Présents dans notre environnement les rayonnements électromagnétiques (EM) suscitent de multiples questions quant à leurs effets potentiels pour les porteurs de dispositifs médicaux actifs implantés (DMAI). Le nombre croissant de porteurs d’implants médicaux, y compris dans la population active, a entraîné un questionnement quant à leur comportement en présence d’un champ EM. L’interaction entre le corps humain et les champs EM reste complexe et dépend de multiples facteurs tels que la fréquence, la puissance et la modulation des champs. Nous présentons ici une revue de cette problématique dans le cas des champs EM basse fréquence.

The separate contributions of all source regions to organ doses from 131I and 123I administered to the body were calculated using voxelized reference phantoms. The photon and electron components of organ doses were also evaluated for each source region. The MCNPX Monte Carlo particle transport code was utilized for dose calculations. All organs and tissues of male and female phantoms were taken into account as source regions with their corresponding cumulated activities. The results showed that cumulated activities assigned to source regions and inter-organ distances were two factors that strongly affected the contribution of each source to the organ dose. The major contribution of the dose to the main source regions arose from self-irradiation of electrons, while for nearby organs it was due to photons emitted by the main source organs. In addition, self-irradiation plays an important role in the dose delivered to most target organs for lower thyroid uptakes.

Interventional cardiologists (ICs) are repeatedly exposed to scattered ionising radiation during the cardiac procedures they perform, and radiation protection is an important issue for these medical professionals. The use of radiation protection tools is particularly relevant to this population. SISERI (Système d’Information de la Surveillance de l’Exposition aux Rayonnement Ionisants, that is, an information system for monitoring exposure to ionising radiation) is a register that stores personal dosimeter readings for dosimetric monitoring. This paper, based on data for a sample of French ICs from the O’CLOC epidemiological study, aims to provide an overview of the use of radiation protection equipment and dosimetric devices reported by ICs in a specific questionnaire as well as the dosimetric information found in the SISERI database for this population. Material and Methods − Annual information on interventional cardiology activity for the period from 01/01/2005 to 31/12/2009 was collected in an occupational questionnaire. ICs were asked to report the frequency in which they used individual dosimeter and radiation protection tools (lead apron, thyroid shield, eyewear or face shield, ceiling-suspended shield) as follows: never (0% of the time), occasionally (<50%), regularly (>50%), always (100%). We retrieved their medical radiation exposure information (monitored status and monthly effective doses) from the SISERI database for the period 2005−2009. Results – Information for 132 ICs (mean age in 2005 = 46 ± 7 years) was available. All ICs reported routine use of lead aprons, in contrast to their occasional use of lead eyewear or face shields. During the study period, 49% reported systematic use of personal dosimeters, and 21% more regular use. On the other hand, 18% never used a dosimeter during this period. The SISTERI database included 92% of our population, 73% of whom had complete annual dose monitoring in SISERI (corresponding to at least 11 months per year of recorded data). Conclusion − ICs must improve their regular use of radiation protection tools and systematic use of personal dosimeters. The SISERI database is an appropriate tool for flagging those medical professionals exposed to ionising radiation. Better awareness of the importance of radiation protection rules in this population, in particular, systematic dosimeter use, remains an important issue.

The measurement performances of in vivo monitoring vehicles were studied considering an increase in the radiological background in areas where the population is not evacuated after a nuclear accident. The study focused on 137Cs and 131I Detection Limits (DLs) and corresponding doses, for adults and one-year-old children. These DLs for ground contamination were obtained experimentally using a grid of point sources. Then, the DLs and doses were calculated using the experimental data and a safety factor for two accident scenarios. For these scenarios the 137Cs DL corresponds to a committed effective dose of 0.02 mSv. The 131I DL corresponds to committed equivalent thyroid doses of 3 mSv (adult) and 30 mSv (one-year-old child). To guarantee a 45 mSv thyroid equivalent dose assessment for the child the surface activity of 131I + 132I + 133I should be below 1.6 MBq/m2. This study shows that the vehicles can operate in a contaminated area where the population is not evacuated. However, in such a case, the contamination level outside and inside the vehicle should be kept stable to guarantee efficient body counting.

Classical beta spectra calculations are briefly described, highlighting the usual assumptions and limitations. To go beyond these usual assumptions, the numerical resolution of the Dirac equation for the atomic and beta electrons is necessary. This allowed us to determine the parameters λi involved in the theoretical shape factors exactly. A systematic comparison between theoretical and experimental shape factors led us to disqualify the usual λi = 1 assumption for all forbidden transitions. The usual ξ-approximation was proved to be incorrect for numerous first forbidden non-unique transitions, and for all higherorder non-unique transitions. A more accurate screening correction was defined and the atomic exchange effect was taken into account, an effect which is always neglected in usual calculations. The beta spectra of 63Ni and 241Pu, recently measured down to very low energies, are well reproduced in our calculations. The exchange effect was demonstrated to have a great influence on the spectral shape within this energy range.

For targeted radionuclide therapies, treatment planning usually consists of the administration of standard activities without accounting for the patient-specific activity distribution, pharmacokinetics and dosimetry to organs at risk. The OEDIPE software is a user-friendly interface which has an automation level suitable for performing personalized Monte Carlo 3D dosimetry for diagnostic and therapeutic radionuclide administrations. Mean absorbed doses to regions of interest (ROIs), isodose curves superimposed on a personalized anatomical model of the patient and dose-volume histograms can be extracted from the absorbed dose 3D distribution. Moreover, to account for the differences in radiosensitivity between tumoral and healthy tissues, additional functionalities have been implemented to calculate the 3D distribution of the biologically effective dose (BED), mean BEDs to ROIs, isoBED curves and BED-volume histograms along with the Equivalent Uniform Biologically Effective Dose (EUD) to ROIs. Finally, optimization tools are available for treatment planning optimization using either the absorbed dose or BED distributions. These tools enable one to calculate the maximal injectable activity which meets tolerance criteria to organs at risk for a chosen fractionation protocol. This paper describes the functionalities available in the latest version of the OEDIPE software to perform personalized Monte Carlo dosimetry and treatment planning optimization in targeted radionuclide therapies.

To go further in the optimization of treatment planning in selective internal radiation therapy (SIRT), radiobiological aspects can be accounted for with the OEDIPE software and used to design fractionation protocols. Dosimetry was performed using data from 99mTc-MAA evaluations of 10 patients treated for hepatic metastases with SIRT. The maximal injectable activity (MIA) was calculated, using a tolerance criterion on BEDmean,healthyliver equal to 54 Gy2.5, for different fractionation protocols, varying the number of fractions, the repartition of activity and the time delay between fractions. OEDIPE was also used to calculate BEDmean and the EUD to the tumoral liver (TL) that would be delivered with those MIAs. Compared with a single-injection protocol, the MIA is increased on average by 23% ± 3%, 36% ± 5% and 45% ± 7% for fractionation protocols with 2, 3 and 4 equal fractions, respectively, while BEDmean,TL is increased by 15% ± 2%, 23% ± 4% and 29% ± 5%. EUDTL, calculated for one evaluation, is increased by 51%, 115% and 159% using 2, 3 and 4 equal fractions, respectively. For this evaluation, the optimal activity repartition for two-fraction protocols is (3/4 − 1/4) for time delays of less than 4 days, (2/3 − 1/3) for time delays between 4 and 6 days and (1/2 − 1/2) for time delays superior to 6 days. Finally, this study confirmed that OEDIPE can be regarded as a tool for treatment planning optimization and fractionation protocol design in SIRT.

Les traitements utilisant des rayons X de basse énergie continuent à être réalisés mais en faible nombre. Le praticien se trouve en général près du patient pour maintenir l’appareil et expose donc ses yeux. Avec la modification envisagée de la limite maximale d’exposition du cristallin, des mesures ont été jugées nécessaires pour mieux en connaître l’exposition. Pour cela une simulation des traitements a été réalisée. Pour la dose d’un traitement superficiel de 42 Gy, l’exposition du cristallin derrière des verres radio atténuateurs se situe entre 130 et 43 μSv pour des distances entre 40 et 60 cm. Pour l’intra cavitaire les valeurs obtenues sont vingt fois plus faibles. L’atténuation par les verres est supérieure à 90 %. Le port des lunettes avec verres radio atténuateurs permet de minimiser la dose au cristallin de façon significative. L’application de la nouvelle limite maximale n’aura pas d’impact sur le nombre de traitements.