To improve multi-pinhole single photon emission computed tomography (SPECT) devices we are developing a high-resolution gamma detector consisting of a 3-mm-thick scintillation crystal that converts gamma photons to light, on top of an optically coupled high-resolution, high-sensitivity light sensor (EMCCD). This gamma camera can detect individual gamma interactions with 160 ?m FWHM accuracy and 49% FWHM energy resolution for 99mTc. However, the monolithic nature of the crystal results in large light spread on the sensor, increasing the relative influence of the sensor noise and degrading the performance. The inclusion of silicon photomultipliers (SiPMs) on the sides of the crystal provides additional information on the interactions in the scintillation crystal. This considerably improves the performance of our gamma camera, particularly reducing the background of falsely detected events. The application of the side detectors furthermore expands the detection capabilities of the gamma camera to include low-energy 125I gamma photons.