125I粒子源强度绝对测量方法研究进展

近距离放射治疗是一种有效的癌症治疗手段,¹²⁵I（碘-125）粒子源因其具有短半衰期、易于制成微型结构、易于防护等优势常用于近距离放射治疗。医学物理师进行治疗计划设计时,主要依据粒子源在组织周围剂量分布的公式,公式中表征粒子源强度的物理量由放射源的表观活度改为空气比释动能强度,准确测量粒子源强度已成为国际上研究的热点问题。本研究介绍¹²⁵I粒子源在组织中剂量分布计算公式的发展,分析国际上粒子源强度（包括空气比释动能强度、参考空气比释动能率和水吸收剂量）绝对测量技术的研究现状,总结测量源强度的标准装置及测量方法。针对国内粒子源在癌症治疗中的使用量非常大,国内相关的标准规范不完善及国内对源强度测量技术和方法缺乏的现状,提出源强度测量的相关建议,以期实现国内粒子源强度的量值溯源和传递。

The Progress of Absolute Measurement Methods of the Intensity of 125I Brachytherapy Seeds

Brachytherapy is an effective treatment for cancer. ¹²⁵I seeds are widely used for the low dose rate brachytherapy, which has the advantages of short half-life, easy to make microstructure and easy protection. Medical physicists make treatment plans mainly based on the formula of the dose distribution of particle sources around tissues. The quantity characterizing the intensity of seeds has changed from the quantity of apparent activity to the air kerma strength. In order to measure the intensity of the source accurately, it has become a hot issue in international research. This paper introduces the development of dose distribution formula of ¹²⁵I seeds in tissue. The status of absolute measurement of particle source intensity, such as air-kerma strength, reference air-kerma rate and absorbed dose to water is analyzed. And the primary standard and measurement method of brachytherapy seeds are summarized. In our country, the quantity of ¹²⁵I brachytherapy seeds used for the treatment increases. The relevant domestic standards was imperfection. And there is a lack of measurement technology and the methods of the air kerma strength of ¹²⁵I seeds. In view of the current situation in China, some suggestions on the brachytherapy seeds intensity measurement are put forward to realize the source intensity transmission and traceability in China.