Development of a VHEE accelerator in Sapienza for the treatment of deep seated tumors: planning and radioprotection challenges of a FLASH compact machine

Cancer treatment continues to be a major challenge in modern medicine, necessitating innovative therapies that enhance efficacy while minimizing side effects. Radiotherapy has evolved from conventional X-rays to advanced particle therapies, yet limitations persist that impact both therapeutic outcomes and patient quality of life. Very High Energy Electrons (VHEE) have emerged as a promising alternative for deep-seated tumor treatment, but technical challenges have historically hindered their clinical adoption. Recent advancements in accelerator technology, particularly compact high-gradient LINACs operating in the C-band and X-band, along with the discovery of the FLASH effect—where ultra-high dose rate irradiation significantly reduces healthy tissue toxicity—have renewed interest in VHEE therapy. The SAFEST project (SApienza Flash Electron Source for radio-Therapy) at Sapienza University of Rome aims to develop a hospital-compatible compact LINAC capable of generating VHEE beams at FLASH intensities, paving the way for clinical trials. This Ph.D. research focuses on the development of a dedicated Treatment Planning System (TPS) for VHEE therapy, with a particular emphasis on optimizing treatments in FLASH mode. The research encompasses a comprehensive analysis of VHEE radiotherapy, including dosimetric evaluations, beam dynamics, and treatment optimization strategies for different tumor types, such as intracranial lesions and pancreatic cancer. Additionally, the study addresses key radioprotection challenges, proposing shielding solutions to ensure the safe clinical implementation of VHEE LINACs. By leveraging cutting-edge computational tools and optimization algorithms, this work contributes to the establishment of VHEE as a viable clinical alternative to conventional radiotherapy and particle therapy. The results suggest that, under certain conditions, VHEE could enable dose escalation at the target volume while preserving healthy tissue integrity, reinforcing its potential as a transformative approach in cancer treatment.