Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation

Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation (2014)

要旨訳:

炭素ビームを135〜290AMeVで照射した際のVIPポリマーゲル線量計の放射線に対する特性を調べた。VIPポリマーゲル線量計の応答を、MRI(核磁気共鳴画像化装置)で測定したR2(スピン−スピン緩和速度)を、従来のような侵入深さの関数としてではなく、LET(線エネルギー付与)の関数として評価した。LETは重粒子線輸送計算コードPHITSを用いて評価した。その結果、(1)線量平均LETが増加すると感度が減少すること、(2)線量応答とLETの相関関係は、照射する炭素ビームのエネルギーによっても変化すること、がわかった。(2)は核破砕生成物の影響を考慮することで説明できる。

Abstract:

We study the radiological characteristics of VIP polymer gel dosimeters under carbon beam irradiation with energy of 135 and 290 AMeV. To evaluate dose response of VIP polymer gels, the transverse (or spin–spin) relaxation rate R2 of the dosimeters measured by magnetic resonance imaging (MRI) as a function of linear energy transfer (LET), rather than penetration depth, as is usually done in previous reports. LET is evaluated by use of the particle transport simulation code PHITS. Our results reveal that the dose response decreases with increasing dose-averaged LET and that the dose response–LET relation also varies with incident carbon beam energy. The latter can be explained by taking into account the contribution from fragmentation products.

Source:

T. Maeyama, N. Fukunishi, K. L. Ishikawa, T. Furuta, K. Fukasaku, S. Takagi, S. Noda, R. Himeno, and S. Fukuda, Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation, Radiation Physics and Chemistry 107, 7-15 (2014). (http://dx.doi.org/10.1016/j.radphyschem.2014.09.001)

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