Radiobiology of high doses per fraction: knowledge in 2020 and new preclinical models

Stereotactic body radiation therapy results from technical advances in dose delivery, via imaging optimization, accuracy in patients positioning and in beam geometry modulation. Ballistic accuracy ensures precise conformation to the tumor volume, reducing margins and thus minimizing the volume of exposed healthy tissues and treatment-related toxicity. The reduction of exposed volume allows the use of high doses per fraction and is associated with an excellent tumor control, especially for early stage inoperable non-small cell lung cancer. The possibility to use high doses per fraction considerably changed fractionation schedules, thus impacting tumors and healthy tissues response to radiation exposure and more globally tissue radiation biology. These new therapeutic modalities necessitate the optimization of preclinical models. Thanks to technical progress once again, it is possible nowadays to model stereotactic radiation exposure in rodents. These new models will allow the apprehension of tumor and healthy tissues response to such new modalities of radiation exposure. (authors)