摘要
目的研究肿瘤放疗剂量测量用热释光探测器(TLD)的基本特性,为临床照射剂量测量提供可靠依据。方法应用TLD、NE-Farmer2581-A电离室剂量仪,热释光剂量读出系统,AECL-780C钴-60治疗机,用线性相关、t检验统计分析,了解剂量测量用TLD的质量、敏感度、剂量响应性、剂量重复性。结果 TLD表面洁净、光滑,直径、厚度分别为3.00、0.80mm,精度为±0.01%,面积重量为(29.4±0.9)mg/cm2,敏感度因子(Si)为1.00±0.09,在1 000cGy范围内读出发光值与辐射剂量呈线性关系,r值为0.99,在cGy剂量级重复使用10次,读出值变化0.66%。结论 TLD质量好、性能稳定、线性相关性强、重复测量精度高,符合国际推荐标准,可用于肿瘤放疗剂量测定。
Objective To study the elementary properties of thermo luminescent dosimeter （TLD） and the elementary function of read system for its clinical use. To provide experimental basis for developing its clinical use of in vivo measurements within dose of clinical radiotherapy. Methods Using TLD （51 tablets） and ionization chamber （NE-Farmer 2581-A TYPE） as well as build-up cap （to consist of LTS-TYPE plastics） under clinical conditions of external irradiation with the AECL-780C 60Co, the characteristics of thermo luminescent dosimeter were investigated in phantom and were verified with ionization chamber in the same phantom. Results The surface of TLD was clean and smooth. Its diameter, thickness and weight per square centimeter were 3.00 mm, 0.80 mm and （29.4 ± 0.9）mg/cm^2, respectively. Within 1 000 cGy, the relationship between thermo luminescence values and doses of irradiation was linear, and the correlativity was close （r=0.99）, with a sensitivity of 1.00±0.09. The deviation of 0.66% was derived from cGy rating of repeated irradiation. Conclusion The properties for TLD can be achieved by a good choice, and present excellent reproducibility and stability, negligible dependence on temperature, linear response versus dose from some cGy to some Gy, independence of dose-rate and high spatial resolution. It entirely accord with the norm of ICRU. As shown in this part, TLD is the well-established method used for in vivo dosimetry.
