SU1200695A1 - Scintillation position-sensitive detector - Google Patents

Abstract

1. SCINTILLATION POSITION INB-SENSITIVE DETECTOR, containing a collimator, extended scinti., A laser crystal, a matrix of photomultipliers arranged in a row along the length of the crystal and connected to one of the planes of the crystal, whose inputs are connected to a processing system This is due to the fact that, in order to increase the spatial resolution by distributing the luminous flux from scintillation between the photocathode next to the PMT, regardless of the position of the scintillation across the crystals, married / .... The present invention relates to instruments for detecting G-ionizing radiation. Basically:; It can be used in medical radio diagnostic equipment, where, along with an acceptable positional resolution, parameters such as the Vyssintill cyoin crest should be achieved, so that its lateral surfaces: the lengths of the crystal are planes, d -; The surface of the crystal, opposite to that on the photocathode connected PMT, has a cylindrical shape, with the grooves 2 being made across the cylindrical surface of the crystal under the photomultiplier centers. The detector according to claim 1, characterized in that the leakage profile passing through: the axis of rotation generatrix of the cylindrical surface of the crystal, has a Vdc corresponding to the expression c 9 n 2SX, + Cos 77) Q (l (L where the diameter of the photomultiplier flask;, X is the distance from the center of the photomultiplier; Q is the profiling depth parameter, depending on the cell height crystal; Z - profiling depth from the generator, and the width of the crystal is no more than d, where d is the diameter of the photocathode. FEU. of the juice y.cTBHTe ibHoCTb and the possibility of obtaining an image of large parts, OB of the body of the elder. This equipment has an almost achievable positional resolution limited by physiological life processes of the human organism (for example, breathing), leading to changes in

Description

the geographic location of the studied organs. Physical limitations on the spatial resolution are imposed by the volume of the organs under study, which lead to the scattering of gamma rays in them depending on the positional resolution on the depth of the radioactive source.

The purpose of the invention is to increase the spatial resolution by distributing the luminous flux from scintillation between the photocathodes of a number of photomultipliers, regardless of the scintillation intensity across the crystal.

Figure 1 shows the scheme of the claimed detector; figure 2 - dependence A. .. (X) when the semi-cylindrical shape of the crystal; in FIG. 3, the dependence AQJ (X) for the claimed crystal form; figure 4 - the spatial resolution corresponding dependencies AO; (X) FIGS. 2 and 3.

The scintillation position-sensitive detector contains a long SCINTILLATION crystal 1, a light guide 2, a photomultiplier array 3, a collimator 4, and a signal processing system 5, a FEU signal. The grooves 1 have 6 grooves, and the diameter of the crystal itself is chosen from

D (l, 3 + l, 6) d,

where d is the diameter of the photocathodes used by the photomultiplier, and the peripheral areas of the crystal .. d

la at a distance from the axis of symmetry

the semicylinders are cut off by two planes perpendicular to the median plane.

in the case of thin crystals, the cylindrical surface degenerates into imocKOCTb.

Registration of the radiation by the detector is performed as follows.

Gamma quanta falling into a crystal cause scintillation. Light photons propagate isotropically. Part of the photons, falling at the solid angle of a given photomultiplier, hits the photocathode directly, another part reflects once or several times and again falls on the photocathodes of the photomultiplier.

If the peripheral region is not cut off, scintillation in the peripheral region of the crystal could not be directly recorded, as; the photon hit the photocathode under a large large angle of total internal reflection, which is a value of the order of cC 57, therefore photons from the peripheral region are recorded by a photomultiplier after multiple Go reflections, which increase the fraction of the light flux independent of the X coordinate, i.e. . On the other hand, the presence of grooves in the shape

2px; Z Q (l + COS - 7) allows con: d

center the luminous flux only on two nearby PMTs. The amplitudes of the PMT are processed in the processing system and the scintillation coordinate is fed to the display device.

The dependences of the hpocTpaHCTBeHHoro resolution, shown in Fig. 4, show that the dp of a semi-crystalline crystal without profiling is more than the spatial resolution; 10 mm, whereas for the proposed I half-cylindrical crystal

9

With grooves Z Q (l + cos -77) OD of the photomultiplier centers, the spatial resolution is less than 5 mm.

Claims (1)

<claim-text> 1. SCINTILLATION P03ITI0N- ... BUT-SENSITIVE DETECTOR, containing &gt;; </ claim-text> </ li> </ ul> <claim-text> collimator, extended scinti .. · lating crystal, a matrix of photomultiplier tubes arranged in a row along the length of the crystal and conjugated with one of the crystal planes, the inputs of which are connected to a signal processing system that detects that, in order to increase the spatial resolution by distributing the luminous flux from scintillations between the photocathodes of the adjacent photomultipliers, the length of the scintillation across the crystals is extended </ claim-text> <claim-text> The present invention relates to instruments for recording ionizing radiation. </ claim-text>