抽屉型放射源运输容器辐射漏束预测与屏蔽设计优化研究

Radiation Streaming Prediction and Shielding Design Optimization for Drawer-type Radioactive Source Transport Containers

中文关键词:  放射源  抽屉型运输容器  辐射漏束  蒙特卡罗方法

英文关键词:radioactive source  drawer-type transport container  radiation streaming  Monte Carlo method

中文摘要:

      目的 随着近年来医疗技术水平的提高，可无创无痛进行病变治疗的伽玛刀设备的应用率也提高。其中钴源与圆柱形抽屉组成一体式结构是伽玛刀常用到的一种典型构型，因此设计一种性能可靠且操作便利的抽屉型钴源专运容器具有必要性。该构型容器的抽屉孔道会沿着抽屉径向贯穿容器筒体，导致容器在抽屉两端对应侧出现辐射漏束现象。因此，从设计优化角度解决容器的辐射漏束问题，并分析漏束区域在容器外部的分布特征。方法 采用高精度蒙特卡罗计算程序对经典构型的抽屉型容器展开一系列研究，对其主要漏束路径(抽屉孔道与抽屉间的孔道缝隙)进行建模分析。结果 分析显示，孔道缝隙的尺寸、孔道缝隙与放射源的距离及放射源的驻留位置对容器外部辐射剂量水平均具有高敏感性影响。结论 漏束的剂量率会随着孔道缝隙(10 mm范围内)和源活性区偏离源抽屉中心距离的增大而快速增长，设计单位可参考该结论对容器的屏蔽性能进行优化设计。容器外部的最大漏束影响区向远离抽屉中心的方向偏离，距容器外部越远则偏离越大，容器的操作人员可参考该特性合理规避漏束路径。

英文摘要:

      With the advancement of medical technology in recent years, the use of Gamma Knife equipment for non-invasive and painless lesion treatment has significantly increased. The integrated structure of the cobalt source and the cylindrical drawer is a typical configuration commonly employed in Gamma Knife systems. Therefore, it is essential to design a drawer-type cobalt source transport container that offers reliable performance and ease of operation. In this configuration, the aperture of the drawer extends radially through the cylinder of the container, resulting in radiation streaming at the corresponding sides of the container at both ends of the drawer. Consequently, the work aims to address the radiation streaming phenomenon from a design optimization perspective and analyze the distribution characteristics of the leakage region on the exterior of the container. A series of studies on a drawer-type container with a classical configuration were conducted with the high-precision Monte Carlo computational program to model and analyze its primary radiation screaming path (drawer apertures and aperture gaps between the drawers). According to the analysis results, the size of the aperture gap, the distance between the aperture gap and the radioactive source, and the location of the radioactive source significantly affected the radiation dose level outside the container. The dose rate of the radiation leakage beam increases rapidly with the increasing distance between the aperture gap (up to 10 mm) and the active zone of the radioactive source, relative to the center of the source drawer. Design units can utilize this conclusion to optimize the shielding performance of the container. Furthermore, the maximum impact area of radiation streaming outside the container deviates from the center of the drawer. As the distance from the container increases, this deviation increases. Operators can leverage this characteristic to effectively avoid the path of radiation streaming.