JP4080725B2 - X-ray computed tomography system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray computed tomography apparatus, and to an X-ray CT apparatus compatible with a contrast examination.
[0002]
[Prior art]
An X-ray computed tomography apparatus provides information about a subject based on the intensity of X-rays that have passed through the subject, and includes many images including diagnosis, treatment, and surgical planning of diseases. It plays an important role in medical practice. The appearance of a helical scan that scans a subject in a spiral to obtain a wide range of projection data further increases its usefulness.
[0003]
Due to its usefulness, the application range of helical scans is steadily expanding. For example, when applied to contrast examinations, the state of blood flow can be confirmed over a wide range, and helical scan operations are repeated intermittently at the same or different sites. Thus, the spread of blood can be observed over time.
[0004]
For example, as shown in FIG. 2, it is assumed that three scan operations of # 1, # 2, and # 3 are scheduled with a scan time of 20 seconds and a pause time of, for example, 30 seconds and 25 seconds. According to such a schedule, after the contrast agent is injected, a scanning operation is automatically executed.
[0005]
Here, the scan range of each scan operation is set to a relatively wide range including the examination target region. Typically, the state of the scan operation can be monitored on a tomographic image by CT fluoroscopy. Under this CT fluoroscopy, the operator may confirm that the scan of the entire region to be examined has been completed before the scan operation for the scheduled range is completed. In this case, the operator probably inputs an instruction to interrupt the scan operation and to skip to the next scan operation by operating a skip button prepared in advance. This skip function is an unavoidable function for avoiding unnecessary exposure, and is a useful function for shortening the inspection time.
[0006]
However, this scan skip disturbs the scan schedule as can be seen from the execution scan of FIG. In other words, the scan scheduler manages the start time of the scan operation as a pause time. Therefore, if the scan is interrupted, the start time of the second scan operation # 2 is increased by 5 seconds in FIG. End up. This time lag affects the start time of the subsequent scan operation # 3. For this reason, the elapsed time from contrast agent injection | pouring will shift | deviate and the inflow timing of a contrast agent may be missed. The scan range is also managed as the amount of movement from the end position of the previous scan operation. Therefore, if the end position of the scan operation is changed due to a scan interruption, the start position of the next scan operation is shifted. End up.
[0007]
In order to solve this problem, the operator has to correct the pause time together with the scan skip operation. This work involves the idea of extending the pause time until the next scan operation by the time shortened by the interruption, and the complexity increases due to competition with the progress of the schedule. At the same time, a work for correcting the amount of movement of the top plate is also required, which adds to the complexity.
[0008]
In contrast examination, it is important to manage the start time of the scan operation. This start time is usually managed by the elapsed time starting from the timing when the operator injects the contrast agent and presses the trigger. In contrast examination, there is a technique called real prep that monitors the contrast medium concentration at a specific site and sets the timing when the contrast medium concentration reaches a predetermined value, in which case the timing at which the contrast medium concentration reaches a predetermined value Time management is performed with the starting point.
[0009]
However, depending on the scan site, it may be effective to perform time management of the scan operation starting from the timing at which the contrast medium is injected, but such setting is not possible.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to avoid temporal and spatial shifts in subsequent scans due to scan interruption in an X-ray computed tomography apparatus.
[0011]
[Means for Solving the Problems]
An X-ray computed tomography apparatus according to a first aspect of the present invention includes a scanner that executes a scan operation for collecting projection data relating to a subject into which a contrast medium has been injected, and a movable device that mounts the subject. A bed having a top plate, a reconstruction processing unit for reconstructing tomographic image data from the projection data, a display unit for displaying the reconstructed tomographic image data, the number of scan operations, its order, and the contrast enhancement Start time of each of the scan operations, starting from one of the time at which the agent injection time and the contrast density at a specific site reach a predetermined value, and an arbitrary time, the pause time between the scan operations, and the scan of each scan operation Supports the setting of a scan schedule including the range and the amount of movement of the top plate between the scan operations. Interrupted while resting time between scan operations set as the scan schedule, and a control unit for controlling said bed and said scanner based on the information about the scanning position, the scanning operation during the execution of the scan operations An input device for inputting an instruction, and when the interruption instruction is input through the input device, the control unit is configured to maintain the start time of each of the remaining scan operations. The pause time is corrected, and the amount of movement of the top plate of the scan schedule is corrected in order to maintain the scan position of each of the scan operations.
An X-ray computed tomography apparatus according to a second aspect of the present invention includes a scanner that executes a scan operation for collecting projection data related to a subject into which a contrast medium has been injected, and a movable device that mounts the subject. A bed having a top plate; a reconstruction processing unit for reconstructing tomographic image data from the projection data; a display unit for displaying the reconstructed tomographic image data; and a scan schedule for performing a plurality of scanning operations. It is for setting, pause time between scans operations as the scan schedule, and sets information about the scanning location, pause time between scans operations set as the scan schedule, based on the information on the scanning position, A control unit for controlling the scanner and the bed; An input device for inputting an instruction to interrupt the scan operation during execution of the scan operation, and when the interrupt instruction is input through the input device, the control unit performs the remaining scan operations. In order to maintain the start time and the scan position , the pause time between the scan operations and the amount of movement of the top plate are modified.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an X-ray computed tomography apparatus (X-ray CT apparatus) according to the present invention will be described below with reference to the drawings. The X-ray CT apparatus has a rotation / rotation (ROTATE / ROTATE) type in which an X-ray tube and a radiation detector are rotated as one body, and a large number of detection elements are arrayed in a ring shape. There are various types such as a fixed / rotation (STATIONARY / ROTATE) type in which only the X-ray tube rotates around the subject, and the present invention can be applied to any type. Here, the rotation / rotation type that currently occupies the mainstream will be described. In addition, to reconstruct one slice of tomographic image data, projection data for about 360 ° around the periphery of the subject is required, and projection data for 180 ° + view angle is also required in the half scan method. . The present invention can be applied to any reconstruction method. Here, the half scan method will be described as an example. In addition, the mechanism for converting incident X-rays into electric charges is based on an indirect conversion type in which X-rays are converted into light by a phosphor such as a scintillator and the light is further converted into electric charges by a photoelectric conversion element such as a photodiode. The generation of electron-hole pairs in semiconductors and their transfer to the electrode, that is, the direct conversion type utilizing a photoconductive phenomenon, is the mainstream. Any of these methods may be employed as the X-ray detection element, but here, the former indirect conversion type will be described. In recent years, the so-called multi-tube type X-ray CT apparatus in which a plurality of pairs of X-ray tubes and X-ray detectors are mounted on a rotating ring has been commercialized, and the development of peripheral technologies has been advanced. The present invention can be applied to both a conventional single-tube X-ray CT apparatus and a multi-tube X-ray CT apparatus. Here, a single tube type will be described.
[0013]
FIG. 1 shows the configuration of an X-ray computed tomography apparatus according to this embodiment. The X-ray computed tomography apparatus includes a scanner 1 that executes a scan operation for collecting projection data related to a subject. A computer unit 3 is connected to the scanner 1 via a scanner interface 5. And the computer unit 3.
[0014]
The computer unit 3 has a scan scheduling support function, a scan scheduler function for managing the execution of scans according to the scan schedule, and a function for reconstructing image data based on projection data. The scan scheduling support function and the scan scheduler function are characteristic, and these functions will be described later.
[0015]
A bed 2 having a movable top plate on which a subject is placed is connected to the computer unit 3 via a bed interface 6. At the time of scanning, the subject is held inside the scanner (imaging space) in a state of being placed on a top plate. Further, a contrast agent injector 4 for automatically injecting a contrast agent into a subject is connected to the computer unit 3 via an injector interface 7. The contrast agent injector 4 generates a trigger for the computer unit 3 at the timing when the contrast agent is injected.
[0016]
The above-described scanner 1 includes necessary and general components for performing a single scan, a multi-slice scan, and / or a helical scan (helical scan). The scanner 1 may be a popular type in which one X-ray tube and one X-ray detector are mounted, or a plurality of pairs of X-ray tubes and X-ray detectors that have been developed recently. The so-called multi-tube type may be used. A typical scanner 1 is a so-called third generation type, which has a rotating ring on which one or a plurality of sets of X-ray tubes and X-ray detectors are mounted. During the rotation, X-rays are continuously or intermittently emitted from the X-ray tube, and in synchronization with the X-ray detector, readout of accumulated charges is repeated at a constant cycle. The signal output by this operation is converted into a voltage signal by a data acquisition system generally called DAS (data acquisition system), amplified, further converted into a digital signal, and the digital signal is converted into a previous signal. By passing correction processing such as sensitivity correction in the processing unit, so-called projection data in a stage immediately before reconstruction processing is generated. This projection data is sent to the computer unit 3.
[0017]
The computer unit 3 is centered on a CPU 8, and a scanner interface 5, an injector interface 7, a bed interface 6, an input device 10, a scan expert system 11, a projection data storage unit 12, a reconstruction processing unit via a data / control bus 9 thereto. 13, a real prep processing unit 14, an image data storage unit 15, and a display unit 16 are connected. Projection data collected by the scanner 1 is stored in the projection data storage unit 12 and also supplied to the reconstruction processing unit 13 for CT fluoroscopy. CT fluoroscopy is a process of reconstructing tomographic image data and displaying the tomographic image in parallel with the scanning operation. In other words, the tomographic image is scanned in real time while scanning like an X-ray television system. It is a function that realizes observing. Here, the CT fluoroscopy is exclusively used to monitor the inflow / outflow of the contrast medium, and therefore, quickness is required rather than image quality. Therefore, in the helical scan, the normal reconstruction of the projection data distance is not performed, and the reconstruction is performed when the projection data for 180 ° + view angle required for the reconstruction of one tomographic image data is prepared. carry out.
[0018]
Here, optimization of scan conditions such as tube voltage, tube current, and X-ray exposure time, and optimization of reconstruction conditions such as slice thickness, number of slices, and matrix size require specialized knowledge. A scan expert system 11 is a system developed based on the specialized knowledge so as to enable an equivalent condition setting even for an inexperienced person or a person with little expertise.
[0019]
With the support of the scan expert system 11, the operator can set the number of scan operations, the order thereof, the injection time of the contrast agent, and the contrast density at a specific site, together with the scan condition and the reconstruction condition, to a predetermined value. (The time when the trigger was triggered in real prep) and any time, the start time of each scan operation, the pause time between scan operations, the scan range of each scan operation, and the top plate between scan operations Set the scan schedule including the amount of movement. According to the set scan schedule, the scan expert system 11 controls the scanner 1 and the bed 2 and actually executes the schedule.
[0020]
FIG. 2 shows an example of the scan schedule setting screen. The scan schedule setting screen is displayed on the operation screen of the input device, but may be displayed on the display unit 16 for image display. In the upper right column of the screen, a scanogram is displayed, and a frame line for setting a scan range is displayed on the scanogram. A scanning range can be set by enlarging / reducing, moving, and rotating the frame line. A scan schedule table is displayed in the lower column of the screen. In the scan schedule table, a plurality of scheduled scan operations are arranged vertically according to the order. The operator arranges the desired scan operations in the desired order using the new (addition), copy, and erase functions of the scan operations according to the desired schedule.
[0021]
The row of each scan operation includes the start time of the scan operation (contrast injection time, the time when the contrast density of a specific part reaches a predetermined value (the time when the trigger was triggered by the real prep), and the trigger by the operator. (Elapsed time until start of each scan operation starting from any time when the button is pressed), pause time between scan operations, start / end position (scan range) of each scan operation, scan mode ( Items such as single scan, multi-slice scan or helical scan), the amount of movement of the top plate between scan operations, scan speed (scan speed), FOV size, slice width, and the like are arranged. The initial recommended value is inserted by the scan expert system 11 as the value of each item, and the operator can change the value as necessary.
[0022]
Items that must be input by the operator include a scan operation start time, a scan operation start position, and a scan operation end position. The scan expert system 11 calculates the scan speed (scan time) based on the start time of the input scan operation, the start / end position (scan range) of the scan operation, the slice width, and the like. Based on the start time and the calculated scan speed (scan time), the scan expert system 11 calculates the waiting time from the scan operation to the next scan operation, that is, the pause time.
[0023]
FIG. 3 shows an example of a schedule table display screen displayed during execution of a scan operation by the scan expert system 11. In order to distinguish the scan operation being executed from other scan operations, the display mode is different, and in this case, black and white display is reversed. In particular, a button for helical skip is displayed in the schedule table displayed during execution of the scan operation. Helical skip is defined as an operation in which the operator interrupts the scan operation and proceeds to the next scan operation in the middle of the scan operation. In many cases, the scan range of each scan operation is set to a relatively wide range including the region to be inspected. The operator may confirm that the scan of the entire region to be examined is completed before the scan of the scheduled scan range is completed under CT fluoroscopy. In this case, the operator inputs an instruction to interrupt the scan operation and to skip to the next scan operation by operating a skip button prepared in advance.
[0024]
FIG. 4 shows a processing procedure of the scan expert system 11 for scan skip. FIG. 5 shows the scan schedule updated by the corresponding process of the scan expert system 11. When the scan skip button is pressed (S1), the scan expert system 11 recalculates the pause time of the next scan operation in order to maintain the scheduled start time of each remaining scan operation (S2). ). That is, the scheduled scan time is shortened by the scan skip (scan interruption), and the shortened time is added to the scheduled pause time. In FIG. 5, the scan operation # 1 is interrupted 5 seconds before the schedule, and the pause time of the next scan operation # 2 is extended by 5 seconds, which is the shortened time.
[0025]
Note that this pause time recalculation method is not limited to adding the shortened time to the scheduled pause time, from the time when it was interrupted to the start time of the next scheduled scan operation. May be calculated as the pause time.
[0026]
As a result, the start time of the remaining scan operation (contrast injection time, the time at which the contrast density of a specific part reaches a predetermined value (the time at which the trigger was triggered by the real prep, and any time the operator pressed the trigger button) (Elapsed time until the start of each scanning operation starting from either (time)) is prevented from deviating from the scheduled time.
[0027]
When the scan skip button is pressed (S1), the scan expert system 11 keeps the top scan until the next scan operation in order to maintain the scheduled scan start / end position of each of the remaining scan operations. Is recalculated (S2). That is, the end position of the interrupted scan operation is changed by scan skip (scan interruption), and the changed distance is added to or subtracted from the scheduled scan start position of the next scan operation. FIG. 6A shows the amount of movement Δm1 and Δm2 of the planned top plate. As shown in FIG. 6 (b), when the scan operation # 1 is interrupted, the top plate movement amount to the next scan operation # 2 is shown in FIG. 6 (a). The quantities Δm1 and Δm2 are shown. It is corrected to Δm1 ′. Such correction prevents the scan start positions of the remaining scan operations from deviating from the planned positions.
[0028]
In this way, the scan schedule is updated according to the pause time and the amount of movement of the top board corrected with the scan skip, the updated scan schedule is displayed (S3), and the scan expert system 11 according to the updated scan schedule. Controls the scanner 1 and the bed 2. In the display, the corrected portion, here, the rest time of the scan operation # 2, and the amount of movement of the top plate of the scan operation # 2 are emphasized, and the black and white inversion is performed in order to facilitate the discrimination from other uncorrected items. The display mode such as display color and display size is different from other uncorrected items.
[0029]
Thus, according to the present embodiment, when the scan is interrupted, the scan schedule is updated, and the remaining scan operation start time (contrast agent injection time and time at which the contrast density of a specific part reaches a predetermined value ( The elapsed time until the start of each scan operation starting from either the time when the trigger was activated in Real Prep or the arbitrary time when the operator pressed the trigger button) is avoided from deviating from the scheduled time, Further, it is possible to prevent the scan start positions of the remaining scan operations from deviating from the planned positions.
[0030]
FIG. 7 shows a part of the scan schedule table. As described above, the start time of the scan operation includes the injection time of the contrast agent, the time when the contrast density of the specific part reaches a predetermined value (the time when the trigger is triggered by the real prep), and the operator presses the trigger button. The time is set as an elapsed time from the starting point to the start of each scanning operation.
[0031]
By the scan expert system 11, the scan start time item of the scan schedule table is the time when the contrast medium injection time and the contrast density of a specific part reach a predetermined value for each scan operation (the time when the trigger is triggered by the real prep). And an arbitrary time when the operator presses the trigger button is prepared so that it can be selectively specified.
[0032]
Therefore, for example, as shown in FIG. 8, the start time of the scan operation # 1 is managed as the elapsed time from the injection time of the contrast agent, and the start times of the scan operations # 2 and # 3 are Unlike the scan operation # 1, it can be managed as the elapsed time from the time when the trigger is applied in the real prep.
[0033]
As described above, since the start point of time management can be individually designated for each scan operation, the scan can be executed at the optimum timing corresponding to each part.
[0034]
(Modification)
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. Furthermore, the above embodiment includes various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, some constituent requirements may be deleted from all the constituent requirements shown in the embodiment.
[0035]
【The invention's effect】
According to the present invention, it is possible to avoid temporal and spatial shifts in subsequent scans due to scan interruption.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of a medical image diagnostic apparatus according to the present invention.
2 is a halftone image showing an example of a scan schedule setting screen by the scan expert system of FIG. 1. FIG.
3 is a halftone image showing an example of a scan schedule screen during execution of a scan operation by the scan expert system of FIG.
4 is a flowchart showing a processing procedure for an interruption instruction (skip instruction) by the scan expert system of FIG. 1;
FIG. 5 is a diagram showing a pause time updated by an interruption instruction by the scan expert system of FIG. 1;
6 is a view showing a top board movement amount updated by an interruption instruction by the scan expert system of FIG. 1; FIG.
7 is a view showing an example of a setting screen for setting a start time for each scan operation by the scan expert system in FIG. 1. FIG.
8 is a diagram showing time management for each scan operation by the scan expert system of FIG. 1; FIG.
FIG. 9 is a diagram showing a problem of an execution scan when a scan interruption instruction is given in the related art.
[Explanation of symbols]
1 ... Scanner,
2 ... Sleeper,
3 ... computer unit,
4 ... Contrast injector
5 ... Scanner interface,
6 ... Sleeper interface,
7 ... Injector interface,
8 ... CPU,
9: Data / control bus,
10: Input device,
11 ... Scan Expert System,
12 ... projection data storage unit,
13: Reconfiguration processing unit,
14 ... Real prep processing part,
15: Image data storage unit,
16: Display unit.

Claims (6)

A scanner that performs a scan operation to collect projection data for a subject injected with a contrast agent;
A bed having a movable top plate on which the subject is placed;
A reconstruction processing unit for reconstructing tomographic image data from the projection data;
A display unit for displaying the reconstructed tomographic image data;
The number of scan operations, the order thereof, the start time of each of the scan operations starting from either the time of injection of the contrast agent and the time when the contrast density of a specific site reaches a predetermined value or an arbitrary time, the scan operation Supporting a scan schedule including a pause time between each scan operation, a scan range of each of the scan operations, and a movement amount of the top plate between the scan operations, and a pause time between the scan operations set as the scan schedule, A control unit for controlling the scanner and the bed based on information on a scan position;
An input device for inputting an instruction to interrupt the scan operation during execution of the scan operation;
The control unit corrects the pause time of the scan schedule to maintain the start time of each of the remaining scan operations when an interruption instruction is input through the input device, and scan positions of the scan operations. X-ray computed tomography apparatus, wherein the amount of movement of the top plate of the scan schedule is corrected to maintain   The control unit calculates a pause time between the scan operations based on a start time of each of the scan operations input via the input device, and moves the top board based on a scan range of each of the scan operations. The X-ray computed tomography apparatus according to claim 1, wherein the quantity is calculated.   The X-ray computed tomography apparatus according to claim 1, wherein the control unit displays the scan schedule on the display unit or another display unit so as to emphasize the corrected pause time and movement amount.   In parallel with the scan operation, the reconstruction processing unit sequentially reconstructs tomographic image data from the projection data, and displays the reconstructed tomographic image data on the display unit. The X-ray computed tomography apparatus according to claim 1.   The X-ray computed tomography apparatus according to claim 1, wherein the scan schedule includes a scan mode for distinguishing a single slice scan, a multi-slice scan, and a helical scan. A scanner that performs a scan operation to collect projection data for a subject injected with a contrast agent;
A bed having a movable top plate on which the subject is placed;
A reconstruction processing unit for reconstructing tomographic image data from the projection data;
A display unit for displaying the reconstructed tomographic image data;
It is for setting the scanning schedule for performing a plurality of scanning operations, downtime between scan operations as the scan schedule, and sets information about the scanning location, between scan operations set as the scan schedule A control unit for controlling the scanner and the bed , based on information on pause time and scan position ;
An input device for inputting an instruction to interrupt the scan operation during execution of the scan operation;
When an interruption instruction is input through the input device, the control unit corrects the rest time between the scan operations and the amount of movement of the top plate in order to maintain the remaining scan operation start time and scan position. An X-ray computed tomography apparatus characterized by that.

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