[en] In SPECT, an image representing a distributed in vivo radioisotope is reconstructed from a set of noisy projection images. Every reconstruction algorithm must use some model for the response of the gamma camera to emitted γ-rays. The true camera response is both spatially variant and object dependent. These two properties result from a number of complex factors which forestall determination of the true response with any real accuracy. In this paper, the authors examine two models for the camera response: a 1-D camera response consisting of perfect collimation with attenuation, and a 3-D depth dependent camera response which accounts for septal penetration, scattering, and attenuation. Where the noisy projection images are acquired by a 3-D camera response function, the authors compare the performance of filtered backprojection, maximum likelihood, and a Bayesian reconstruction method, the GEM MAP algorithm, using both a 1-D and a 3-D camera response function