BIORT: An experiment for the assessment of the biological effects of very high dose rate and dose per pulse electron irradiations

Intra Operative Radiation Therapy (IORT) is a treatment modality combining surgery and radiation therapy in which a large single dose of radiation is delivered at the time of an operation for tumour resection. During last years, IORT has become a widespread technique in clinical routine. This was possible thanks to the recent development of small dedicated electron accelerators which overcome all the disadvantages concerning both organizational and radiation protection issues related to the use of conventional Linacs during a surgical operation. However the very high dose per pulse and dose rates delivered by the this new modality (i.e. respectively about 100 and 20 times greater than that of a conventional radiation therapy) open new problems related to dosimetry and radiobiology. For these very reasons we proposed the experiment "radioBiology of IORT" (BIORT) to INFN, aiming at determining biological effectiveness of the very peculiar IORT beams (electrons delivered at very high dose rate, high dose per pulse and a total dose delivered in a single fraction).