Amersham, United Kingdom.
Radiat Res. 2020 Dec 1;194(6):607-617. doi: 10.1667/RADE-19-00016.
Radiation chemists have been routinely using high-dose microsecond-pulsed irradiation for almost 60 years, involving many thousands of studies, in the technique of "pulse radiolysis". This involves dose rates broadly similar to the FLASH regimen now attracting interest in radiotherapy and radiobiology. Using the experience gained from radiation chemistry, two scenarios are examined here that may provide a mechanistic basis for any differential response in normal tissues versus tumors in FLASH radiotherapy. These are: 1. possible depletion of a chemical critical to the response to radiation, and 2. radical-radical reactions as a possible cause of effects occurring mainly with high-intensity pulsed radiation. The evidence for changes in relative levels of so-called "reactive oxygen species" produced after irradiation using FLASH versus conventional irradiation modalities is also examined.
辐射化学家已经常规地使用高剂量微秒脉冲辐射近 60 年，在“脉冲辐射分解”技术中涉及数千项研究。这种方法的剂量率与现在在放射治疗学和放射生物学中引起关注的 FLASH 方案大致相似。利用从辐射化学中获得的经验，这里检查了两种情况，这两种情况可能为 FLASH 放射治疗中正常组织与肿瘤的差异反应提供机制基础。这些情况是：1. 对辐射反应至关重要的化学物质可能耗尽，以及 2. 自由基-自由基反应可能是高强度脉冲辐射主要引起的效应的原因。还检查了使用 FLASH 与传统辐射方式照射后产生的所谓“活性氧物种”的相对水平变化的证据。
