A control systems approach for the simulation of renal dynamic software phantoms for nuclear medicine.

For renal dynamic studies, the COST B2 hybrid phantom is an example of an artificially created software phantom. Although this phantom is useful, it is not possible to implement the phantom in a self-consistent fashion to produce, for example, a collection of tracer in the bladder which is related to the flow from the kidneys. In this study control systems are used to provide a self-consistent model. A feed-forward control system was designed for the transport of DTPA in the human body using SIMULINK. The system is based on a three-compartment model described by a set of differential equations with flow rates which may be set by the operator. The differential uptake in the kidneys may also be specified, while the flow of tracer through the renal parenchyma and collecting system of each kidney is determined using two-parameter retention functions. Curves corresponding to normal or pathological conditions may be simulated for plasma, parenchyma, collecting system and bladder by appropriate selection of parameters. The system is user-friendly and can be used to simulate almost all conditions seen in patient studies. The next stage of using this information to design dynamic image simulations is in progress.