The homeland security nuclear/radiological threat, accentuates the need for a Spectroscopy Personal Radiation Detector (SPRD). The CsI(Tl) capacity to discriminate the energy-lines of a gamma-radiation source along side with robust nature, makes these detectors suitable for isotope identification under harsh environmental conditions. However the CsI(Tl) detectors are also known for the temperature dependence of their response presenting itself in varying pulse time constant and crystal light yield. When observing a detection system as a whole this dependence appears as spectrum gain shift. For a radioisotope identification device it is paramount to correctly evaluate and compensate for any variation in spectrum parameters that may result in a faulty identification result. This work presents a theoretical analysis along side its practical application aiming at handling temperature transients. Step by step method for constructing a comprehensive scintillation detector temperature gain compensation schema will be presented and an application example will be demonstrated. Experimental lab work combined with digital signal processing techniques, including system identification and digital filtering methods are being used throughout this work and implemented for the solution of the real life problem of scintillation detector temperature gain compensation.