Flash radiotherapy-gateway to promised land or another mirage.

Radiation therapy damages cancer cells with ionizing radiation, leading to their death. However, radiation‑induced toxicity limits the dose delivered to the tumor, thereby constraining the control effect of radiotherapy n tumor growth. In addition, the delayed toxicity caused by radiotherapy significantly harms the physical and mental health of patients. FLASH‑RT, an emerging class of radiotherapy, causes a phenomenon known as the 'FLASH effect', which delivers radiotherapy at an ultra‑high dose rate with lower toxicity to normal tissue than conventional radiotherapy to achieve local tumor control.