1. A medical imaging system comprising: non-invasive examination means for examining a subject and producing electrical signals indicative thereof, the examination means having a plurality of adjustable operating parameters; an image reconstructing means for reconstrucing an image from the electrical signals, the image being described by a plurality of performance indices which are related to the operating parameters by a preselected mathematical model, each performance index having a preselected idal value which ideal values are unattainable for all performance indices simultaneously, the image reconstruction means being operatively connected with the examination means to receive the electrical signals therefrom; a performance index means for calculating selected relative priorities for optimizing each performance index value from received clinical information on the subject and an intended diagnostic application for the image; an optimizing means for optimizing conformity of the performance index values predicted by the mathematical model and the ideal values in accordance with the relative priorities and providing an output of corresponding operating parameter adjustments, the optimizing means being operatively connected with the performance index means for receiving the priorities therefrom and with the examination means for supplying the operating parameter ajustments thereto.