Film dosimeter and method of determining radiation dose using thereof

Patent metadata

Field	Value
Publication number	US-9329275-B2
Application number	US-201313886183-A
Country	US
Kind code	B2
Filing date	May 2, 2013
Priority date	Oct 23, 2012
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A film dosimeter is disclosed in the present invention and doped with a sensitizer for determining a neutron and gamma-ray mixed radiation field. The sensitizer comprises quantitative lithium atoms with a different atom percentage of lithium-6 and lithium-7. Theoretically, the atom percentage of the lithium-6 in the lithium atoms is ranged from 0.1 to 99. On the other hand, a method of determining radiation doses of a neutron and gamma-ray mixed radiation field by using the abovementioned film dosimeter is also disclosed in the present invention.

First claim

What is claimed is:

1. A film for detecting a dose of a mixed radiation field, comprising:
a base;
an active layer being placed on the base and doped with a sensitizer with a quantity of nitrogen atoms, chloride atoms, potassium atoms and bromine atoms;
a surface layer being placed on the active layer and doped with the sensitizer with a quantity of chloride atoms;
an adhesive being placed on the surface layer; and
a top covering on the adhesion layer;
wherein the sensitizer has quantitative lithium atoms with different atom percentages of lithium-6 ( 6 Li) and lithium-7 ( 7 Li), the atom percentage of 6 Li in the lithium atoms is ranged from 0.1 to 99.

2. The film according to claim 1 , wherein the atom percentage of 6 Li in the lithium atoms of the sensitizer doped in the active layer of the film is ranged from 7 to 99.

3. The film according to claim 1 , wherein the atom percentage of 6 Li in the lithium atoms of the sensitizer doped in the active layer of the film is ranged from 0.1 to 7.

4. The film according to claim 1 , wherein the mixed radiation field is a neutron and gamma-ray radiation mixed field.

5. The film according to claim 1 , wherein the sensitizer is further doped with quantitative hydrogen elements ( 1 H) to decrease a neutron kinetic energy for detecting a fast neutron dose.

6. A method of determining radiation doses in a mixed radiation field, comprising the following steps:
providing several film dosimeters doped with a sensitizer comprising quantitative lithium atoms, wherein the lithium atoms comprise different atom percentages of lithium-6 ( 6 Li) and lithium-7 ( 7 Li) and a structure and a atom fraction of the sensitizer doped in each of the several film dosimeters are the same but a composition between the lithium-6 and lithium-7 atoms of the sensitizer doped in each of the film dosimeters is different;
irradiating the film dosimeters by a neutron beam;
placing the film dosimeters for a self-developing time till a colorization reaches a stable end-point;
scanning the film dosimeters; and
measuring values of the colorization, wherein the values correspond to a coloration degree of the colorization and are applied for calculating a neutron dose of the mixed radiation field.

7. The method according to claim 6 , wherein after the step of scanning the film dosimeters further comprising:
obtaining optical density values.

8. The method according to claim 7 , wherein the step of calculating the neutron dose of the mixed radiation field is performed to obtain the neutron dose and a gamma-ray dose of the colorization by utilizing the optical density values and an equivalent coloration value of the film dosimeters with respect to thermal neutrons.

9. The method according to claim 8 , wherein the step of calculating the neutron dose of the colorization is performed according to a conversion equation set up by a plurality of equivalent doses and colorization values measured by the film dosimeters with different sensitivities with respect to the thermal neutrons.

10. The method according to claim 6 , wherein the mixed radiation field is a neutron and gamma-ray radiation mixed field.

11. The method according to claim 6 , wherein a sensitivity of each of the film dosimeters with respect to thermal neutrons is decreased or increased by adjusting the atom percentage of 6 Li in the lithium atoms.

12. The method according to claim 11 , wherein the atom percentage of 6 Li in the lithium atoms is ranged from 0.1 to 99.

13. The method according to claim 6 , wherein the film dosimeter is further doped with quantitative hydrogen elements ( 1 H) to decrease a neutron kinetic energy for detecting a fast neutron dose.

14. A method of determining radiation doses in a mixed radiation field, comprising the following steps:
providing several film dosimeters doped with a sensitizer comprising quantitative lithium atoms, wherein the lithium atoms comprise different atom percentages of lithium-6 ( 6 Li) and lithium-7 ( 7 Li) and a structure and a atom fraction of the sensitizer doped in each of the several film dosimeters are the same but a composition between the lithium-6 and lithium-7 atoms of the sensitizer doped in each of the film dosimeters is different;
performing to calibrate each of the several film dosimeters before using any one, and obtaining a calibration function (k) of an optical density value to a photon absorbed dose in a standard photon field;
using the calibration function (k) to obtain a reverse calibration function (h);
irradiating the film dosimeters by an epithermal neutron beam of known thermal neutron and photon absorbed doses;
measuring the optical density values of the film dosimeters and calculating each of relative effectiveness values of the several film dosimeters;
irradiating the film dosimeters by an unknown neutron and gamma-ray mixed radiation field;
computing a neutron and photon absorbed dose rates in the unknown neutron and gamma-ray mixed radiation field.

Assignees

• Nat Univ Tsing Hua

Inventors

• Liu Yuan-Hao
• Hsiao Ming-Chen

Classifications

• G01T3/00 Primary

  Measuring neutron radiation (G01T5/00 takes precedence) · CPC title

• G01T1/06 Primary

  Glass dosimeters {using colour change; including plastic dosimeters} · CPC title

• G01T1/11

  Thermo-luminescent dosimeters {(thermo-luminescent compositions C09K11/00)} · CPC title