An iterative method for the determination of the start and end of the tracer flow through a compartment was developed and used to create a digital image of the compartment of interest. This digital image was then used to select a region-of-interest corresponding to a selected compartment. Dynamic curves were corrected for background, dead time, and for possible overlapping of different physiological compartments. The shape of the corrected curves was then compared with expected behavior of the tracer in a compartment. On the basis of the physiological considerations, mathematical models are developed. Once the mathematical model is developed, the experimental data is used as suggested by the model. We applied these general considerations to the studies of the heart, lungs, kidneys and hepatobiliary system.