论文标题

用于铅笔光束扫描粒子疗法的通用和动态脊过滤器:超快速治疗的新概念

Universal and dynamic ridge filter for pencil beam scanning particle therapy: novel concept for ultra-fast treatment delivery

论文作者

Maradia, Vivek, Colizzi, Isabella, Meer, David, Weber, Damien Charles, Lomax, Antony John, Actis, Oxana, Psoroulas, Serena

论文摘要

PBS粒子疗法的目的是,短期治疗时间对于通过运动缓解技术(例如呼吸持续,恢复和门控)有效地治疗移动靶标的最重要。能量和点位置变化时间是减少治疗时间的限制因素。在这项研究中,我们设计了一个通用和动态的能量调节器(脊过滤器,RF)来扩大Bragg峰,以减少覆盖目标体积所需的能量和斑点的数量,从而降低了治疗时间。方法我们的RF单元包含在同心之前放置的两个相同的RF。两个RF相对移动,并动态更改Bragg峰特征。我们在TOPAS中使用RF模拟了不同的Bragg峰形状,并通过实验验证了它们。然后,我们向水中的不同几何靶标提供了具有1GY/分数的单场计划,以使用RF测量剂量输送时间,并将其与临床环境进行比较。在不同位置将RF对准的结果会在布拉格峰中产生不同的扩展。我们达到了2厘米的最大扩展。对于RF,对于所有研究的几何靶标,我们将田间的能量数量减少了60%以上,而剂量输送时间则减少了50%,而不会损害剂量分布横向和远端下降。结论我们的新型通用和动态RF允许根据目标体积中剂量成形的要求,适应了斑点和/或能量层的bragg峰拓宽。它大大减少了能量层和斑点的数量,以覆盖目标体积,从而覆盖了治疗时间。这种RF设计非常适合在单次呼吸含量(5-10秒)内进行超快速的治疗,有效的运动缓解技术和具有超高剂量率的小动物照射(Flash)。

Purpose In PBS particle therapy, short treatment delivery time is paramount for the efficient treatment of moving targets with motion mitigation techniques (such as breath-hold, rescanning, and gating). Energy and spot position change time are limiting factors in reducing treatment time. In this study, we designed a universal and dynamic energy modulator (ridge filter, RF) to broaden the Bragg peak, to reduce the number of energies and spots required to cover the target volume, thus lowering the treatment time. Methods Our RF unit comprises two identical RFs placed just before the isocenter. Both RFs move relative to each other, changing the Bragg peaks characteristics dynamically. We simulated different Bragg peak shapes with the RF in TOPAS and validated them experimentally. We then delivered single-field plans with 1Gy/fraction to different geometrical targets in water, to measure the dose delivery time using the RF and compare it with the clinical settings. Results Aligning the RFs in different positions produces different broadening in the Bragg peak; we achieved a maximum broadening of 2 cm. With RF we reduced the number of energies in a field by more than 60%, and the dose delivery time by 50%, for all geometrical targets investigated, without compromising the dose distribution transverse and distal fall-off. Conclusions Our novel universal and dynamic RF allows for the adaptation of the Bragg peak broadening for a spot and/or energy layer based on the requirement of dose shaping in the target volume. It significantly reduces the number of energy layers and spots to cover the target volume, and thus the treatment time. This RF design is ideal for ultra-fast treatment delivery within a single breath-hold (5-10 sec), efficient delivery of motion mitigation techniques, and small animal irradiation with ultra-high dose rates (FLASH).

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