Quantitative Assessment of 3D Dose Rate for Proton Pencil Beam Scanning FLASH Radiotherapy and Its Application for Lung Hypofractionation Treatment Planning.
Quantitative Assessment of 3D Dose Rate for Proton Pencil Beam Scanning FLASH Radiotherapy and Its Application for Lung Hypofractionation Treatment Planning.
复制标题
对质子铅笔梁扫描闪光放射疗法的3D剂量率的定量评估及其用于肺部低分治疗计划的应用。
DOI：
10.3390/cancers13143549
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发表时间：
2021-07-15
期刊：
影响因子：
5.2
通讯作者：
Lin H
中科院分区：
文献类型：
--
作者：
Kang M;Wei S;Choi JI;Simone CB 2nd;Lin H
由于笔形束扫描（PBS）质子治疗通过点扫描提供剂量，因此剂量率量化与FLASH放射治疗中的电子和散射质子技术有很大不同。目前，对于正常组织和靶点的PBS质子治疗剂量率计算的定义尚未达成共识。本研究的重点是剂量率量化的危险器官和目标的基础上提出的三个剂量率度量使用质子传输束。剂量率指标的差异导致了危及器官剂量率评估的较大变化，并可能导致临床前实验的剂量率和生物效应之间的相关性预期不同。了解质子PBS剂量率计算的差异对于设计实验和临床试验以揭示FLASH-RT的生物学和生理学机制非常重要。基于三种建议的质子PBS剂量率指标定量评估靶和危及器官（OAR）剂量率，并研究使用传输射束的FLASH调强质子治疗（IMPT）治疗计划。开发了一个内部FLASH计划平台，以优化先前计划使用质子SBRT的9名连续肺癌患者的传输（直通）计划。开发了剂量和剂量率计算代码，以根据体模和患者治疗计划量化三种类型的剂量率计算方法（剂量平均剂量率（DADR）、平均剂量率（ADR）和剂量阈值剂量率（DTDR））。使用两种不同的最小MU/斑点设置来优化两种不同的剂量方案，一次34-戈伊和三次45-戈伊。OAR节省和目标覆盖可以以良好的均匀性（热点<处方剂量的110%）进行优化。ADR考虑了点驻留和扫描时间，给出了最低剂量率; DTDR不考虑该时间，而是考虑剂量阈值，给出了中间剂量率，而DADR给出了最高剂量率，不考虑任何时间或剂量阈值。三种剂量率都沿束流方向沿着衰减，ADR和DTDR的最高剂量率区域通常出现在射野边缘，而DADR具有更好的剂量率均匀性。剂量率指标的差异导致OAR剂量率评估出现很大差异，给FLASH临床实施带来挑战。这是首次尝试研究剂量率模型的影响，需要对质子PBS FLASH参数的细节进行更多的调查和证据，以探索FLASH疗效与剂量率指标之间的相关性。
As pencil beam scanning (PBS) proton therapy delivers doses via spot-scanning, the dose rate quantification is very different from the electron and scattering proton techniques in FLASH radiotherapy. Currently, there is no consensus on the definition of the PBS proton therapy dose rate calculation for normal tissues and targets. This study focuses on the dose rate quantification of organs-at-risk and target based on three proposed dose rate metrics using proton transmission beams. The differences in dose rate metrics have led a large variation for organs-at-risk dose rate assessment and may result in a different correlation expectation between dose rate and biological effects for pre-clinical experiments. An awareness of the differences in proton PBS dose rate calculation is important to design experiments and clinical trials to uncover FLASH-RT’s biological and physiological mechanisms. To quantitatively assess target and organs-at-risk (OAR) dose rate based on three proposed proton PBS dose rate metrics and study FLASH intensity-modulated proton therapy (IMPT) treatment planning using transmission beams. An in-house FLASH planning platform was developed to optimize transmission (shoot-through) plans for nine consecutive lung cancer patients previously planned with proton SBRT. Dose and dose rate calculation codes were developed to quantify three types of dose rate calculation methods (dose-averaged dose rate (DADR), average dose rate (ADR), and dose-threshold dose rate (DTDR)) based on both phantom and patient treatment plans. Two different minimum MU/spot settings were used to optimize two different dose regimes, 34-Gy in one fraction and 45-Gy in three fractions. The OAR sparing and target coverage can be optimized with good uniformity (hotspot < 110% of prescription dose). ADR, accounting for the spot dwelling and scanning time, gives the lowest dose rate; DTDR, not considering this time but a dose-threshold, gives an intermediate dose rate, whereas DADR gives the highest dose rate without considering any time or dose-threshold. All three dose rates attenuate along the beam direction, and the highest dose rate regions often occur on the field edge for ADR and DTDR, whereas DADR has a better dose rate uniformity. The differences in dose rate metrics have led a large variation for OARs dose rate assessment, posing challenges to FLASH clinical implementation. This is the first attempt to study the impact of the dose rate models, and more investigations and evidence for the details of proton PBS FLASH parameters are needed to explore the correlation between FLASH efficacy and the dose rate metrics.
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影响因子：
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作者：
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