Online ISSN: 1884-4111 Print ISSN: 0033-8303
Radioisotopes 68(4): 277-283 (2019)

特集Special Issues

3.2.6 放射線架橋ゲルを母材とするポリマーゲル線量計のLET効果3.2.6 LET Effects of Polymer Gel Dosimeters Based on Radiation-crosslinked Gel

量子科学技術研究開発機構高崎量子応用研究所先端機能材料研究部Department of Advanced Functional Materials Research, Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology ◇ 370–1292 群馬県高崎市綿貫町1233 ◇ 1233 Watanuki, Takasaki, Gunma 370–1292, Japan

発行日:2019年4月15日Published: April 15, 2019

放射線架橋ゲルとメタクリル酸エステルモノマー水溶液から成るポリマーゲル線量計材料に対して,HIMACでヘリウム線(150 MeV/u),炭素線(290 MeV/u),鉄線(500 MeV/u)の照射を行い,ゲル中でのポリマー生成に伴う白濁化への線質の影響を調べた。粒子ビーム照射後のポリマーゲル線量計材料の白濁度合いは,線量率や線エネルギー付与(LET)が高いほど低下した。高LET条件下では,生成する重合開始剤の量が低減するため,白濁因子であるポリマーの生成が抑制された。

Polymer gel dosimeters containing of 2-hydroxyethyl methacrylate, polyethylene glycol dimethacrylate, and tetrakis(hidroxymethyl) phosphonium chloride with radiation-crosslinked hydroxypropyl cellulose gel were prepared. Effects of a dose rate and a linear energy transfer (LET) on the optical property of the polymer gel dosimeters were investigated. The polymer gel dosimeters showed the color change from colorless to white with the irradiation of heavy ions such as He ions (150 MeV/u), C ions (290 MeV/u), Fe ions (500 MeV/u). Absorbance of the dosimeters at the same total dose decreased with increasing dose rate in the range of 0.1 to 6.8 Gy/min. The absorbance decreased in order of He, C, Fe ions, which was in agreement with an increase in LET. The increase in LET affected the decrease in the number of polymerization initiator, resulting in the reduction of the absorbance of the dosimeters.

Key words: HIMAC (Heavy Ion Medical Accelerator in Chiba); polymer gel dosimeter; radiation-crosslinked gel; linear energy transfer

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