Radiation detector and a method of manufacturing the detector

Abstract

A scintillator array has a compact, two-dimensional arrangement of scintillators partitioned by light reflecting elements and light transmitting elements interposed between the scintillators. That is, the scintillator array has a lattice frame in the form of a crosswise combination of plate-like optical elements such as light reflecting elements and light transmitting elements. The lattice frame defines a plurality of cubicles. A transparent adhesive is poured into a rectangular vessel for receiving the lattice frame, the lattice frame is placed in the rectangular vessel, and then the scintillators are placed in the rectangular vessel. A cured resin object integrating the optical adhesive having cured, the lattice frame and the scintillators is removed from the vessel, and is contoured to make the scintillator array. In this way, the optical elements are arranged in the scintillator array without cutting them with a dicing saw or wire saw.

Description

BACKGROUND OF THE INVENTION [0001] (1) Field of the Invention [0002] This invention relates to a radiation detector having scintillators, a light guide and photomultiplier tubes arranged in the stated order and optically combined to one another, and to a method of manufacturing the radiation detector. [0003] (2) Description of the Related Art [0004] This type of radiation detector is used in a medical diagnostic apparatus such a PET (Positron Emission Tomography) apparatus or a SPECT (Single Photon Emission Computed Tomography) apparatus for detecting radiation (e.g. gamma rays) released from radioisotopes (RI) introduced into a patient and accumulated in a region of interest, and obtaining sectional images of RI distribution in the region of interest. The radiation detector includes scintillators that emit light in response to incident gamma rays released from the patient, and photomultiplier tubes for converting the light emitted from the scintillators to pulsed electric signals. ...

AI Technical Summary

Benefits of technology

[0016] It is relatively easy to prepare the lattice frame as designed, and therefore the cubicles in this lattice frame are also easy to form as designed. The scintillators in the respective cubicles are also easy to form as designed. This results in a reduced chance of gaps being formed between the scintillators and optical elements interposed between the scintillators. Thus, the discriminating ability is improved to maintain high resolution and high image quality.

[0018] With the positioning elements arranged at equal intervals, the light transmitting elements are arranged at equal intervals at least on the plane of the scintillator array opposed to the light guide. With the aid of the positioning elements, the scintillators are arranged at equal intervals on the plane of the scintillator array opposed to the light guide. This further promotes the discriminating ability.

[0028] In the above radiation detector manufacturing method, it is preferred that a release agent is applied to the rectangular vessel before executing the step (B) of pouring the transparent liquid resin into the rectangular vessel. Then, when executing the step (D), i.e. removing from the rectangular vessel a cured resin object integrating the liquid resin having cured, the lattice frame and the scintillators, and contouring the resin object to make the scintillator array, the resin object may be removed from the rectangular vessel easily.

[0029] Preferably, the liquid resin is defoamed when executing the step (B) of pouring the transparent liquid resin into the rectangular vessel. By defoaming the liquid resin, the cured resin becomes free from voids formed therein, thus avoiding lowering of resolution due to such voids. As a defoaming method, the liquid resin may be poured in after being defoamed, or the liquid resin may be poured in while carrying out vacuum degassing, after placing the rectangular vessel in a space that may be vacuum-degassed.

Problems solved by technology

This reduces the capability of discriminating, and thus detecting, positions of incidence of gamma rays.

This will results in a complicated manufacturing process, and thus high cost.

When suitable light reflecting elements DA are inserted in the slits MA after a shaping process, gaps are formed between the reflecting elements DA and slits MA, thereby lowering reflection efficiency also.

As these factors reduce output by incident gamma rays to make an accurate discrimination of positions impossible, an overall image quality will also deteriorate.

More particularly, a reduced discriminating ability results in a reduction in resolution.

Where such radiation detector RDA is used in a medical diagnostic apparatus such as a PET apparatus or SPECT apparatus, images obtained by the apparatus will have poor quality.

When a region of interest is a tumor, for example, the tumor may not be accurately outputted on the image.

Further, the light reflecting elements DA or light transmitting elements inserted or filled as optical elements between the scintillator S make an accurate discrimination of positions even more difficult, particularly where light transmitting elements are used.

However, since the optical adhesive forms adhesive layers, it is difficult to control the thickness of the light transmitting elements.

This further encumbers an accurate discrimination of positions of gamma ray incidence.

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