What is Meant with Medical Exposure?
Medical uses of ionizing radiation involves three categories of exposure:
- Medical exposure that is exposure incurred by patients* for the purposes of medical or dental diagnosis or treatment; by carers and comforters; and by volunteers subject to exposure as part of a programme of biomedical research;
- Occupational exposure for those involved in the performance of radiological procedures;
- Public exposure for members of the public, such as in waiting rooms.
A patient is an individual who is a recipient of services of health care professionals and/or their agents that are directed at (a) promotion of health; (b) prevention of illness and injury; (c) monitoring of health; (d) maintaining health; and (e) medical treatment of diseases, disorders and injuries in order to achieve a cure or, failing that, optimum comfort and function. Some asymptomatic individuals are included. For the purpose of the requirements on medical exposure in the IAEA safety standards, the term patiente erefers only to those individuals undergoing radiological procedures.
The requirements for radiation protection and safety differ according to the category of exposure, so it is important that the exposure of persons is categorized correctly. For example, a nurse assisting with image guided interventional procedures would be considered to be occupationally exposed, whereas a nurse working in an inpatient ward where occasional mobile radiography is performed by a medical radiation technologist would not be considered to be occupationally exposed but rather as subject to public exposure.
The term carer and comforter has been introduced into GSR Part 3 to cover those persons who, outside an occupational capacity, willingly and voluntarily help in the care, support and comfort of a patient undergoing a radiological procedure. Carers and comforters are subject to medical exposure, whereas a casual acquaintance visiting a patient who has undergone radionuclide therapy would be considered a member of the public and hence subject to public exposure.
How are radiation protection principles applied to medical exposure?
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 summarizes the radiation protection principles as applied to medical exposure in comparison with occupational exposure and public exposure:
| Application for 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). |
