A pixellated CdZnTe detection system has been designed and fabricated.By using the 2×2 pixellated detector,the 59.5 keV gamma spectra has been gotten based on the 241Am source,the highest energy resolution is 14.6%,and the spectrum of the corner pixel has a little drift to the low energy region.In order to optimize radiation imaging,the data from the testing is investigated and analyzed.It shows that the uniformity of electric field within the crystal is the major reason making the differences a...