The Postgraduate Program in Radiological Science provides recent doctoral graduates in physics, chemistry, engineering, and mathematics with additional training and experience in the field of radiological science. Physicians and scientists from other disciplines, who have well-developed, appropriate career goals may also apply. The rationale for this program is based on several factors: 1) the growing need for basic scientists with training in functional and multi-modality imaging;2) the availability of high quality research programs that can provide exciting opportunities for research fellows;3) the availability of modern well-equipped facilities;4) the availability of an unusually strong group of preceptors and, in addition, a faculty who provide additional expertise and extend the range of contacts available to fellows in the program;5) the existence of long-standing, diverse collaborations, both within the MGH and with investigators at Harvard Medical School, Harvard University, and other HMS-affiliated hospitals;and 6) the availability of the resources of the Department of Radiology and those of the academic and medical community of the greater Boston area. The program is designed to provide a two-year training experience and includes courses, tutorials and participation in research seminars and laboratory meetings, in addition to active participation in research projects. Individual training programs are created for each fellow based on his/her interest and abilities, the availability of suitable preceptors and research funding. Training is conducted in the environment of a major medical center whose physical setting, intellectual resources and research activities provide an exciting milieu for scientists in training. Research opportunities currently exist in the areas of positron emission tomography (PET), molecular imaging, and cardiac imaging combining PET and other modalities, e.g. MRI, and/or CT.