CN85101399A

CN85101399A - Radiation detector

Info

Publication number: CN85101399A
Application number: CN 85101399
Authority: CN
Inventors: 山本诚一; 田中三博
Original assignee: Shimadzu Corp
Current assignee: Shimadzu Corp
Priority date: 1985-04-01
Filing date: 1985-04-01
Publication date: 1987-01-31
Also published as: CN85101399B

Abstract

Radiation detector of the present invention, have a plurality of scintillators of injecting radioactive ray, one or more photomultiplier with a plurality of separate optical detection systems and with the separate optical waveguide of above-mentioned optical detection system with number, the output face of its each optical waveguide respectively only with an optical detection system coupling, each scintillator output face ratio is in accordance with regulations cut apart, input face and each divided part coupling with each optical waveguide, utilize the difference of the ration of division, the scintillator of having injected radioactive ray is distinguished in output separately according to above-mentioned a plurality of optical detection systems.

Description

Radiation detector

This invention relates to the radiation detector that positron ECT device (computer-controlled radial faults camera) and single photon ECT device etc. use.

Fig. 1 is the stereographic map of existing apparatus profile, and Fig. 2 is the stereographic map of one embodiment of the invention device profile, and Fig. 3 is the calcspar of the used circuit of same embodiment, and Fig. 4 is for arranging the schematic isometric of example.

1～6: scintillator; 22: adding circuit;

11,12: photomultiplier; 23: division circuit;

20a, 20b: optical waveguide; 24: analog-digital converter;

21: subtraction circuit; 25: the crest identification circuit;

As shown in Figure 1, in existing positron ECT device and single photon ECT device etc., a photomultiplier (hereinafter to be referred as PMT) 11 optics couplings are on a scintillator 1, the radiation detector of forming is like this pressed a plurality of annular arrangements, make the PMT11 miniaturization that certain limit be arranged, can't make the width d of detecting device become very little, its spatial resolving power is restricted.

And for example, promptly enable to produce less PMT, but if it is pressed annular arrangement, then the quantity of PMT increases, the manufacturing cost of whole device also increases.

The purpose of this invention is to provide, its position probing resolving power is very high, and the quantity of required PMT is few, is applicable to the ECT device that detecting device is arranged circlewise, the radiation detector that price is cheap again.

Radiation detector with the present invention's manufacturing, have a plurality of scintillators of injecting radioactive ray, the one or more photomultipliers that have a plurality of separate optical detection systems, the input face coupling of the output face of above-mentioned a plurality of scintillators and a plurality of optical detection systems, and be equal to the number of said detecting system, separate optical waveguide, the output face of each optical waveguide respectively only with an optical detection system coupling, and the input face of each optical waveguide is connected in coupling in the output face of each scintillator, simultaneously, the output face of each scintillator is cut apart with given ratio, again with input face and each divided part coupling of each optical waveguide.The above-mentioned ration of division is different to the output face of each scintillator, utilizes the difference of the ration of division, distinguishes the scintillator of having injected radioactive ray with the output separately of above-mentioned a plurality of optical detection systems.

Among Fig. 2, with a plurality of

thin scintillators

1,2 ... optical crosstalk ground is not arranged along 1 direction mutually.Except that with the output face of optical waveguide 20a, 20b coupling, on each surface of these scintillators, coat the reflected light material, to improve light gathering efficiency.In addition, also can be at each

scintillator

1,2 ... between insert rolled lead etc., leak with the string that reduces radioactive ray.Like this, radioactive ray are just injected from the front (below the figure) of these scintillators, optical waveguide 20a, 20b just overleaf the output face of a side (among the figure for top) carry out optical coupling.Optical waveguide 20a and 20b adopt respectively corresponding to

scintillator

1,2 ... emission wavelength, absorb making such as few glass of light wave or propylene, form distinctive shape.And in the output face at the back side of optical waveguide 20a, 20b, carry out the optics coupling with the input face of PMT12.In this example, PMT12 is the square body, in independently two circuit of two optical detection system A, B of pretending mutually, each input face of optical detection system A, B carries out optical coupling with the output face of optical waveguide 20a and the output face of optical waveguide 20b respectively.

As shown in Figure 2, the shape of optical waveguide 20a and 20b is respectively like the triangular prism that is cut off a part.The output face that is about to scintillator 1～6 is as quadrilateral PQRS, and as quadrilateral TUVW, the input face of optical detection system A is as quadrilateral TUZX the input face of PMT12, and the input face of optical detection system B is as quadrilateral XZVW.The mid point of XZ is decided to be Y, and then quadrangular PQRSTUVW is divided into two parts with its diagonal line PRVT, form two triangular prisms after, if YZRV and YXPT part is cut away from triangular prism, just can form optical waveguide 20a and 20b.In addition, optical waveguide 20a, 20b except that with the input face of scintillator 1～6 coupling and with the output face of PMT12 coupling each surface, for not making it produce optical attenuation and the light string leaks, applied reflecting material and light screening material.The output face of optical waveguide 20a is trapezoidal TUZY, and only the input face with optical detection system A carries out coupling.The output face of optical waveguide 20b is trapezoidal VWXY, and it only carries out optical coupling with the input face of optical detection system B.Each input face of optical waveguide 20a and 20b is PQR triangular in shape and RSP respectively, optical coupling is carried out in all output faces of these leg-of-mutton input faces and scintillator 1～6, in the output face of a scintillator, the input face of optical waveguide 20a and 20b all carries out coupling with it, but with the input face of optical waveguide 20a mutually coupling area and with the ratio of the area of the input face phase coupling of optical waveguide 20b, be different to each scintillator.In other words, the output face of scintillator 1～6 is divided into 20a one side and 20b one side with diagonal line PR, divided each several part area has nothing in common with each other according to each scintillator 1～6, and the area of optical waveguide 20a one side becomes greatly with the increase of scintillator sequence number, and optical waveguide 20b one side then diminishes on the contrary.

Radioactive ray are injected

scintillator

1,2 ... one of the time, when for example injecting scintillator 4, the there is just luminous, this light penetrates from the output face at its back side by thin scintillator 4 inside.This light is injected optical waveguide 20a and 20b, propagates by optical waveguide 20a and 20b respectively, injects optical detection system A and the B of PMT12.The ratio of light quantity of injecting each optical detection system A and B is corresponding with the ration of division of the output face of cutting apart scintillator 4 with optical waveguide 20a and 20b, determines because this ration of division is given earlier, from luminous than scintillator 4 as can be known of the output of optical detection system A and B.That is each export ratio of optical detection system A and B is different and different with luminous scintillator.From its export ratio as can be known radioactive ray injected that scintillator.

Therefore, as shown in Figure 3, output input subtraction circuit 21 and adding circuit 22 with A, B just can obtain difference signal and and signal.Corresponding with signal with the energy of the radioactive ray of incident, so as energy signal.Carry out crest identification by 25 pairs of these energy signals of crest identification circuit, to eliminate ray at random.When being used for positron ECT device, obtain timing signal from crest identification circuit 25.On the other hand, difference signal contains positional information.This difference signal quilt in division circuit 23 makes it normalization divided by energy signal, thereby obtains to have the more signal of accurate location information, and this signal is by the A/D(analog/digital) converter 24 converts digital signal to, thus the acquisition position signalling.When radioactive ray were injected scintillator 1, this position signalling can obtain maximum negative value, and at

scintillator

2,3 ... Deng the place then move closer on the occasion of, can obtain during to scintillator 6 maximum on the occasion of.

If the radiation detector of this structure is carried out a plurality of arrangements by Fig. 4 with ring-type, can constitute ring-type ECT device, its available less PMT and higher position resolution of internal circuit acquisition.

In addition, the shape of optical waveguide also is not limited to the shape in the above-mentioned example.The PMT12 that uses in above-mentioned example adorns two circuit types in being, also can use a plurality of cylinder type PMT that respectively have an internal circuit, and the shape that only change the optical waveguide output face this moment gets final product.Have, discerning that is that the identification loop of the scintillator of radioactive ray incident is not limited to the structure among Fig. 3, can adopt various structures again.

According to the present invention, owing to discern the scintillator that is radioactive ray incident, so without limits to the geometric size of PMT from the output of a plurality of PMT.Can reduce the size of scintillator.Improve position resolution.Owing to do not increase the quantity of PMT, also just limited the increase of manufacturing cost again.

Claims

Radiation detector, it is characterized in that, have a plurality of scintillators of injecting radioactive ray, one or more photomultipliers with a plurality of separate optical detection systems, the output face of above-mentioned a plurality of scintillators and the input face of above-mentioned a plurality of optical detection systems carry out optical coupling, and with the separate optical waveguide of above-mentioned optical detection system with number, the output face of its each optical waveguide respectively only with an optical detection system coupling, and the input face of each optical waveguide and scintillator output face coupling separately, simultaneously, each scintillator output face ratio is in accordance with regulations cut apart, input face and each divided part coupling with each optical waveguide, the above-mentioned ration of division is different with the output face of each scintillator, according to the output separately of above-mentioned a plurality of optical detection systems, distinguish the scintillator of injecting radioactive ray by each ration of division.