ASN Report 2017

100 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 03  - Regulations 2.2.2 Optimisation of exposure In medical imaging (radiology and nuclear medicine) optimisation consists in delivering the lowest possible dose compatible with obtaining a quality image; that is an image that provides the diagnostic information being sought. In therapy (external radiotherapy, brachytherapy and nuclear medicine) optimisation consists in delivering the prescribed dose to the tumour to destroy cancerous cells while limiting exposure of healthy tissues to the strict minimum. To facilitate the practical application of the optimisation principle, standardised procedure guides for the performance of procedures utilising ionising radiation are produced and regularly updated (Table 1). Diagnostic reference levels The Diagnostic Reference Levels (DRL) are one of the tools used for dose optimisation. As required in Article R. 1333-61 of the Public Health Code, the DRL are defined in the Order of 24th October 2011 concerning diagnostic reference levels in radiology and nuclear medicine. 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. Depending on the type of examination, periodic measurements or readings must be taken in each radiology and nuclear medicine unit. On the basis of the information received by IRSN, an update of these diagnostic reference levels is planned during the course of 2018 by an ASN resolution. Dose constraints In the field of research involving human beings to evaluate or use methods entailing exposure to ionising radiation, dose constraints to optimise the doses delivered must be established by the physician, according to the nature of the protocol and the risk/benefit trade-off for the participating subject. Medical physics The safety of radiotherapy and optimisation of the doses delivered to the patients in medical imaging require particular expertise in the field of medical physics. The use of a medical physicist has been extended to cover radiology. Pursuant to Ordinance 2017-48 of 19th January 2017 concerning the profession of medical physicist, the medical physicist, whose presence was already mandatory in radiotherapy and nuclear medicine, is now recognised as a health care professional. The roles of the medical physicist were clarified by the Order of 19th November 2004 as amended, relative to the training, duties and conditions of involvement of medical physicists. Thus they 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 exposure to ionising radiation. More particularly in the field of radiotherapy, the medical physicist guarantees that the radiation dose received by the tissues being exposed 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. The conditions regarding the presence of medical physicists in radiotherapy centres are defined by the National Cancer Institute, pursuant to Decree 2007-388 of 21st March 2007 on the layout conditions applicable to cancer treatment activities. This Decree notably makes the presence of the medical physicist mandatory during the treatment sessions. Pursuant to the Ordinance of 19th January 2017, a decree should be published shortly to define medical physics procedures. It will repeal the modified Order of 19th November 2004. Since 2005, heads of facilities have had to draw up plans for medical physics (Order of 19th November 2004, modified), defining the resources to be allocated, primarily in terms of staffing, in the light of the medical procedures carried out in the establishment, the actual or probable patient numbers, existing dosimetry skills and the resources allocated to quality assurance and control. The conditions of training of the medical physicists were updated by the Orders of 28th February and 6th December 2011. In the same way as the physician or the radiographer, the medical physicist can be designated as the RPE-O by the employer in accordance with the Labour Code. In operating theatres using X-ray generators, optimisation of the doses delivered to the patients, which is the competence of the medical physicist, also contributes to reducing the doses received by the professionals performing the procedure. SPECIALTIES MEDICAL RADIOLOGY NUCLEAR MEDICINE RADIOTHERAPY DENTAL RADIOLOGY DOCUMENTS Procedure guide Indication guide Indication and procedure guide Procedure guide in external radiotherapy Indication and procedure guide AVAILABLE ON www.sfrnet.org www.irsn.org www.sfrnet.org www.irsn.org www.sfmn.org www.sfro.org www.adf.asso.fr www.has-sante.fr TABLE 1: List of Imaging and Procedure Guides for the performance of medical procedures entailing exposure to ionising radiation