Presently, the gamma scintillation camera is widely used in various industrial, environmental and medical diagnostic fields. Hence, the objective and quantitative evaluation of its imaging performance is required for imaging quality assurance and excessive exposures prevention. In this study, the detective quantum efficiency (DQE) of a small gamma camera with three pinholes (1, 2, and 4 mm in hole diameter) and one-coded aperture (uniformly redundant array (URA); 286 holes, hole diameter 2 mm) collimator was determined using modulation transfer function (MTF), normalized noise power spectrum (NNPS), and incoming signal-to-noise ratio (SNR). We found that the resolution of URA was a little lower than that of the pinhole, 2 mm in hole diameter, and the noise of URA was prominently lower than that of all pinholes. Thus, the DQE of URA was higher than that of the pinhole. We found that the determination of DQE could be a quantitative and effective method to evaluate gamma camera systems performances. (C) 2008 Elsevier B.V. All rights reserved.