Ricerc@Sapienza

Cancer is one of the leading causes of death worldwide. Several therapies are adopted for its treatment, with photon radiotherapy (RT) generally being the preferred option. Surgery, chemotherapy and conventional radiotherapy can in fact intervene in 65% of cancer cases, but leave a significant number of patients with untreatable tumours such as radio-resistant tumours. So far, apart from photons, only protons have been implemented as an alternative radiotherapy for such tumours. The use of very high energy electron beams (VHEE) (100-200 MeV) has been suggested in the literature, but the required accelerators are bulkier and more expensive than standard photon devices, with only limited advantages over protons or other heavy ions. The VHEE treatment planning system combining accurate Monte Carlo (MC) simulation with simple modelling of the FLASH effect (sparing healthy tissue at very high doses) compared with conventional RT show that FLASH therapy with VHEE beams of 70-130 MeV could be a viable alternative to standard RT, allowing better sparing of healthy tissue surrounding the tumour, within the framework of an affordable technological development. The first results obtained with a preliminary device are encouraging, and a new prototype is about to be tested. The final goal is the construction of a Treatment Planning System (TPS) capable of optimising the beam intensity and spatial distribution of small radiation fields in the FLASH regime by evaluating the best instantaneous intensity of a typical Flash pulse with a spatial resolution of ~ mm. Evaluations will be performed comparing treatment plans for conventional RT with VHEE FLASH treatment plans.