SiCNeutronFlash · Out-of-field neutron dosimetry for FLASH therapy based on SiC sensors

Out-of-field neutron dosimetry for FLASH therapy based on SiC sensors

Cancer represents one of the most significant public health challenges worldwide. A large proportion of patients will require radiotherapy at some point during their treatment, making this modality a cornerstone of modern oncology. In recent years, a novel approach known as ultra-high dose-rate radiotherapy (UHDR), also referred to as FLASH therapy, has emerged as a highly promising innovation. FLASH therapy delivers radiation doses several orders of magnitude faster than conventional radiotherapy, while maintaining equivalent or improved tumor control and significantly reducing damage to surrounding healthy tissues. This is called “FLASH effect” has the potential to overcome current dose-limiting toxicities and to open a new paradigm in cancer treatment. Following encouraging preclinical results, major technological efforts are underway to translate FLASH therapy into clinical practice. One of the most important is the development of reliable dosimetry and monitoring systems capable of operating accurately under ultra-high dose-rate and ultra-short pulse conditions, where conventional radiation detectors fail or suffer from severe limitations. An additional and largely unexplored challenge concerns the production of secondary radiation, particularly neutrons, during high-energy radiotherapy treatments. In conventional radiotherapy, secondary neutrons generated by particle interactions can scatter far from the treatment field, delivering unwanted doses to healthy tissues and sensitive organs. In FLASH therapy, the extremely high dose per pulse introduces new uncertainties regarding neutron production, detector response, and dose quantification. At present, the measurement and characterization of out-of-field neutron doses under FLASH conditions remain largely unaddressed, representing a critical knowledge gap for patient safety and risk assessment. The overall objective of this project is to address this gap by developing and validating a new generation of active neutron detectors specifically designed for use in FLASH radiotherapy and other ultra-high dose-rate radiation environments. The project builds on recent advances in solid-state radiation detector technology based on silicon carbide (SiC), a material with a high radiation hardness, low noise, thermal stability, and improved tissue equivalence compared to conventional silicon. These characteristics make SiC particularly well suited for operation in extreme radiation conditions where traditional detectors are inadequate. The first main objective of the project is the development of a novel matrix of SiC-based neutron detectors capable of measuring out-of-field neutron fluxes in FLASH facilities and mixed radiation fields. This has been achieved by optimizing SiC diodes combined with tailored neutron conversion/moderation layers, enabling high gamma rejection and enhanced sensitivity to a wide range of neutron energies. The second main objective is the experimental validation of these detectors in representative radiation environments, including reference neutron fields, mixed radiation beams, and pulsed neutron sources, to demonstrate their performance, reliability, and suitability for ultra-high dose-rate applications. By delivering the first active neutron monitoring system adapted to FLASH radiotherapy conditions, this project is expected to make a significant contribution to the safe clinical implementation of this emerging treatment modality.

Data: CORDIS, © European Union