JP4406104B2 - X-ray CT system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a whole-body X-ray CT apparatus, and more particularly to an X-ray CT apparatus that injects a contrast medium into a subject and scans the subject at an optimal contrast timing.
[0002]
[Prior art]
Conventionally, in an X-ray CT apparatus, a real prep scan is known in which a contrast medium is injected into a subject in order to clarify a cancerous part, and the subject is scanned at an optimal contrast timing.
[0003]
In this real prep scan, first, a cross-sectional image of a subject is used, a region of interest such as an aorta (hereinafter abbreviated as ROI) within this cross-section is designated, and the CT value of that ROI is monitored. To do.
[0004]
Then, when the CT value of the ROI is increased by the contrast medium injected into the subject and the CT value reaches a certain threshold value, it is confirmed that the ROI is sufficiently stained by the contrast medium. Thereafter, collection of test data of the subject is started. Therefore, since scanning can be performed at an optimal contrast timing, it is extremely effective for capturing a reliable contrast timing independent of the subject.
[0005]
[Problems to be solved by the invention]
However, in the conventional real prep scan, since the CT value of the ROI in only one section of the subject is monitored, it is possible to observe whether or not the entire region of the organ to be observed is best stained with the contrast medium. There wasn't.
[0006]
Also, for example, when it is desired to observe the arterial layer and the portal vein layer, it is difficult to monitor both the arterial blood vessel and the portal vein blood vessel at the same time if there is no optimal arterial blood vessel or portal vein blood vessel in the same cross-sectional image. there were.
[0007]
An object of the present invention is to provide an X-ray CT apparatus capable of collecting examination data of a subject at an optimal contrast timing by monitoring the contrast state of the whole organ or the contrast state of different blood vessel groups. There is.
[0008]
[Means for Solving the Problems]
The present invention has the following configuration in order to solve the above problems. The present invention provides an X-ray beam generating means arranged to emit X-rays toward a subject, and arranged to detect X-rays transmitted through the subject, and a plurality of detection elements in the slice direction. An arrayed two-dimensional detector, an image generating means for generating three-dimensional data by scanning the subject by rotating the X-ray beam generating means and the two-dimensional detector, and a three-dimensional object the multiple ROI in 3-dimensional space based on the data, a designation unit which the operator is configured to be specified, after injecting a contrast agent into the subject, scans the three-dimensional region of the subject Thus, for each region of interest specified by the specifying unit , a monitoring unit for determining whether or not the CT value of the region of interest has reached a scan start condition individually set for the region of interest , Based on judgment CT value of the ROI in each region of interest, characterized in that it comprises a scan control unit for the starting the test scanning of the subject to when it reaches the scan start condition set individually to the region of interest, the .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the X-ray CT apparatus of the present invention will be described in detail with reference to the drawings.
[0017]
<First Embodiment>
FIG. 1 is a system configuration diagram showing a schematic configuration of the X-ray CT apparatus according to the first embodiment of the present invention. In FIG. 1, an X-ray CT apparatus 10 according to the first embodiment includes a system control unit 11, an operation unit 12, a gantry / bed control unit 13, a bed moving unit 15, an X-ray control device 17, and a high voltage generator 19. , An X-ray beam generation source 21, a detector 23, a rotating base 25, a data collection unit 27, a collected data storage device 29, an image reconstruction unit 31, and a display unit 33. The X-ray CT apparatus 10 exposes an X-ray beam while rotating an X-ray beam generation source 21 around a subject P.
[0018]
The operation unit 12 is a mouse, a keyboard, or the like, and inputs various information. The system control unit 11 includes a central processing unit (CPU) and the like, and the slice thickness, rotation speed, bed movement amount, and the like input from the operation unit 12 are used as a table / bed control signal with respect to the table / bed control unit 13. Output. The system control unit 11 outputs an X-ray beam generation control signal for controlling X-ray beam generation to the X-ray control device 17.
[0019]
The system control unit 11 outputs a detection control signal indicating the detection timing of the X-ray beam to the data collection unit 27. The system control unit 11 outputs a data collection control signal for data collection to the data collection unit 27.
[0020]
The gantry / bed control unit 13 rotates the gantry 25 based on the gantry / bed control signal output by the system control unit 11 and outputs a bed movement signal to the bed movement unit 15.
[0021]
The X-ray controller 17 controls the timing of high voltage generation by the high voltage generator 19 based on the X-ray beam generation control signal output by the system controller 11. The high voltage generator 19 supplies a high voltage for exposing the X-ray beam to the X-ray beam generation source 21 in accordance with a control signal from the X-ray controller 17.
[0022]
The X-ray beam generation source 21 emits a fan-shaped X-ray beam having a thickness in the slicing direction toward the subject from multiple directions by the high voltage supplied from the high voltage generator 19. The detector 23 detects the X-ray beam that has been exposed from the X-ray beam generation source 21 and transmitted through the subject.
[0023]
FIG. 2A is a diagram showing the detector 23 three-dimensionally. The detector 23 includes a two-dimensional detector having a multi-channel detection element and a plurality of detectors arranged in the slice direction. For each row, as in the single slice CT detector of FIG. 2B, detection elements of about 1,000 channels are arranged in an arc shape with the focal point of the X-ray beam generation source 21 as the center.
[0024]
The rotary mount 25 holds the X-ray beam generation source 21 and the detector 23. The rotating gantry 25 is rotated around a rotation axis passing through an intermediate point between the X-ray beam generation source 21 and the detector 23 by a gantry rotating mechanism (not shown). Collecting projection data of a plurality of slices (a plurality of cross sections) of the subject while the X-ray beam generation source 21 and the detector 23 make one rotation around the subject is referred to as one scanning operation.
[0025]
The data collection unit 27 simultaneously collects and outputs projection data of a plurality of slices of the subject based on the data collection control signal output by the system control unit 11. The collection data storage device 29 stores projection data of a plurality of slices of the subject collected by the data collection unit 27.
[0026]
The image reconstruction unit 31 simultaneously reconstructs a plurality of tomographic images of the subject based on the projection data of a plurality of slices stored in the acquired data storage device 29. The display unit 33 simultaneously displays a plurality of tomographic images of the subject reconstructed by the image reconstruction unit 31 on the monitor.
[0027]
Further, the system control unit 11 includes an ROI designation unit 41, a scan start condition setting unit 43, a CT value determination unit 45, and a scan control unit 47. The ROI designation unit 41 designates a plurality of ROIs in the three-dimensional data based on the plurality of tomographic images of the subject obtained by the image reconstruction unit 31.
[0028]
The scan start condition setting unit 43 sets a scan start condition for stopping a real prep scan performed by injecting the contrast agent from the contrast agent injector 44 into the subject P and starting a normal scan.
[0029]
The CT value determination unit 45 determines whether the CT values of the plurality of ROIs specified by the ROI setting unit 41 satisfy the scan start conditions set by the scan start condition setting unit 43.
[0030]
The scan control unit 47 starts a normal scan when the CT values of a plurality of ROIs satisfy the scan start condition. The scan control unit 47 performs low-dose X-ray exposure in the real prep scan, and relatively high-dose X-ray exposure in the normal scan.
[0031]
Next, the three-dimensional real prep processing by the X-ray CT apparatus of the first embodiment configured as described above will be described with reference to the flowchart of FIG.
[0032]
First, the ROI designation scan is performed by rotating the X-ray beam generation source 21 and the multi-slice detector 23 around the subject P, and three-dimensional data (volume data) of the subject P is collected. (Step S11). This three-dimensional data is volume data based on a plurality of tomographic images reconstructed by the image reconstruction unit 431.
[0033]
Next, the ROI designation unit 41 designates a plurality of ROIs for monitoring CT values in the three-dimensional data collected in step S11. For example, as shown in FIG. 4, R1, R2, and R3 are designated as three ROIs in the organ 51 of the three-dimensional data 50. Each of R1, R2, and R3 extends over a plurality of cross sections. The three ROIs are actually designated on the screen of the display unit 33 using a mouse or the like.
[0034]
For example, the following two methods can be exemplified as the ROI designation method. The first method is a method in which an appropriate window width is set for the CT value of the three-dimensional data, and the ROI is specified by using, for example, a 3D image obtained by extracting only the blood vessel portion that falls within the set window width. . The second method is a method of performing edge detection by performing differentiation processing or the like on the CT value of the three-dimensional data, extracting the contour of only a certain organ, and specifying the ROI.
[0035]
Next, the scan start condition setting unit 43 sets a scan start condition for starting collection of examination data (normal scan) of the subject P (step S13). As the scan start condition, for example, conditions as shown in FIG. 5A and FIG. 5B can be exemplified.
[0036]
In the example shown in FIG. 5A, the vertical axis is the CT value, the horizontal axis is the time, X ₀ is the threshold value, the CT value at R1 is CT1, the CT value at R2 is CT2, and the CT value at R3 is CT value. When CT3 is set, CT1> X ₀ , CT2> X ₀ , CT3> X ₀ are set as scan start conditions. That, CT1, CT2, each CT3 are all subject to the whether exceeds the threshold value X _0.
[0037]
In the example shown in FIG. 5B, (CT1 ² + CT2 ² + CT3 ² ) ^1/2 > X ₁ is scanned when the vertical axis is the CT value, the horizontal axis is the time, and X ₁ is the threshold value. Start condition. That, CT1, CT2, CT3 of the square root of the sum of the squares of each value to a condition whether exceeds the threshold value X _1.
[0038]
Note that scan start conditions other than the scan start conditions shown in FIGS. 5A and 5B may be used, or an appropriate name may be added to register the scan start conditions in advance. It may be set by reading the scan start condition.
[0039]
Next, after injecting the contrast medium into the subject P from the contrast medium injector 44 (step S15), the scan control unit 47 sends a low-dose control signal to the X-ray control device 17. The real prep scan is executed (step S17). In this real prep scan, the exposure dose to the subject P can be reduced by lowering the tube current mA of the X-ray beam generation source 21 to a lower dose than in the normal scan, or by using a special X-ray filter. it can.
[0040]
The scan control unit 47 may start the real prep scan in synchronization with the injection of the contrast medium from the contrast medium injector 44. In this case, when the contrast agent is injected from the contrast agent injector 44, an injection signal indicating the injection of the contrast agent is sent to the scan control unit 47, and the scan control unit 47 starts the real prep scan in synchronization with the injection signal. You can do it. In this way, the real prep scan can be surely performed at an appropriate timing.
[0041]
Further, the scan control unit 47 may intermittently emit X-rays for a while by sending an intermittent signal to the X-ray control device 17. In this way, the exposure dose to the subject P can be reduced.
[0042]
In this way, the CT value determination unit 45 monitors whether or not the CT values of a plurality of designated ROIs have reached the scan start condition (step S19). For example, in the example shown in FIG. 5A, all CT values of R1, R2, and R3 reach the threshold value X ₀ at time t ₁ . Further, in the example shown in FIG. 5 (b), at time t _2, R1, R2, respectively of the square root of the sum of the squares of the CT values of R3 reaches the threshold X _1.
[0043]
Furthermore, when the CT values of a plurality of designated ROIs reach the scan start condition, the scan control unit 47 performs a normal scan of the subject P (step S21). In this case, examination data is collected by exposing a relatively large amount of X-rays to the subject P.
[0044]
As described above, when a plurality of ROIs are designated using three-dimensional data, and the CT values of the designated plurality of ROIs reach the scanning start condition, the normal scan is started by increasing the X-ray dose. Inspection data can be collected at the timing when the color is best stained by the contrast medium. For this reason, cancer inflections etc. can be made clearer.
[0045]
FIG. 6 is a diagram illustrating the contrast timing by the conventional real prep scan. FIG. 7 is a diagram for explaining the contrast timing by the real prep scan of the first embodiment.
[0046]
As shown in FIG. 6A, in the conventional method, R1 is designated in the organ 51a of one cross section S1 (one slice), and the CT value of the designated R1 is the threshold value X ₀ at time t _3. When this is reached, a normal scan is started. Since only one cross section is observed in this method, the CT value of R2 does not reach the threshold value X ₀ at time t ₃ as can be seen from FIG. 7B. For this reason, examination data was collected at a timing when the entire organ was not sufficiently stained.
[0047]
On the other hand, as shown in FIG. 7 (a), in the method of the first embodiment, R1, R2, and R3 are designated in the organ 51b across a plurality of cross sections, and the CT values of R1, R2, and R3 are calculated. A normal scan is started at time t ₄ when all have reached the threshold value X ₀ . Therefore, examination data can be collected at the timing when the whole organ is best stained with the contrast medium.
[0048]
<Second Embodiment>
Next, an X-ray CT apparatus according to a second embodiment of the present invention will be described. The X-ray CT apparatus of the second embodiment is characterized in that examination data is collected at an optimal contrast timing for each blood vessel group of different blood vessel groups. A three-dimensional real prep process by the X-ray CT apparatus of the second embodiment will be described with reference to the flowchart of FIG.
[0049]
First, a scan for specifying ROI is performed, and three-dimensional data of the subject P is collected (step S31).
[0050]
Next, the ROI designation unit 41 designates a plurality of ROIs for monitoring CT values from the collected three-dimensional data. For example, as shown in FIG. 9, R4 is designated in the aorta 55 of the three-dimensional data 50 and R5 is designated in the organ 53.
[0051]
Next, the scan start condition setting unit 43 sets a scan start condition for starting the collection of examination data (normal scan) of the subject P (step S33). As the scan start condition, for example, a condition as shown in FIG. 10 can be exemplified.
[0052]
In the example shown in FIG. 10, when the vertical axis is a CT value, the horizontal axis is time, X ₀ and X ₁ are threshold values, the CT value at R4 is CT4, and the CT value at R5 is CT5, CT4 > X ₀ is a first scan start condition, and CT5> X ₁ is a second scan start condition. Incidentally, | CT4-CT5 | <X 2 may be used as the second scan start condition.
[0053]
Next, after starting the injection of the contrast medium into the subject P from the contrast medium injector 44 (step S35), the scan control unit 47 performs the first real prep scan for the designated R4 ( Step S37).
[0054]
Then, the CT value determination unit 45 monitors whether or not the designated CT value of R4 has reached the first scan start condition (step S39). If the CT value of the designated R4 has reached the first scan start condition at time t ₅ as shown in FIG. 10, the scan control unit 47 is generally of the object P to collect first test data A scan is performed (step S41).
[0055]
Next, the scan control unit 47 causes the second real prep scan for the designated R5 to be performed (step S43).
[0056]
Then, the CT value determination unit 45 monitors whether or not the designated CT value of R5 has reached the second scan start condition (step S45). If the CT value of the designated R5 has reached the second scan start condition at time t _6, as shown in FIG. 10, the scan control unit 47 is generally of the object P to collect second test data A scan is performed (step S47). Note that the processing from step S43 to step S47 is repeated as many times as necessary.
[0057]
In this way, the ROI is designated for each of the two blood vessels, the scan start condition is individually set for each ROI, and whether the CT value of the ROI has reached the scan start condition set for the ROI is determined. In order to determine, examination data can be collected at two different optimal contrast timings.
[0058]
In this case as well, the scan start timing may be synchronized with the contrast agent injection timing from the contrast agent injector 44, or X-rays may be intermittently emitted.
[0059]
FIG. 11 is a diagram illustrating the contrast timing by a conventional real prep scan. FIG. 12 is a diagram for explaining the contrast timing by the real prep scan of the second embodiment.
[0060]
As shown in FIG. 11A, in the conventional method, R4 (aorta) is designated in one cross section S2 (one slice), and the CT value of the designated R4 is the threshold value X ₀ at time t _7. When reaching the above, a normal scan (first scan) is started. In this method, the optimal contrast timing is provided for the arterial layer. However, since only R4 is observed, the optimal contrast timing of the balanced layer and the portal vein layer is not known. For this reason, the contrast timing of the balance layer and the portal vein layer depended on the operator's skill and experience. In FIG. 11B, the time td from the end time of the arterial layer to the start time of the equilibrium layer is a time depending on the operator's can and experience.
[0061]
On the other hand, as shown in FIG. 12A, in the method of the second embodiment, R4 (aorta) is designated in the blood vessel 55, R5 (portal vein) is designated in the blood vessel 53, and R4 CT value is the first scan starts when it reaches the first scan start condition at time t _7, the second scan begins when the CT value of R5 has reached the second scan start condition at time t ₉ the . Therefore, examination data can be collected at an optimal contrast timing for each of the arterial layer, the portal vein layer, and the equilibrium layer.
[0062]
<Third Embodiment>
Next, an X-ray CT apparatus according to a third embodiment of the present invention will be described. FIG. 13 is a configuration block diagram of a main part of the X-ray CT apparatus according to the third embodiment. As shown in FIG. 13, the X-ray CT apparatus further includes a slit 61 and a slit control unit 63.
[0063]
The slit 61 includes two X-ray shielding plates that are provided between the X-ray beam generation source 21 and the subject P and are movable along the slice direction. The slit control unit 63 is based on the plurality of ROIs specified by the ROI specification unit 41 in the system control unit 11a, and the two slits 61 so as to emit X-rays only to a plurality of slices corresponding to the plurality of ROIs. The width between the X-ray shielding plates is controlled.
[0064]
According to the X-ray CT apparatus configured as described above, as shown in FIG. 13, the slit control unit 63 exposes the X-ray FB to only, for example, three slices corresponding to designated R1 and R2. In order to control the width between the two X-ray shielding plates of the slit 61 as described above, the X-rays are not exposed to the remaining part of the organ 57 other than R1 and R2, and therefore the unnecessary exposure dose to the subject P Can be reduced.
[0065]
The present invention is not limited to the X-ray CT apparatuses of the first to third embodiments described above. In the first to third embodiments, the multi-slice detector 23 is used. For example, as shown in FIG. 14, the flat detector 65 is used, and the X-ray beam generation source 21 and the flat detector 65 are used. May be collected around the subject P to collect three-dimensional data.
[0066]
Further, using a single slice detector 23a as shown in FIG. 2B, a helical scan is performed by moving the bed 15a at a predetermined speed in the slice direction by the bed moving unit 15, and obtained by the helical scan. Helical data, that is, three-dimensional data of the subject may be collected.
[0067]
【The invention's effect】
According to the present invention, a plurality of regions of interest are designated by three-dimensional data, and the contrast state of the whole organ and the contrast state of different blood vessel groups are monitored. Test data of the subject can be collected at the timing.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing a schematic configuration of an X-ray CT apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a detector three-dimensionally.
FIG. 3 is a flowchart showing a three-dimensional real prep process by the X-ray CT apparatus according to the first embodiment.
FIG. 4 is a diagram showing three ROIs designated in an organ.
FIG. 5 is a diagram illustrating scan start conditions according to the first embodiment.
FIG. 6 is a diagram illustrating contrast timing by a conventional real prep scan.
FIG. 7 is a diagram illustrating the contrast timing by the real prep scan of the first embodiment.
FIG. 8 is a flowchart showing three-dimensional real prep processing by the X-ray CT apparatus according to the second embodiment.
FIG. 9 is a diagram showing ROIs designated for the aorta and the portal vein, respectively.
FIG. 10 is a diagram illustrating scan start conditions according to the second embodiment.
FIG. 11 is a diagram illustrating contrast timing by a conventional real prep scan.
FIG. 12 is a diagram for explaining contrast timing by a real prep scan according to the second embodiment;
FIG. 13 is a configuration block diagram of a main part of an X-ray CT apparatus according to a third embodiment.
FIG. 14 is a diagram showing an X-ray CT apparatus that collects three-dimensional data using a flat detector.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... X-ray CT apparatus, 11 ... System control part, 12 ... Operation part, 13 ... Stand / bed control part, 15 ... Bed movement part, 15a ... Bed, 17 ... X-ray control apparatus, 19 ... High voltage generator, DESCRIPTION OF SYMBOLS 21 ... X-ray beam generation source, 23 ... Detector, 25 ... Rotary mount, 27 ... Data collection part, 29 ... Collection data storage device, 31 ... Image reconstruction part, 33 ... Display part, 41 ... ROI designation part, 43 ... Scan start condition setting unit, 44 ... Contrast medium injector, 45 ... CT value determination unit, 47 ... Scan control unit, 61 ... Slit, 63 ... Slit control unit, 65 ... Flat panel detector, P ... Subject, R1- R5 ... ROI (region of interest).

Claims (4)

X-ray beam generating means arranged to emit X-rays toward the subject;
A two-dimensional detector arranged to detect X-rays transmitted through the subject and having a plurality of detection elements arranged in the slice direction;
Image generating means for generating three-dimensional data by scanning the subject by rotating the X-ray beam generating means and the two-dimensional detector;
The multiple ROI in 3-dimensional space based on three-dimensional data of the object, a designation unit which the operator is configured to be designated,
After injecting the contrast agent into the subject, the CT value of the region of interest is individually set in the region of interest for each region of interest designated by the designation means by scanning the three-dimensional region of the subject Monitoring means for determining whether or not the designated scan start condition has been reached ;
Scan control means for starting an examination scan of the subject when the CT value of the region of interest for each region of interest reaches a scan start condition set individually for the region of interest based on the determination of the monitoring unit; ,
An X-ray CT apparatus comprising:   The specifying means extracts a specific part by comparing a CT value of the three-dimensional data with a predetermined threshold value, and specifies the plurality of regions of interest in the extracted specific part. The X-ray CT apparatus according to claim 1. A slit provided between the X-ray source and the subject and having two X-ray shielding plates movable along the slice direction of the subject;
While the monitoring means is monitoring the change in the CT value, the two X-ray shields of the slit are exposed so that only a plurality of slices corresponding to the plurality of regions of interest are exposed to the X-rays from the X-ray source. Slit control means for controlling the width between the plates;
The X-ray CT apparatus according to claim 1, further comprising:   2. The X-ray CT apparatus according to claim 1, wherein a width of the two-dimensional detector in the slice direction is a width capable of simultaneously detecting X-rays transmitted through one whole organ in a human body.

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