Computer Aided Diagnosis (CAD) is rapidly entering the radiology mainstream. Computer Aided Diagnosis systems evaluate the conspicuous structures. It has been used in clinical environments for over 40 years, CAD cannot and may not substitute the doctor, but rather plays a supporting role. The doctor (generally a radiologist) is always responsible for the final interpretation of a medical image. It is fundamentally based on highly complex pattern recognition. X-ray images are scanned for suspicious structures. Normally a few thousand images are required to optimize the algorithm.