A system includes a detector and a processing module. The detector includes pixels configured to detect an event corresponding to energy from a radiopharmaceutical. The processing module is configured to receive a request for each pixel that detects energy during a reading cycle. The processing module is configured to determine an energy level for each requesting pixel. For each requesting pixel, the processing module is configured to count the event when the energy level corresponds to an energy of the radiopharmaceutical, and to determine a combined energy level of the pixel and at least one adjacent pixel when the energy level does not correspond. The processing module is configured to count the event when the combined energy level corresponds to the energy of the radiopharmaceutical, and to disregard the event when the combined energy level does not correspond to the energy of the radiopharmaceutical.