JPS5897344A - Computer tomography 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 The present invention relates to a radiation based, ambient tomography apparatus.

Conventionally, this combination X-ray tomography system uses a radiation source that spreads out in a plane and irradiates nine radiations, and a radiation source that irradiates radiation that passes through different routes in the subject at a position facing the radiation source. A radiation detector (hereinafter referred to as a "detector") that detects part or all of the radiation source is installed at a general company. First, the detector is moved in a straight line to collect some 0 data, and then the radiation source is detected. The detector is rotated by an angle that allows the radiation to spread in multiple directions, and then data is collected while moving in a straight line again. Thereafter, this operation is repeated until 180@ data are collected to complete one scan, and from the obtained data the distribution of the radiation attenuation coefficient in the cross section within the subject is calculated and reconstructed. With such a device, there is a significant difference in time between the beginning and the end of the scanning angle, for example between 0° and 180°, and due to the spread of the radiation beam, Although the paths calculated at 180° and 180° are exactly the same, there is a difference in the shape of the actual path, and distortion occurs in the reconstructed image. To compensate for this,
Apparatus have been proposed that rotate 360 degrees instead of 180 degrees, obtain radiation beams with substantially different paths, and reconstruct images with less distortion than these. However, these devices rotate the radiation source and detector 360°, which increases the amount of winding of cables attached to the rotating head and increases direct radiation exposure to the human body, such as the eyeballs. The purpose of the present invention is to obtain radiation beams with an amount of data equivalent to that of a device that rotates 360 degrees with a rotational movement of 180 degrees, and a radiation beam with non-overlapping paths. An object of the present invention is to provide an intramural nasal tomography apparatus that provides higher quality images than conventional ones while minimizing the amount of direct radiation exposure to the body.

According to the present invention, there is provided a radiation source that irradiates radiation such that the radiation spreads in a planar fan shape and passes through the subject; a plurality of radiation detectors, a holding means for holding the radiation source and the radiation detector, a driving means for linearly and (b) rotationally moving the holding means, and a signal receiving means for receiving signals from the radiation detectors. In a combinator tomography system having means for calculating the distribution of radiation attenuation coefficient in a cross section within the specimen, the maximum odd number not exceeding the angle formed by the radiation source and two adjacent radiation edge detectors and the number of radiation detectors. By rotating the stage + hold at half the angle of the product of , for each half of the set of sampling angles of data obtained in the previous linear movement in turn, a ray with a sampling angle substantially in between. A combinatorial tomography apparatus is provided, which is characterized in that the beam can be obtained in a manner that increases the speed of the beam.

The present invention will be described in detail below with reference to the drawings of one embodiment of the present invention.

First, to explain the principle of the present invention, as shown in Figure 1, data is collected while moving the radiation source 1 and the detectors 10 to 14 in a straight line.
' and 10' to 14' by an angle α with respect to the rotation center 2. At this time, α is an angle expressed by the following formula.

α=β・n/2 ・・Dan・(1)
and ζ and β: angle between two adjacent detectors and the radiation source,
n: Maximum odd number not exceeding the number of detectors, plate wave This linear movement and rotational movement are repeated until substantially 1800 minutes of data are obtained.

According to the present invention, as shown in FIG. 2, the initial position 1.
The sampling angle of the data obtained by the linear movement in steps 10 to 14 is DOJ), DcLx,..., and after the completion of the linear movement, the sampling angle of the data obtained by rotating by the angle α and moving linearly again is DI. , O, DI mountain...
Then, the sampling angle D i,j generally obtained in one scan is expressed by the following equation, where m is the number of detectors.

Di, j = α amount + βj = β・n-1/2 + βj ・・・・・・
(2) Here, 1: rotational movement degree (integer of ≧0) j: detector number (integer of Ojj≦m−1) Now, n is the largest odd number that does not exceed the number of detectors, so n= 21-1...River (8
) J=[(n+1)/2)...Represented by the river (4). Here, [] in equation (4) is a Gauss symbol o (2) (Equation 8)) Di, J = β・C21-1)・1/2+βj=(A!
-,) f) i β+jβ scream...
(As is clear from Equation (6), the sampling angle of the data obtained by linear movement after receiving the 111th rotation is the sampling angle obtained by iI linear movement after receiving the i-1st rotation.) ?For half of the set, the sampling angle is exactly in the middle.@'119 As can be seen from Figure 2, for the first half of the set, the sampling angle at the midpoint is set by the next rotation. Although one ring angle cannot be obtained, it is possible to obtain these by rotation after IIIk, and from these data it is possible to correct the influence due to temporal differences.In the present invention, the rotation in the angular direction The sampling density is twice that of the conventional rounding method, so it is possible to obtain a higher quality image than the conventional method, and even if β is twice that of the conventional method, the configuration is simplified. According to this method, it is possible to obtain images that are comparable in performance to conventional ones.

As explained above, according to the present invention, by rotating the radiation source and the detector at each angle α expressed by equation (1) and obtaining data by their linear movement, the angular range is the same as that of the conventional method. In other words, it is possible to obtain data that can correct the path of the same radiation beam #1, which is temporally spaced within a range of 180 degrees, and has a higher quality than before, and also reduces the amount of cable winding and A combination tomography apparatus is provided that does not increase direct radiation exposure to the eyeballs.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic operation of the device in the present invention;
FIG. 2 is a diagram showing the effect of the apparatus according to the present invention, and shows the sampling angle of each data obtained by the apparatus according to the present invention. In the figure, l...Radiation source, 2...
Center of rotation, 10~14. 10'~14'...Detector, Do, o, Do, t, -DI, j...
- Sampling angle. Figure 1 Figure 2

Claims (1)

[Claims] A radiation source that spreads in a fan shape and irradiates nine radiations, a plurality of radiation detectors arranged at a distance from each other at a position facing the radiation source with the subject in between, and the radiation source and the plurality of radiation detectors. a holding means for maintaining the relative position of the object and holding it in a nine-sided shape; a driving means for linearly and rotationally moving the holding means; and a drive means for receiving detection signals from the plurality of radiation detectors to form a tomographic image of the object half the product of the angle β between the radiation source and the two radiation detectors and the largest odd number n not exceeding the number of the plural radiation detectors; The holding means is sequentially rotated at an angle of 1 [
A combination tomography apparatus characterized by scanning at a sampling angle of half C1.