Range monitoring capabilities with the SiFi-CC detector : spectral-spatial imaging with Monte Carlo-simulated data

The SiFi-CC group is developing a scintillating-fiber-based Compton camera for high-efficiency gamma-ray imaging, specifically tailored for online range verification in particle therapy. After thorough optimization studies, including the development of neural-network approaches for event selection, the capability of the prototype for detecting range deviations is being studied by using realistic Monte Carlo simulations. We have implemented a spectral-spatial reconstruction based on the LM-MLEM algorithm and spectral analytical models for the system matrix and the sensitivity. In this work, we show the reconstructed images obtained from the irradiation of PMMA phantoms with 4 $\times$ 10$^{9}$ protons at therapeutic energies. The results show the capability of the SiFi-CC detector prototype to recover the 4.44 MeV prompt-gamma line and to detect 5 mm Bragg peak shifts.