超高剂量率放疗在恶性肿瘤中的应用

放疗作为一种局部治疗手段，在肿瘤治疗中扮演重要的角色。在过去数十年间，放疗技术取得了进步，适形性、均质性不断增强，放疗效率提高，结果令人鼓舞。尽管如此，正常组织最大耐受剂量成为制约肿瘤区域放疗剂量进一步提升的瓶颈。如果能够减轻正常组织不良反应，则可给予肿瘤病灶较高的放疗剂量，从而取得更好的疗效。近年来，超高剂量率放疗（FLASH-RT）诱导的FLASH效应，使得保持相同的抗肿瘤效果的同时，对正常组织能够降低放疗诱发的不良反应。因此，成为国内外放疗界热门研究领域。目前，部分学者倾向于采用急性氧消耗学说解释FLASH效应，但FLASH-RT的正常组织保护作用仍有待阐明。此外，FLASH-RT的临床研究已初步展开，结果令人期待。本文基于现有的证据，对FLASH-RT在恶性肿瘤治疗中的研究进行了阐述，以期为该项新技术的临床转化应用提供参考。

Application of FLASH radiotherapy with an ultra-high dose rate in malignant tumor

As a method for local treatment, radiotherapy plays a key role in the management of tumors. In the past few decades, great progress has been made in radiotherapy technology, with improvements in conformity, homogeneity, and radiotherapy efficiency, and the results are encouraging. Nevertheless, the maximum tolerated dose of normal tissue has limited the further increase in radiotherapy dose in the tumor area. If radiation-induced toxicities can be reduced, a higher radiotherapy dose can be delivered to tumor tissue, so as to achieve a better treatment response. In recent years, the unique FLASH effect of ultra-high-dose-rate radiotherapy (FLASH-RT) is capable of maintaining a consistent tumor response whilst reducing radiation-induced toxicities in normal tissue, and therefore, FLASH-RT has become a research hotspot in the field of radiotherapy across the world. At present, some scholars tend to explain the FLASH effect using the theory of acute oxygen depletion, but the protective effect of FLASH-RT on normal tissue remains to be clarified. In addition, preliminary clinical studies have been conducted for FLASH-RT, and the results are promising. Based on existing evidence, this article elaborates on the research advances in FLASH-RT in the treatment of malignant tumor, so as to provide a reference for the translation and application of this new technique.