The systems and methods described herein measure a collected energy signal from a first pixel of a radiation pixelated detector during at least one event, and measure adjacent energy signals from at least two pixels adjacent to the first pixel of the radiation pixelated detector during the at least one event. The systems and methods generate a first spectrum based on the collected energy signal of the at least one event within an energy window. The energy window is a predetermined energy range for medical imaging. The systems and methods determine a delta charge based on the collected energy signal and the adjacent energy signals generated during the at least one event, generate a second spectrum based on the delta charge of the at least one event outside the energy window, and stretch the second spectrum to combine with the first spectrum to form a corrected energy spectrum.