JPS5892974A - Radial computer tomography device - Google Patents

Abstract

PURPOSE:To enable immediate determination of a radioactive isotope (RI) distribution in a body with an absorptive correction of radiation in the body by detecting radiation emitted from the RI accumulated in an object to be inspected (body of a patient) outside the body to obtain a distribution image of radiation absorption coefficient on the same condition as the RI distribution image simultaneously. CONSTITUTION:Parallel gamma ray beams (as indicated in the dotted line) are irradiated on an object 7 from the side of a camera 1 to be inspected and those transmitting the object 7 enter a camera 8. The gamma rays (as indicated by the solid line) emitted from the RI accumulated in a specific organ of the object 7 enter the camera 8 and a camera 1 facing it. The RI dosed to the object 7 and the RI buried in a collimator 2 are different in the type of energy of gamma rays to be emitted therefrom. In the camera 8, discrimination of energy of incident gamma rays enables detection of only the gamma rays transmitting the object 7 from the side of the camera 1 thereby affording a data concerning the intensity of the radiation transmitted.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention detects radiation emitted from radioactive substances (radioisotopes, hereinafter referred to as RI) accumulated within the subject (patient's body) outside the body. R of
Radial combinator tomography device f that reconstructs the I distribution image
(hereinafter abbreviated as ECT) Klm.

In ECT, radiation (e.g. gamma rays) emitted from the RI in the body is partially absorbed by the tissue fibers of the body before reaching the body surface, so the stationary bond value of the tomographic image obtained as an RI distribution image is different. There is an inherent drawback.

In view of the above, the present invention is capable of simultaneously obtaining a radiation absorption coefficient distribution image by transmitted radiation under the same conditions as an R1 distribution image, thereby correcting the absorption of radiation in the body, and improving the internal RI.
The purpose is to provide an ECT that allows immediate distribution emplacement.

An embodiment of the present invention will be described below with reference to the drawings. This example is of a type that rotates two scintillation cameras arranged oppositely at an angle of 180°.
This is a so-called digital head camera rotating type ECTK to which the present invention is applied. In FIG. 1, reference numerals 1.8 are synchronized cameras each equipped with parallel multi-hole collimators 2.9, which are mounted on the rotating frame 3 and are opposed to each other at an angle of 180°. This rotating frame 3 has a support base 5
The subject 70 lying on the bed 6 is rotated about the body axis 0 as a central axis.

The radiation shielding wall 21 of the collimator 2 is provided with a groove 22 of an appropriate depth as shown in FIG. It is spread out over a wide area. A scintillator 11 such as a NaI (TJ) crystal is arranged at the back of the collimator 2, and a large number of photomultipliers 3 are arranged via a light guide 12.

In this way, a parallel gamma ray beam (indicated by a dotted line) is irradiated from the camera l side toward the subject 7 as shown in FIG. 3, and the beam that passes through the subject 7 is incident on the camera 8. In addition, gamma rays (indicated by IJ! lines) 4 emitted from RI accumulated in a specific organ 71 of the subject 7 enter this camera 8 and the camera 1 opposite to it. The RI administered to the subject 7 and the RI embedded in the collimator 2 are of different types in the energy of the gamma rays emitted from them, and by discriminating the energy of the incident gamma rays in the camera 8, It is designed to detect only the intensity of gamma rays transmitted through the subject 7 from the camera 1 side, and to obtain data regarding the intensity of transmitted radiation. Similarly, by energy discrimination, if there is a gamma ray that passes through the radiation shielding wall 21 of the collimator 2 and enters the camera 1 side, it can be removed. can be detected.

When these facing cameras 1 and 8 are rotated 360 degrees,
RII position data is obtained from camera 1, and transmitted radiation intensity data is obtained from camera z)8. By processing the RII position data using a computer, it is possible to reconstruct the distribution image of the RI within the subject 7, and to determine the intensity of the transmitted radiation. These distribution images are 2 for the same new surface.
Dimensional - I am the ninth, and both can be obtained under exactly the same conditions regarding position. By using this ninth radiation absorption coefficient distribution image, it is possible to accurately and easily correct errors caused by internal absorption of the υR1 distribution distribution image sample 70.

Note that the frame 3 is arranged so that the radiation ## (not shown, but for example, the collimator 2 in the diagram jlIz) having the RI 23 arranged as shown in FIG. 2 is located at the position of the camera 8.
If the signal obtained from the camera is separated by a wave height analyzer with two energy windows to obtain data from the RI inside the object 7 and data about the intensity of transmitted gamma rays, one camera can be used. And RI distribution color radiation Ii!
It is also possible to obtain an absorption coefficient distribution tube at the same time.

Further, as the scintillator cameras 71 and 8, various radiation position detectors such as an Anger-type one and an autofluoroscope can be used.

As described above with respect to the embodiments, according to the present invention, when obtaining the RI distribution on a certain tomographic plane of a subject, the radiation absorption coefficient distribution on the Oka tomographic plane at the same time and under exactly the same positional conditions. Since the image can be obtained, R
Accurately and easily perform I distribution color absorption correction for R1 in one body.
It becomes possible to immediately fix the distribution.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a partially enlarged sectional view, and FIG. 3 is a schematic diagram. 1.8... Synthesis camera 2.9... Collimator 3... Rotating frame 4...
・Drive part 5... Support stand 6... Ped
7... Subject 21... Radiation lotus shielding wall 22.
...Groove 23...RI 11...Scintillator 12...Light guide l3...Photomultiplier Applicant: Shimadzu Corporation

Claims (1)

[Claims] (1) At least one radiation position detector facing the subject in which radioactive material is accumulated, and a radiation position detector facing the radiation position detector with the subject sandwiched therebetween, and radiation emitted from the radioactive material. A radiation source that irradiates a parallel radiation beam of true energy toward the subject, and a radiation position detector and a radiation source that face each other and maintain a positional relationship so that they are connected to the subject. by rotating around the radioactive substance and distinguishing radiation from the radioactive substance and radiation from the radiation source by energy,
A radiation tomography device that simultaneously reconstructs the distribution image of radioactive substances within the subject and the distribution image of the radiation absorption coefficient within the subject = □