A thesis submitted to the faculty of Engineering, University of the Witwatersrand, Johannesburg , in fulfillment of the requirements for the degree of Doctor of Philosophy. Johannesburg, November 1994 / Organ function is often characterised using imaging techniques. In particular a tracer is often used which does not react with tissue, is low in concentration, follows body fluid flows and is distinguishable from the observed system and thus measurable. These requirements ensure linear characteristics of the tracer. In this thesis, these linear characteristics are used to develop a generalised mathematical theory to determine organ function from imaged tracer experiments. The theory is based on anatomical and physiological information for single and multiple input organs. [Abbreviated Abstract. Open document to view full version] / MT2018