Novel ion imaging concept based on time-of-flight measurements with low gain avalanche detectors

Abstract Treatment planning in ion beam therapy requires accurate knowledge of the relative stopping power (RSP) distribution within patient. Currently, RSP maps are obtained via conventional x-ray computed tomography (CT) by converting measured attenuation coefficients photons into values for ions. Alternatively, to avoid conversion errors that inherent this method, (iCT) can be used since it allows determining directly. In typical iCT systems, which usually consist a tracking system and separate residual energy detector, is measuring particle trajectory corresponding water equivalent path length (WEPL) single ions travelling through work, we explore novel approach does not require detector. Instead, WEPL estimated indirectly change time flight (TOF) due loss along ion’s path. For purpose, have created Geant4 model TOF-iCT based on low gain avalanche detectors (LGADs), fast 4D-tracking measure arrival position individual particles with high spatial precision. To assess performance concept, determined resolution accuracy different settings using Catphan ® CTP404 sensitometry phantom. Within set investigated parameters, lower limit was found at 0.91%, demonstrating proof-of-principle concept. The main advantage could potentially facilitate clinical integration its compact design, which, however, experimental verification an improvement current calibration procedure.