MultiRBE: Treatment planning for protons with selective radiobiological effectiveness.
MultiRBE: Treatment planning for protons with selective radiobiological effectiveness.
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MultiRBE：具有选择性放射生物学有效性的质子治疗计划。
DOI：
10.1002/mp.13718
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发表时间：
2019
期刊：
影响因子：
3.8
通讯作者：
Udías,JoséManuel
中科院分区：
文献类型：
--
作者：
Sánchez-Parcerisa,Daniel;López-Aguirre,Miguel;DolcetLlerena,Ana;Udías,JoséManuel
目的质子的临床治疗计划方案建议在整个治疗范围内将质子的放射生物学有效性 (RBE) 统一定为 1.1，尽管体外和动物研究的证据表明质子 RBE 随着线性能量转移 (LET) 的增加而增加，导致位于目标位置远端的组织接受的生物剂量可能高于估计值。虽然医学物理界有一些声音主张基于可变 RBE 的优化，但 RBE 模型的不确定性阻碍了其在临床实践中的实施，因为高估 RBE 可能会导致明显的目标剂量不足。方法我们提出了一种混合 RBE 模型（MultiRBE），其中在目标轮廓中使用统一的 RBE 以确保物理剂量方面足够的肿瘤覆盖，但在其他地方使用可变 RBE。我们的模型在开源治疗计划系统 matRad 中实施，并计划了三个示例病例：同质体模、前列腺肿瘤和头颈病例。 MultiRBE 用于计划优化，随后根据危险器官中的物理剂量覆盖率 (V95%) 和可变 RBE 加权剂量以及正常组织并发症概率 (NTCP) 进行评估，其中预测模型可用。结果规划算法显示出减少计划目标周围器官的生物剂量的潜力，从而降低正常组织并发症的概率（前列腺病例中最多可降低 62%，头颈患者可降低 37%）。这是在不影响物理剂量的目标覆盖或均匀性的情况下实现的，这是由于在优化约束条件下在周围组织之间进行了更智能的剂量重新分配。结论结果证明，MultiRBE 模型能够在不影响肿瘤剂量覆盖的情况下减少健康组织的生物剂量，并且与所使用的可变 RBE 模型无关。
PurposeClinical treatment planning protocols for protons recommend a uniform value radiobiological effectiveness (RBE) of protons of 1.1 throughout the treatment field, despite evidence from in‐vitro and animal studies that proton RBE increases with linear energy transfer (LET), causing tissues placed distally to the target location to receive a presumably higher biological dose than estimated. While several voices in the medical physics community have advocated for variable RBE‐based optimization, the uncertainties in RBE models have prevented its implementation in clinical practice, since an overestimation of RBE could cause significant target underdosage.MethodsWe propose a mixed RBE model (MultiRBE), where a uniform RBE is used in the target contours to ensure an adequate tumor coverage in terms of physical dose, but a variable RBE is used elsewhere. Our model was implemented in the open‐source treatment planning system matRad and three example cases were planned: a homogeneous phantom, a prostate tumor and a head‐and‐neck case. MultiRBE was used for plan optimization, and the produced plans were subsequently evaluated in terms of physical dose coverage (V95%) and variable RBE‐weighted dose in organs at risk and normal tissue complication probabilities (NTCP), where prediction models were available.ResultsThe planning algorithm showed potential for reducing the biological dose in organs surrounding the planning target and thus decreasing the probability for complications in normal tissue (by up to 62% in the prostate case and 37% in the head‐and‐neck patient). This was achieved without compromising the target coverage or homogeneity in terms of physical dose, as a result of a smarter redistribution of dose among the surrounding tissues with regard to the optimization constraints.ConclusionsThe results prove the ability of the MultiRBE model to reduce biological dose at healthy tissues without compromising the dose coverage of the tumor, with independence of the variable RBE models used.