A DOI-Dependent Extended Energy Window Method to Control Balance of Scatter and True Events.

In a conventional PET scanner, coincidence events are limited by an energy window for detection of photoelectric events. In contrast, Compton scatter events are occurred both in patient and crystal. Scatter within patient causes scatter coincidence, but scatter with crystal has useful information of activity distribution. The PET scanner with extended energy window has higher sensitivity but higher scatter fraction than the PET scanner with default energy window. In this work, we develop scatter reduction method using depth-of-interaction (DOI) detector. DOI detector can make upper layer as absorber of patient scatter for lower layer. Therefore, crystal scatter with interacted lower layer have a potential to discriminate to patient scatter. This method has the different energy windows for each layer. The energy window of upper layer is limited the region of photoelectric events. The energy window of lower layer is extended the region of crystal scatter and photoelectric events. We applied the proposal technique for whole-body PET scanner using GATE simulation. DOI-PET scanner can be increased extra true events keeping low scatter fraction using this scatter reduction method. This method promises high image quality using DOI information and energy information from simulation results.IEEE 2007 Nuclear Science Symposium and Medical Imaging Conferenc