JP2004174088A - X-ray computerized tomographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve operability in setting a real prep tomographic conditions in an X-ray computerized tomographic apparatus corresponding to real prep tomography. <P>SOLUTION: The X-ray computerized tomographic apparatus includes a function of repeating a real prep tomography for obtaining a timing for starting main scanning based on the density of a contrast agent monitored by pre-scanning at the same or different part after injecting the contrast agent. The real prep tomographic condition includes respective setting items, i.e. the position of a region of interest (ROI) to be monitored concerning the density of the contrast agent, the position of a slice comprising the ROI, and a threshold with respect to the density of the contrast agent. The apparatus includes a function of copying the setting values of the respective items in the real prep tomographic condition, which are set for one real prep tomography, to respectively corresponding item columns on the setting screen of the real prep tomographic condition with respect to the other real prep radiographies, in order to support a work for setting the real prep tomographic condition to each one of the real prep tomographies. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray computed tomography apparatus compatible with real prep imaging that monitors the inflow of a contrast agent and optimizes the start timing of a main scan.
[0002]
[Prior art]
An X-ray computed tomography apparatus provides information on a subject by an image based on the intensity of X-rays transmitted through the subject, and is used for many purposes such as diagnosis of disease, treatment and surgical planning. Plays an important role in medical practice. In recent years, helical scans that scan the object in a spiral to obtain a wide range of projection data, real-time CT that realizes image reconstruction and display in real time in parallel with the scan, and monitors the inflow of contrast agent Various advancements have been made, such as a real-prep imaging technique that optimizes the timing of starting a scan.
[0003]
With the recent increase in the speed of scanning, it has become possible to repeat real prep imaging at a plurality of sites such as the chest and lower limbs for one injection of a contrast agent. Also, regarding the monitoring method of the contrast agent concentration, in the past, the contrast agent concentration (CT value average) of one region of interest in one slice was monitored, but recently, the contrast agent concentration is monitored at a plurality of positions. By setting a region and monitoring the contrast agent concentration (CT value average) of each region of interest with a unique threshold value, the start timing of the main scan can be further optimized.
[0004]
However, in the real prep shooting technique, the finer settings are made possible and the reliability is increased, but the increase in the setting items causes a decrease in operability, thereby imposing a burden on the operator. Will be.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to improve the operability of setting real prep imaging conditions in an X-ray computed tomography apparatus compatible with real prep imaging.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an X-ray computed tomography having a function of repeating real prep imaging for measuring a start timing of a main scan based on a contrast agent concentration monitored by a prescan for the same or different site after injection of a contrast agent. In the imaging device, the position of the region of interest to monitor the contrast agent concentration, the position of the slice containing the region of interest, the real prep imaging conditions including each setting item of the threshold for the contrast agent concentration, the real prep imaging In order to support the work to be set for the real prep shooting conditions, the setting value of each item of the real prep shooting conditions set for one of the real prep shootings is set on a real prep shooting condition setting screen for another real prep shooting. It is characterized in that it has a function of copying in the corresponding item columns.
According to a second aspect of the present invention, X has a function of extracting projection data corresponding to a designated heartbeat phase from projection data collected by helical or conventional scanning, and reconstructing image data based on the extracted projection data. In the X-ray computed tomography apparatus, in order to support the work of setting reconstruction conditions including each setting item of the image slice thickness and the number of slices for each of the plurality of specified heartbeat phases for the reconstruction, A function of copying the set value of each item of the reconstruction condition set for any one of the plurality of heartbeat phases to the corresponding item column on the setting screen of the reconstruction condition for the other heartbeat phases. Features.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an X-ray computed tomography apparatus (X-ray computed tomography apparatus) according to the present invention will be described with reference to the drawings. The X-ray computed tomography apparatus has a rotation / rotation (ROTATE / ROTATE) type in which an X-ray tube and a radiation detector rotate as one body around a subject, and a large number of detection elements arranged in a ring. There are various types such as a fixed / rotated type in which only the X-ray tube rotates around the subject, and the present invention is applicable to any type. Here, the rotation / rotation type which occupies the mainstream at present is described. Further, in order to reconstruct one slice of tomographic image data, projection data of about 360 ° around one circumference of the subject and projection data of 180 ° + view angle are required even in the half scan method. . The present invention is applicable to any reconstruction method. Here, the half scan method will be described as an example. The mechanism of converting incident X-rays into electric charges is an indirect conversion type in which X-rays are converted into light by a phosphor such as a scintillator and the light is converted into electric charges by a photoelectric conversion element such as a photodiode. The mainstream is the generation of an electron-hole pair in a semiconductor and its transfer to an electrode, that is, a direct conversion type utilizing a photoconductive phenomenon. As the X-ray detecting element, any of those methods may be adopted, but here, the former indirect conversion type will be described. In recent years, a so-called multi-tube X-ray computed tomography apparatus in which a plurality of pairs of an X-ray tube and an X-ray detector are mounted on a rotating ring has been commercialized, and peripheral technology has been developed. I have. The present invention is applicable to both conventional single-tube X-ray computed tomography apparatuses and multi-tube X-ray computed tomography apparatuses. Here, the description will be made as a single tube type.
[0008]
FIG. 1 shows a configuration of an X-ray computed tomography apparatus according to the present embodiment. This X-ray computed tomography apparatus has a gantry 1 for collecting projection data on a subject. A computer system 17 is connected to the gantry 1 via the gantry interface 5. The bed 2, the contrast agent injector 4, and the electrocardiograph (ECG) 3 are connected to the computer system 17 via interfaces 6, 7, and 8, respectively.
[0009]
The gantry 1 includes necessary and general components for performing a single scan, a multi-slice scan, and / or a helical scan (spiral scan). The gantry 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, which have been developed recently, are mounted. A so-called multi-tube type may be used. A typical gantry 1 is a so-called third generation type, which has a rotating ring on which one or more sets of an X-ray tube and an X-ray detector are mounted. During rotation, X-rays are continuously or intermittently emitted from the X-ray tube, and in synchronism therewith, reading out of the stored charges by the X-ray detector is repeated at regular intervals. The signal output by this operation is converted to a voltage signal by a data acquisition system generally called a DAS (data acquisition system), amplified, further converted to a digital signal, and the digital signal is converted to a digital signal. By passing correction processing such as sensitivity correction in the processing unit, so-called projection data immediately before the reconstruction processing is generated. This projection data is sent to the computer system 17 and stored in the data storage unit 15. The data storage unit 15 stores electrocardiographic waveform data of the subject measured by the electrocardiograph 3.
[0010]
The computer system 17 mainly includes a system control unit 12 and interfaces 5, 6, and 7, an input device 10, a scan expert system 11, a reconstruction processing unit 13, a real prep processing unit 14, and a data / control bus 9. The data storage unit 15 and the display unit 16 are connected. The projection data collected by the gantry 1 is stored in the data storage unit 15 and is also supplied to the reconstruction processing unit 13 for real-time CT. The real-time CT is to execute reconstruction of tomographic image data and display the tomographic image in parallel with the scanning operation. That is, the tomographic image is scanned almost in real time like an X-ray television system while scanning. Is a function that realizes the observation of Here, the real-time CT is used exclusively for monitoring the state of inflow / outflow of the contrast agent, that is, for real-prep imaging, and therefore requires higher speed than image quality or the like. Therefore, in the helical scan, without performing the distance correction of the projection data which is usually performed, the reconstruction is performed when the projection data for 180 ° + view angle required for the reconstruction of one piece of tomographic image data is completed. carry out.
[0011]
With the support of the scan expert system 11, the operator can quickly and easily set the scan schedule, real-prep imaging conditions, reconstruction conditions, and the like.
[0012]
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 10, but may be displayed on the display unit 16 for displaying images. On the scan schedule setting screen, a plurality of scheduled scan operations are vertically arranged from top to bottom in the order of execution. A scan schedule is planned by adding, deleting, and moving scan operations on this array. In FIG. 2, it is planned that three scan operations are performed, specifically one conventional scan operation is performed first, followed by two helical scan operations in order.
[0013]
In the expert system 11, a plurality of, in this case, up to four types of reconstruction conditions can be set for each scan operation. The reconstruction conditions include various setting items such as a reconstruction function, use / non-use of a filter, an image slice thickness, a display FOV (reconstruction area), and a center position of the reconstruction. The setting values of these setting items are stored in the data storage unit 15. Based on the projection data collected in the scan operation, tomographic image data is reconstructed according to reconstruction conditions set corresponding to the scan operation. When a plurality of reconstruction conditions are set for the scan operation, reconstruction of tomographic image data is repeated according to each reconstruction condition.
[0014]
In the scan schedule setting screen, a button described as “Copy from” is arranged outside the lower left column. When the operator clicks the "Copy from" button by operating the pointing device of the input device 10, the scan expert system 11 activates the copy function. Under the copying function, immediately after clicking the “Copy from” button, the setting value of each setting item of the reconstruction condition already set for another scan operation or the same scan operation selected by the operator is stored in the data. The information is read from the storage unit 15 and is automatically input as a candidate value in the input field of the corresponding setting item in the screen when the “Copy from” button is clicked. The operator changes only the values of the items that need to be changed via the input device 10 and can fix the reconstruction conditions by clicking the “Confirm” button. This input support function realizes an improvement in workability rather than inputting all items one by one.
[0015]
Here, “P” in the “start” column of each scan operation in the scan schedule table is a notation meaning that the setting is such that the real scan start timing is automated. When the notation area of "P" is clicked through the pointing device of the input device 10, the scan expert system 11 activates a function for setting a real prep shooting condition and switches the display to a screen corresponding to the function. In FIG. 2, it is assumed that all three scan operations have applied real prep imaging.
[0016]
FIG. 3 shows an example of a setting screen for real prep shooting conditions. On this screen, three real prep shooting conditions are set here according to the number of scan operations using real prep set in the scan schedule. The screen switching of the real prep shooting conditions is performed by selectively clicking three tabs of “1st Position”, “2nd Position”, and “3rd Position”.
[0017]
In the real prep imaging condition setting screen, in the range indicated by “Reference image information”, information on the position of the slice for monitoring the contrast agent concentration, here, the series number (Series No.) of the image, the image number ( Image No.) and the tabletop position (Table Pos.). When the “Select” button is clicked, a scanogram of the subject already captured is displayed as shown in FIG. On this scanogram, a line indicating the position of the monitor slice is displayed together with a frame indicating the helical scan range (main scan range or position), and the line can be arbitrarily moved by, for example, dragging.
[0018]
Under the “Reference image information”, information on a method of calculating the contrast agent concentration is displayed in a range described as “ROI information”. The scan expert system 11 permits setting of up to three regions of interest in one slice (one image). Two of the three regions of interest are the starting ROI1, ROI2 set on a vascular region, such as an artery, to monitor contrast agent inflow, and the other one is a stable or rapid transmission X-ray intensity. This is a fixed ROI for monitoring any fluctuation and urgently stopping X-ray irradiation as necessary. The fixed ROI is set, for example, on a bone region where no contrast agent flows.
[0019]
The calculation method can be selectively specified for each of the three regions of interest (start ROI1, start ROI2, and fixed ROI). The options are an average of the CT values of the pixels in the region of interest (Mean), and the region of interest. The maximum value of the CT value of the inner pixel, the average of the top few percent of the CT value distribution of the pixel in the region of interest, and the like are prepared.
[0020]
When the notation of any of the three regions of interest (start ROI1, start ROI2, fixed ROI) is clicked, a screen for setting the position of the region of interest in the monitor slice corresponding to “Reference image information” is displayed. You. As shown in FIG. 5, a tomographic image at a position corresponding to the monitor slice is displayed. On this tomographic image, frames corresponding to the start ROI1, the start ROI2, and the fixed ROI are displayed. Move each frame by dragging with the pointing device, and selectively specify the desired shape from the shape options such as circle, rectangle, polygon, freehand from the submenu that pops up according to the right button operation of the pointing device, for example, Use the enlarge / reduce command in the submenu to adjust to any size.
[0021]
At the lower right of “ROI information”, a setting range of a main scan start condition described as “Sure start condition” is displayed. For the start of the main scan, a manual (manual) and an automatic (automatic) are selectively prepared. In the auto mode, a threshold is set for each of the start ROI1 and the start ROI2. That is, when the average value of, for example, the CT value of the pixels in the start ROI1 reaches the threshold value specified here, the main scan starts or shifts to the start preparation. This threshold is one of the most important factors that determine the start timing of the main scan, and needs to be set to an appropriate value corresponding to the position of the monitor slice and the position of the set region of interest in the monitor slice. Be careful. Below the threshold input fields for the start ROI1 and the start ROI2, input fields for a composite condition using the start ROI1 and the start ROI2 are provided. The notation “ROI1 OR ROI2” means that the main scan shifts to start or start preparation when either of the start ROI1 and the start ROI2 reaches the threshold value of the CT value average. Although not shown, the notation “ROI1 AND ROI2” means that the main scan shifts to start or start preparation when the CT value average of both the start ROI1 and the start ROI2 reaches the threshold value. Means. Below that, a threshold value for the fixed ROI, that is, an input field for the exposure stop condition is displayed, and the value is set to a suitable value according to the X-ray conditions (tube voltage, tube current, etc.) and the thickness of the subject. There is a need.
[0022]
On the left side of the range of “Sure start condition”, a setting range of another additional shooting condition described as “Other condition” is displayed. Here, the scan conditions for monitoring the contrast agent concentration are set. In order to reduce the exposure dose, the selection of the application of the intermittent scan during the monitoring of the contrast agent concentration, the interval of the intermittent scan, and the start ROI1 are set. When the CT value average approaches the threshold value for the start of the main scan, it is necessary to increase the time resolution, so that a transition condition from intermittent scan to continuous scan can be set.
[0023]
As described above, the setting items of the real prep photographing conditions are diversified, and the selection of the setting values may require a high degree of knowledge and prudence, which is extremely troublesome. This tendency can easily be predicted to increase further in the future. In order to reduce this trouble and improve the workability, a button labeled "Copy from" is arranged in the margin at the lower left of the real prep shooting condition setting screen in the same manner as the reconstruction condition setting. Is done.
[0024]
When the operator clicks the “Copy from” button by operating the pointing device of the input device 10, the scan expert system 11 activates the copy function in the real prep shooting condition setting mode. Under the copy function, the setting values of the other setting items of the real prep shooting conditions that have been selected by the operator immediately after clicking the “Copy from” button are read out from the data storage unit 15. , Are automatically input as candidate values in the input fields of the corresponding setting items in the screen when the “Copy from” button is clicked. The operator changes only the values of the items that need to be changed via the input device 10 and can fix the reconstruction conditions by clicking the “Confirm” button. This input support function realizes an improvement in workability rather than inputting all items one by one.
[0025]
The conditional copy function of this embodiment using the “Copy from” button is a function clearly different from a simple copy function or a so-called auto-complete function. The copy function is a simple function of selecting the copy source, copying it to the clipboard, and pasting it to the specified copy destination, and the auto-complete function is to input the first character of the character string that has already been input This function displays the candidate of the character string that matches with it, and automatically inputs the rest only by pressing the enter key. In contrast to the copy function and the auto-complete function, the condition copy function according to the present embodiment is not a separate function, but is a collective copy source for all items of reconstruction conditions and real prep shooting conditions including many setting items. And a copy destination, and a setting value of each setting item of the copy source is input as a candidate in an input field of a corresponding setting item of the copy destination.
[0026]
The condition copying function of the present embodiment using the “Copy from” button works effectively when applied to a condition setting work including many setting items. For this, the above-described reconstruction conditions and real prep imaging conditions are suitable, but are not limited thereto.
[0027]
For example, as shown in FIG. 6, the effect can be greatly expected even when applied to the condition setting of ECG-gated reconstruction. This ECG-gated reconstruction is not performed in real-time reconstruction processing in which reconstruction processing is performed in parallel with scanning, but is performed after scanning is completed. When the execution of the reconstruction process is instructed, a file selection window is displayed with the support of the expert system 11. In the file selection window, a list of processable projection data files stored in the data storage unit 15 is displayed. When any of the files is selected, a data processing condition setting screen shown in FIG. 6 is displayed. You.
[0028]
When the check box of “ECG synchronization” is checked, the ECG synchronization reconstruction function is activated, and the ECG waveform data associated with the selected projection data file is read from the data storage unit 15, The electrocardiographic waveform is displayed in a window.
[0029]
The position of the desired heartbeat phase (reconstruction center position) in the input field of “heartbeat phase” is represented by a numerical value as a percentage representing the ratio of the time width from the R wave to the position relative to the time interval from the R wave to the R wave. It is input or set by specifying the position on the electrocardiographic waveform via a pointing device. At the same time, the target period of the ECG-gated reconstruction is numerically input as the “start” time position, “end” time position of the period, or by specifying the position on the electrocardiogram waveform via a pointing device. Then, the thickness of the image slice and the number of images to be reconstructed are input.
[0030]
Further, the condition of “RR allowable range” is arbitrarily set in a range of 0.0 seconds to 10.0 seconds. Although the reconstruction position is automatically set for each interval (R-R interval) from R-wave to R-wave based on the percentage, the RR interval may fluctuate excessively due to arrhythmia or the like. In this case, the automatically set position may greatly deviate from the intended heartbeat phase. If the reconstructed image is used for diagnosis as it is, there is a concern that the diagnosis may be erroneously made. Therefore, an allowable range is set for the RR interval, and image reconstruction is prohibited during a heartbeat period outside the range. In addition, setting items such as selection of a reconstruction function, selection of a reconstruction method (application / non-application of half reconstruction), selection of a filter type, and the like are common parameters.
[0031]
In order to reduce this trouble and improve workability, the "Copy from" field is also displayed on the ECG-gated reconstruction condition setting screen in the lower right margin of the screen in the same manner as the reconstruction condition setting and the real prep imaging condition. Button is placed. When the operator clicks the “Copy from” button by operating the pointing device of the input device 10, the button is selected by the operator immediately after clicking the “Copy from” button under the copy function of the scan expert system 11. The setting values of the other setting items of the previously set electrocardiographic synchronization reconstruction condition are read out from the data storage unit 15, and the corresponding setting items in the screen when the “Copy from” button is clicked are displayed. It is automatically entered as a candidate value in the input field. The operator changes only the value of the item that needs to be changed via the input device 10. This input support function realizes an improvement in workability rather than inputting all items one by one.
[0032]
As described above, according to the present embodiment, it is possible to improve the operability of setting real prep imaging conditions in an X-ray computed tomography apparatus compatible with real prep imaging. The operability can be improved by applying to the setting of the synchronization reconfiguration condition.
[0033]
(Modification)
The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the invention at the stage of implementation. Furthermore, the above-described embodiment includes various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, some components may be deleted from all the components shown in the embodiment.
[0034]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, in the X-ray computed tomography apparatus corresponding to a real prep imaging | photography, the operability of the setting of a real prep imaging | photography condition can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an X-ray computed tomography apparatus according to an embodiment of the present invention.
FIG. 2 is a view showing an example of a screen for setting a scan schedule by the scan expert system shown in FIG. 1;
FIG. 3 is a view showing an example of a setting screen of real prep shooting conditions set by the scan expert system of FIG. 1;
FIG. 4 is a supplementary diagram of the scan schedule in FIG. 2;
FIG. 5 is a supplementary view of the real prep shooting conditions of FIG. 3;
FIG. 6 is a view showing an example of a setting screen of ECG-gated reconfiguration conditions by the scan expert system of FIG. 1;
[Explanation of symbols]
1… Gantry,
2 ... sleeper,
3: Electrocardiograph (ECG),
4 ... Contrast injector
5 ... Gantry interface,
6 ... Bed interface,
7 ... Injector interface,
8 ... ECG interface,
9 data / control bus,
10 input devices,
11 ... scan expert system,
12 ... System control unit,
13. Reconstruction processing unit
14 Real prep processing section
15 Data storage unit,
16 Display unit,
17 Computer system.

Claims (4)

An X-ray computed tomography apparatus having a function of repeating real prep imaging for measuring the start timing of the main scan based on the contrast agent concentration monitored by the prescan for the same or different portions after the injection of the contrast agent,
The position of the region of interest for monitoring the contrast agent concentration, the position of the slice including the region of interest, and the real prep imaging condition including each setting item of the threshold value for the contrast agent concentration are set for each of the real prep imaging. In order to support the work of performing the real prep shooting, the setting value of each item of the real prep shooting condition set for one of the real prep shooting is corresponded to the setting screen of the real prep shooting condition for the other real prep shooting. An X-ray computed tomography apparatus having a function of copying in an item column to be performed. 2. The X-ray computed tomography apparatus according to claim 1, wherein a copy button for instructing a copy of the set value of the real prep shooting condition is displayed on the real prep shooting condition setting screen. From the projection data collected by helical or conventional scan, the projection data corresponding to the specified heartbeat phase is extracted, and in the X-ray computed tomography apparatus having a function of reconstructing image data based on the extracted projection data,
Any of the plurality of heartbeat phases in order to support an operation of setting reconstruction conditions including the setting items of the image slice thickness and the number of slices for each of the plurality of specified heartbeat phases. X-ray computed tomography having a function of copying the set values of each item of the reconstruction condition set for each of the items into corresponding item columns on the setting screen of the reconstruction condition for other heartbeat phases. Shooting equipment. 4. The X-ray computed tomography apparatus according to claim 3, wherein a copy button for instructing to copy the set value of the reconstruction condition is displayed on the reconstruction condition setting screen.

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