Balcer-Kubiczek Elizabeth K, Eley John G
Department of Radiation Oncology, Translational Radiation Sciences Division, Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore MD 21201, U.S.A.
Maryland Proton Treatment Center, Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland School of Medicine, Baltimore, Maryland.
Crit Rev Oncog. 2018;23(1-2):93-112. doi: 10.1615/CritRevOncog.2018025830.
Although modern radiation therapy delivers a localized distribution of ionizing energy that can be used to cure primary cancers for many patients, the inevitable radiation exposure to non-targeted normal tissue leads to a risk of a radiation-related new cancer. Modern therapies often produce a complex spectrum of secondary particles, both charged and uncharged, that must be considered both in their physical radiation transport throughout the patient and their potential to induce biological damage, which depends on the microscopic energy deposition from the cascade of primary, secondary, and downstream particles. This work summarizes the experimental data for relative biological effectiveness for particles associated with modern radiotherapy in light of their capacity to induce secondary malignancies in patients. A distinction is highlighted between the radiobiological experimental data and the coarser metrics used frequently in radiation protection. For critical assessment of the risks of secondary malignancies for patients undergoing radiation therapy, a detailed description of primary and secondary radiation fields is needed, though not routinely considered for individual patient treatments. Furthermore, not only the particle type, but also the microscopic dose and track structure, must be considered, which points to a demand for detailed physics models and high-performance computing strategies to model the risks.
尽管现代放射治疗能够提供局部的电离能量分布，可用于治愈许多患者的原发性癌症，但不可避免地会使非靶向正常组织受到辐射，从而导致患与辐射相关的新发癌症的风险。现代治疗方法通常会产生复杂的次级粒子谱，包括带电和不带电的粒子，在考虑这些粒子在患者体内的物理辐射传输以及它们诱发生物损伤的可能性时，都必须将其纳入考量，而这又取决于初级、次级和下游粒子级联产生的微观能量沉积。鉴于与现代放射治疗相关的粒子诱发患者继发性恶性肿瘤的能力，本文总结了相关的相对生物效应实验数据。文中强调了放射生物学实验数据与辐射防护中常用的较为粗略的指标之间的区别。对于接受放射治疗的患者继发性恶性肿瘤风险的关键评估，需要详细描述初级和次级辐射场，不过在个体患者治疗中通常不会进行常规考虑。此外，不仅要考虑粒子类型，还必须考虑微观剂量和径迹结构，这表明需要详细的物理模型和高性能计算策略来模拟风险。
