Positron Emission Tomography (PET) is a functional imaging modality used in brain research to map in lively neurotransmitter and receptor activity and to investigate glucose utilization or blood flow patterns both in healthy and disease states. We are developing a Double-sector PET (DPET) system, which is employed as a tumor imaging detector for the heavy-ion therapy at Institute of Modern Physics (IMP). Positron Emission Tomography (PET) is a functional imaging modality used in brain research to map in lively neurotransmitter and receptor activity and to investigate glucose utilization or blood flow patterns both in healthy and disease states. We are developing a Double-sector PET (DPET) system, which is employed as a tumor imaging detector for the heavy-ion therapy at Institute of Modern Physics (IMP).