Quantitative assessment of range fluctuations in charged particle lung irradiation
Quantitative assessment of range fluctuations in charged particle lung irradiation
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DOI：
10.1016/j.ijrobp.2007.08.049
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发表时间：
2008-01-01
影响因子：
7
通讯作者：
Chen, George T. Y.
中科院分区：
文献类型：
--
作者：
Mori, Shinichiro;Wolfgang, John;Chen, George T. Y.
目的：由呼吸作用引起的水等效路径长度（WEL）变化可以改变带电粒子束的范围，导致束超调到关键器官或束过调到肿瘤。我们通过分析四维计算机断层扫描数据和定量评估潜在波束超调来研究距离波动。方法和材料：通过结合四维计算机断层扫描研究中每个呼吸期的大体肿瘤体积轮廓来计算最大强度体积。第一个靶体积计算整个呼吸周期的最大强度体积（内靶体积[ITV] -放疗[RT]），第二个靶体积是门控RT（门控RT，类似于呼气周围30%相窗）对应的最大强度体积。计算了每个呼吸相的补偿器。然后，通过选择各自呼吸阶段的最小补偿器深度，设计了两个“复合”补偿器，分别用于tv - rt和门控rt。然后将这些补偿器应用于四维计算机断层扫描数据以估计光束穿透。分析指标;包括范围波动和超调量，两者都是龙门角度的函数。我们比较了11例肺部患者在治疗ITV-RT和门控rt时观察到的WEL波动。结果：WEL波动为
Purpose: Water equivalent path length (WEL) variations due to respiration can change the range of a charged particle beam and result in beam overshoot to critical organs or beam undershoot to tumor. We have studied range fluctuations by analyzing four-dimensional computed tomography data and quantitatively assessing potential beam overshoot.Methods and Materials: The maximal intensity volume is calculated by combining the gross tumor volume contours at each respiratory phase in the four-dimensional computed tomography study. The first target volume calculates the maximal intensity volume for the entire respiratory cycle (internal target volume [ITV] -radiotherapy [RT]), and the second target volume is the maximal intensity volume corresponding to gated RT (gated-RT, similar to 30% phase window around exhalation). A compensator at each respiratory phase is calculated. Two "composite" compensators for ITV-RT and gated-RT are then designed by selecting the minimal compensator depth at the respective respiratory phase. These compensators are then applied to the four-dimensional computed tomography data to estimate beam penetration. Analysis metrics; include range fluctuation and overshoot volume, both as a function of gantry angle. We compared WEL fluctuations observed in treating the ITV-RT versus gated-RT in 11 lung patients.Results: The WEL fluctuations were