A serial 4DCT study to quantify range variations in charged particle radiotherapy of thoracic cancers.
A serial 4DCT study to quantify range variations in charged particle radiotherapy of thoracic cancers.
复制标题
一项系列 4DCT 研究，旨在量化胸部癌症带电粒子放射治疗的范围变化。
DOI：
10.1093/jrr/rrt114
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发表时间：
2014
影响因子：
2
通讯作者：
Chen,GeorgeTY
中科院分区：
文献类型：
--
作者：
Mori,Shinichiro;Dong,Lei;Starkschall,George;Mohan,Radhe;Chen,GeorgeTY
每周在自由呼吸条件下进行连续 4DCT 扫描，以评估由于组织厚度和密度的分次内和分次间变化引起的水当量路径长度 (WEL) 变化，并计算连续 4DCT 中观察到的解剖变化导致的质子剂量分布。在前后 (AP) 光束的视野上定义了感兴趣区域 (ROI) 模板，并对这些 ROI 进行 WEL 测量以量化胸壁厚度变化。计算分次间质子剂量分布以评估由范围变化引起的预期剂量分布的变化。呼吸期间平均分次内胸壁WEL变化变化如下：ITV、上肺、中肺和下肺区域呼吸期间分别为-4.1毫米（<-10.2毫米）、-3.6毫米（<-7.1毫米）、-3.2毫米（<-5.6毫米）和-2.5毫米（<-5.1毫米）。第6周时，ITV、上肺、中肺和下肺区域的平均分次胸壁WEL变化分别减少了-4.0毫米（<-8.6毫米）、-9.1毫米（<-17.9毫米）、-9.4毫米（<-25.3毫米）和-4.5毫米（<-15.6毫米）。这些变化被分解为前胸壁厚度变化和后胸壁厚度变化。当在整个治疗过程中应用初始玻利时，观察到超出目标的剂量超调。这种超调是由于胸壁厚度变化和目标位置变化造成的。在呼吸期间以及几周的带电粒子治疗过程中，放射路径长度可能会发生显着变化。分次内/分次间胸壁厚度变化可能是带电粒子束治疗肺部肿瘤的范围变化的重要来源，导致初始计划的剂量分布扰动。在选择治疗带电粒子束范围时应考虑这些范围变化。
Weekly serial 4DCT scans were acquired under free breathing conditions to assess water-equivalent path length (WEL) variations due to both intrafractional and interfractional changes in tissue thickness and density and to calculate proton dose distributions resulting from anatomical variations observed in serial 4DCT. A template of region of interests (ROIs) was defined on the anterior–posterior (AP) beam's eye view, and WEL measurements were made over these ROIs to quantify chest wall thickness variations. Interfractional proton dose distributions were calculated to assess changes in the expected dose distributions caused by range variations. Mean intrafractional chest wall WEL changes during respiration varied by: −4.1 mm (<−10.2 mm), −3.6 mm (<−7.1 mm), −3.2 mm (<−5.6 mm) and −2.5 mm (<−5.1 mm) during respiration in the ITV, upper, middle and lower lung regions, respectively. The mean interfractional chest wall WEL variation at Week 6 decreased by −4.0 mm (<−8.6 mm), −9.1 mm (<−17.9 mm), −9.4 mm (<−25.3 mm) and −4.5 mm (<−15.6 mm) in the ITV, upper, middle and lower lung regions, respectively. The variations were decomposed into anterior and posterior chest wall thickness changes. Dose overshoot beyond the target was observed when the initial boli was applied throughout the treatment course. This overshoot is due to chest wall thickness variations and target positional variations. The radiological path length can vary significantly during respiration as well as over the course of several weeks of charged particle therapy. Intrafractional/interfractional chest wall thickness changes can be a significant source of range variation in treatment of lung tumors with charged particle beams, resulting in dose distribution perturbations from the initial plan. Consideration of these range variations should be made in choosing the therapeutic charged particle beam range.