Benzazon Nathan, Colnot Julie, de Kermenguy François, Achkar Samir, de Vathaire Florent, Deutsch Eric, Robert Charlotte, Diallo Ibrahima
Unité Mixte de Recherche (UMR) 1030 Radiothérapie Moléculaire et Innovation Thérapeutique, ImmunoRadAI, Université Paris-Saclay, Institut Gustave Roussy, Inserm, Villejuif, France.
Department of Radiation Oncology, Gustave Roussy, Villejuif, France.
Front Oncol. 2023 May 9;13:1197079. doi: 10.3389/fonc.2023.1197079. eCollection 2023.
A growing body of scientific evidence indicates that exposure to low dose ionizing radiation (< 2 Gy) is associated with a higher risk of developing radio-induced cancer. Additionally, it has been shown to have significant impacts on both innate and adaptive immune responses. As a result, the evaluation of the low doses inevitably delivered outside the treatment fields (out-of-field dose) in photon radiotherapy is a topic that is regaining interest at a pivotal moment in radiotherapy. In this work, we proposed a scoping review in order to identify evidence of strengths and limitations of available analytical models for out-of-field dose calculation in external photon beam radiotherapy for the purpose of implementation in clinical routine. Papers published between 1988 and 2022 proposing a novel analytical model that estimated at least one component of the out-of-field dose for photon external radiotherapy were included. Models focusing on electrons, protons and Monte-Carlo methods were excluded. The methodological quality and potential limitations of each model were analyzed to assess their generalizability. Twenty-one published papers were selected for analysis, of which 14 proposed multi-compartment models, demonstrating that research efforts are directed towards an increasingly detailed description of the underlying physical phenomena. Our synthesis revealed great inhomogeneities in practices, in particular in the acquisition of experimental data and the standardization of measurements, in the choice of metrics used for the evaluation of model performance and even in the definition of regions considered out-of-the-field, which makes quantitative comparisons impossible. We therefore propose to clarify some key concepts. The analytical methods do not seem to be easily suitable for massive use in clinical routine, due to the inevitable cumbersome nature of their implementation. Currently, there is no consensus on a mathematical formalism that comprehensively describes the out-of-field dose in external photon radiotherapy, partly due to the complex interactions between a large number of influencing factors. Out-of-field dose calculation models based on neural networks could be promising tools to overcome these limitations and thus favor a transfer to the clinic, but the lack of sufficiently large and heterogeneous data sets is the main obstacle.
越来越多的科学证据表明，暴露于低剂量电离辐射（<2 Gy）会增加患放射性癌症的风险。此外，它已被证明对先天免疫反应和适应性免疫反应均有重大影响。因此，在光子放射治疗中，对治疗区域外不可避免地产生的低剂量（野外剂量）进行评估，是放射治疗关键时期重新受到关注的一个话题。在这项工作中，我们提出了一项范围综述，以确定用于外部光子束放射治疗中野外剂量计算的现有分析模型的优势和局限性的证据，以便在临床常规中应用。纳入了1988年至2022年发表的提出一种新分析模型的论文，该模型估计了光子外照射放疗野外剂量的至少一个组成部分。专注于电子、质子和蒙特卡洛方法的模型被排除在外。分析了每个模型的方法学质量和潜在局限性，以评估其通用性。选择了21篇已发表的论文进行分析，其中14篇提出了多室模型，表明研究工作正朝着对潜在物理现象进行越来越详细的描述方向发展。我们的综述揭示了实践中存在很大的异质性，特别是在实验数据的获取和测量的标准化方面，在用于评估模型性能的指标选择上，甚至在被视为野外区域的定义上，这使得定量比较变得不可能。因此，我们建议澄清一些关键概念。由于其实施过程不可避免地繁琐，分析方法似乎不太容易适用于临床常规的大量使用。目前，对于全面描述外部光子放射治疗中野外剂量的数学形式尚无共识，部分原因是大量影响因素之间的复杂相互作用。基于神经网络的野外剂量计算模型可能是克服这些局限性并因此有利于向临床转化的有前途的工具，但缺乏足够大且异质的数据集是主要障碍。
