新型水等效液体闪烁体的研究

Study on a new water equivalent liquid scintillator

本研究旨在研制具有水等效性的液体闪烁体材料,以用于肿瘤放射治疗和辐射防护的剂量测量。实验中的液体闪烁体由十二烷基苯、二甲基亚砜(Dimethyl sulfoxide,DMSO)、曲拉通X-100(Triton X-100)、2,5-二苯基恶唑(2,5-Diphenyloxazole,PPO)和1,4,双2(5苯基恶唑)苯(1,4Bis(5-phenyloxazol-2-yl)benzene,POPOP)组成。首先根据有效原子序数、电子密度公式和蒙特卡罗程序GEANT4(GEometry And Tracking 4)计算上述材料具有良好水等效性时的最佳浓度配比;根据最佳浓度配比配制液体闪烁体,并利用生物学X射线辐照仪和多道谱仪分别测量其水等效性能和辐射发光性能。研究结果表明:配制1 L新型液体闪烁体的最优配方为0.09 L的DMSO、0.36 L的十二烷基苯、0.55 L的Triton X-100、4 g·的PPO和0.2 g·的POPOP。上述配方液体闪烁体材料具有良好的水等效性(吸收剂量与水对应的吸收剂量比值几乎为1,最大相差在0.1%以内),并且保留了液体闪烁体的辐射发光功能(发光效率为一般商用液体闪烁体的1/3)。研制的新型液体闪烁体可用作肿瘤放射治疗和辐射防护中的测量体模材料和剂量探测器。

[Background] With the development of radiotherapy technology, new challenges have been posed for radiation dose planning techniques. Liquid scintillators have been studied a lot for dose measurement, its luminous intensity is proportional to the deposition energy, which can be used to measure the absorbed dose. [Purpose] This study aimed to develop water-equivalent liquid scintillator materials for the measurement of absorbed dose in tumor radiotherapy and radioprotection. [Methods] The liquid scintillator used in this experiment is composed of dodecylbenzene, dimethyl sulfoxide（DMSO）, Triton X-100, 2,5-diphenyloxazole（PPO） and 1,4-bis-（5-phenyloxazol-2-yl）-benzene（POPOP）. First, the best concentration ratio of the above materials with good water-equivalence was calculated according to the effective atomic number, electron density formula and Monte Carlo program GEANT4（GEometry And Tracking 4）. The liquid scintillator was prepared according to the optimal concentration ratio, and its water-equivalence as well as radioluminescent properties were verified using the biological X-ray irradiance and multi-channel spectrometer respectively. [Results] The results showed that the optimal component of 1 L liquid scintillator is 0.09 L of DMSO, 0.36 L of dodecylbenzene, 0.55 L of Triton-X, 4 g·L-1 of PPO and 0.2 g·L-1 of POPOP. The as-prepared liquid scintillator material has good water-equivalence（the ratio of absorbed dose to water is close to 1 with difference less than 0.1%） and retains radioluminescent property（its luminous efficiency is 1/3 of that of a typical commercial liquid scintillator）. [Conclusion] This new liquid scintillator can be used as a phantom and dose detector in cancer radiotherapy and radioprotection.