Tumour tracking with scanned proton beams: assessing the accuracy and practicalities
Tumour tracking with scanned proton beams: assessing the accuracy and practicalities
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DOI：
10.1088/0031-9155/54/21/007
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发表时间：
2009-11-07
影响因子：
3.5
通讯作者：
Lomax, A. J.
中科院分区：
文献类型：
--
作者：
van de Water, S.;Kreuger, R.;Lomax, A. J.
评估了肿瘤追踪用于主动点扫描质子治疗的潜力。使用 4D 剂量计算和模拟目标运动，实现了肿瘤跟踪算法，并将其应用于同质和异质硅模型中的简单目标体积。对于跟踪和重跟踪（肿瘤跟踪和重新扫描相结合的混合解决方案），分析了三种跟踪模式：“无跟踪”（移动目标的未校正照射）、“完美跟踪”（无时间延迟且准确了解目标位置）和“不完美跟踪”（模拟时间延迟或位置预测误差）。对于所有计划，目标体积中的剂量均匀性通过 CTV 中 D5 和 D95 之间的差异进行评估。对于均匀体模，完美的跟踪可以检索所有运动相位和幅度的标称剂量均匀性，而不完美的跟踪会导致治疗结果严重恶化。重跟踪的使用显着降低了同质体模中对位置误差的敏感性。在异质模型（接近目标的模拟肋骨）中，无法通过完美的跟踪获得标称剂量均匀性。笔形光束位置的调整可能会导致笔形光束在骨骼的影响下变形，从而导致剂量均匀性丧失。由于重新跟踪无法减少这些影响，因此重新扫描为本研究中移动异质目标提供了最佳治疗结果。
The potential of tumour tracking for active spot-scanned proton therapy was assessed. Using a 4D-dose calculation and simulated target motion, a tumour tracking algorithm has been implemented and applied to a simple target volume in both homogenous and heterogeneous in silico phantoms. For tracking and retracking (a hybrid solution combining tumour tracking and rescanning), three tracking modes were analysed: 'no tracking' (uncorrected irradiation of a moving target), 'perfect tracking' (no time delays and exact knowledge of target position) and 'imperfect tracking' (simulated time delays or position prediction errors). For all plans, dose homogeneity in the target volume was assessed as the difference between D5 and D95 in the CTV. For the homogeneous phantom, perfect tracking could retrieve nominal dose homogeneity for all motion phases and amplitudes while severe deterioration of treatment outcomes was found for imperfect tracking. The use of retracking reduced the sensitivity to position errors significantly in the homogeneous phantom. In the heterogeneous phantoms (simulated rib proximal to target), the nominal dose homogeneity could not be obtained with perfect tracking. Adjustments in pencil beam positions could cause pencil beams to deform under the influence of the bone, resulting in loss of dose homogeneity. As retracking was not capable of reducing these effects, rescanning provided the best treatment outcomes for moving heterogeneous targets in this study.