This work is aimed to assess the feasibility of a gamma-ray scintillation detector for radionuclide imaging characterized by good energy resolution and point-of-interaction measurement at room temperature. To obtain such performances the single-event scintillation light must be read from more than one crystal face. We have preliminarily analyzed the energy response using CsI:Tl crystals and Si-APD. Results concerning energy response are presented in terms of linearity and resolution. The single-APD configuration, chosen as a reference, has shown very good energy linearity in the range 80–662 keV and a 7.6% FWHM energy resolution at 662 keV. Similar linearity results have been obtained for the 5-APD case, while energy resolution worsens down to 13.2% FWHM. These results could be further improved using APD with reduced peripheral dead zones.