast medium (t ₀ ), imaging of the arterial phase is started, and then the flow of the contrast medium in the body is followed. Helical scan is performed.

  Thus, since the imaging of the arterial phase starts immediately after the start of bolus tracking, it is impossible to change the imaging conditions. In fact, in clinical practice, differences in the body's blood flow dynamics such as body weight, body surface area, circulating blood volume, heart rate, cardiac output, blood vessel diameter, cardiac ejection fraction, blood flow velocity, disease, and location of blood vessels. Thus, many delays in the arrival time of the contrast agent have been reported. In clinical practice, as long as the patient receives an invasive examination, the result is required, so it is possible to reduce the overtaking of the contrast agent and the taking of the image at a time when it is too stained. We have to go.

  However, in the above-described prior art, the imaging conditions cannot be changed after the start of bolus tracking, and contrast medium injection conditions (contrast medium concentration, injection rate, injection method, blood vessel securing site) due to individual differences among subjects. ) And contrast medium dynamics, the imaging conditions may not be able to be adjusted to the optimal imaging timing. In addition, it is necessary to manually determine the imaging conditions and imaging conditions from information on the patient's physique and circulatory function, which makes the examination complicated.

  Accordingly, the present invention has been made in view of the above circumstances, and its purpose is to optimize imaging conditions based on contrast agent conditions, bolus tracking CT value measurement data, patient physique, and circulatory function. It is an object to provide an X-ray computed tomography diagnostic apparatus that improves the function of matching the optimum timing and the complexity of the examination.

  That is, the X-ray computed tomography diagnostic apparatus of the present invention is an X-ray computed tomography diagnostic apparatus that performs bolus tracking prior to a main scan for imaging a tomographic image for diagnosis using a contrast agent. The imaging start timing of the main scan is changed according to the state of bolus tracking.

  The X-ray computed tomography diagnostic apparatus of the present invention is an X-ray computed tomography diagnostic apparatus that performs bolus tracking prior to a main scan for imaging a tomographic image for diagnosis using a contrast agent. Control means for controlling the imaging start timing of the main scan according to the bolus tracking state is provided.

  In the present invention, the contrast agent dynamics in the blood vessel are measured and reflected in the imaging conditions by using a temporal change curve of the CT value created during bolus tracking after the contrast agent injection.

  According to the present invention, the function of matching the optimal timing and the complication of the examination are improved by optimizing the imaging conditions based on the contrast medium conditions, the bolus tracking CT value measurement data, the patient's physique, and the circulation function. An X-ray computed tomography diagnostic apparatus can be provided.

  In addition, when performing a CT contrast examination, it is possible to take an image at an optimal timing for the target disease regardless of an empirical contrast method by a facility or an examiner. Further, the inspection operation is simplified.

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

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a main part of an X-ray computed tomography diagnostic apparatus (X-ray CT diagnostic apparatus) according to the first embodiment of the present invention.

  In FIG. 1, the X-ray CT diagnostic apparatus according to the present embodiment includes a scan gantry 1 and a computer apparatus 3. The scan gantry 1 is a component for collecting projection data related to a subject. The projection data collected by the scan gantry 1 is subjected to processing such as image reconstruction and real prep in the computer device 3.

  The scan gantry 1 includes a bed 10, an X-ray tube device 11, an X-ray detector 12, a gantry rotation drive unit 13, a high voltage generation unit 14, a bed drive unit 15, and a data collection unit 16.

  In the scan gantry 1, the X-ray tube device 11 and the X-ray detector 12 are mounted on an annular rotary mount (not shown) in an opposing relationship. The rotating gantry is driven to rotate by the gantry rotation driving unit 13. At this time, the X-ray tube device 11 and the X-ray detector 12 rotate around the same rotation axis RA. The scan gantry 1 forms a cavity (imaging port) inside the rotation trajectory of the X-ray tube device 11 and the X-ray detector 12.

  The X-ray tube device 11 has an X-ray tube 21 and an X-ray filter 22. The X-ray tube 21 receives power supply from the high voltage generator 14 and emits X-rays toward the X-ray detector 12. The X-ray filter 22 removes low energy components to reduce exposure. The high voltage generator 14 includes a high voltage transformer, a filament current generator, and a rectifier.

  In addition, the high voltage generator 14 includes a tube voltage switch, a filament current switch, and the like in order to adjust the tube voltage and the filament current arbitrarily or stepwise.

  The X-ray detector 12 is configured by arranging a plurality of X-ray detection element arrays in a direction along the rotation axis RA. The X-ray detector 12 detects incident X-rays and outputs an electrical signal corresponding to the intensity.

  The subject is placed on the top 20 of the bed 10. The bed 10 is driven by the bed driving unit 15 to move the top plate 20 in the longitudinal direction (left-right direction in FIG. 1). Usually, the bed 10 is installed such that the longitudinal direction thereof is parallel to the rotation axis RA. In general, the subject is placed on the top plate 20 so that the body axis is along the rotation axis RA. Thus, the subject is inserted into the cavity of the scan gantry 1 as the top plate 20 moves.

  The data collection unit 16 collects the output of the X-ray detector 12 and supplies it to the computer apparatus 3. Note that an interface using a slip ring, optical communication, or the like is interposed between the X-ray detector 12 and the data collection unit 16. Thereby, the data collection unit 16 can collect the output of the X-ray detector 12 while continuously rotating the rotary mount.

  The computer apparatus 3 includes a gantry control unit 31, a preprocessing unit 32, an image reconstruction unit 33, a display unit 34, and an operation panel 35. The gantry control unit 31, the preprocessing unit 32, the image reconstruction unit 33, the display unit 34, and the operation panel 35 are connected to each other via a data / control bus 36.

  Data supplied from the scan gantry 1 to the computer apparatus 3 is supplied as projection data to the image reconstruction unit 33 via the preprocessing unit 32. The image reconstruction unit 33 reconstructs tomographic image data based on the projection data. The tomographic image data is displayed on the display unit 34 and also supplied to the gantry control unit 31 to be used for processing for determining the timing of starting the main scan.

  The operation panel 35 is provided for the operator to input various information and various instructions including, for example, main scanning conditions and prep processing conditions. The operation panel 35 includes an operation screen.

  The gantry control unit 31 controls the operation of the scan gantry 1 so as to perform a prep scan and a main scan. The gantry control unit 31 further has the following functions.

  The first function is to determine the speed of blood flow based on an image obtained by a prep scan. The second function determines the waiting time from the end of the prep scan to the start of the main scan based on the determined blood flow speed. The third function outputs guidance related to the main scan in synchronization with the start timing of the main scan determined by the waiting time. The fourth function is to determine the scanning speed in the direction along the rotation axis RA in the main scan, that is, the moving speed of the top board 20 based on the determined blood flow speed. The fifth function sets the moving speed of the top plate 20 during the main scan to the determined speed. The sixth function changes the information collection density per unit time in the direction along the rotation axis RA according to the moving speed of the top board 20 in the main scan.

  Next, the operation of the X-ray CT diagnostic apparatus configured as described above will be described.

The present invention adds the following processing to the above-described prior art. That is,
(1) The imaging condition is set from the contrast condition, and the imaging condition is manually changed during the bolus tracking.
In this case, i) information on the physique of the subject, circulatory function information, lesion, and imaging region is set from the interface of the CT apparatus or the injector, and the contrast condition is automatically set. In addition, the imaging condition is set based on the physique of the subject, circulatory function information, lesion, imaging region information, and contrast agent condition, and a bolus tracking CT value curve (time density curve; TDC) is used. To change the shooting conditions.

    ii) The inclination is detected from the curve obtained from the CT value measurement data obtained by moving average of the physique, circulation function and bolus tracking of the subject, and the time from the start of bolus tracking to reaching the threshold is detected.

    iii) Change to the optimum shooting conditions based on the shooting range, breath holding time, and data of ii) above.

(2) The imaging condition is set from the contrast condition, and the imaging condition is manually changed during the bolus tracking.
i) Set the contrast conditions. This sets the shooting conditions.

    ii) During the bolus tracking, the user manually changes the imaging condition by visually observing the curve of the image data obtained by bolus tracking and the curve of the CT value over time.

  In this way, examinations depending on individual differences such as contrast medium dynamics are standardized, and an auxiliary function is added to always provide image quality that can contribute to diagnosis to the clinical site.

  Hereinafter, the processing flow of the X-ray CT diagnostic apparatus according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.

  When this sequence is started, first, in step S1, an imaging condition is set according to the patient's physique, circulatory function, lesion, and imaging region so that the operator can create an imaging plan. The imaging conditions are automatically set by the contrast condition parameters and the patient. These operations are performed when the operator performs an input operation on the operation panel 35 while referring to the display screen of the display unit 34 of the computer device 3.

  For example, when the above-described contrast condition is changed, the imaging condition setting is changed. When the contrast agent injection time is changed, the pause time after bolus tracking, the intermittent scan time, the pause time before bolus tracking, the threshold value at the time of bolus tracking, and the like change. Further, the contrast agent amount may be used instead of the contrast agent injection time. When the injection speed of the contrast agent is changed, the inclination calculation correction coefficient and the threshold during bolus tracking change.

  Further, when the contrast agent concentration is changed, the slope calculation correction coefficient and the threshold value during bolus tracking change. Furthermore, the pause time after bolus tracking changes depending on the presence or absence of the physiological salt number flash, and the pause time after bolus tracking changes depending on the viscosity of the contrast agent.

  If the plan is created in this manner, in step S2, a scano, which is a positioning image for determining the photographing range, is photographed. Next, in step S3, the gantry control unit 31 operates the scan gantry 1 so that a prep scan for one slice is performed, and imaging in a non-contrast phase is performed. In step S4, a bolus tracking cross section and a threshold are set from the image created in the non-contrast phase.

  In step S5, the injector is synchronized, the contrast medium is injected into the subject, and the measurement of the CT value in the blood of the subject is started by bolus tracking. Next, in step S6, while the moving average of the curve of the CT value over time is being performed, the curve of the CT value over time is raised and bolus tracking is performed as shown in FIG.

FIG. 3 is a graph showing changes in CT values over time, with the horizontal axis representing time and the vertical axis representing CT values. Here, the time (A) from the start of bolus tracking until the curve of change with time (CT value) reaches a predetermined threshold (TH _t ) at time t ₁ is detected. As a result, the processes in steps S6 and S7 are repeated until the time until the CT value reaches the predetermined threshold value (TH _t ) is detected in step S7.

If the time (B) until the CT value reaches the predetermined threshold value (TH _t ) at time t ₂ is detected in step S7, the process proceeds to step S8. In step S8, the gantry control unit 31 changes the imaging condition to the optimum imaging condition based on the parameters, ie, the imaging range, breath holding time, circulation function, and time from the start of bolus tracking until the time-dependent change curve reaches the threshold value. Is done.

  In the gantry control unit 31, for example, the imaging condition is changed by data obtained as a parameter. However, in the imaging range, the HP, the number of columns, the bed speed, the image acquisition slice thickness, the pause time after bolus tracking, and the imaging range are changed. Is done. When the time from the start of bolus tracking to the time-varying curve reaching the threshold value is changed, the pause time after bolus tracking changes. When the heart rate, cardiac output, blood pressure, blood viscosity, etc. are changed, the pause time after bolus tracking changes.

Then, if the CT value of a preset threshold TH _h at temporal change curve described above at the step S9 is reached, the process proceeds to step S10, since it took trigger helical scan (main scan) Is started. That is, by changing the pause time after bolus tracking, the imaging start time by the helical scan can be changed. Therefore, in order to obtain the optimum imaging start time by helical scanning, the pause time after bolus tracking is changed. Thereafter, when the helical scan is performed and the photographing is finished, this sequence is finished.

  As described above, in the present embodiment, in order to match the imaging timing for starting the helical scan described above, the pause time after bolus tracking (B in FIG. 3) is changed as shown in the correspondence table of FIG. . This is because a patient with a long time from the start of injection of contrast medium to the end of bolus tracking (A in FIG. 3) takes a long time to reach the contrast contrast peak after completion of bolus tracking compared to many cases. This is because (B) is often slow. In the X-ray CT diagnostic apparatus according to this embodiment, the computer apparatus 3 automatically determines the rest time (B) after bolus tracking according to the correspondence table of FIG. . Thereby, it can test | inspect at the optimal timing according to contrast agent conditions, and can improve complication of a test | inspection.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  In the first embodiment described above, the time from the start of injection of the contrast agent to the end of bolus tracking is detected by setting a predetermined threshold value. In the second embodiment described below, the time period of the CT value is detected. It is obtained by detecting the slope of the curve of the change of the target.

  In the second embodiment, the configuration of the X-ray CT diagnostic apparatus is the same as the configuration of the X-ray CT diagnostic apparatus of the first embodiment shown in FIG. Are denoted by the same reference numerals, and illustration and description thereof are omitted.

  FIG. 5 is a flowchart for explaining the processing flow of the X-ray CT diagnostic apparatus according to the second embodiment of the present invention.

  The processing operations of steps S21 to S26 and steps S29 to S30 in the flowchart of FIG. 5 are the same as steps S1 to S6 and steps S9 to S10 in the flowchart of FIG. The description thereof will be omitted.

In steps S21 to S25, setting of imaging conditions, scan imaging, non-contrast imaging, contrast agent injection, and bolus tracking are executed. Next, in step S26, a moving average of the curve of the CT value with time is performed, and as shown in FIG. 3, the curve of the CT value with time rises and bolus tracking is performed. Here, the slope of the curve of change with time (CT value) from the start of bolus tracking is detected. This inclination is an inclination immediately before the end of bolus tracking (immediately before the CT value reaches a predetermined threshold value (TH _t )). As a result, the processing in steps S26 and S27 is repeated until the slope of the curve of change over time is detected in step S27.

  Then, if the slope of the time-dependent change curve is detected in step S27, the process proceeds to step S28. In this step S28, the shooting conditions are changed to the optimum shooting conditions based on the shooting range, breath holding time, circulation function, and inclination.

  For example, although the parameters of the imaging conditions are changed by the obtained data, HP, the number of columns, the bed speed, the image collection slice thickness, the pause time after bolus tracking, and the imaging range are changed depending on the imaging range and inclination. When the heart rate, cardiac output, blood pressure, blood viscosity, etc. are changed, the pause time after bolus tracking changes.

Thereafter, if the CT value reaches the threshold value TH _h previously set by time-dependent change curve described above in step S29, helical scan (main scan) is started in step S30. Then, when the helical scan is performed and the photographing is finished, this sequence is finished.

  Thus, according to the second embodiment, the slope of the curve of the CT value with time is detected, and the pause time after bolus tracking is changed according to the detection result. Also according to the second embodiment, similarly to the above-described first embodiment, the inspection can be performed at the optimum timing according to the contrast agent condition, and the complication of the inspection can be improved.

(Third embodiment)
Next, a third embodiment of the present invention will be described.

  In the first and second embodiments described above, the method for determining the pause time after bolus tracking has been described. In the third embodiment described below, the contrast agent condition for changing the pause time after bolus tracking is set. , Different from the first and second embodiments described above.

  In the second embodiment, the configuration of the X-ray CT diagnostic apparatus is the same as the configuration of the X-ray CT diagnostic apparatus of the first embodiment shown in FIG. Are denoted by the same reference numerals, and illustration and description thereof are omitted.

  FIG. 6 is a flowchart for explaining the processing flow of the X-ray CT diagnostic apparatus according to the third embodiment of the present invention.

  The processing operations of steps S41 to S46 and steps S49 to S50 in the flowchart of FIG. 6 are the same as steps S1 to S6 and steps S9 to S10 in the flowchart of FIG. The description thereof will be omitted.

In steps S41 to S45, setting of imaging conditions, scanography, non-contrast imaging, contrast agent injection, and bolus tracking are executed. Next, in step S46, a moving average of the curve of the CT value with time is performed, and as shown in FIG. 3, the curve of the CT value with time increases and bolus tracking is performed. Here, the time from the start of bolus tracking until the curve of change with time (CT value) reaches a predetermined threshold value (TH _t ) at time t ₁ is detected. Alternatively, the slope of the time-dependent change curve (CT value) may be detected from the start of bolus tracking. As a result, in step S47, the time until the CT value reaches the predetermined threshold value (TH _t ) is detected, or until the slope of the curve of change over time is detected, the above steps S46 and S47 are performed. The process is repeated.

In step S47, if the CT value has reached a predetermined threshold value (TH _t ) or if the slope of the time-varying curve is detected, the process proceeds to step S48. In step S48, the imaging conditions are changed to the optimum imaging conditions based on the contrast medium amount, the contrast medium injection speed, the CT value, the patient's weight, and the scan time. Depending on the amount of contrast medium, the injection speed of the contrast medium, the CT value, the weight of the patient, and the scan time, the rest time after bolus tracking and the imaging range change.

  For example, in the case of patients having different weights, it is necessary to change the injection rate of the contrast medium as shown in the table shown in FIG. This is because the total amount of blood is considered to be roughly proportional to body weight, and in order to maintain a high contrast medium contrast for each patient and effectively diagnose with as little contrast medium as possible, This is because it is necessary to make the agent concentration constant.

  Therefore, the operator performs an input operation according to the table of FIG. In this case, when the patient's body weight is 45 kg or less, the contrast medium injection rate is set to 2.5 ml / s, for 46 to 119 kg, 3 ml / s, and for 120 kg or more, 4 ml / s.

And the pause time after bolus tracking is
Pause time B = (contrast medium amount / injection rate) −0.75 * scan time
Is required.

Thereafter, if the CT value reaches the threshold value TH _h previously set by time-dependent change curve described above In step S49, the helical scan (main scan) is started in step S50. Then, when the helical scan is performed and the photographing is finished, this sequence is finished.

  As described above, according to the third embodiment, the injection speed of the contrast medium corresponding to the weight of the patient is manually set to make the examination very complicated, but the injection speed is automatically set. Therefore, the inspection can be simplified.

  According to the embodiment described above, the imaging conditions are automatically changed after the start of the bolus tracking, so that the imaging unevenness of the blood vessel lumen due to the imaging timing of the main scan being too early or too late is eliminated. In addition, it is possible to prevent additional imaging in the case of poor rendering at the target site. It is also considered useful in terms of excessive exposure. Furthermore, since imaging can be performed at an optimal timing, it is useful for reducing the amount of contrast medium injection and reducing side effects due to contrast medium allergy.

  And by realizing these things, it is possible to perform a patient-friendly examination.

  In the embodiment described above, the change of the pause time after the bolus tracking has been described with the computer apparatus 3 (gantry control unit 31). However, the present invention is not limited to this. May be changed manually. For example, if it is performed according to the correspondence table as shown in FIG. 4, it can be changed manually.

  In addition, the computer apparatus may be provided with calculation formulas and tables for the parameters, whereby the contrast condition and the imaging condition can be automatically determined.

  In determining the imaging conditions, the parameters to be considered are the contrast agent conditions (contrast agent injection time, contrast agent injection speed, contrast agent concentration, presence or absence of saline flush, contrast agent viscosity, contrast agent injection amount, contrast medium Type of agent), personal physique (breath holding time, weight, height, body surface area), circulatory function (heart rate, cardiac output, blood pressure, blood viscosity, blood pressure), lesion, imaging site (by bolus tracking) The threshold value is not limited to the set threshold value, the slope of the collected CT value over time curve, the time from the start of contrast agent injection or bolus tracking to the end time, and the set threshold value). In addition, imaging conditions corresponding to these contrast conditions (pause time before bolus tracking, intermittent scan time and threshold during bolus tracking, pause time after bolus tracking, main scan speed, main scan range, number of collection columns, collection The slice thickness is not limited to that described above.

  Furthermore, the sites to be subjected to contrast examination are the heart, abdomen (liver, pancreas, kidney, gallbladder), lower limbs, and the like.

  As mentioned above, although embodiment of this invention was described, in the range which does not deviate from the summary of this invention other than embodiment mentioned above, this invention can be variously modified.

  Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

It is a block diagram which shows the structure of the principal part of the X-ray computed tomography diagnostic apparatus (X-ray CT diagnostic apparatus) which concerns on the 1st Embodiment of this invention. It is a flowchart explaining the flow of a process of the X-ray CT diagnostic apparatus by the 1st Embodiment of this invention. It is a graph showing a time-dependent change of CT value by setting time as a horizontal axis and CT value as a vertical axis. It is the table | surface which showed the response | compatibility with the time from the contrast agent injection start to the end of bolus tracking, and the rest time after the bolus tracking until the main scan is started. It is a flowchart explaining the flow of a process of the X-ray CT diagnostic apparatus by the 2nd Embodiment of this invention. It is a flowchart explaining the flow of a process of the X-ray CT diagnostic apparatus by the 3rd Embodiment of this invention. It is the table | surface which showed the response | compatibility with a patient's body weight and the injection rate of a contrast agent. It is a schematic sectional drawing of the subject by the conventional general bolus tracking. It is the graph showing the time-dependent change of CT value by the conventional bolus tracking.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Scan gantry, 3 ... Computer apparatus, 10 ... Bed, 11 ... X-ray tube apparatus, 12 ... X-ray detector, 13 ... Mount rotation drive part, 14 ... High voltage generation part, 15 ... Bed drive part, 16 ... Data collection unit, 20 ... top plate, 21 ... X-ray tube, 22 ... X-ray filter, 31 ... gantry control unit, 32 ... preprocessing unit, 33 ... image reconstruction unit, 34 ... display unit, 35 ... operation panel, 36: Control bus.

Claims (11)

In an X-ray computed tomography diagnostic apparatus that performs bolus tracking prior to a main scan for taking a diagnostic tomographic image using a contrast agent,
An X-ray computed tomography diagnostic apparatus, wherein the main scan imaging start timing is changed according to the bolus tracking state.   2. The X-ray computed tomography diagnostic apparatus according to claim 1, wherein when the contrast agent dynamics in the subject are different, the imaging start timing of the main scan is changed.   2. The X-ray computed tomography according to claim 1, which has a function of manually determining imaging conditions when contrast medium dynamics in the subject are different during imaging by the bolus tracking. Imaging diagnostic device. In an X-ray computed tomography diagnostic apparatus that performs bolus tracking prior to a main scan for taking a diagnostic tomographic image using a contrast agent,
An X-ray computed tomography diagnosis apparatus comprising: control means for controlling imaging start timing of the main scan in accordance with the bolus tracking state.   5. The X-ray computed tomography diagnosis apparatus according to claim 4, wherein the control means changes the imaging start timing of the main scan when the contrast agent dynamics in the subject are different.   The control means detects a time from the start of the bolus tracking until the CT value of the subject reaches a predetermined threshold, and starts the main scan after the end of the bolus tracking according to the detected time. 6. The X-ray computed tomography diagnostic apparatus according to claim 5, wherein the resting time until is changed.   The control means detects the slope of the time-varying curve of the CT value until the CT value of the subject reaches a predetermined threshold after the bolus tracking is started, and according to the detected slope, 6. The X-ray computed tomography diagnosis apparatus according to claim 5, wherein a pause time from the end of the bolus tracking to the start of the main scan is changed.   The said control means has a function which determines the imaging start timing of the said main scan according to at least contrast agent conditions, a subject's physique, a circulatory function, a lesion, and an imaging | photography site | part. X-ray computed tomography diagnostic equipment.   The control means includes at least a contrast agent injection amount, a contrast agent injection time, a contrast agent injection speed, a contrast agent concentration, the presence or absence of a saline flush, a contrast agent viscosity, and a temporal change curve of CT values collected by bolus tracking. 6. The X-ray computed tomography diagnosis apparatus according to claim 5, wherein the imaging start timing of the main scan is changed according to one of the body weight of the subject and the image.   10. The X-ray computed tomography diagnostic apparatus according to claim 5, wherein the main scan imaging start timing can be changed by an input operation on an operation panel.   The X-ray computed tomography diagnostic apparatus according to any one of claims 5 to 10, wherein the target sites are at least a heart, an abdomen, and a lower limb.

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