Janicki C, Duggan D M, Gonzalez A, Coffey C W, Rahdert D A
Centre Hospitalier de l'Université de Montréal, Dept. de Médecine Nucléaire, Québec, Canada.
Med Phys. 1999 Nov;26(11):2451-60. doi: 10.1118/1.598813.
A model for the description of the near-field dose deposition from a 32p impregnated stent in an arterial system consisting of soft tissue and dense plaque is presented. The model is based on the scaling property of the dose-point-kernel (DPK) function which is extended to a heterogeneous medium consisting of a series of layers of different materials. It is shown that, for each point source originating from the stent surface, the DPK function for water can be scaled consistently along the path through the different layers of material to predict the dose at a given point in the heterogeneous medium. Radiochromic film dosimetry on actual 32p stents is used to test the new model. The experimental setup consists of a water-equivalent phantom in which a stent is deployed and on which a thin layer of polytetrafluoroethylene (PTFE) is deposited to simulate the presence of plaque. Layers of radiochromic films stacked over the phantom are used to measure the dose at distances varying from approximately 0.1 mm to approximately 3 mm from the stent surface with and without PTFE. It is shown that the proposed new DPK model for a heterogeneous medium agrees very well with the experimental data and that it compares favorably to the usual homogeneous DPK model. These results indicate that the new model can be used with confidence to predict the dose in a realistic artery in the presence of plaque.
本文提出了一种用于描述32P浸渍支架在由软组织和致密斑块组成的动脉系统中近场剂量沉积的模型。该模型基于剂量点核（DPK）函数的缩放特性，该特性被扩展到由一系列不同材料层组成的非均匀介质中。结果表明，对于源自支架表面的每个点源，水的DPK函数可以沿着穿过不同材料层的路径一致地缩放，以预测非均匀介质中给定点的剂量。使用实际32P支架上的放射变色膜剂量测定法来测试新模型。实验装置包括一个水等效体模，在其中部署了一个支架，并在其上沉积了一层聚四氟乙烯（PTFE）以模拟斑块的存在。堆叠在体模上的放射变色膜层用于测量在有和没有PTFE的情况下距离支架表面约0.1 mm至约3 mm处的剂量。结果表明，所提出的用于非均匀介质的新DPK模型与实验数据非常吻合，并且与通常的均匀DPK模型相比具有优势。这些结果表明，新模型可以可靠地用于预测存在斑块的实际动脉中的剂量。
