Effect of inorganic salt on the dose sensitivity of polymer gel dosimeter

The effect of inorganic salts, non-transition metal chlorides, on the dose sensitivity of methacrylic-acid-based polymer gel dosimeter is investigated. Dose-R2 responses are obtained from magnetic resonance imaging data. Temperature increase due to exothermic polymerization reaction in the gel is also measured directly during irradiation. As a result, substantial increases in R2 response are observed in the polymer gel dosimeter containing inorganic salt, especially with MgCl2. The sensitivity of the gel with 1.0 M MgCl2 is approximately 2.8 times higher than that of without MgCl2. As the salt concentration increases, an increase of polymerization rate is also observed via the temperature measurements. These results indicate that inorganic salt acts as an accelerator for radiation-induced free-radical polymerization in methacrylic-acid-based gel. - Highlights: ► The effect of inorganic salt on the NMR dose sensitivity of polymer gel dosimeter. ► The high sensitivity of 3D dosimeter has been required for radiation treatment. ► The inorganic salt added, especially MgCl2, acts as a sensitizer in the dosimeter. ► The enhancement is correlated with the attractive ability of cations of the salts. ► The results may lead to a novel direction in the development of polymer gel dosimeters.