This book is about the development of a tool by using Matlab module "Image Processing Toolkit". A rule based system has been proposed to aid the physicians in the diagnosis of thyroid abnormalities. This system is intended just to facilitate the physicians not replace them. The major contributions of this research are: A methodology to automatically diagnose of cold and hot spots nodules has been proposed. The size of lobes on the scan is calculated. The location of the nodule is determined; the location is given in terms of lobes. This book also give deep insight into methodology of how to develop any kind of application in Matlab. Dr Asma Haque and Muhammad Ali provides me excellent assistance and technical guidance for the completion of this work.