Radiation detector and method of detecting radiation

• US 5,780,856 A
• Filed: 04/18/1996
• Issued: 07/14/1998
• Est. Priority Date: 04/27/1995
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Oka, Toru, Yoda, Kiyoshi, Ikegami, Kazunori
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US08/634,677
• Time in Patent Office: 817 Days
• Field of Search: 250/368, 250/367, 250/366
• US Class Current: 250/367
• CPC Class Codes: G01T 1/201 using scintillating fibres
• CPC Class Codes: G01T 1/203 the detector being made of plastics

Abstract

A radiation detecting section including scintillation fibers is arranged in a one-dimensional, two-dimensional or three-dimensional manner. A multichannel amplitude analyzer can obtain an incident position of radiation in the radiation detecting section, and a radiation dose rate at the incident position depending upon a signal having amplitude according to a difference in arrival time between two input signals. A microcomputer carries out inverse problem analysis to estimate a radiation source distribution or a spatial radiation intensity distribution.

Claims

1. A radiation detector comprising:

scintillator fibers responsive to radiation to generate light pulses,

photo detectors receiving the light pulses, propagated in two directions, from the scintillator fibers and converting the light pulses into electric pulses; and

radiation analyzers responsive to the electric pulses to determine an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses, and

analyzing means for carrying out inverse problem analysis depending upon the incident position of radiation and the radiation dose rate at the incident position found by the radiation analyzers, and estimating a radiation source distribution or a spatial radiation intensity distribution; and

wherein a radiation detecting section including the scintillation fibers is arranged in a two-dimensional or three-dimensional manner.

2. A radiation detector comprising:

photo detectors receiving light pulses, propagated in two directions, from a radiation detecting section and converting the light pulses into electric pulses;

radiation analyzers responsive to the electric pulses to determine an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses; and

,

wherein the radiation detecting section comprises a scintillation fiber bundle, wave length shift optical fibers, and light guides, each of the light guides having one end connected to a respective end of the scintillation fiber bundle and another end connected to one of the wavelength shift optical fibers.

3. A radiation detector according to claim 2, wherein the wavelength shift optical fiber connected to the light guide is spirally wound in the light guide.

4. A radiation detector comprising:

scintillator fibers responsive to radiation to generate light pulses,

photo detectors receiving the light pulses, propagated in two directions, from the scintillator fibers and converting the light pulses into electric pulses;

radiation analyzers responsive to the electric pulses to determine an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses;

wherein a radiation detecting section including the scintillation fibers is arranged in a two-dimensional or three-dimensional manner; and

wherein a radiation detecting section comprises radiation detecting portion including scintillation fiber, and transmission optical fiber connected to the radiation detecting portion, for transmitting a light pulse and causing no reaction with the radiation;

and wherein a reflector layer is mounted on an outer periphery of a cladding of the scintillation fiber.

5. A radiation detector comprising:

scintillator fibers responsive to radiation to generate light pulses,

photo detectors receiving the light pulses propagated in two directions, from the scintillator fibers and converting the light pulses into electric pulses; and

radiation analyzers responsive to the electric pulses to determine an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses;

wherein a radiation detecting section including the scintillation fibers is arranged in a two-dimensional or three-dimensional manner; and

wherein a radiation detecting section comprises radiation detecting portion including scintillation fiber, and transmission optical fiber connected to the radiation detecting portion, for transmitting a light pulse and causing no reaction with the radiation; and

wherein the radiation detecting section includes a bundle of a plurality of portions, each portion having scintillation fibers and the transmission optical fibers connected alternately, and the plurality of portions being tied in a bundle such that the plurality of scintillation fibers are present in a direction perpendicular to a propagation direction of the light pulse.

6. A radiation detector comprising:

scintillator fibers responsive to radiation to generate light pulses,

photo detectors receiving the light pulses, propagated in two directions, from the scintillator fibers and converting the light pulses into electric pulses;

radiation analyzers responsive to the electric pulses to determine an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses;

wherein a radiation detecting section including the scintillation fibers is arranged in a two-dimensional or three-dimensional manner; and

wherein a radiation detecting section comprises radiation detecting portion including scintillation fiber, and transmission optical fiber connected to the radiation detecting portion, for transmitting a light pulse and causing no reaction with the radiation; and

wherein the radiation detecting section includes a bundle of a plurality of portions, each portion having scintillation fibers and the transmission optical fibers connected alternately, and the plurality of portions being tied in a bundle such that each scintillation fiber on each portion does not overlap with other scintillation fibers in a direction perpendicular to a propagation direction of the light pulse.

7. A radiation detector comprising:

scintillator fibers responsive to radiation to generate light pulses,

photo detectors receiving the light pulses, propagated in two directions, from the scintillator fibers and converting the light pulses into electric pulses; and

radiation analyzers responsive to the electric pulses to determine an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses, and;

wherein a radiation detecting section including the scintillation fibers is arranged in a two-dimensional or three-dimensional manner;

and wherein a radiation detecting section has a repeating amplifier mounted in the course of the radiation detecting section, to amplify a light pulse.

8. A method of detecting radiation, used in a radiation detector including:

photo detectors to convert into electric pulses light pulses propagated in two directions from scintillation fibers to detect radiation and generate the light pulses;

radiation analyzers to find an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses; and

analyzing means for carrying out inverse problem analysis depending upon the found incident position of radiation and the found radiation dose rate at the incident position, and estimating a radiation source distribution or a spatial radiation intensity distribution,

the method comprising the steps of;

measuring a radiation intensity distribution around an object area divided into a plurality of elements so as to create a pattern vector according to the radiation intensity distribution;

calculating a calculation pattern vector of a radiation intensity distribution which must be measured assuming that a radiation source exists at a center of each of the elements;

determining a position of a radiation source which is assumed when the calculation pattern vector is generated to have a direction proximate to a direction of the pattern vector according to the measured radiation intensity distribution; and

creating a two-dimensional or three-dimensional radiation source distribution in the object area depending upon the determined positions of the radiation sources.

9. A method of detecting radiation according to claim 8, wherein the spatial radiation intensity distribution is calculated depending upon the two-dimensional or three-dimensional radiation source distribution to display the calculated radiation intensity distribution.

10. A radiation detector comprising:

photo detectors to convert into electric pulses light pulses propagated in two directions from scintillation fibers to detect radiation and generate the light pulses; and

radiation analyzers to find an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses,

wherein a radiation detecting section including scintillation fibers is arranged in a one-dimensional manner; and

wherein said radiation detecting section has a repeating amplifier mounted in the course of the radiation detecting section, to amplify a light pulse.

11. A radiation detector comprising:

photo detectors receiving light pulses, propagated in two directions, from a radiation detecting section and converting the light pulses into electric pulses;

radiation analyzers responsive to the electric pulses to determine an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses;

wherein the radiation detecting section is arranged in a one-dimensional manner; and

wherein the radiation detecting section comprises a fiber bundle including a plurality of scintillation fibers and a plurality of transmission optical fibers; and

a plurality of light guides, each of the light guides having one end connected to a respective end of the fiber bundle and another connected to a wavelength shift optical fiber.

12. A radiation detector according to claim 11, wherein the wavelength shift optical fiber connected to the light guide is spirally wound in the light guide.

13. A radiation detector comprising:

photo detectors to convert into electric pulses light pulses propagated in two directions from scintillation fibers to detect radiation and generate the light pulses; and

radiation analyzers to find an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses,

wherein a radiation detecting section is arranged in a one-dimensional manner,

wherein said radiation detecting section comprises radiation detecting portion including scintillation fiber and transmission optical fiber connected to the radiation detecting portion, for transmitting a light pulse and causing no reaction with the radiation, and

wherein a reflector layer is mounted on an outer periphery of a cladding of the scintillation fiber.

14. A radiation detector comprising:

photo detectors to convert into electric pulses light pulses propagated in two directions from scintillation fibers to detect radiation and generate the light pulses; and

radiation analyzers to find an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses,

wherein a radiation detecting section is arranged in a one-dimensional manner, and

wherein the radiation detecting section includes a bundle of a plurality of portions, each portion having scintillation fibers and the transmission optical fibers connected alternately, and the plurality of portions being tied in a bundle such that the plurality of scintillation fibers are present in a direction perpendicular to a propagation direction of the light pulse.

15. A radiation detector comprising:

photo detectors to convert into electric pulses light pulses propagated in two directions from scintillation fibers to detect radiation and generate the light pulses; and

radiation analyzers to find an incident position of the radiation and a radiation dose rate at the incident position depending upon a difference in arrival time between the electric pulses from the photo detectors and the number of electric pulses,

wherein a radiation detecting section is arranged in a one-dimensional manner, and

wherein the radiation detecting section includes a bundle of a plurality of portions, each portion having scintillation fibers and the transmission optical fibers connected alternately, and the plurality of portions being tied in a bundle such that each scintillation fiber on each portion does not overlap with other scintillation fibers in a direction perpendicular to a propagation direction of the light pulse.