Radiation monitoring device

Patent metadata

Field	Value
Publication number	US-12085682-B2
Application number	US-202017614410-A
Country	US
Kind code	B2
Filing date	May 18, 2020
Priority date	May 27, 2019
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

A radiation monitoring device realizes a high measurement function. Therefore, a radiation monitoring device includes: a radiation detection unit including a phosphor that emits light by incident radiation; a photodetector that converts a single photon or a photon group having a plurality of the single photons generated by the radiation detection unit into an electric pulse signal; and an analysis unit that analyzes the electric pulse signal. The phosphor emits light based on a plurality of light emission phenomena having different decay time constants. The analysis unit includes: a signal discrimination circuit that discriminates the electric pulse signal output from the photodetector; a dose rate calculation circuit that calculates a dose rate of the radiation based on a count rate of the discriminated electric pulse signal; and an application energy calculation circuit that calculates application energy of the radiation based on a peak value of the discriminated electric pulse signal.

First claim

The invention claimed is:

1. A radiation monitor device comprising:
a radiation detection unit including a phosphor that emits light by incident radiation;
a photodetector that converts a single photon or a photon group having a plurality of the single photons generated by the radiation detection unit into an electric pulse signal;
a signal discrimination circuit coupled to the photodetector;
a dose rate calculation circuit coupled to the signal discrimination circuit; and
an application energy calculation circuit coupled to the signal discrimination circuit,
wherein the phosphor emits light based on a plurality of light emission phenomena having different decay time constants, and
wherein the signal discrimination circuit discriminates the electric pulse signal output from the photodetector by determining whether the electric pulse signal is of a signal of a photon group or of a single photon,
wherein the dose rate calculation circuit calculates a dose rate of the radiation based on a count rate of the discriminated electric pulse signal, and
wherein the application energy calculation circuit calculates an application energy of the radiation based on a peak value of the discriminated electric pulse signal.

2. The radiation monitor device according to claim 1 ,
wherein the signal discrimination circuit discriminates the electric pulse signal based on determining whether a peak value of the electric pulse signal output from the photodetector is greater than a predetermined peak value threshold.

3. The radiation monitor device according to claim 2 ,
wherein the signal discrimination circuit, upon determining the peak value of the electric pulse is equal to or greater than the peak value threshold, the electric pulse signal is determined to be of a signal of a photo group, and upon determining the peak value of the electric pulse is less than the peak value threshold, the electric pulse signal is determined to be of a signal of a single photon.

4. The radiation monitor device according to claim 1 ,
wherein the signal discrimination circuit discriminates the electric pulse signal based on a relationship between a time width of the electric pulse signal output from the photodetector and a predetermined time width threshold.

5. The radiation monitor device according to claim 1 ,
wherein the signal discrimination circuit discriminates the electric pulse signal based on a relationship between an integration result of the electric pulse signal output from the photodetector and a predetermined integration result threshold.

6. The radiation monitor device according to claim 1 ,
wherein the signal discrimination circuit discriminates the electric pulse signal based on a frequency characteristic of the electric pulse signal output from the photodetector.

7. The radiation monitor device according to claim 1 ,
wherein the signal discrimination circuit discriminates the electric pulse signal based on a peak value spectrum of the electric pulse signal output from the photodetector.

8. The radiation monitor device according to claim 1 , further comprising
an optical filter that filters a photon transmitted from the radiation detection unit.

9. The radiation monitor device according to claim 1 , further comprising:
an optical switch that routes photons transmitted from the radiation detection unit,
wherein a plurality of the photodetectors are provided, and each of the photodetectors converts photons routed by the optical switch into the electric pulse signal, and
the plurality of photodetectors are connected to the signal discrimination circuit.

10. The radiation monitor device according to claim 9 ,
wherein a plurality of the signal discrimination circuits are provided to correspond to the photodetectors, and
wherein the plurality of photodetectors are connected to the corresponding signal discrimination units, respectively.

11. The radiation monitor device according to claim 1 , further comprising:
a plurality of optical filters that filter a photon transmitted from the radiation detection unit; and
an optical filter selection unit that selects any of the optical filters.

12. The radiation monitor device according to claim 1 , further comprising:
an optical transmission unit that connects the radiation detection unit and the photodetector,
wherein the radiation detection unit is provided inside a predetermined area to be measured,
wherein the photodetector and the signal discrimination circuit are provided outside the area to be measured, and
wherein the dose rate and the application energy inside the area to be measured are measured.

Assignees

• Hitachi Ltd

Inventors

• Hatakeyama Shuichi
• Okada Kouichi
• Ueno Katsunori
• Tadokoro Takahiro
• Ueno Yuichiro
• SHIBUTANI Tooru
• Sasaki Keisuke

Classifications

• G01T1/023 Primary

  Scintillation dose-rate meters · CPC title

• G01T3/085

  Spectrometry · CPC title

• G01T1/366

  with semi-conductor detectors · CPC title

• G01T1/2008

  using a combination of different types of scintillation detectors, e.g. phoswich · CPC title

• G01T1/247 Primary

  Detector read-out circuitry (for processing gain or off-set correction H04N) · CPC title