Book excerpt: Written to assist the implementation in medical imaging practice of the requirements of the IAEA Safety Standards Series No. GSR Part 3, Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, this publication provides consolidated information and detailed advice for setting and implementing patient radiation exposure monitoring programmes at the local or national level. In medical imaging using ionizing radiation, including X ray diagnostic radiology, diagnostic nuclear medicine and image guided interventional procedures, radiation protection of patients is achieved by selecting the most appropriate imaging procedure for the individual needs of the patient and by keeping exposure to the minimum necessary to achieve the diagnostic and interventional objective. Monitoring of radiation exposure of patients provides critical information for health care professionals and authorities who are responsible for ensuring justified and optimized use of radiation in medicine. This Safety Report provides guidance on recording, collecting and analysing relevant patient exposure data by using manual or automatic means. An aim of the publication is to encourage the future use and development of automatic digital systems to improve access to information about patient radiation exposure and thus contribute to improved implementation of the requirements for radiation protection of patients throughout the world.