Optimisation in medical imaging (radiology and nuclear medicine) consists in delivering the lowest possible dose compatible with obtaining a quality image that provides the diagnostic information sought for. Optimisation in therapy (external radiotherapy, brachytherapy and nuclear medicine) consists in delivering the prescribed dose to the tumour to destroy cancerous cells while limiting the dose to healthy tissues to the strict minimum. The optimisation approach is thus a pledge of the quality of the procedures conducted. Standardised guides for conducting procedures using ionising radiation have or are being written by health professionals to make optimisation easier in practice (see table above).

Diagnostic reference levels

New statutory concepts specific to radiation protecting for patients have been introduced for this very purpose and reference diagnostic levels were set in the order of 12 February 2004. For radiology, this consists of dose values, while for nuclear medicine it consists of activity levels administered in the course of the most common or most heavily irradiating examinations. These reference levels will be updated by conducting regular measurements or readings in line with the type of examination in each radiology and nuclear medicine department and centralizing them at the IRSN. Therefore, since June 2004, any new radiology appliances which enter service must be fitted with a device for estimating the dose delivered during an examination (article R. 5211-22 of the Public Health Code).

Dose constraints

In the field of biomedical research, where exposure to ionising radiation entails no direct benefit for the persons exposed, dose constraints designed to encompass the doses delivered must be established by the practitioner. An order currently being drafted will specify the methods for validating these dose constraints.

Medical radiological physics

Special medical physics skills are called for in optimising the dose delivered to patients. The employment of a specialised medical radiological physicist, formerly called a "radiophysicist", has been extended to radiology having already been compulsory in radiotherapy and nuclear medicine. Qualification of such specialists involves obtaining a master's degree (the list of which was published in the order of 7 February 2005), followed by specialist training including clinical work placements.

The duties of this specialist have been specified and expanded (order of 19 November 2004). Thus medical radiological physics specialists must ensure the appropriateness of the equipment, data and computing processes for determining and delivering the doses and activity levels administered to the patient in any procedure involving ionising radiation. In the field of radiotherapy they guarantee that the radiation dose received by the tissues due to be irradiated matches that prescribed by the prescribing physician.

Furthermore, they estimate the dose received by the patient during diagnostic procedures and play a part in quality assurance including inspecting the quality of the medical devices. Finally they contribute to teaching and training the medical and paramedical personnel in medical radiological physics.

As part of the new measures, heads of establishments will have to draw up plans for medical radiological physics as of the year 2005, defining the resources allocated, primarily in terms of staffing, in the light of the medical practices carried out in the establishment, the actual or probable patient numbers, existing dosimetry skills and resources allocated to quality assurance and control.