Four-dimensional Monte Carlo dose calculation

描述（由申请人提供）：质子治疗目前正在兴起，因此被认为是治疗肺癌患者。大多数质子治疗患者目前正在接受被动散射质子治疗。由于正在设计仅用于笔形射束扫描的新设施，而现有设施正在升级为射束扫描，因此可以预期射束扫描将成为未来的首选方法。由于远端剂量急剧下降，质子治疗中运动的剂量效应可能比常规治疗更严重。此外，质子束扫描会引起笔形束流运动和靶运动之间的相互影响。在射束扫描可用于临床肺部治疗之前，我们必须了解使用时间依赖性输送系统治疗移动目标时的剂量效应。这项研究需要现在就做，在光束扫描建立之前！因此，我们建议应用四维Monte Carlo研究质子束扫描治疗运动目标时，笔形束运动和目标运动之间的潜在相互作用的影响。我们预计，根据运动参数和射束输送参数，可能存在肿瘤剂量不足或风险器官的剂量变化超过30%。因此，对于某些输送和运动参数，可能不使用质子束扫描（甚至不使用门控输送）代替标准被动散射质子束治疗。相互作用效应的影响可以通过改变射束输送参数，例如，笔形射束光斑尺寸，重绘策略等，我们还建议研究高局部剂量率的扫描射束输送的生物影响。 公共卫生相关性：质子治疗目前正在兴起，因此被认为是治疗肺癌的方法。然而，质子束扫描可以引起笔形束运动和目标运动之间的相互作用效应。在射束扫描可用于临床肺部治疗之前，我们必须了解使用时间依赖性输送系统治疗移动目标时的剂量效应。这项研究需要现在就做，在射束扫描成为临床建立之前！因此，我们建议应用四维Monte Carlo研究质子束扫描治疗运动目标时，笔形束运动和目标运动之间的潜在相互作用的影响。

DESCRIPTION (provided by applicant): Proton therapy is currently on the rise and is thus considered for treating lung cancer patients. The majority of proton therapy patients are currently being treated with passive scattered proton therapy. As newer facilities are being designed for pencil beam scanning only and existing facilities are upgrading towards beam scanning, it can be expected that beam scanning will be the method of choice in the future. Dosimetric effects of motion are potentially more severe in proton therapy than in conventional therapy due to the sharp distal dose fall-off. Furthermore, proton beam scanning can cause interplay effects between pencil beam motion and target motion. Before beam scanning can be used clinically for lung treatments it is mandatory that we understand dosimetric effects when treating moving targets with a time-dependent delivery system. This study needs to be done now, before beam scanning becomes established! Consequently, we propose to apply four-dimensional Monte Carlo to study potential interplay effects between pencil beam motion and target motion when treating moving targets with proton beam scanning. We expect that there could be under-dosage of the tumor or dose changes in organs at risk in excess of 30% depending on motion parameters and beam delivery parameters. Thus, for certain delivery and motion parameters, proton beam scanning might not be used (not even with gated delivery) instead of standard passive scattered proton beam therapy. The impact of interplay effects can be influenced by varying beam delivery parameters, e.g. pencil beam spot size, re-painting strategy, etc. We also propose to study the biological impact of scanned beam delivery with high local dose rate. PUBLIC HEALTH RELEVANCE: Proton therapy is currently on the rise and is thus considered for treating lung cancer. However, proton beam scanning can cause interplay effects between pencil beam motion and target motion. Before beam scanning can be used clinically for lung treatments it is mandatory that we understand dosimetric effects when treating moving targets with a time-dependent delivery system. This study needs to be done now, before beam scanning becomes clinically established! Consequently, we propose to apply four-dimensional Monte Carlo to study potential interplay effects between pencil beam motion and target motion when treating moving targets with proton beam scanning.