Improvement of detection efficiency in coincidence data acquisition with CdTe detector

Describes a new method to improve the sensitivity of a CdTe detector for coincidence imaging. The problem in the use of the semiconductor detector is low sensitivity for high-energy photons such as 511 keV photons. To increase the number of events we record the time, location and energy of an event whose energy ranges from 166 keV to 350 keV. The event list is then checked to see if the succeeding two events occur at almost the same time and if the sum of the energy for these two events is nearly equal to 511 keV and if the locations of these two events are in neighboring detector elements. If the above conditions are satisfied we consider these two events as a single event. Because most of the photons that are scattered once in the semiconductor detector loss their energy in the detector elements next to the detector element in which an incident photon is scattered, we can treat these scattered photons just like primary photons. The results of Monte Carlo simulations showed that the proposed method increased the sensitivity by a factor of 1.48 compared with the detection of 511 keV photons with a single energy window