HDR brachytherapy with surface applicators: Technical considerations and dosimetry
HDR brachytherapy with surface applicators: Technical considerations and dosimetry
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DOI：
10.1177/153303460400300304
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发表时间：
2004-06-01
影响因子：
2.8
通讯作者：
Nori, D
中科院分区：
文献类型：
--
作者：
Sabbas, AM;Kulidzhanov, FG;Nori, D
HDR表面模具为治疗皮肤病变提供了电子的替代放射疗法模式。治疗计划和剂量测定讨论了两种类型的表面模具在我们的诊所。标准矩形施源器用于表面曲率最小的各种部位。在这些情况下，理想化的平面几何形状用于治疗计划剂量计算。计算得出组织中处方深度处的治疗剂量均匀性以及皮肤剂量（作为治疗剂量的百分比）及其剂量均匀性。优化技术的可用性导致深度处的上级剂量均匀性，但必须仔细评估皮肤处的剂量。我们已经研究了这些剂量学参数的依赖关系的表面模具的尺寸和类型的优化程序中使用的剂量学计算。第二种类型的表面施用器涉及使用附接到患者的热塑性面罩的定制硅橡胶模具。我们已经使用它们来治疗面部病变，其中表面曲率是可观的，并且设置的再现性更重要。在这些情况下，CT数据集用于重建导管、激活相关驻留位置和剂量测定，包括优化。为了建立有效的方法，优化的HDR表面模具规划计算的质量保证，我们已经比较了他们的剂量学的一个经典的近距离放射治疗系统和一个基于分析模型的施源器。经典的系统产生的规划计算中使用的集成活动的独立验证，而分析模型用于评估深度剂量依赖于模具尺寸和优化。
HDR surface molds offer an alternative radiotherapy modality to electrons for the treatment of skin lesions. Treatment planning and dosimetry are discussed for two types of surface molds used in our clinic. Standard rectangular applicators are used on a variety of sites where surface curvature is minimal. In these cases an idealized planar geometry is used for treatment planning dose calculations. The calculations yield treatment dose uniformity at the prescription depth in tissue as well as skin dose, as a percentage of the treatment dose, and its dose uniformity. The availability of optimization techniques results in superior dose uniformity at depth but the dose at the skin has to be carefully evaluated. We have studied the dependence of these dosimetric parameters on the size of the surface mold and the type of optimization procedure used in the dosimetry calculations. The second type of surface applicator involves the use of a customized silicone rubber mold attached to a thermoplastic mask of the patient. We have used them to treat lesions of the face where surface curvatures are appreciable and reproducibility of setup is more critical. In these cases a CT data set is used for reconstruction of the catheters, activation of relevant dwell positions and dosimetry, including optimization. Towards establishing effective methods for quality assurance of the optimized HDR surface mold planning calculations, we have compared their dosimetry to both a classical brachytherapy system and to one based on an analytical model of the applicator. The classical system yields an independent verification of the integrated activity used in the planning calculations, whereas the analytical model is used to evaluate depth dose dependence on mold size and optimization.