Abstract：
Objective. Proton therapy reduces the integral dose to the patient compared to conventional photon treatments. However,in vivoproton range uncertainties remain a considerable hurdle. Range uncertainty reduction benefits depend on clinical practices. During intensity-modulated proton therapy (IMPT), the target is irradiated from only a few directions, but proton arc therapy (PAT), for which the target is irradiated from dozens of angles, may see clinical implementation by the time considerable range uncertainty reductions are achieved. It is therefore crucial to determine the impact of PAT on range uncertainty reduction benefits.Approach. For twenty head-and-neck cancer patients, four different treatment plans were created: an IMPT and a PAT treatment plan assuming current clinical range uncertainties of 3.5% (IMPT3.5%and PAT3.5%), and an IMPT and a PAT treatment plan assuming that range uncertainties can be reduced to 1% (IMPT1%and PAT1%). Plans were evaluated with respect to target coverage and organ-at-risk doses as well as normal tissue complication probabilities (NTCPs) for parotid glands (endpoint: parotid gland flow <25%) and larynx (endpoint: larynx edema).Main results. Implementation of PAT (IMPT3.5%-PAT3.5%) reduced mean NTCPs in the nominal and worst-case scenario by 3.2 percentage points (pp) and 4.2 pp, respectively. Reducing range uncertainties from 3.5% to 1% during use of IMPT (IMPT3.5%-IMPT1%) reduced evaluated NTCPs by 0.9 pp and 2.0 pp. Benefits of range uncertainty reductions subsequently to PAT implementation (PAT3.5%-PAT1%) were 0.2 pp and 1.0 pp, with considerably higher benefits in bilateral compared to unilateral cases.Significance. The mean clinical benefit of implementing PAT was more than twice as high as the benefit of a 3.5%-1% range uncertainty reduction. Range uncertainty reductions are expected to remain beneficial even after PAT implementation, especially in cases with target positions allowing for full leveraging of the higher number of gantry angles during PAT.
摘要：
目的：与常规光子治疗相比，质子治疗减少了患者的总剂量。然而,体内质子范围的不确定性仍然是一个相当大的障碍。范围不确定性降低的好处取决于临床实践。在强度调节质子治疗（IMPT）期间，目标仅从几个方向照射，但是质子电弧疗法(PAT)，从几十个角度照射目标，在实现相当大的范围不确定性降低时，可能会看到临床实施。因此，确定PAT对范围不确定性降低益处的影响至关重要。
方法：对于20名头颈部癌症患者，创建了四种不同的治疗计划：IMPT和PAT治疗计划，假设当前临床范围不确定性为3.5％（IMPT3.5％和PAT3.5％），以及IMPT和PAT治疗计划，假设范围不确定性可以降低到1％（IMPT1%和PAT1%）。针对腮腺（终点：腮腺流量<25％）和喉（终点：喉水肿）的目标覆盖率和危险器官剂量以及正常组织并发症概率（NTCPs）评估计划。＆＃xD;主要结果：实施PAT（IMPT3.5％-PAT3.5％）将名义和最坏情况下的平均NTCP降低了3.2个百分点（pp）和4.2pp，分别。在使用IMPT（IMPT3.5%-IMPT1%）期间，将范围不确定性从3.5%降低到1%，可将评估的NTCPs降低0.9pp和2.0pp。PAT实施后范围不确定性降低的好处（PAT3.5%-PAT1%）分别为0.2pp和1.0pp，与单边病例相比，双边病例的获益要高得多。＆＃xD;意义：实施PAT的平均临床益处是3.5％至1％范围不确定度降低的益处的两倍以上。即使在PAT实施之后，预计范围不确定性降低仍将是有益的，特别是在目标位置的情况下，允许在PAT期间充分利用更多数量的机架角度。
