Motion interplay as a function of patient parameters and spot size in spot scanning proton therapy for lung cancer.
Motion interplay as a function of patient parameters and spot size in spot scanning proton therapy for lung cancer.
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DOI：
10.1016/j.ijrobp.2013.01.024
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发表时间：
2013-06-01
影响因子：
7
通讯作者：
Paganetti, Harald
中科院分区：
文献类型：
--
作者：
Grassberger, Clemens;Dowdell, Stephen;Lomax, Antony;Sharp, Greg;Shackleford, James;Choi, Noah;Willers, Henning;Paganetti, Harald
量化呼吸运动对点扫描质子治疗肺部肿瘤的影响。4D蒙特卡罗模拟用于评估肿瘤和质子束的相对运动对患者体内剂量分布的相互作用效应。10例肿瘤大小（2.6 - 82.3cc）和运动幅度（3 - 30 mm）不同的患者纳入研究。我们调查了点的大小，不同的质子设施之间的影响，并研究了单一馏分和传统的分馏治疗。分析中使用了以下指标：最小/最大/平均剂量、目标剂量均匀性和2年局部控制率（2年LC）。呼吸运动降低了靶剂量均匀性，在最高运动幅度下观察到的影响最大。较小的光斑尺寸（σ ≤ 3 mm）对运动更敏感，与较大的光斑尺寸（σ ≤ 13 mm）相比，平均降低靶剂量均匀性约2.8倍。使用较小的光斑尺寸治疗具有30 mm运动幅度的肿瘤，将最小剂量降低至处方剂量的44.7%，将建模的2y-LC从87.0%降低至2.7%（假设为单次分割）。常规分馏部分地减轻了这种降低，产生71.6%的2y-LC。对于大光斑尺寸，常规分割增加了靶剂量均匀性，并防止所有患者的2年LC恶化。未观察到与肿瘤体积的相关性。对正常肺剂量分布的影响很小：观察到的平均肺剂量和肺V20的变化分别<0.6Gy（RBE）和<1.7%。对于本研究中的患者，在存在相互作用的情况下，使用大光斑尺寸和常规分割可以保留2y-LC。对于采用较小光斑尺寸的治疗和/或在单次分次输送中，相互作用效应可能导致剂量分布的显著恶化和较低的2y-LC。
Quantify the impact of respiratory motion on the treatment of lung tumors with spot scanning proton therapy. 4D Monte Carlo simulations were used to assess the interplay effect, which results from relative motion of the tumor and the proton beam, on the dose distribution in the patient. Ten patients with varying tumor sizes (2.6-82.3cc) and motion amplitudes (3-30mm) were included in the study. We investigated the impact of the spot size, which varies between proton facilities, and studied single fractions and conventionally fractionated treatments. The following metrics were used in the analysis: minimum/maximum/mean dose, target dose homogeneity and 2-year local control rate (2y-LC). Respiratory motion reduces the target dose homogeneity, with the largest effects observed for the highest motion amplitudes. Smaller spot sizes (σ≈3mm) are inherently more sensitive to motion, decreasing target dose homogeneity on average by a factor ~2.8 compared to a larger spot size (σ≈13mm). Using a smaller spot size to treat a tumor with 30mm motion amplitude reduces the minimum dose to 44.7% of the prescribed dose, decreasing modeled 2y-LC from 87.0% to 2.7%, assuming a single fraction. Conventional fractionation partly mitigates this reduction, yielding a 2y-LC of 71.6%. For the large spot size, conventional fractionation increases target dose homogeneity and prevents a deterioration of 2y-LC for all patients. No correlation with tumor volume is observed. The effect on the normal lung dose distribution is minimal: observed changes in mean lung dose and lung V20 are <0.6Gy(RBE) and <1.7% respectively. For the patients in this study, 2y-LC could be preserved in the presence of interplay using a large spot size and conventional fractionation. For treatments employing smaller spot sizes and/or in the delivery of single fractions, interplay effects can lead to significant deterioration of the dose distribution and lower 2y-LC.
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DOI：
10.1016/j.ijrobp.2009.06.091
发表时间：
2010-03-01
影响因子：
7
作者：
Marks, Lawrence B.;Bentzen, Soren M.;Deasy, Joseph O.;Kong, Feng-Ming (Spring);Bradley, Jeffrey D.;Vogelius, Ivan S.;El Naqa, Issam;Hubbs, Jessica L.;Lebesque, Joos V.;Timmerman, Robert D.;Martel, Mary K.;Jackson, Andrew
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发表时间：
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DOI：
10.1016/j.ijrobp.2009.04.028
发表时间：
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影响因子：
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