Ma Yangguang, Zhang Tengda, Selvaraj Balaji, Shen Jiajian, Wei Shouyi, Cheng Chingyun, Gao Hao, Poulsen Per Rugaard, Li Heng, Diffenderfer Eric, Schuemann Jan, Lin Liyong, Morris Zachary, Durkee Benjamin, Hesser Jürgen, Lin Haibo, Simone Charles B, Kang Minglei, Wu Hui
Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
MIISM, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Department of Human Oncology, University of Wisconsin-Madison, Madison, Wisconsin.
Int J Radiat Oncol Biol Phys. 2025 Jun 11. doi: 10.1016/j.ijrobp.2025.05.076.
Proton FLASH radiation therapy (RT) is an emerging technique that offers highly conformal doses similar to conventional intensity modulated proton therapy but with the added potential benefit of protecting organs at risk through the FLASH-sparing effect. This review examines recent advancements in proton FLASH-RT, including transmission beams (TB), single-energy Bragg peak, single-energy spread-out Bragg peak, hybrid FLASH, and multiple-energy spread-out Bragg peak. These proton FLASH technologies are discussed in detail, highlighting their advantages, limitations, and dosimetric comparisons with intensity modulated proton therapy and other FLASH techniques. Although TB achieves dose conformity through multifield optimization, it also has unnecessary exit doses. In contrast, single-energy Bragg peak and single-energy spread-out Bragg peak offer improved organ at risk protection and superior target conformity at the cost of using range compensators and/or ridge filters. Additionally, hybrid FLASH-RT combines TB and Bragg peak methods to target the tumor core and edges separately, whereas multiple-energy spread-out Bragg peak FLASH leverages ultra-fast energy switching. Despite these advancements, only nonconformal TB FLASH-RT has been applied clinically with single fields for palliative RT because of the complexity of other methods and uncertainties about the FLASH effect. This review summarizes the technical details of these FLASH-RT methods and discusses their utilization across various anatomical sites.
质子FLASH放射治疗（RT）是一种新兴技术，它能提供与传统调强质子治疗相似的高度适形剂量，但具有通过FLASH保护效应保护危及器官的潜在额外益处。本综述探讨了质子FLASH-RT的最新进展，包括透射束（TB）、单能布拉格峰、单能扩展布拉格峰、混合FLASH和多能扩展布拉格峰。详细讨论了这些质子FLASH技术，突出了它们的优势、局限性以及与调强质子治疗和其他FLASH技术的剂量学比较。虽然TB通过多野优化实现剂量适形，但也存在不必要的出射剂量。相比之下，单能布拉格峰和单能扩展布拉格峰以使用射程补偿器和/或脊形滤过器为代价，提供了更好的危及器官保护和更高的靶区适形性。此外，混合FLASH-RT结合了TB和布拉格峰方法，分别靶向肿瘤核心和边缘，而多能扩展布拉格峰FLASH利用了超快速能量切换。尽管有这些进展，但由于其他方法的复杂性和FLASH效应的不确定性，只有非适形的TB FLASH-RT已在临床上用于单野姑息性放疗。本综述总结了这些FLASH-RT方法的技术细节，并讨论了它们在不同解剖部位的应用。
