EFFECTS OF INTERFRACTIONAL, MOTION AND ANATOMIC CHANGES ON PROTON THERAPY DOSE DISTRIBUTION IN LUNG CANCER
EFFECTS OF INTERFRACTIONAL, MOTION AND ANATOMIC CHANGES ON PROTON THERAPY DOSE DISTRIBUTION IN LUNG CANCER
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DOI：
10.1016/j.ijrobp.2008.03.007
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发表时间：
2008-12-01
影响因子：
7
通讯作者：
Chang, Joe Y.
中科院分区：
文献类型：
--
作者：
Hui, Zhouguang;Zhang, Xiaodong;Chang, Joe Y.
目的：质子剂量对切片内和切片间的解剖变化敏感。我们分析了剂量对质子治疗肺肿瘤的解剖改变的影响。方法与材料：对8例行调强光子放疗的移动期非小细胞肺癌患者进行每周四维计算机断层扫描（4D-CT）。为每位患者设计了适形质子治疗被动散射方案。在每周的4D-CT数据集上，使用基于骨配准的相同计划，在吸气末和呼气末呼吸阶段重新计算剂量分布。结果：由于解剖改变和运动模式改变，1例患者的临床靶体积（CTV）覆盖率降低（从99%到90.9%）。对于其余患者，每周重复4D-CT数据集的平均CTV覆盖率为98.4%，而原始计划为99%。然而，在所有8例患者中，在重复的4D-CT数据集中观察到，接受至少5 Gy （V5）剂量的对侧肺体积平均增加4%，脊髓最大剂量平均增加4.4 Gy。观察到由肿瘤缩小或解剖变化引起的CTV密度变化与对侧平均肺剂量之间有很强的相关性。结论：选择性非小细胞肺癌患者在质子治疗期间可进行适应性重新规划。然而，对于大多数患者，如果在最初的模拟和计划过程中考虑到肿瘤的运动，CTV覆盖是足够的。(C) 2008爱思唯尔公司
Purpose: Proton doses are sensitive to intra- and interfractional anatomic changes. We analyzed the effects of interfractional anatomic changes in doses to lung tumors treated with proton therapy.Methods and Materials: Weekly four-dimensional computed tomography (4D-CT) scans were acquired for 8 patients with mobile Stage III non-small cell lung cancer who were actually treated with intensity-modulated photon radiotherapy. A conformal proton therapy passive scattering plan was designed for each patient. Dose distributions were recalculated at end-inspiration and end-expiration breathing phases on each weekly 4D-CT data set using the same plans with alignment based on bone registration.Results: Clinical target volume (CTV) coverage was compromised (from 99% to 90.9%) in 1 patient because of anatomic changes and motion pattern variation. For the rest of the patients, the mean CTV coverage on the repeated weekly 4D-CT data sets was 98.4%, compared with 99% for the original plans. For all 8 patients, however, a mean 4% increase in the volume of the contralateral lung receiving a dose of at least 5 Gy (V5) and a mean 4.4-Gy increase in the spinal cord maximum dose was observed in the repeated 4D-CT data sets. A strong correlation between the CTV density change resulting from tumor shrinkage or anatomic variations and mean contralateral lung dose was observed.Conclusions: Adaptive re-planning during proton therapy may be indicated in selected patients with non-small cell lung cancer. For most patients, however, CTV coverage is adequate if tumor motion is taken into consideration in the original simulation and planning processes. (C) 2008 Elsevier Inc.