The current international requirements related to medical uses of ionizing radiation are established in the Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards (IAEA Safety Standards Series No. GSR Part 3). The full text of the publication in the official IAEA languages is available here.
While dealing with issues pertaining to radiation protection, the following situations could occur:
Such situations emphasize the need for credible international standards that are based on worldwide consensus.
International Standards are a set of requirements agreed on by worldwide consensus, based on the knowledge of biological effects of radiation and on principles for protection from undesirable effects. The findings of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and the recommendations of international expert bodies, notably the International Commission on Radiological Protection (ICRP), are taken into account in developing the IAEA safety standards.
The Standards place requirements on those authorized to conduct a practice using radiation, and are based on the presumption that there is a national infrastructure enabling Governments to discharge their responsibilities for protection and safety. It is this aspect that implicitly makes it necessary for international requirements to be established only by organizations with official status to establish these requirements. Which organizations fit into this slot? The official status accrues to international organization under the United Nation family. The IAEA is specifically authorized by its Member States, under the terms of its Statute to establish standards of safety for the protection of health and minimization of danger to life, in collaboration with the competent organs of the United Nations and the specialized agencies concerned and to provide for the application of these standards. Professional organizations can, however, collaborate and provide advice during the process of establishing and applying Standards.
The Standards have been developed with specific objectives to establish requirements for the protection of people and the environment from harmful effects of ionizing radiation and for the safety of radiation sources. The requirements have the force that is derived from the statutory provisions of the sponsoring organizations and further scope as contained therein.
Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards (IAEA Safety Standards Series No. GSR Part 3) is published in 2014. It is jointly sponsored by the European Commission (EC), the Food and Agriculture Organization of the United Nations (FAO), the IAEA, the International Labour Organization (ILO), the OECD Nuclear Energy Agency (OECD/NEA), the Pan American Health Organization (PAHO), the United Nations Environment Programme (UNEP) and the World Health Organization (WHO).
Medical uses of ionizing radiation involves three categories of exposure [GSR Part 3]
Medical exposure differs from occupational and public exposure in that persons (primarily patients) are deliberately, directly and knowingly exposed to radiation for their benefit. In medical exposure applying a ‘dose limit’ is inappropriate, as it may limit the benefit for the patient; consequently, only two of the radiation protection principles apply – justification and optimization.
The following table summarises the radiation protection principles as applied to medical exposure in comparison with occupational exposure and public exposure:
Application to medical exposure
Application to occupational exposure and public exposure
Justification: The diagnostic or therapeutic benefits of exposure are weighed against the radiation detriment they might cause, with account taken of the benefits and risks of available alternative techniques that do not involve medical exposure.
Justification of practices: Adopting a practice that entails exposure to radiation only if it yields sufficient benefit to the exposed individuals or to society to outweigh the radiation detriment.
Optimization of protection and safety:
In diagnostic and interventional medical exposure, keeping the exposure of patients to the minimum necessary to achieve the required diagnostic or interventional objective.
In therapeutic medical exposure, keeping the exposure of normal tissue as low as reasonably achievable consistent with delivering the required dose to the planning target volume.
Optimization of protection and safety: Providing the best available protection and safety measures under the prevailing circumstances, so that the magnitudes and likelihood of exposures and the numbers of individuals exposed are as low as reasonably achievable, economic and social factors being taken into account.
Limitation of doses: Does not apply to medical exposure.
Limitation of doses: Doses to individuals are limited (for occupational exposure and public exposure).
There is a hierarchy of responsibilities within the framework for safety, from governments to regulatory bodies to the organizations responsible for, and the persons engaged in, activities involving radiation exposure. The government is responsible for the adoption within its national legal system of such legislation, regulations, and standards and measures as may be necessary to fulfil all its national and international obligations effectively [GSR Part 3, Req. 2]. Specifically to medical exposure, the government has the responsibility to ensure that as a result of consultation between the health authority, relevant professional bodies and the regulatory body [GSR Part 3, Req. 34]:
Professional bodies is the collective term used in GSR Part 3 to include the various organizations and groups of health professionals. These include societies, colleges, and associations of health professionals often within a particular specialty. Professional bodies represent the collective expertise of the given health profession and specialty and, as such, they also should play a role in contributing to radiation protection and safety in medical uses of ionizing radiation.
Proactive involvement of the professional bodies in the process of establishing standards and regulations and in their application produces a number of benefits. Not only does it minimize the need for enforcement actions to ensure compliance, but also more importantly, it ensures a better understanding of radiation protection requirements and improves safety for patients. Professionals should be made aware of their responsibilities on the overall patient protection and safety in the referring to and during the delivery of medical exposure. This includes:
The process of justification allows determining whether the medical exposure will take place or not. The goal of justification is to avoid unnecessary radiological procedure, which would result in patient being unnecessary exposed to ionizing radiation and its potential risks.
First, a given radiological procedure shall be justified. This applies to the justification of new technologies and techniques as they evolve. This generic justification shall be carried out by the health authority in conjunction with appropriate professional bodies. [GSR Part 3, para. 3.156].
The justification of medical exposure for an individual patient shall be carried out by means of consultation between the referring medical practitioner (who initiates the request for a radiological procedure) and the radiological medical practitioner (who is responsible for performing a procedure) [GSR Part 3, para. 3.157]. A referral should be regarded as a request for a professional consultation or opinion rather than an instruction or order to perform. The referring medical practitioner brings the knowledge of the medical context and the patient’s history to the decision process, while the radiological medical practitioner has the specialist expertise on the radiological procedure. Therefore, the joint approach is required to justification and shared decision at the level of an individual patient considering:
The process of determining appropriateness of a medical procedure is an evidence based approach to choosing the best test for a given clinical scenario, with account taken of the diagnostic efficacy of the proposed radiological procedure as well as of alternative procedures that do not use ionizing radiation, for example, ultrasound, magnetic resonance imaging (MRI) or endoscopy.
Useful tools to support this decision making process include national or international imaging referral guidelines developed by professional societies. Imaging referral guidelines can be disseminated or utilized through electronic requesting systems and clinical decision support tools or systems. It should be ensured that such systems correctly apply the regulatory requirements for justification, in particular with respect to roles and responsibilities.
In determining the appropriateness of the radiological procedure for an individual patient, the following questions should be asked by the referring medical practitioner:
Justification for radiological procedures to be performed as part of a health screening programme for asymptomatic populations shall be carried out by the health authority in conjunction with appropriate professional bodies [GSR Part 3, Para 3.159].
Any radiological procedure on an asymptomatic individual that is intended to be performed for the early detection of disease, but not as part of an approved health screening programme, shall require specific justification for that individual by the radiological medical practitioner and the referring medical practitioner, in accordance with the guidelines of relevant professional bodies or the health authority. As part of this process, the individual shall be informed in advance of the expected benefits, risks and limitations of the radiological procedure [GSR Part 3, para 3.160].
The medical exposure of volunteers as part of a programme of biomedical research is deemed to be not justified unless [GSR Part 3, para 3.161]:
(a) It is in accordance with the provisions of the Helsinki Declaration  and takes into account the guidelines published by the Council for International Organizations of Medical Sciences , together with the recommendations of the ICRP ; (b) It is subject to approval by an ethics committee (or other institutional body that has been assigned functions similar to those of an ethics committee by the relevant authority), subject to any dose constraints that may be specified, and subject to applicable national regulations and local regulations.
Once justified, the radiological procedure should be optimized and performed such that the exposure of the patient is managed in order to achieve the medical objective. Too low a radiation dose could be as bad as too high a radiation dose, in that the consequence could be that a cancer is not cured or the images taken are not of suitable diagnostic quality. The medical exposure should always lead to the required clinical outcome. Optimization is a prospective and iterative process that requires judgements to be made using both qualitative and quantitative information. The following aspects and tools have to be used to ensure optimization of protection and safety [GSR Part 3, Req. 38]:
Unintended and accidental medical exposures can occur from flaws in design and operational failures of medical radiological equipment, from failures of and errors in software, or as a result of human error. The hospital management has responsibility to ensure that all practicable measures are taken to prevent such exposures, and, if such an exposure does occur, that it is properly investigated and corrective actions are taken [GSR Part 3, Req. 41]. Any of the following unintended or accidental medical exposures shall be promptly investigated and corrective actions implemented:
Because of the medical setting in which medical exposures occur, primary responsibility for radiation protection and safety for patients lies with the health professional responsible for the radiological procedure, who is referred to in GSR Part 3 as the ‘radiological medical practitioner’. The term radiological medical practitioner is the generic term that GSR Part 3 uses to refer to a health professional with specialist education and training in medical uses of radiation, who is competent to perform independently or to oversee procedures involving medical exposure in a given specialty. Health professionals that could take on the role of the radiological medical practitioner, depending on the particular use of radiation and on the laws and regulations in a State, include radiologists, nuclear medicine physicians, radiation oncologists, cardiologists, orthopaedic surgeons, other specialist physicians, dentists, chiropractors and podiatrists.
GSR Part 3 requires involvement of medical physicist who provides specialist expertise with respect to radiation protection of the patient. Medical physicist is a health professional with specialist education and training in the concepts and techniques of applying physics in medicine, and competent to practice independently in one or more of the subfields (specialties) of medical physics (e.g. diagnostic radiology, radiation therapy, nuclear medicine).
The medical physicist has responsibilities in the optimization of radiation protection and safety in medical exposures, including source calibration, clinical dosimetry, image quality and patient dose assessment, and physical aspects of the quality assurance programme, including medical radiological equipment acceptance and commissioning. The medical physicist is also likely to have responsibilities in providing radiation protection and safety training for health professionals. In addition, he or she may also perform the role of the radiation protection officer, whose responsibilities are primarily in occupational and public radiation protection.
 Fundamental Safety Principles – Safety Fundamentals SF-1. IAEA, 2006
 Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards (IAEA Safety Standards Series No. GSR Part 3, IAEA, 2006
 WORLD MEDICAL ASSOCIATION, 18th World Medical Assembly, Helsinki, 1974, as amended by the 59th World Medical Assembly, Seoul (2008).
 COUNCIL FOR INTERNATIONAL ORGANIZATIONS OF MEDICAL SCIENCES, WORLD HEALTH ORGANIZATION, International Ethical Guidelines for Biomedical Research Involving Human Subjects, CIOMS, Geneva (2002).
 INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION, Radiological Protection in Biomedical Research, ICRP Publication 62, Pergamon Press, Oxford and New York (1991).