Comparison of flat cleaved and cylindrical diffusing fibers as treatment sources for interstitial photodynamic therapy
Comparison of flat cleaved and cylindrical diffusing fibers as treatment sources for interstitial photodynamic therapy
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DOI：
10.1118/1.4862078
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发表时间：
2014-02-01
期刊：
影响因子：
3.8
通讯作者：
Foster, Thomas H.
中科院分区：
文献类型：
--
作者：
Baran, Timothy M.;Foster, Thomas H.
目的：对于大体积肿瘤的间质光动力疗法（iPDT），需要仔细的治疗计划，以确保治疗剂量被递送到肿瘤，同时最小化对周围正常组织的损伤。在临床背景下，iPDT通常使用平裂或圆柱形漫射光纤作为光源进行。在这里，作者直接比较这两个源的几何形状的光纤的数量和治疗所需的时间，以提供规定的光剂量到肿瘤volume.Methods：治疗规划软件iPDT的图形处理单元增强蒙特卡罗模拟的基础上开发。该软件用于优化光纤的数量、每根光纤输送的总能量以及单个光纤的位置，以便将目标光剂量（D-90）输送到90%的肿瘤体积。治疗计划的制定，使用平裂和圆柱形扩散纤维，根据组织体积从CT数据从头部和颈部癌症患者。结果：当源光纤的数量固定为8根时，基于平劈光纤的治疗计划需要每根光纤输送7180-8080 J，以便在90%的肿瘤体积中存款90 J/cm（2）。对于扩散器，每根光纤需要提供2270-2350 J（333-1178 J/cm），以实现相同的结果。对于输送固定的900 J的光纤的情况，需要13个扩散器或19个间隔为1 cm的平劈光纤来输送所需的剂量。在每根纤维的能量固定在2400 J并且纤维的数量固定在8个的情况下，扩散纤维将所需剂量递送到肿瘤体积的93%，而平裂纤维将该剂量递送到79%。与能量和光纤数量允许变化，六个扩散器提供3485-3600 J，相比，十个扁平劈开光纤提供2780-3600 J。结论：对于相同数量的光纤，圆柱形扩散器允许较短的治疗时间相比，扁平劈开光纤。对于每根光纤传递的相同能量，漫射器允许插入更少的光纤，以便将相同的光剂量传递到目标体积。(C)2014年美国医学物理学家协会。
Purpose: For interstitial photodynamic therapy (iPDT) of bulky tumors, careful treatment planning is required in order to ensure that a therapeutic dose is delivered to the tumor, while minimizing damage to surrounding normal tissue. In clinical contexts, iPDT has typically been performed with either flat cleaved or cylindrical diffusing optical fibers as light sources. Here, the authors directly compare these two source geometries in terms of the number of fibers and duration of treatment required to deliver a prescribed light dose to a tumor volume.Methods: Treatment planning software for iPDT was developed based on graphics processing unit enhanced Monte Carlo simulations. This software was used to optimize the number of fibers, total energy delivered by each fiber, and the position of individual fibers in order to deliver a target light dose (D-90) to 90% of the tumor volume. Treatment plans were developed using both flat cleaved and cylindrical diffusing fibers, based on tissue volumes derived from CT data from a head and neck cancer patient. Plans were created for four cases: fixed energy per fiber, fixed number of fibers, and in cases where both or neither of these factors were fixed.Results: When the number of source fibers was fixed at eight, treatment plans based on flat cleaved fibers required each to deliver 7180-8080 J in order to deposit 90 J/cm(2) in 90% of the tumor volume. For diffusers, each fiber was required to deliver 2270-2350 J (333-1178 J/cm) in order to achieve this same result. For the case of fibers delivering a fixed 900 J, 13 diffusers or 19 flat cleaved fibers at a spacing of 1 cm were required to deliver the desired dose. With energy per fiber fixed at 2400 J and the number of fibers fixed at eight, diffuser fibers delivered the desired dose to 93% of the tumor volume, while flat cleaved fibers delivered this dose to 79%. With both energy and number of fibers allowed to vary, six diffusers delivering 3485-3600 J were required, compared to ten flat cleaved fibers delivering 2780-3600 J.Conclusions: For the same number of fibers, cylindrical diffusers allow for a shorter treatment duration compared to flat cleaved fibers. For the same energy delivered per fiber, diffusers allow for the insertion of fewer fibers in order to deliver the same light dose to a target volume. (C) 2014 American Association of Physicists in Medicine.