Proton therapy requires range verification in order to exploit its full potential. One of the most promising approaches is to monitor prompt gamma-rays produced by nuclear interactions of the therapeutic particles in the patient tissues. In our paper, we test PETsys electronics with a detector with a wide energy range from 100 keV to 15 MeV. We tested what time resolution we could achieve as a high time resolution is required to achieve millimetric precision in the proton range. PETsys should survive high count rates and the fraction of pile-up events should be low or separatable. We are investigating a full acceptance approach with increased granularity in order to reduce the size of the scintillators and consequently the count rate per channel. Ideally, we want to stack the scintillators in matrices that require suitable multi-channel photo-multipliers and a fitting acquisition system. Here, we present two geometries of CeBr3 crystals 5 × 5 × 20 mm3 and 10 × 10 × 30 mm3, together with modern silicon photo-multipliers (SiPM) adapted to work with the PETsys TOFPET2 ASIC. The TOFPET2 ASIC was developed for Time-of-Flight Positron Emission Tomography (TOF-PET) applications. Here are our data measured for the publication for time resolution and coincidence time resolution, energy resolution with AmBe source, and dead time studies.