JPS6114817B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for obtaining an axial tomogram using X-rays. Recently, an X-ray microbeam is scanned at an arbitrary cross section (cross section) of the human body, and the scanning direction is successively varied to measure the intensity of the X-rays transmitted through each point of the human body.
A device has been developed that can obtain a tomographic image of the cut plane based on the signal and more accurately capture the internal structure of the human body. Conventional devices of this type have an X-ray tube with a collimator and a detector facing each other, a subject is placed between both collimators, and the X-ray tube with a collimator and the detector are connected integrally and intermittently. The object is moved in a transverse direction, and the intensity of X-rays transmitted through the object is measured at each stop position. However, with this device, in order to obtain a tomographic image of a cross section, the aforementioned X-ray intensity measurement must be performed over the entire circumference of the object, that is, the X-ray tube and detector must be rotated at a wide angle around the object. As a result, it takes a long time to obtain one tomographic image, and the imaging work is extremely inefficient. In order to solve such drawbacks, it is possible to consider an apparatus in which a plurality of the X-ray tubes and detectors are arranged around the object so as to face each other, and these are rotated together around the object. However, in such an apparatus, a plurality of power supplies for the X-ray tube must be prepared, and the cost becomes extremely high. The present invention provides a device that can eliminate such inconveniences, and will be described in detail below based on an embodiment shown in FIGS. 1 to 3. FIG. 1 is a diagram showing the positional relationship between the subject, the X-ray generator, and the detector. Reference numeral 1 indicates the subject, and around the subject are three X-ray generators 2a , 2b , and
2c are placed at equal intervals (every 120 degrees). Columns 3a, 3b and 3c of these X-ray generators
As shown in the cross-sectional view in FIG. 2, the longitudinal direction thereof is parallel to the body axis 0 of the subject 1. In FIG. 2, columns (lens barrels) 3b and 3c are omitted because they have the same structure as 3a. The column 3a
An electron gun 7a consisting of a filament 4a, a Wehnelt electrode 5a, and an anode 6a is provided at one end, and the electron beam EB generated from the electron gun is narrowly focused by a focusing lens 8a, projected onto a target 9a, and deflected. The target is scanned by system 10a. The X-rays _{X a} generated from the electron beam irradiation point of the target 9a are transmitted through the pinhole lens 11.
It is taken out to the outside as an X-ray microbeam through a, and irradiates the subject 1. Now, the electron beam EB is scanned in the direction perpendicular to the plane of the paper in the figure, that is, the electron beam is moved from point A to B on the target 9a shown in FIG.
When scanning from X _a1 to X
_a2 , and a fan-shaped scan is performed with the pinhole lens 11a at the center. In the other X-ray generators 2b and 2c , the object 1 can be scanned with the X-ray microbeams _Xb and _Xc by scanning the targets 9b and 9c with electron beams. The X-ray microbeams X _a , X _b , and X _c that have passed through each point of the subject 1 during the scanning are detected by dedicated detectors 12 a, 12 b, and 12 c, respectively, and the signals detected by each detector are not shown. is sent to an electronic computer. The X-ray generators 2a , 2b , 2c are each integrally fixed to the rotating body 13, and the detectors 12a, 12b, 12c are also connected to the rotating body 1 via support rods 14a, 14b, 14c.
3, and the three X-ray generators and detectors are rotated together around the body axis 0 of the subject 1. On the other hand, as is clear from FIG. 3, a negative high voltage of, for example, about 150 KV is applied to each of the electron gun filaments 4a, 4b, and 4c in the three X-ray generators from one high-voltage power supply 15. Also, bias circuits 16a, 1 in each electron gun
The bias voltages of 6b and 16c are set to be deep to keep the electron beam in a cut-off state. In this state, the bias control circuit 17 to the bias circuit 16
A signal is supplied to the electron gun 7a to release the cut-off state of the electron gun 7a to generate an electron beam, and the object 1 is scanned by the X-ray microbeam X _a from the X-ray generator 2a . When this scanning is completed, the signal being supplied to the bias circuit 16a is stopped, and the electron gun 7a is kept in the cut-off state again. Then, a signal is supplied from the bias control circuit 17 to the bias circuit 16b, and the X-ray generator
The object 1 is scanned by the X-ray microbeam X _b from 2b , and then a signal is supplied from the bias control circuit to the bias circuit 16c, and the X-ray generator 2c
The object is scanned by an X-ray microbeam X _c from When the scanning is completed, the rotating body 13 is rotated, and the X-ray generators 2a , 2b , and 2c and the detectors 12a, 12b, and 12c are aligned with the subject's body axis 0.
The object 1 is scanned while rotating by a certain angle (for example, 1 degree) around , and repeating the above-described operations. By doing so, only one power source for generating X-rays is required, so that costs can be reduced. In addition, since the X-ray microbeam is irradiated onto the subject from three sides one after another instead of all at once, scattered X-rays from the subject can also be reduced and the S/N ratio can be improved. etc., it has great practical effects. Incidentally, in the above-mentioned embodiment, a case was described in which three X-ray generators were used, but two or four or more X-ray generators may be used. In addition, we have described the case where a pinhole lens is used to scan an object in a fan shape with an X-ray microbeam, but by using a narrow aperture instead of a pinhole lens, it is possible to scan the entire object with a thin fan-shaped X-ray beam. It may be configured to irradiate.
In this case, it is necessary to arrange not one detector but a plurality of minute detectors in a row.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG.
The figure is a cross-sectional view of the X-ray generator used in the present invention.
FIG. 3 is a schematic diagram showing the electrical circuit of the present invention. In the figure, 1 is the subject, 2a , 2b and 2c are the X-ray generators, 3a, 3b and 3c are columns, and 6
a, 6b and 6c are electron guns, 8a is a focusing lens,
9a, 9b and 9c are targets, 10a is a deflection system, 11a, 11b and 11c are pinhole lenses, 12a, 12b and 12c are detectors, 13 is a rotating body, 15 is a high voltage power source, 16a, 16b and 1
6c is a bias circuit, and 17 is a bias control circuit.

Claims (1)

[Claims] 1 A plurality of X-ray generation devices each having an electron gun and an X-ray generation target that generates X-rays by irradiation with an electron beam from the electron gun, and a plurality of X-ray generation devices arranged opposite to each of the X-ray generation devices. , a plurality of X-ray detectors for measuring the X-rays transmitted through each part of the object, and the plurality of X-ray detectors;
A single high-voltage power supply for applying high voltage to the electron guns in the radiation generator, a control means for controlling the bias voltage of each electron gun so that the electron guns are sequentially put into operation, and each of the detectors. An apparatus for obtaining an X-ray body axial tomogram, comprising: an arithmetic unit to which an output signal of is supplied;