Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
Semin Radiat Oncol. 2018 Jun;28(3):256-263. doi: 10.1016/j.semradonc.2018.02.010.
Current clinical implementation of proton radiation therapy assumes a constant relative biological effectiveness (RBE) value of 1.1 throughout the treatment field, for both the target and organs at risks. Although few in vivo clinical data suggest that this approximation is clinically significant, in vitro studies demonstrate the dependency of RBE on dose, fractionation, proton energy, and linear energy transfer, as well as patient radiosensitivity and definition of endpoint. This article provides a brief review on the principles and individual factors contributing to RBE uncertainties, with emphasis on clinical practice. Clinical considerations regarding the effect of RBE uncertainties and implications for beam arrangements in proton therapy treatment planning are discussed through clinical examples for treatments of prostate cancer and posterior fossa tumors as well as craniospinal irradiation for medulloblastoma. Approaches on biological optimization in proton therapy are presented, including a discussion on linear energy transfer-based optimization as an alternative method for biological optimization and its implementation both in multicriteria optimization and inverse optimization modules.
目前质子放射治疗的临床实施假设在整个治疗区域内，靶区和危及器官的相对生物学效应（RBE）值均为 1.1，保持不变。尽管很少有体内临床数据表明这种近似在临床上有意义，但体外研究表明 RBE 依赖于剂量、分割、质子能量和线性能量转移以及患者的放射敏感性和终点定义。本文简要回顾了导致 RBE 不确定性的原则和个体因素，重点是临床实践。通过前列腺癌和后颅窝肿瘤以及髓母细胞瘤的颅脊髓照射治疗的临床实例，讨论了 RBE 不确定性的临床考虑因素及其对质子治疗计划中射束排列的影响。本文还介绍了质子治疗中的生物学优化方法，包括基于线性能量转移的优化作为生物学优化的替代方法的讨论，以及在多标准优化和逆优化模块中的实现。
