JPS63151886A - Radiation detector - Google Patents

Abstract

PURPOSE:To obtain a detection element with limited dispersion of characteristic thereof near a block joint, by inserting a wedge-shaped spacer into a wedge- shaped clearance generated at a joint of a detector block to improve the adhesivity of a reflector. CONSTITUTION:A phosphor element 35 which absorbs radiation energy of X rays, a light transmitting element 36 junctioned thereto 35 to introduce the fluorescence into a photoelectric conversion element 32 and a radiation detecting element which is formed covering a part of the elements 35 and 36 with reflectors 37, 38 and 39 for reflecting the fluorescence, having a photoelectric conversion element 32 in contact with the element 36 are arranged in plurality adjacent thereto to be in a block. A wedge-shaped elastic body, for example, rubber member 41 is grasped with a wedge-shaped clearance between blocks to secure the adhesion of the reflector 39 at the block joint. Besides the member 41 as wedge-shaped elastic body, a plate spring-shaped member or rubber cord- like member may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a multichannel radiation detector for X-ray CT, and particularly to a structure of a solid-state detector element suitable for reducing characteristic variations.

[Background of the invention]

FIG. 2 is a configuration diagram of a scanning section of an X,1iCT apparatus of a type called the third generation. A subject 1 is placed between an X-ray tube 2 and a detector 3. Both the x4 tube and the detector rotate and scan around the subject, and a computer reconstructs a CT image based on the X-ray attenuation data acquired during that time. As shown in FIG. 3, the detector 2 houses a large number (approximately 500) of radiation detection elements 11, and converts incident X-rays into electric current. The detection element 11 is arranged on a circular arc so that the front face is in the XHH2C direction. When a part of it is enlarged, as shown in FIG. 4, a plurality of detection elements (channels) are arranged in a straight line as one block 21. This is because consideration was given to simplifying the manufacturing method.

FIG. 5 shows the structure of each block. A substrate 31 serves as a support for the entire structure, and a photoelectric conversion element (for example, a photodiode) 32 and a connector 33 for taking out the output thereof.
A conductor pattern is printed to connect them.

The photoelectric conversion element 32 is divided into as many channels as the number of channels assigned to the block, and has the same number of output terminals.
The same number of phosphor elements 35 and a transparent element 36 that guides the fluorescence generated from the phosphor elements 35 to the photoelectric conversion element are attached. The transparent element is made of lead glass because it also serves to prevent X-rays from directly entering the photoelectric conversion element.

The fluorescence generated by Xm is transferred to the photoelectric conversion element 32 without any loss.
The phosphor 35 and the light transmitting body 36 are surrounded by light reflecting bodies 37, 38, and 39 except for the bonding surface to the photoelectric conversion element. The light reflector 37 is sandwiched between the phosphor translucent elements and is in close contact with the elements on both sides. Further, the light reflector 38 covers the X-ray incident side of the phosphor element. In the structures shown in FIGS. 4 and 5, the reflectors 39 at both ends of the block are free on one side, so they do not necessarily come into close contact with the phosphor translucent element. If the element is not in close contact with the transparent body 36, the characteristics of only that element will change. That is, due to differences in the distance of close contact, differences in the uniformity of close contact, etc., the output values output by the detector will differ for the same dose of X-rays that have passed through the same attenuated area. In the third-generation CT shown in Figure 2, it is difficult to compensate for the effects of such variations in detector characteristics.
<1 Immediately affects image quality.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a detection element in which the variation in detection element characteristics near a block joint is small in a block detector.

[Summary of the invention]

In order to improve the adhesion of the reflector of the element in contact with the detector block joint, a wedge-shaped spacer is inserted into the wedge-shaped gap created at the joint. The spacer is made of an elastic material, and if its thickness is made larger than the thickness of the wedge, the adhesion of one reflector is improved by the pressure generated by compressing the margin.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, in which a wedge-shaped elastic body, for example a rubber member 41, is sandwiched between blocks.
To ensure close contact of the reflector 39 at the block joint.

The one shown in FIGS. 6(a) and 6(b) uses a plate spring-like elastic body, and both plate springs 42 and 43 are
Since the bent portion tends to expand elastically, this action pushes the block joints apart, resulting in complete adhesion of the reflector. Furthermore, the leaf springs 42, 43 themselves can also be used as reflectors. In this case, a leaf spring 42 or 43 is used in place of the reflector 39, but its surface must be finished to have the same reflectance characteristics as the reflector.

FIG. 7 shows an example in which a string-like member 44 made of rubber or the like is used as a spacer. If the reflector has an elongated shape and is made of a material with some degree of rigidity, the string-like member 44 placed along the long axis of the reflector will have the same effect as the wedge-like member 41.

In the above embodiments, when the wedge-shaped spacers 41 to 43 or the string-shaped spacer 44 are pushed into the gaps between the blocks, the adhesion of one reflective film differs depending on the pushing depth. need to be strictly managed.

In order to reduce this inconvenience, an elastic spacer 41 is shown in FIG.
or 44 is glued onto the reflector 39 in advance. Or the elastic body is made of resin.

It is directly placed on the reflective vA39 by screen printing or ejection from a syringe, and is polymerized and cured by heat treatment or ultraviolet irradiation to become an elastic body.

When assembling each block, phosphor 35. Translucent element 36
are integrally stacked alternately with reflective films 37. At this time, a reflective film with spacers adhered to one or both of the reflective films 39 at both ends of the block is used.

As a result of the above, the position of the spacer is always constant with respect to the detection element, and uniform adhesion of the reflective film is achieved.

〔Effect of the invention〕

As detailed above, according to the present invention, there is no variation in the adhesion of the reflective film to the phosphor element between the block joint element and other elements, and as a result, irregularities in detector characteristics are reduced. It is possible to achieve ideal characteristics as a radiation detector.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a spacer and a sectional view of a block joint according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a scanning section of an XMCT apparatus,
Fig. 3 is a structural diagram of a CT detector, Fig. 4 is a detector block layout diagram, Fig. 5 is a perspective view showing the structure of the detector block,
FIG. 6 is a perspective view showing another embodiment of the spacer, FIG. 7 is a perspective view and block joint sectional view showing one embodiment of the spacer, and FIG. 8 is a perspective view showing still another embodiment of the spacer. be. 2...Detector, 11...Detection element, 21...Detector block, 32...Photoelectric conversion element, 36...Fluorescent element, 37.38.39...Reflector, 41, 42.4
3゜44...Spacer. - Agent: Patent attorney Katsuo Ogawa ゛. Figure 1 Figure 2 Figure 4 Figure 7n (b) Figure 5 (V

Claims (1)

[Scope of Claims] 1. A phosphor element that absorbs radiant energy of X-rays and generates fluorescence, a translucent element bonded to the element that introduces the fluorescence to a photoelectric conversion element, and the translucent element A plurality of radiation detection elements are arranged adjacent to each other, each having a photoelectric conversion element in contact with the element, and each of which is formed so as to cover at least a portion of the phosphor element and the translucent element with a reflective film that reflects fluorescence. A radiation detector, characterized in that an elastic spacer is formed between the radiation detection elements. 2. The radiation detector according to claim 1, wherein the spacer is configured by adhering onto a reflective film.