Rachel A. Powsner, MD, is Head of the Nuclear Medicine Section at the Veterans Administration Boston Healthcare System, and an Associate Professor of Radiology at Boston University. She is a practicing nuclear medicine physician, radiology faculty member at Boston University, and an author of the first two editions of this text. Matthew R. Palmer, PhD, is the Nuclear Medicine Physicist at the Beth Israel Deaconess Medical Center and Assistant Professor of Radiology at Harvard Medical School in Boston, where he teaches in the nuclear medicine residency training program. Dr. Palmer is a welcome addition to the author team for the third edition of this book. Edward R. Powsner, MD, is Former Chief of the Nuclear Medicine Service at the Veterans Administration Hospital in Ann Arbor, Michigan, where he is also Emeritus Professor and Associate Chairman, Department of Pathology, at Michigan State University. He is Former Chair of the Joint Review Committee for Educational Nuclear Medicine Technology and was a member of the American Board of Nuclear Medicine.