The book covers all the radiation safety aspects while working with unsealed radionuclides. Radiation safety plays a significant role in routine nuclear medicine practices and is necessary to protect occupational workers, patients, members of the general public and the environment. A fair knowledge of radiation safety is expected from all nuclear medicine professionals. Chapters include basics of radiation physics, biological bases of radiation protection, planning and design of nuclear medicine facilities, cyclotron and high dose therapy facilities, radiation safety considerations in nuclear medicine, cyclotron while preparing radiopharmaceuticals. It also includes the working mechanism of radiation detectors, quality assurance of positron emission tomography (PET) and gamma camera, including single photon emission computed tomography (SPECT), emergency preparedness plan, nuclear medicine and CT dosimetry, transport regulations, the role of national regulatory authorities and radioactive waste management. The last chapter provides probable model questions asked in the radiological safety officer certification examination and includes 250 multiple-choice questions (MCQs), 100 true or false, 60 fill in the blanks, and 40 match the following questions. The book is written in a simple language for a better understanding of the occupational workers of any grade. It serves as reference material for nuclear medicine professionals on radiation safety, related to planning, quality assurance, dosimetry and various regulations pertaining to nuclear medicine. It is a ready reckoner for the students pursuing a degree/diploma in nuclear medicine and preparing for certification courses in radiation safety to understand the subject matter along with options to attempt practice questions.