Fig 2.

Flow diagram for iRENEX. This diagram shows the flow depicting how a renal scan is acquired, processed, and quantified to extract parameters of renal function and how these parameters are converted to certainty factors that are then input to the expert system. iRENEX contains a library to translate parameter values to certainty factors, a knowledge base with 116 heuristic interpretation rules, a forward chaining inference engine to determine obstruction and a justification engine which records the sequence of each rule that is fired and the current certanity factor value of all input and output parameters at the time of instantiation in order to track and justify the logic of the conclusions. The trapezoidal blocks indicate domain expert; the rectangular blocks indicate software algorithms.