The Fourth Edition of Dr. Gopal B. Saha Physics and Radiobiology of Nuclear Medicine was prompted by the need to provide up-to-date information to keep pace with the perpetual growth and improvement in the instrumentation and techniques employed in nuclear medicine since the last edition published in 2006. Like previous editions, the book is intended for radiology and nuclear medicine residents to prepare for the American Board of Nuclear Medicine, American Board of Radiology, and American Board of Science in Nuclear Medicine examinations, all of which require a strong physics background. Additionally, the book will serve as a textbook on nuclear medicine physics for nuclear medicine technologists taking the Nuclear Medicine Technology Certification Board examination. The Fourth Edition includes new or expanded sections and information for: * PET/MR, including the attenuation correction method and its quality control tests; * accreditation of nuclear medicine and PET facilities; * solid state digital cameras; * time of flight and scatter correction techniques; * CT scanners and attenuation correction in SPECT/CT; * partial volume effects; * quality control of CT scanners; * ion chamber survey meters, proportional counters, and G-M counters.