A system of four 5phix5 in. cylindrical NaI (TI) is required for the study of regional deposition and lung clearance of inhaled γ emitting aerosol contaminants. Each of the four detectors is coupled to a collimation system of rectangular opening to achieve uniformity in response across the lung volume. The uniformity in response can be adjusted to any equired degree for the different γ ray energies by displacement of the detectors relative to the fixed collimation system. The parameters of the system are optimized by a computational study based on the theoretical evaluation of detection efficiency and response. The measured response of the system for a 137Cs point source at different positions of the assumed lung model is presented. The detection limits of the system with lead collimators of 4 cm wall thickness range from 6 to 17 nCi depending on photon energy and can be improved by additional shielding.