JP2890623B2 - ECT equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

This invention is a gamma camera rotation type or ring type
The present invention relates to an ECT (emission computer tomography) device.

[Prior art]

In ECT, radiation from a radioisotope (RI) taken into the body of a subject is incident on a gamma camera placed outside the body, a radiation detector placed in a ring shape, etc. This is to collect projection data, perform image reconstruction processing such as back projection, and obtain an RI density distribution image on a predetermined cross section as a tomographic image. Conventionally, the collection of the ECT data is terminated when the collection time is fixed and the time comes, or when the collected radiation incident count reaches a fixed amount.

[Problems to be solved by the invention]

However, there is a problem that it is not possible to cope with individual differences among subjects by setting a fixed collection time as in the related art. In other words, there is an individual difference in the amount of RI taken in, and if data collection is completed in a certain period of time, the image quality of the reconstructed image will deteriorate for subjects with a small amount of taken in In the case of the subject, the collection time is unnecessarily lengthened, which imposes an extra burden on the subject. In addition, when the data collection is terminated when the count reaches a certain count, when a large amount of RI is accumulated in a local area, the collection time may be short and a small lesion may be missed. In any case, since it is a uniform process ignoring individual differences between subjects and the state of RI accumulation, good tomographic images are often not obtained, in which case data must be collected again. There is the inconvenience of having to do it. The present invention displays a reconstructed tomographic image in real time even during data acquisition so that data acquisition can be terminated when a good image quality image is obtained. And improved so as not to impose an extra burden on the subject. It is intended to provide an ECT device.

[Means for Solving the Problems]

In order to achieve the above object, in the ECT apparatus according to the present invention, means for collecting data in all directions necessary for image reconstruction within a certain time, and the above-mentioned collected data at every certain time interval Image processing means for capturing and performing image reconstruction processing in parallel with the data collection; means for displaying a reconstructed image in parallel with the data collection and image processing; and setting the image in the reconstructed image. Control means for calculating the standard deviation of the image data in the region of interest and terminating the data collection when the standard deviation is smaller than a predetermined value.

[Action]

The data collecting means can collect data in all directions required for image reconstruction within a certain period of time. In other words, for example, data in all directions necessary for reconstructing one image in a time of rotating by 180 ° can be collected.
Therefore, an image can be reconstructed by taking in the collected data at regular intervals. Therefore, here, the image reconstruction processing is performed in parallel with the data collection, and the display of the reconstructed image is performed in parallel with the data collection and the image reconstruction processing. Then, the standard deviation of the image data in the region of interest set in the reconstructed image is calculated. If the standard deviation of the image data in the region of interest is smaller than a predetermined value, it can be determined that a good image has been obtained at least in the region of interest. Therefore, when the standard deviation of the image data in the region of interest becomes smaller than a predetermined value, the data collection is automatically terminated. As described above, when the data collection is continued, the data collection is automatically terminated when the standard deviation of the image data in the region of interest becomes smaller than a predetermined value. Regardless of individual differences in the amount of RI uptake and the state of accumulation in the body, it is possible to obtain a tomographic image in which the image in the region of interest is good, and when the image in the region of interest becomes good. Since the data collection is completed, a good image can be obtained in the shortest collection time. This means that the burden on the subject can be reduced without imposing a useless burden on the subject.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a gamma camera rotating type EC according to the present invention.
1 shows an embodiment applied to a T apparatus. This first
In the figure, a subject 1 is lying on a top plate 3 of a bed 2 and a gamma camera 4 is rotated by 360 ° around the subject 1 by a rotating device 5. The subject 1 has been administered RI beforehand, and gamma rays are emitted outside the body from the RI accumulated in the organs and the like. This radiation is made incident on the gamma camera 4, and data on the incident position is sent to the computer 6. On the other hand, the rotation device 5 rotates the gamma camera 4 at a predetermined minute angle based on a control signal from the computer 6 while rotating, and returns a rotation angle signal to the computer 6 for each stationary angle. The computer 6 counts the data from the gamma camera 4 in a stationary state for each incident position and obtains projection data at that angle. This projection data is stored together with the rotation angle signal at that time. Such data collection is repeated for each minute rotation angle, and 360
Obtain projection data in the ゜ direction. If this projection data is collected at least in the direction of 180 °, image reconstruction by an image reconstruction algorithm such as convolution or back projection becomes possible. The reconstructed image is displayed by the display device 7. The input device 8, such as a keyboard or a mouse, inputs, for example, a longest data collection time and a region of interest. Inside the computer 6, a data collection program,
A data processing (image processing) program and an image display program run. Here, as shown in FIG. 2, they are operated in parallel with each other by multitasking. For example, if the input device 8 is set so that it takes 5 seconds for the gamma camera 4 to make a 180 ° rotation, collecting data for at least 5 seconds means that data enough to reconstruct one image can be collected. Therefore, in this case, as shown in FIG. 2, data is transferred from the collection program to the image processing program every 5 seconds, and the image data obtained as a result of the image processing is transferred to the image display program, and
I1, I2, I3, ... are displayed. This image processing and display must be performed within 5 seconds. The tomographic image displayed by the display device 7 is as shown in FIG. The tomographic image 9 shown in FIG. 3 is an example of a tomographic image of the head. In this tomographic image 9, regions of interest 91 to 95
But. The input is made manually by operating the input device 8 while looking at the display device 7 or automatically set by the computer 6. Here, it is assumed that five regions of interest 91 to 95 are set. The setting of this region of interest is contour 10
May be automatically extracted. The entire operation flows as shown in FIG. That is, first, the input device 8 presets the longest data collection time considered to be acceptable in consideration of the actual burden on the subject 1 and then starts and starts data collection. Data collected for 5 seconds, data collected for 10 seconds, data collected for 15 seconds,... Are sequentially passed to the image processing program at intervals of 5 seconds, and image processing is performed each time. Then, the process A is performed on the image data obtained as a result. This processing A is performed, for example, by setting five regions of interest 91.
One of the most appropriate ones from .about.95 is selected and the standard deviation of the data in the region of interest is calculated. There are various methods for selecting the data. Here, the average of the number of data in the regions of interest 91 to 95 is averaged, and the region of interest having the number of data closest to the average value is selected. This image data is passed to the image display program and displayed on the display device 7 until the standard deviation in the selected region of interest obtained in the above process A becomes smaller than a certain value. Collection continues and data collection is automatically terminated when it falls below a certain value. Thereby, the data collection can be automatically terminated when the image quality becomes good in all the five regions of interest 91 to 95. If the preset maximum allowable data collection time comes before the standard deviation becomes smaller than a certain value, the data collection is terminated at that time. Alternatively, when the doctor or the like observes each image I1, I2,... Which becomes clear every 5 seconds on the display device 7 and determines that the image quality in the regions of interest 91 to 95 is good, the doctor forcibly performs the same. Data collection may be terminated. Although the embodiment applied to the gamma camera rotation type ECT device has been described above, it is needless to say that the embodiment can also be applied to a ring type ECT device.

【The invention's effect】

According to the ECT apparatus of the present invention, data acquisition can be terminated when the image quality in the region of interest in the tomographic image becomes good, so that a tomographic image with good image quality can always be obtained in the shortest necessary time. And the burden on the subject can be reduced without imposing an unnecessary burden on the subject.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, FIG. 2 is a time chart for explaining the operation, FIG. 3 is a diagram showing a tomographic image and a region of interest, and FIG. It is. 1 ... subject 2 ... bed 3 ... top plate 4 ... gamma camera 5 ... rotating device 6 ... computer 7
... Display device, 8 ... Input device, 9 ... Tomographic image, 91-95 ...
… Region of interest, 10 …… Contour.

Claims (1)

(57) [Claims] 1. A means for collecting data in all directions required for image reconstruction within a fixed time, and acquiring the collected data at the fixed time intervals and reconstructing the image in parallel with the data collection. Image processing means for performing configuration processing, means for displaying a reconstructed image in parallel with the data collection and image processing, and standard deviation of image data in a region of interest set in the reconstructed image. Control means for calculating and terminating data collection when the standard deviation is smaller than a predetermined value.