Abstract：
Objective.Hybrid proton-photon radiotherapy (RT) is a cancer treatment option to broaden access to proton RT. Additionally, with a refined treatment planning method, hybrid RT has the potential to offer superior plan quality compared to proton-only or photon-only RT, particularly in terms of target coverage and sparing organs-at-risk (OARs), when considering robustness to setup and range uncertainties. However, there is a concern regarding the underestimation of the biological effect of protons on OARs, especially those in close proximity to targets. This study seeks to develop a hybrid treatment planning method with biological dose optimization, suitable for clinical implementation on existing proton and photon machines, with each photon or proton treatment fraction delivering a uniform target dose.Approach.The proposed hybrid biological dose optimization method optimized proton and photon plan variables, along with the number of fractions for each modality, minimizing biological dose to the OARs and surrounding normal tissues. To mitigate underestimation of hot biological dose spots, proton biological dose was minimized within a ring structure surrounding the target. Hybrid plans were designed to be deliverable separately and robustly on existing proton and photon machines, with enforced uniform target dose constraints for the proton and photon fraction doses. A probabilistic formulation was utilized for robust optimization of setup and range uncertainties for protons and photons. The nonconvex optimization problem, arising from minimum monitor unit constraint and dose-volume histogram constraints, was solved using an iterative convex relaxation method.Main results.Hybrid planning with biological dose optimization effectively eliminated hot spots of biological dose, particularly in normal tissues surrounding the target, outperforming proton-only planning. It also provided superior overall plan quality and OAR sparing compared to proton-only or photon-only planning strategies.Significance.This study presents a novel hybrid biological treatment planning method capable of generating plans with reduced biological hot spots, superior plan quality to proton-only or photon-only plans, and clinical deliverability on existing proton and photon machines, separately and robustly.
摘要：
目的：
混合质子-光子放射治疗（RT）是一种癌症治疗选择，以扩大获得质子RT的途径。此外,有了精细的治疗计划方法，与仅质子或仅光子的RT相比，混合RT具有提供卓越计划质量的潜力，特别是在目标覆盖率和保护风险器官(OAR)方面，当考虑对设置和范围不确定性的鲁棒性时。然而,人们担心质子对OAR的生物效应被低估，尤其是那些靠近目标的人。本研究旨在开发一种具有生物剂量优化的混合治疗计划方法，适用于现有质子和光子机器的临床实施，每个光子或质子治疗部分提供均匀的目标剂量。＆＃xD;方法：＆＃xD;提出的混合生物剂量优化方法优化了质子和光子计划变量，随着分数的数量，最小化OAR和周围正常组织的生物剂量。混合计划旨在在现有的质子和光子机器上单独可靠地交付，对质子和光子分数剂量具有强制的均匀目标剂量约束。概率公式用于质子和光子的设置和范围不确定性的鲁棒优化。非凸优化问题，由最小监测单位(MMU)约束和剂量-体积直方图(DVH)约束引起，使用迭代凸松弛法求解。
主要结果:
生物剂量优化的混合规划有效消除了生物剂量的热点,特别是在目标周围的正常组织中，优于仅质子计划。与仅质子或仅光子的计划策略相比，它还提供了出色的整体计划质量和OAR节省。＆＃xD;意义：＆＃xD;这项研究提出了一种新颖的混合生物治疗计划方法，能够生成具有最小化生物热点的计划，优于仅质子或仅光子计划的计划质量，以及现有质子和光子机器的临床输送能力，分开和健壮。
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