This thesis studies the user-oriented design and development lifecycle of a medical image retrieval system. It investigates the user information needs of a target user group in Radiology. These needs are translated into requirements and specifications of a system that could assist radiologists to gain easy and quick access to medical information found in the open access literature and the internal hospital databases. The development of Parallel Distributed Image Search Engine is described and its architecture and applications are presented. The system is evaluated both empirically on the widely used ImageCLEF medical test challenge and on user tests with real users to assess its usability.