放射肿瘤学的最终目标是消除肿瘤而不对非恶性组织产生毒性。快速FLASH放射疗法，即以超高剂量率的辐射（>40 Gy/s）进行治疗，成为一种辐射疗法模式，可以保持肿瘤控制的同时减少对周围非恶性组织的毒性。近年来的临床前研究表明，FLASH放射疗法可以在很短的时间内进行，实质性地扩大放射疗法的治疗窗口。这种超快的辐射传递可以减少毒性，从而提高抗肿瘤疗效，额外的好处是减少治疗时间和器官运动相关问题，最终增加接受治疗的病人数量。目前，FLASH放射疗法被认为是放射肿瘤学中最有前途的突破之一，处于技术、物理、化学和生物学的交汇处；然而，几个障碍使其临床转化变得困难，包括对生物机制更好的理解、参数的优化和技术挑战。在这个角度上，我们提供了FLASH放射疗法原理的概述，并讨论了在其临床应用的道路中所面临的挑战。© 2022. Springer Nature Limited.

The ultimate goal of radiation oncology is to eradicate tumours without toxicity to non-malignant tissues. FLASH radiotherapy, or the delivery of ultra-high dose rates of radiation (>40 Gy/s), emerged as a modality of irradiation that enables tumour control to be maintained while reducing toxicity to surrounding non-malignant tissues. In the past few years, preclinical studies have shown that FLASH radiotherapy can be delivered in very short times and substantially can widen the therapeutic window of radiotherapy. This ultra-fast radiation delivery could reduce toxicity and thus enable dose escalation to enhance antitumour efficacy, with the additional benefits of reducing treatment time and organ motion-related issues, eventually increasing the number of patients who can be treated. At present, FLASH is recognized as one of the most promising breakthroughs in radiation oncology, standing at the crossroads between technology, physics, chemistry and biology; however, several hurdles make its clinical translation difficult, including the need for a better understanding of the biological mechanisms, optimization of parameters and technological challenges. In this Perspective, we provide an overview of the principles underlying FLASH radiotherapy and discuss the challenges along the path towards its clinical application.© 2022. Springer Nature Limited.