中文摘要：

源到位精度是近距离放射治疗后装机的重要性能指标之一,多种因素可导致源到位误差,影响放射剂量准确度。从理论和实验角度探究了多种因素对源到位精度的影响。首先,基于后装机传动特点,建立了源缆—导管静力学模型,分析源缆输入和输出力比值随摩擦因数和治疗导管弯曲形状变化关系。然后建立源缆传输动力学模型,分析了柔性源缆进给过程中弹性变形量与源缆长度和导管弯曲半径的关系。最后设计制造出测试平台,实验探究多种因素对源到位精度的影响,间接证明了理论分析的正确性。

英文摘要：

Source positioning accuracy is one of the key performance indicators. Several factors can cause source positioning inaccuracy,in order to affect the precision of radiation dose. Theoretical and experimental approach for investigating multiple factors affecting source positioning accuracy is presented in this paper. Firstly,static model of cable-catheter based on transmission characteristics of afterloader is built,the relation of the cable force ratio（ input force versus output force） changing with the friction coefficient and the curvature of catheter is deduced. Furthermore,dynamical model of source-catheter transmission is built,the relation of the amount of elastic deformation with the length of source cable and the curvature radius of catheter is analyzed during the feeding process of the cable. Finally,the test platform is designed and manufactured,and experiment is carried out to study the effect of factors on source positioning accuracy,which indirectly validates the correctness of proposed theoretical analysis.