PDF(Pubmed)
Abstract：
OBJECTIVE: A computational method based on Monte-Carlo calculations is presented and used to calculate isodose curves for a new upright and tilting CT scanner useful for radiation protection purposes.
METHODS: The TOPAS code platform with imported CAD files for key components was used to construct a calculation space for the scanner. A sphere of water acts as the patient would by creating scatter out of the bore. Maximum intensity dose maps are calculated for various possible tilt angles to make sure radiation protection for site planning uses the maximum possible dose everywhere.
RESULTS: The resulting maximum intensity isodose lines are more rounded than ones for just a single tilt angle and so closer to isotropic. These maximum intensity curves are closer to the isotropic assumption used in CTDI or DLP based methods of site planning and radiation protection. The isodose lines are similar to those of a standard CT scanner, just tilted upwards. There is more metal above the beam that lessens the dose above versus below isocenter.
CONCLUSIONS: Aside from the orientation, this upright scanner is very similar to a typical CT scanner, and nothing different for shielding needs to be done for this new upright tilting CT scanner, because an isotropic scatter source is often assumed for any CT scanner.
METHODS: The TOPAS code platform with imported CAD files for key components was used to construct a calculation space for the scanner. A sphere of water acts as the patient would by creating scatter out of the bore. Maximum intensity dose maps are calculated for various possible tilt angles to make sure radiation protection for site planning uses the maximum possible dose everywhere.
RESULTS: The resulting maximum intensity isodose lines are more rounded than ones for just a single tilt angle and so closer to isotropic. These maximum intensity curves are closer to the isotropic assumption used in CTDI or DLP based methods of site planning and radiation protection. The isodose lines are similar to those of a standard CT scanner, just tilted upwards. There is more metal above the beam that lessens the dose above versus below isocenter.
CONCLUSIONS: Aside from the orientation, this upright scanner is very similar to a typical CT scanner, and nothing different for shielding needs to be done for this new upright tilting CT scanner, because an isotropic scatter source is often assumed for any CT scanner.
摘要：
目的：提出了一种基于蒙特卡罗计算的计算方法，并用于计算用于辐射防护目的的新型直立和倾斜CT扫描仪的等剂量曲线。
方法：使用带有关键组件导入CAD文件的TOPAS代码平台为扫描仪构建计算空间。水的球体通过从孔中产生散射而起到患者的作用。计算各种可能的倾斜角的最大强度剂量图，以确保现场规划的辐射防护在任何地方都使用最大可能的剂量。
结果：所得的最大强度等剂量线比仅单个倾斜角的线更圆，因此更接近各向同性。这些最大强度曲线更接近于基于CTDI或DLP的场地规划和辐射防护方法中使用的各向同性假设。等剂量线类似于标准CT扫描仪，只是向上倾斜。光束上方有更多的金属，可以减少等中心上方与下方的剂量。
结论：除了方向之外，这种直立式扫描仪与典型的CT扫描仪非常相似，对于这种新的直立倾斜CT扫描仪，屏蔽需要做什么不同，因为各向同性散射源通常被假定为任何CT扫描仪。
方法：使用带有关键组件导入CAD文件的TOPAS代码平台为扫描仪构建计算空间。水的球体通过从孔中产生散射而起到患者的作用。计算各种可能的倾斜角的最大强度剂量图，以确保现场规划的辐射防护在任何地方都使用最大可能的剂量。
结果：所得的最大强度等剂量线比仅单个倾斜角的线更圆，因此更接近各向同性。这些最大强度曲线更接近于基于CTDI或DLP的场地规划和辐射防护方法中使用的各向同性假设。等剂量线类似于标准CT扫描仪，只是向上倾斜。光束上方有更多的金属，可以减少等中心上方与下方的剂量。
结论：除了方向之外，这种直立式扫描仪与典型的CT扫描仪非常相似，对于这种新的直立倾斜CT扫描仪，屏蔽需要做什么不同，因为各向同性散射源通常被假定为任何CT扫描仪。
