Development of Ultra-High Dose-Rate (FLASH) Particle Therapy

Research efforts in FLASH radiotherapy (FLASH-RT) have increased at an accelerated pace recently. FLASH-RT involves ultra-high dose rates and has been shown to reduce toxicity to normal tissue while maintaining tumor response in preclinical studies when compared to conventional dose rate radiotherapy. The goal of this review is to summarize the studies performed to date with proton, electron, and heavy-ion FLASH-RT, with particular emphasis on the physical aspects of each study and the advantages and disadvantages of each modality. Beam delivery parameters, experimental setup, and the dosimetry tools used are described for each FLASH modality. In addition, modeling efforts and treatment planning for FLASH-RT are discussed along with potential drawbacks when translated into the clinical setting. The final section concludes with further questions that have yet to be answered before safe clinical implementation of FLASH-RT.