Asymptomatic individuals

Individuals who display no physical symptoms.

Clinical Audits

A systematic examination or review of medical radiological procedures which seeks to improve the quality and the outcome of patient care through structured review whereby radiological practices, procedures and results are examined against agreed standards for good medical radiological procedures, with modification of practices where indicated and the application of new standards if necessary.

Computer Tomography

X-ray computed tomography (CT) is a medical imaging method to generate a three-dimensional image of the inside of a patient from a large series of two-dimensional X-ray images taken around a single axis of rotation. CT revolutionized the medical x-ray field with its unprecedented ability to visualize the anatomic structure of the body.


Presence of radioactive substances on or in a material or a person, where this is unintended or undesirable.

Diagnostic reference levels

Dose levels in medical radiodiagnostic practices or, in the case of radio-pharmaceuticals, levels of activity, for typical examinations for groups of standard-sized patients or standard phantoms for broadly defined types of equipment. These levels are expected not to be exceeded for standard procedures when good and normal practice regarding diagnostic and technical performance is applied.

Effective dose

Effective dose is used in radiation protection, to compare the stochastic risk of a non-uniform exposure to ionizing radiation, with the risks caused by a uniform exposure of the whole body. The stochastic risks are carcinogenesis and hereditary effects.


Inspection is an investigation by any competent authority to verify compliance with national provisions on radiological protection for medical radiological procedures, equipment in use or radiological installations.


The process of determining whether a practice is, overall, beneficial, as required by the International Commission on Radiological Protection’s System of Radiological Protection, i.e. whether the benefits to individuals and to society from introducing or continuing the practice outweigh the harm (including radiation detriment) resulting from the practice.

Medical applications of ionizing radiation

Today ionizing radiation is used in many medical fields. The adjective “ionizing” refers to the property of this radiation to eject electrons from an atomic shell; a process called “ionisation”. Ionizing radiation can be produced in devices like X-ray tubes (radiology) or for higher energies in accelerators (radio-oncology, radiotherapy). In nuclear medicine, the ionizing radiation is produced through the decay of radioactive substances.

Metabolic radiotherapy

Therapy with radiopharmaceuticals using their specific metabolic pathway to bring the radioactive substance to the target cells. In the case of a cancer treatment, the target cells are the malignant tumor cells.


All doses due to medical exposure for radiological purposes except radio therapeutic procedures shall be kept as low as reasonably achievable (ALARA), consistent with obtaining the required diagnostic information, taking into account economic and social factors.


Radiographers are medical imaging and radiotherapy experts who :

  • are professionally accountable to the patients’ physical and psychosocial well being, prior to, during and following examinations or therapy;
  • take an active role in justification and optimisation of medical imaging and radiotherapeutic procedures
  • are key-persons in radiation safety of patients and third persons in accordance with the “As Low As Reasonably Achievable (ALARA)” principle and relevant legislation.

EFRS definition of a radiographer.pdf


Drugs containing a radioactive component (radionuclide, radio-isotope) whose radiation is used for diagnostic or therapeutic purposes.

Screening programmes

Screening programmes systematically invite all members of a certain population to take a screening test. Examples of this are the breast screening programmes in Europe where all women between 50 and 69 routinely receive invitations to have an X-ray mammography.


Persons or organisations with an interest in radiation protection in the medical field, e.g. scientific or professional bodies in radiology, radio-oncology, nuclear medicine, medical physics, technicians such as radiographers, patient organisations, manufacturers of medical devices, regulatory bodies, health ministries , etc.