JPH0145594B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a radiation tomography apparatus.

A radiation tomography device uses a computer to construct a distribution image of the concentration of radioisotopes (hereinafter referred to as RI) distributed within the body on a certain cross-sectional plane. In other words, the subject (patient)
When RI is taken in as a drug and accumulated in a specific organ, the radiation emitted from this is detected by a radiation detector outside the body, data is collected, and this data is processed by a computer. The aim is to construct a distribution image of RI concentration on a surface and use it for diagnosis of the characteristic organ.

An object of the present invention is to provide an inexpensive radiation tomography apparatus that can construct RI concentration distribution images of multiple tomographic planes at once.

An embodiment of the present invention will be described below with reference to the drawings. As shown in Figures 1 and 2,
A large number of radiation detectors 2 are arranged in a ring shape around the central axis O-O in a plane approximately perpendicular to the central axis O-O, with the body axis O-O of the subject (patient) 1 as the approximate central axis. Fixed. A ring-shaped rotating collimator 3 is arranged inside the ring-shaped array of the radiation detector 2, and this rotating collimator 3 has a slit array 31, 32 formed in two layers in the central axis O-O direction. have. The slit array 31 is located in the layer on the left side of FIG. 2 (the front side of FIG. 1), and a large number of slits 41 are formed within the right half (180 degrees) of FIG. The angle of this slit 41 is sequentially changed from -θ to +θ with respect to the center axis O-O within a plane substantially perpendicular to the center axis O-O. The slit array 32 is located in the layer on the right side of FIG. 2 (on the back side of the paper in FIG. 1), and is located in the left half of FIG. −θ to + with respect to −O
A large number of slits 42 whose angles are sequentially changed up to θ
is formed. These slits 41, 42
is for regulating the direction of radiation incidence. Specifically, for example, a large number of ring-shaped radiation shielding plates are arranged perpendicular to the central axis O-O, and radiation shielding pieces perpendicular to the shielding plates are arranged as shown in Fig. 1. The rotating collimator 3 is formed by arranging the collimators at different angles as shown in FIG. 2, and a large number of lattice-shaped holes formed by the shielding plate and the shielding pieces are used as slits 41 and 42. Then, the semicircular portion of each layer is covered with another radiation shielding member to close the openings of the slits 41 and 42, so that the slits 41 and 42 are formed only in the semicircular portion of each layer as described above. do. Each of the radiation detectors 2 has a predetermined length in the direction of the central axis OO, as shown in FIG. 2, so that the radiation passing through the slits 41 and 42 is incident thereon.

When the rotating collimator 3 is driven by an appropriate drive mechanism (not shown) and rotates as shown by the arrow with the axis O-O as the rotation center axis, focusing on one radiation detector 2-1, the first 1/2 First in rotation
Radiation is incident through each slit 41 of the slit array 31 of the layer, and in the following 1/2 rotation, radiation is incident through each slit 42 of the slit array 32 of the second layer. By detecting the rotation angle of the rotating collimator 3, it is possible to know at which angle the slit 41 is located in front of the radiation detector 2-1, that is, in which direction the radiation is incident. From the output of the radiation detector 2-1 and the rotation angle information, - in the first layer with 1/2 rotation
Fan-shaped radiation data from θ to +θ can be obtained, and in the next 1/2 rotation, fan-shaped radiation data from +θ to −θ in the second layer can be obtained. This is the same for other radiation detectors 2, so in the end all the data regarding two tomographic planes can be obtained from a large number of radiation detectors 2 in one rotation of the rotating collimator 3, and this data is processed using a computer. By doing so, it is possible to construct RI concentration distribution images within the subject 1 on two tomographic planes.

In the above embodiment, the slit arrays 31, 3 in each layer are
2 are arranged every 180°, as shown in Figure 3.
The slits can be arranged every 90 degrees, every 120 degrees as shown in Figure 4, or each slit can be arranged every 4 degrees as shown in Figure 5.
They can be arranged intricately every 1,42.
In short, the openings on the outside (radiation detector 2 side) of each slit 41 and 42 should not overlap when viewed from the direction parallel to the central axis O-O (both end directions of the central axis O-O), and each layer should be In other words, in order to prevent the radiation passing through the slits 41 and 42 from entering one radiation detector 2 at the same time, in other words, the output of one radiation detector 2 at a certain angular position of the rotating collimator 3 is determined to which tomographic plane it relates. Just make sure you can tell them apart.

In Fig. 3, parallel slits 41 are drawn with solid lines.
are arranged in the first layer, and parallel slits 42 drawn by dotted lines are arranged in the second layer, and since these are arranged every 90 degrees, the rotating collimator 3
Just by rotating it, you can obtain data on two layers of tomographic planes.

In FIG. 4, parallel slits 41 are arranged in the first layer, parallel slits 42 in the second layer, and parallel slits 43 in the third layer, so that they are arranged in three layers every 120 degrees. Therefore, when the rotating collimator 3 rotates once, data of three layers of tomographic planes can be obtained. Of course, by dividing the radiation detector into smaller pieces and arranging the slits in multiple layers, and by making the length of each radiation detector in the central axis direction longer than the length of each of these slits, it is possible to create even more layers of tomographic planes. It is also possible to obtain data in one revolution of the rotating collimator.

In the rotating collimator 3 shown in FIG. 5, the outer openings of the slits 41 in the first layer and the outer openings of the slits 42 in the second layer are arranged so that they do not overlap when viewed from a direction parallel to the central axis O-O. Since they are arranged alternately, the output of each radiation detector 2 includes the first
Those related to the tomographic plane of the layer and those related to the tomographic plane of the second layer will be displayed in sequence.

As described above with respect to the embodiments, according to the present invention, it is possible to simultaneously obtain data on two or more layers of tomographic planes using one layer of radiation detectors. It is possible to construct an RI concentration distribution image of a tomographic plane.

[Brief explanation of drawings]

FIG. 1 is a schematic front view of an embodiment of the present invention;
FIG. 2 is a schematic vertical cross-sectional view of the same embodiment, FIGS. 3 and 4 are schematic front views of the second and third embodiments, respectively, and FIG. 5 is a schematic longitudinal sectional view of the fourth embodiment. FIG. 1... Subject (patient), 2... Radiation detector,
3...Rotating collimator, 41, 42, 43...Slit.

Claims (1)

[Claims] 1. With the subject's body axis as a substantially central axis, a large number of radiation detectors are arranged and fixed in a ring shape around the central axis in a plane substantially perpendicular to this central axis, and the ring-shaped array of radiation detectors is A ring-shaped rotating collimator is disposed inside the ring-shaped rotating collimator provided with a large number of radiation incident direction defining slits oriented in various directions within a predetermined angular range within which the central axis is included in the plane. In a radiation tomography apparatus in which each radiation detector obtains fan-shaped radiation data by rotating this rotating collimator, at least two layers of tomography are arranged in the direction of the central axis of the rotating collimator. The slits are arranged in at least two layers so as to correspond to each surface, and the outer openings of the slits in the at least two layers of slits do not overlap when viewed from a direction parallel to the central axis of the rotating collimator. and the length in the central axis direction of the rotating collimator of each of the plurality of radiation detectors is set to such a length that radiation passing through each slit of the at least two-layer slit array is incident on the radiation detector. A radiation tomography device that is characterized by its sharpness.