JPS5835209Y2 - tomography device - Google Patents

Description

[Detailed description of the invention] This invention irradiates a radiation beam to a predetermined tomographic plane of an object from all directions within that plane, collects data regarding the transmitted radiation intensity, and processes the data using a computer. Obtain an image of the radiation absorption rate distribution of the tomographic plane,
The present invention relates to a so-called computerized tomography apparatus.

In a tomography apparatus, when imaging the head, the irradiation field may be narrower than when imaging the whole body, such as the torso, but high-resolution images are required.

For this reason, conventional devices have been used that have a structure that allows them to be switched between use for the head and for the whole body.

Conventional examples are shown in FIGS. 1 and 2, respectively.

In FIG. 1, a large number of X-ray beams 3 are emitted from an X-ray tube 2 in a fan shape, and each X-ray beam is transmitted to a large number of X-ray detectors 41, 42, .
...4n is detected respectively.

The X-ray detectors 41, 42, . . . , 4n are arranged on a circular arc to form a detector row 4.

Necessary scanning is completed when the X-ray tube 2 and the detector array 4 are rotated once around the center O of the object as shown by the arrow.

In this case, since the irradiation field 11 is large during full-body imaging,
Although all the detectors 41, 42, .

In the system shown in Figure 1, the detectors used for the head and the whole body are switched in this way.
In the case of head imaging, high resolution is required as described above, so it is necessary to increase the density of the detectors arranged in the section 5.

Therefore, in the conventional arrangement, detectors 41, 42, . . . , 4n are arranged at high density throughout the detector row 4.

In Fig. 2, "X" indicates the difference between when scanning the whole body irradiation field 11 and when scanning the head irradiation field 12.
The ray tube 2 and the detector row 4 are moved in parallel as shown by dotted lines, so that a small irradiation field 12 is scanned with a high-density X-ray tube beam.

Conventional tomography equipment, as shown in Figure 1, requires a large number of detectors to be arranged in a high density arrangement, which poses difficulties in assembly, and as shown in Figure 2, it is difficult to assemble the X-ray tube and detector array. Since both must be moved in parallel and rotated together at the position of the parallel movement, there is a drawback that the mechanism is complicated.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks and provide a tomography apparatus that can switch between whole-body imaging and head imaging without the need for densely arranging detectors or using a complicated mechanism. shall be.

An embodiment of the present invention will be described below with reference to FIG.

According to the present invention, as shown in FIG. 3, two detector rows 6,
7, the detector row 6 is arranged close to the object center O, and the detector row 7 is arranged far away.

The detector rows 6 and 7 are arranged on almost the same plane, and have the same number of detectors (n) of detectors 61 to 6n, respectively.
It consists of 71 to 7n.

Even though the arrangement density of the detectors is almost the same between detector row 6 and detector row 7, detector row 7 is farther away and the irradiation field 12
Since the radiation field 12 is also small, the X-ray beam passing through the irradiation field 12 has a high density, making it possible to obtain high-density data in the case of head photography.

In the case of head imaging, the detector row 6 is retracted along the subject's body axis by the width of the X-ray beam so that the detector row 6 does not interfere with the X-ray beam incident on the detector row 7. There is a need.

It is preferable to use highly sensitive B, G, and 0 scintillators for each of the detectors 61 to 6n and 71 to 7n, and a light cable (optical guide path) 9 is connected from each detector to n photomultiplier tubes 81 to 8n. are connected so that the photomultiplier tubes 81 to 8n are commonly used by the detector row 6 and the detector row 7.

In this way, if the X-ray tube 2 and the detector rows 6 and 7 are rotated together around the subject center O without the detector row 6 being evacuated, the data in the whole body irradiation field 11 can be transferred to the detector. Obtained from the column.

On the other hand, if the detector row 6 is rotated in the same manner with it retracted, data within the head irradiation field 12 can be obtained from the detector row 7.

As explained in the embodiments above, according to the present invention, there is a detector row close to the subject and a detector row farther from the subject, so there is no need to increase the density of the detectors arranged in each detector row. Also, it is mechanically simple because it requires only a mechanism for retracting the closer detector row 6 of the detector rows 6 and 7 arranged on the same plane from the plane.

[Brief explanation of the drawing]

FIGS. 1 and 2 are block diagrams showing conventional examples, and FIG. 3 is a block diagram showing an embodiment of the present invention. . 11... Whole body irradiation field,
12... Head irradiation field, 2... X-ray tube, 3... X-ray beam, 4, 6.7...
Detector rows, 41-4n, 61-6n, 71-7n...
...Detector, 81-8n...Photomultiplier tube,
9...Light cable.

Claims (1)

[Scope of utility model registration request] A radiation detector row close to the subject and a radiation detector row far from the subject are arranged on substantially the same plane, and the two
Two radiation detectors whose arrangement positions in the row of radiation detectors correspond to each other are connected to one photomultiplier tube through a light guide path, and the row of radiation detectors near the subject is connected from the plane. A tomography apparatus that is held retractably and rotates the plane detector array together with a radiation source around a subject in a retracted state or in a non-retracted state.