Impact of instrumentation parameters on the performance of neural network based positioning algorithms for monolithic scintillator blocks

The information embedded in the light distribution generated in monolithic scintillator blocks allows the incidence position of an impinging 511 keV gamma to be estimated with an average resolution of 1.8 mm FWHM. To study which instrumentation parameters limit the performance, a validated Monte Carlo simulation was used. It was concluded that the preamplifier noise of 600 electrons rms was the most limiting factor since all other parameters in the set-up such as a photon beam width of 1 mm FWHM, beam step size of 250 mum and an ADC resolution of 12 bits are already at an optimal level. The indiscernible presence of events that undergo multiple interactions in the scintillator block also adds 0.2 mm to the achievable FWHM resolution.