Medical imaging: ASN is contributing to an international harmonisation of practices

At a colloquium organised by the World Health Organisation (WHO), 1-3 March 2010, in which the French Nuclear Safety Authority (ASN) participated, representatives of 23 international organisations and learned societies agreed on a "roadmap" aimed at both establishing international good practice guidelines for medical imaging issues and at facilitating their implementation. The "roadmap" also envisages monitoring and evaluation of the impact of this approach for the various clinical situations.

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Medical imaging is being employed to an ever increasing degree for diagnosis of a large variety of illnesses, for monitoring treatments and for direct performance of treatments. Available international data shows a very clear increase in the average doses delivered in the field of medical imaging, in particular for scanography and radiological interventions.

Medical exposure of patience to ionising radiation has now become the major source of exposure for the population. It exceeds exposure to natural radiation. Under these conditions, any use to medical imaging needs to be justified [2] by clearly established medical requirements and its practice must be optimised [3] to improve the radiological protection of patients and medical personnel.

The colloquium in March 2010 follows on from the WHO "Global Initiative on Radiation Safety in Healthcare Settings" launched in December 2008.

In France, the "Guide du bon usage des examens d’imagerie médicale" (Guidelines on the correct use of medical imaging examinations), published in 2005, is currently being revised to take account of developments in techniques, to establish a better hierarchy of examinations and to indicate when non-irradiating techniques should be used in preference; in particular where an MRI imager should be preferred to a radiograph scanner. This review is being carried out jointly by the Société Française de Radiologie (French Radiology Society), the Société Française de Médecine Nucléaire (French Nuclear Medicine Society), the Haute Autorité de santé (French National Authority for Health) and ASN. It will contribute to drawing up of the international good practice guidelines recommended by the WHO.

[1] In France, IRSN and InVS report a mean dose of medical origin of 1.3 mSv/year.inhabitant in 2007, compared with 0.8 mSv/year.inhabitant in 2002. The values for the USA and Japan are 3 and 5 times higher, respectively.

[2] Radiological protection of individuals exposed to radiation for medical purposes rests on two regulatory principles: the justification for the action and the optimisation of exposure, under the responsibility of the medical practitioner applying for the imaging examination that leads to the exposure to ionising radiation and the medical practitioner carrying out these actions. These principles cover all diagnostic or therapeutic applications of ionising radiation, including radiological examinations requested in the case of screening, occupational health, sports medicine or forensic applications.

 [3] In medical imaging (radiology and nuclear medicine), optimisation involves delivering the lowest dose possible that is compatible with obtaining a good quality image, i.e. an image that can provide the diagnostic information being sought.