In silico evaluation of the potential of very high energy electrons delivered in both conventional and FLASH regimes for the SBRT treatment of pancreatic cancer: A report of three case studies

Background and purpose: As the incidence and mortality rates of pancreatic cancer continue to rise, the search for effective treatments is becoming increasingly urgent. Among the therapeutic approaches, highly hypofractionated stereotactic treatments are being explored. This paper explores the potential of Very High Energy Electrons (VHEE) in the range of 80-130 MeV, in light of recent advances in compact accelerator technology and its compatibility with ultra-high dose rate (UHDR) delivery. Materials and methods: Using dose-volume histograms and dose maps, we compared VHEE treatment plans simulated and optimized assuming both conventional and UHDR delivery scenarios against state-of-the-art volumetric modulated arc therapy (VMAT) treatment plans that were used to treat three patients. Dose maps have been obtained assuming an IMRT-like geometry. The implemented VHEE beam model assumes a C-band compact accelerating technology. Results show that electrons below 130 MeV have a clear potential for the effective treatment of pancreatic cancer, even if delivered in conventional conditions. UHDR delivery has been explored evaluating the gain that the FLASH effect could provide in terms of dose escalation to the PTV while constraining the maximum allowed biological dose to the duodenum. Conclusion: The obtained results demonstrate the suitability of VHEE for pancreatic cancer treatment with optimized plans that are clinically acceptable even without considering the additional sparing from the FLASH effect. Their suitability for being delivered at FLASH rates makes them an excellent candidate for the future of external beam radiotherapy.