Abstract Body

FLASH radiation has emerged as a potential game changer in radiation oncology. Preclinical data has shown electrons, protons, and photons are all capable of being delivered at FLASH dose rates (>40 Gy / sec). Each of these modalities have shown normal tissue sparing while comparable tumor control rates for a variety of targets. However, electrons are limited by the superficial nature of the treatment or loss of tissue sparing when higher energies are utilized. Current linear accelerators in the clinic cannot deliver FLASH dose rates with photons and clinical units are likely many years away. Clinical application of FLASH radiation will likely be first seen on a broad scale with protons; accelerators in the clinic today can reach FLASH dose rates and protons have the ability to treat deep seated tumors commonly seen in the adult population. The mechanism of action of FLASH radiation has yet to be fully elucidated although there are numerous hypotheses. However, preclinical studies with protons have shown sparing of the stem cells and stem cell compartment in a number of organ systems. Vendors are investing heavily in proton technology to bring clinical trials to rapid fruition. Significant investigation continues to define the FLASH effect, understand the mechanism of action, and mature the technology to deliver the best possible treatment. This presentation will review the state of the art data and assess where clinical use of FLASH radiation may be defined. It will also discuss the design and implementation of clinical trials to delineate the future of FLASH in the patient setting.