Mouse cardiac tissue received greater protection from and had better tolerance to the maximum dose of FLASH versus conventional radiation

Abstract Radiation therapy is used to treat patients with various types of cancer by killing tumor cells or inhibiting their growth. However, conventional radiation (CONV) not only shrinks the tumor, but also irradiates the surrounding normal tissue, causing normal tissue toxicity. Here, we investigated the potential benefits of high-dose FLASH irradiation therapy applied over a short period and compared the effects of FLASH irradiation and CONV irradiation on mouse cardiac tissue. Our results showed that compared to CONV irradiation, FLASH irradiation resulted in lower mortality and prevented radiation-induced cardiac fibrosis, according to in the survival curves of irradiated mice. FLASH irradiation was more effective than CONV irradiation at higher doses and showed a protective effect and greater cardiac tissue tolerance. These findings can be used to evaluate the efficacy, safety, and potential side effects of FLASH radiation therapy in animal models before application to human patients. Thus, our results on cardiac tissue changes in mice after FLASH irradiation in this study will be an important reference for predicting and measuring cardiotoxicity in preclinical and clinical applications of FLASH treatment in the future.