Toward the use of Silicon Carbide based detector for protontherapy microdosimetry

This study explores the potential of a Silicon Carbide (SiC)-based microdosimeter for use in proton therapy. Thanks to its high radiation hardness, minimal leakage current, and stable charge collection efficiency, SiC is proposed as an innovative solid-state material for measuring microdosimetric quantities and enhancing radiobiological modeling in hadrontherapy.

A custom SiC p-n junction diode with a 10 μm epitaxial layer was fabricated and electrically characterized. Microdosimetric spectra were acquired under proton beams at 30, 70, and 150 MeV at various depths in water. The SiC detector's performance was compared with benchmark microdosimeters, including a silicon-based MicroPlus probe and a single-crystal diamond device. Monte Carlo simulations were used to determine the water-equivalent thickness and to validate the measured spectra. Key microdosimetric quantities, such as frequency-mean and dose-mean lineal energy, were extracted and used to estimate the relative biological effectiveness (RBE) via the Microdosimetric Kinetic Model (MKM).

The SiC detector demonstrated full charge collection efficiency and an energy resolution of approximately 2% under alpha irradiation. The measured spectra showed depth-dependent trends consistent with LET variations. The microdosimetric parameters derived from SiC data were in good agreement with both reference detectors and simulations. RBE values estimated from SiC measurements accurately reflected experimental data for U87 glioblastoma cells.

SiC-based detectors prove to be promising tools for microdosimetry in proton therapy. The consistency with reference systems and simulations supports their use in RBE estimation and biologically optimized treatment planning. Future work will target further miniaturization and application to heavier ions.