In this study we present the initial results for the construction and the evaluation of a small field of view gamma ray detector based on a R8900U-00-C12 position sensitive photomultiplier tube (PSPMT) coupled to a 2x2 LuAG:Pr scintillator array with 5x5x5mm3 crystal size elements. We have used a resistor network readout circuit, reducing the 6X and 6Y photomultiplier anode signals to 4 position signals (Xa, Xb, Yc and Yd). A Field Programmable Gate Array (FPGA) Spartan 6 LX16 was used for triggering and signal processing of the signal pulses acquired using a free running sampling technique. We have obtained raw images and energy histograms, under various gamma ray energies irradiation. Energy resolution and linearity of the detector response under various gamma ray energies ranging from 81 to 1332.5 keV were measured. The system presented an excellent performance in terms of energy resolution, measured 9.3%@511KeV and 8.5%@662keV.