THE USE OF TEST PHANTOMS IN KNOWLEDGE-BASED SYSTEMS FOR DIAGNOSING MALFUNCTIONS OF THE RADIOLOGICAL EQUIPMENT

A prototype of an expert system for diagnosing malfunctions of the mam mographic system during the routine use of a common phantom (Leeds TOR [MAX]) has been developed. The knowledge concerning malfunctions and t heir manifestations is organised in frames. Malfunctions are described by means of the expected deviations of the phantom observables from t he baseline values. Diagnoses are produced by relating observed data o f the phantom to a pre-enumerated set of possible malfunctions. Phanto m observables do not seem very sensitive to changes of the system from the baseline conditions, caused by malfunctions. However, where the e ffects of a malfunction exceed the lower limit of detection of an obse rvable, the ability of a phantom to discriminate between different mal functions (the diagnostic power) can be evaluated with a cluster analy sis of the prototypical descriptions of the malfunctions.