IP Library Granted Patent US 7,655,912
Granted Patent B2
US 7,655,912 · App. 10/584,838 · Granted Feb 2, 2010

Direction finding radiation detector, and radiation monitoring method and apparatus

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Quick Facts
Patent No.
US 7,655,912
App. No.
10/584,838
Granted
Feb 2, 2010
Kind
B2
Abstract

A direction finding radiation detector for detecting the direction of incidence of radioactive rays, comprising: a plurality of scintillators ( 41, 42, 43 ) ( 101, 102, 103 ) made of the same material, being arranged to overlap circumferentially at least in part so that they are shadowed by each other from radioactive rays incident in circumferential directions and so that light emitted from one of the scintillators is not incident on the other scintillators; and photoreceptor devices ( 51, 52, 53 ) ( 111, 112, 113 ) having light receiving surfaces optically coupled to the respective scintillators, wherein a combination of proportions of radioactive rays incident directly on the respective scintillators and radioactive rays incident indirectly thereon, being shadowed by the other scintillators, varies with the direction of incidence circumferentially. This achieves weight saving of the detector, improves the detection efficiency of the radioactive rays, elaborates detection information through measurements in half the circumferential directions or all the circumferential directions, and simplifies setting for improved operability.

Claims (20)

1. A direction finding radiation detector for detecting a direction of incidence of radioactive rays, the detector comprising:

three or more scintillators, formed by splitting a single scintillator in a circumferential direction and being arranged to overlap circumferentially, such that: (1) the scintillators are shadowed by each other from radioactive rays incident in circumferential directions, (2) the light emitted from one of the scintillators is not incident on the other scintillators; and (3) the direction of incidence is detected all around in the range of 0° to 360°,

photoreceptor devices each having a light receiving surface optically coupled to each of the scintillators, wherein

a combination of proportions of radioactive rays incident directly on the respective scintillators and radioactive rays incident indirectly, being shadowed by the other scintillators, varies with the direction of incidence circumferentially,

the scintillators are connected to amplifiers having respective different gains to shift peak positions with each other, the amplifiers are connected to a single A/D converter, and the A/D converter is connected to a single pulse height analyzer, and

the detector is connected to a computer that calculates a ratio R of counts of photoelectric peaks ascribable to the scintillators by calculating a sum total T and ratios R=(A/T, B/T, C/T), wherein A, B and C are counts of the photoelectric peaks.

2. A radiation monitoring method comprising the steps of

setting the direction finding radiation detector according to claim 1 ; and

measuring a circumferential radiation using the direction finding radiation detector.

3. A radiation monitoring apparatus comprising the direction finding radiation detector according to claim 1 .

4. A direction finding radiation detector for detecting a direction of incidence of radioactive rays, the detector comprising:

three or more scintillators, formed by splitting a single scintillator in a circumferential direction and being arranged to overlap circumferentially, such that: (1) the scintillators are shadowed by each other from radioactive rays incident in circumferential directions, (2) the light emitted from one of the scintillators is not incident on the other scintillators; and (3) the direction of incidence is detected all around in the range of 0° to 360°,

photoreceptor devices each having a light receiving surface optically coupled to each of the scintillators, wherein

a combination of proportions of radioactive rays incident directly on the respective scintillators and radioactive rays incident indirectly, being shadowed by the other scintillators, varies with the direction of incidence circumferentially,

the scintillators are connected to amplifiers having respective different gains to shift peak positions with each other, the amplifiers are connected to a single A/D converter, and the A/D converter is connected to a single pulse height analyzer, and

the detector is connected to a computer that calculates a ratio R of counts of photoelectric peaks ascribable to the scintillators by calculating a sum total T and ratios R=(A/T, B/T, C/T), wherein A, B and C are counts of the photoelectric peaks.

5. A radiation monitoring method comprising the steps of

setting the direction finding radiation detector according to claim 4 ; and

measuring a circumferential radiation using the direction finding radiation detector.

6. A radiation monitoring apparatus comprising the direction finding radiation detector according to claim 4 .

Assignments (4)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Mar 6, 2017
From: HITACHI ALOKA MEDICAL, LTD.
To: HITACHI, LTD.
Reel/Frame 041891/0325 →
CHANGE OF NAME Recorded Aug 9, 2016
From: NATIONAL INSTITUTE OF RADIOLOGICAL SCIENCES
To: NATIONAL INSTITUTES FOR QUANTUM AND RADIOLOGICAL SCIENCE AND TECHNOLOGY
Reel/Frame 039634/0067 →
CHANGE OF NAME Recorded Jul 7, 2011
From: ALOKA CO., LTD.
To: HITACHI ALOKA MEDICAL, LTD.
Reel/Frame 026566/0907 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jun 27, 2006
From: SHIRAKAWA, YOSHIYUKI; YAMANO, TOSHIYA
To: NATIONAL INSTITUTE OF RADIOLOGICAL SCIENCES; ALOKA CO., LTD.
Reel/Frame 018030/0847 →