Radiation-induced change of optical property of hydroxypropyl cellulose hydrogel containing methacrylate compounds; As a basis for development of a new type of radiation dosimeter

メタクリル酸エステルを含むヒドロキシプロピルセルロースゲルへの放射線照射に伴う光学特性の変化; 新規ゲル線量計の開発に向けた基礎研究

山下 真一*; 廣木 章博; 田口 光正

Yamashita, Shinichi*; Hiroki, Akihiro; Taguchi, Mitsumasa

It was aimed to develop a novel polymer gel dosimeter to overcome weakness of earlier ones. A cellulose derivative, hydroxypropyl cellulose (HPC), was chosen as a polymer composing gel matrices and processed with a radiation-crosslinking technique in advance to manufacture of a gel dosimeter. Two methacrylate-type monomers, 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) dimethacrylate (9G), were selected as vinyl-type monomers polymerizing with irradiations. Visual change with irradiation of Co -rays was observed, and haze and UV-vis absorption analyses were conducted to quantify visual changes of irradiated dosimeters. Radiation-induced white turbidity was easily observable directly by our eyes even with Co -irradiation of 1 or 2 Gy. Sensitivity, which was evaluated by haze, toward -ray dose was dependent on the composition of the vinyl-type monomers. UV-vis spectroscopy indicated that there are at least two different mechanisms leading to white turbidity. It was shown that dose rate effect can be less significant by optimizing composition of the vinyl-type monomers.