Développements actuels à l'IRSN sur des outils numériques dédiés à l'évaluation dosimétrique concernant à la fois les expositions internes et externes.

I. Aubineau-Lanièce, L. De Carlan, I. Clairand, A. Lemosquet, S. Chiavassa, N. Pierrat, M. Bardies, D. Franck, ICRS 10 RPS 2004, 9-14/05/2004, Madère.

In dosimetry, physical anthropomorphic phantoms adequate to represent human bodies have been used for many years. However, direct measurements do not always allow taking into account complex configurations. Thus, new approaches using numerical phantoms have been developed in association with particle transport codes, either of analytic or of Monte Carlo type, to assess the absorbed dose distribution for both external or internal exposure configurations. For twenty years, mathematical models have been used to calculate the dose distribution for anatomical configurations that were difficult or even impossible to study with physical phantoms. However, human body is too complex to be realistically modeled with mathematical equations. Besides, progresses concerning both medical imaging techniques and the computing power made possible to develop new methods for dose assessment considering various applications.

In that context, IRSN has developed a new dose assessment tool using voxel phantoms from MRI or CT images in association with the Monte Carlo N-Particle codes (MCNP and MCNPX). The originality of this tool is to allow the construction of personalised voxel phantom and its great power is to be a friendly using graphical interface (written in PV-WAVE) which not only creates automatically the input file of the MCNP(X) code, but also allows an automatic visualisation of the requested results.

As a result of its flexibility, this method has been applied to two distinct fields.

In internal dosimetry, a computational tool called OEDIPE (french acronym meaning “tool for internal personalised dose assessment”) allows either to simulate in vivo measurements in order to improve their calibration, or to calculate the dose distribution at the tissue scale considering both internal contamination and metabolic therapy cases.

In external dosimetry, a computational tool called SESAME for “Simulation of External Source Accident with Medical images” allows dose reconstruction of radiological overexposures, modelling the victim, the source and the environment of the accident.

The global principle of these new tools will be presented and their specificities linked to each of its three application domains will be detailed and briefly illustrated.