This paper reports a simple model for calculation of maximal scintiphoto contrast caused by a spherical cold or hot lesion located in an arbitrary position inside an organ with uniformly distributed radioactivity. By applying this model, equidetection curves were constructed for cross sections through the liver. Comparison of equidetection curves obtained for different camera views enabled determination of the view to be selected for the best visualization of a given lesion. The minimum size of a cold lesion that can be detected without regard to the location in the liver in 3.0 cm diameter using anterior, right oblique anterior, right lateral, and posterior views. 99mTc is found to be a more suitable radionuclide for liver scintigraphy than 113mIn.