作为一种颇具特点的近距离放疗技术，放射性粒子植入在肿瘤治疗中具有重要作用，近年来在我国发展迅猛。剂量分布是影响粒子植入肿瘤控制和正常组织损伤的最重要因素。研究组以往研究发现不同核素粒子具有不同的剂量学特性，相同核素的不同粒子剂量学特性也差异很大。我国生产的I-125粒子广泛应用于临床，但尚没有其剂量学特性的基本数据。本课题通过蒙特卡罗模拟和热释光测量研究我国生产I-125粒子的剂量学特性，确定其基本剂量学参数：剂量率常数、径向剂量函数和各向异性函数。为临床剂量计算提供必需数据，保证计算准确性和粒子植入质量，提高疗效、降低毒副作用。促进粒子植入技术规范化实施和推广，为厂商改进生产技术、相关部门制定规范和标准提供参考。另外，本研究研制的热释光测量I-125粒子剂量学特性的模体可直接用于粒子剂量学特性和热释光剂量学特性研究，热释光剂量学特性及其测量粒子剂量的校准方法可供国内外开展相关工作参考。

As a brachytherapy technique with its' own distinguished characteristics, radioactive seed implant plays an important role in the management of cancer. It was developed rapidly in China recently. Dose distribution is the most important factor determining the tumor control and normal tissue toxicity. In our previous studies, we found that the dosimetric properties are different for different nuclide seeds. The dose distribution varies very much even for different seeds with the same nuclide. The basic dosimetric properties are not known yet now for home made I-125 seeds widely used in China. This study aims to perform a comprehensive dosimetric characterization of the I-125 seeds home made in China using both Monte Carlo simulation and thermoluminescent dosimetry (TLD) measurement, to determine the basic dosimetry parameters: dose-rate constant, radial dose function and anisotropy function. These dosimetry parameters are urgently needed for clinical treatment planning, to insure the accuracy of dose calculation and implant quality, to improve the clinical efficacy and reduce the toxicity. This study can promote the standardization and popularization of seeds implant technique, provide technical reference for seeds manufacturers improving manufacture technique, regulatory agencies compiling guideline and standards. In addition, the phantom developed in this study can be used for the study of dosimetric properties of I-125 seeds and TLD chips. The dosimetric properties of TLD chips, and calibration method of TLD dosimeter can be referenced for related studies home and abroad.