JPS59222134A - Computer tomographic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Application of Industry-1- This invention relates to improvement of a computerized tomography apparatus.

(b) Prior art] As is well known, computerized tomography equipment
A radiation source and a radiation detector are placed facing each other with the subject in between, and radiation attenuation data is collected in various directions within a specific slice plane of the subject, and from this data a radiation absorption coefficient distribution image on the slice plane is generated. Conventionally, when attempting to obtain a tomographic image by reducing the slice thickness, a collimator is used to shield the radiation to narrow down the radiation that enters the radiation detector and collect data. I try to collect them. However, this poses a problem in that the radiation dose decreases as the aperture is narrowed down, resulting in poor data S/N ratio and deterioration in the quality of the reconstructed image.

(c) Purpose The purpose of this invention is to provide a computerized tomography apparatus that can obtain tomographic images with good image quality without deteriorating the S/N ratio of data when obtaining tomographic images with a thin slice thickness. shall be.

(d) Configuration A computed tomography apparatus according to the present invention is:

A plurality of radiation detectors are arranged in the slice thickness direction, and radiation is simultaneously applied from the radiation source to these, and the radiation source and the radiation detector are connected to each other by the thickness of each of the plurality of radiation detectors in the slice thickness direction. Collect data at each position while shifting the object in the slice thickness direction, and collect data corresponding to the slice position among the data obtained from each of the multiple radiation detectors by collecting data at each position. 6 (e) Embodiment In FIG. 1, a plurality of small detectors (five in the figure) are arranged in the slice thickness direction. It consists of a detector (detector segment) DI-D5, and these detectors D1 to
D5 is n from CHI to CHn in the direction parallel to the slice plane.
divided into channels. These detectors are composed of semiconductor radiation detectors or combinations of scintillators and semiconductor photodetectors. The thickness of the entire slice thickness direction of the detector 1 is TI, and the detectors D1 to D
5 is assumed to be T2 (115 of Tl). The signals from these many (5×n) detectors are each sent to a multiplexer 3 via an amplifier 2, and are sequentially selected by this multiplexer 3 and sent to an A/D converter 4, where they are digitized and then sent to a CPU 5. The data is taken into the memory 6 via.

As shown in FIG. 2 or 3, the detector 1 is placed opposite the X-ray tube 7 with the subject 8 in between.

When obtaining a tomographic image with a normal slice thickness T1, the second
As shown in the figure, there is a detector L in the plane of the slice surface Sl.
and the X-ray tube 7 (see solid line) so that the X-rays within the range of thickness TI are incident on all of the detector 1. The data in each channel is the sum of the data from the detector DI-D5. Scanning is performed by rotating the detector 1 and the X-ray tube 7 together around the subject 8 within this slice plane Sl, and data is collected in various directions within this slice plane Sl. When this operation is completed, the detector 1 and the X-ray tube 7 are shifted in the slice thickness direction by the slice thickness Tl with respect to the subject 8, and positioned within the plane of the next adjacent slice plane S2, and the same rotational movement is performed. and collect data. In this way, by scanning and collecting data at each position while shifting the slice in the thickness direction, it is possible to reconstruct tomographic images of a large number of slice planes SL, S2,... data can be obtained.

When obtaining a tomographic image of a thin slice plane, for example, assuming the slice thickness is T2, the detector 1 and the X-ray tube 7 are shifted by a thickness T2 with respect to the subject 8, as shown in FIG. At each position, the X-rays are incident on all of the detector l within the range of thickness TI, and the detector l is
Data is collected by scanning using the rotational movement of the X-ray tube 7 and the X-ray tube 7. In this case, in the first scanning, data regarding each of the slice planes 5t-S5 is obtained from each of the detectors DI-05. In the next second scanning, data regarding each of the slice planes 52 to S6 is obtained from each of the detectors Di to D5.

In the third time, data related to each of the slice planes S3 to S7, in the fourth time, data related to each of the slice planes S4 to S8, and in the fifth time, data related to each of the slice planes S5 to S9, respectively. -D5. Then, among the data obtained in these multiple scanning operations, data regarding the same slice plane are added together to obtain data regarding the slice plane. That is, for example, data regarding the slice plane 55 is detected by the detector D5 in the first scanning, the detector D4 in the second scanning, the detector D3 in the third scanning, and the detector D3 in the fourth scanning. Since the data are obtained from the detector D2 and from the detector D1 in the fifth scanning, it is assumed that these are added together. Then, in one scanning, slice plane S5
．． For this, only the 115 doses shown above (Figure 2) are used, but since the data consists of 5 doses, the 2nd dose is
Data on the slice plane S5 with the same dose as in the case of the figure is obtained.

Therefore, the slice thickness is 175 mm compared to the case in Figure 2.
However, the dose is exactly the same, and the quality of each image can be maintained without deteriorating the S/N ratio of the data.

Conventionally, when reducing the slice thickness as shown in Fig. 3, the slice planes Sl and S are simply
2. Narrow down the X-rays to a thickness T2 for each of...
Since scanning is performed while shifting the thickness a T by 2, only 115 doses are used in each scan, and the other 415 doses are simply shielded. This results in significant image deterioration, and if this is to be avoided, it is necessary to take five times as long to scan each scan to ensure the same dose. In contrast, in the present invention, since all X-rays are used as described above, image quality can be maintained without spending time on each scan.

(f) Effects According to this invention, when obtaining a tomographic image with a thin slice thickness, the radiation is utilized to the maximum without constricting the radiation, resulting in deterioration of the data S/N ratio and resulting deterioration of image quality. can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIGS. 2 and 3 are schematic diagrams for explaining the operation. ■...Detector? ...Amplifier 3...
Multiplexer 4...A/D converter 5...C
PU 6...Memory 7...X-ray tube 8...Subject patent applicant Shimadzu Corporation

Claims (1)

[Claims] (1) A radiation source and a radiation detector are arranged facing each other with the subject in between, and radiation attenuation data is collected in various directions within a specific slice plane of the subject, and from this data, the formation of In a computed tomography apparatus that reconstructs a radiation absorption coefficient distribution image using a computer, a plurality of radiation detectors are arranged in the slice thickness direction, radiation is simultaneously applied to these from a radioDI radiation source, and the radiation detection of the plurality of radiation detectors is performed. Collect data at each position while shifting the radiation source and radiation detector in the slice thickness direction relative to the subject by the thickness of each slice of the device. Computed tomography characterized in that among the data obtained from each of the plurality of radiation IN #fA detectors recorded in the data collection, data corresponding to the slice position is added together to form data for the slice plane. Device.