Shielding Calculations on Waste Packages – The Limits and Possibilities of different Calculation Methods by the example of homogeneous and inhomogeneous Waste Packages

For nuclear waste packages the expected dose rates and nuclide inventory are beforehand calculated. Depending on the package of the nuclear waste deterministic programs like MicroShield® provide a range of results for each type of packaging. Stochastic programs like “Monte-Carlo N-Particle Transport Code System” (MCNP®) on the other hand provide reliable results for complex geometries. However this type of program requires a fully trained operator and calculations are time consuming. The problem here is to choose an appropriate program for a specific geometry. Therefore we compared the results of deterministic programs like MicroShield® and stochastic programs like MCNP®. These comparisons enable us to make a statement about the applicability of the various programs for chosen types of containers. As a conclusion we found that for thin-walled geometries deterministic programs like MicroShield® are well suited to calculate the dose rate. For cylindrical containers with inner shielding however, deterministic programs hit their limits. Furthermore we investigate the effect of an inhomogeneous material and activity distribution on the results. The calculations are still ongoing. Results will be presented in the final abstract

VARIAN CLINAC 6 MeV Photon Spectra Unfolding using a Monte Carlo Meshed Model

[EN] Energy spectrum is the best descriptive function to determine photon beam quality of a Medical Linear Accelerator (LinAc). The use of realistic photon spectra in Monte Carlo simulations has a great importance to obtain precise dose calculations in Radiotherapy Treatment Planning (RTP). Reconstruction of photon spectra emitted by medical accelerators from measured depth dose distributions in a water cube is an important tool for commissioning a Monte Carlo treatment planning system. Regarding this, the reconstruction problem is an inverse radiation transport function which is ill conditioned and its solution may become unstable due to small perturbations in the input data. This paper presents a more stable spectral reconstruction method which can be used to provide an independent confirmation of source models for a given machine without any prior knowledge of the spectral distribution. Monte Carlo models used in this work are built with unstructured meshes to simulate with realism the linear accelerator head geometry.Ha recibido financiación de DESARROLLO E IMPLEMENTACION DE UN SISTEMA DE PLANIFICACION RADIOTERAPÉUTICA (TELETERAPIA Y BRAQUITERAPIA) BASADO EN EL MÉTODO MONTECARLO PARA EL HUPLAFE (UNIVERSIDAD POLITECNICA DE VALENCIA), DESARROLLO Y VALIDACION EXPERIMENTAL DE UN SISTEMA DE PLANIFICACION DE TRATAMIENTOS RADIOTERAPEUTICOS UTILIZANDO TECNICAS DE MONTE CARLO (UNIVERSIDAD POLITECNICA DE VALENCIA), Dosimetría in vivo en radioterapia sin filtro aplanador (FFF) (UNIVERSIDAD POLITECNICA DE VALENCIA), MONTE CARLO TREATMENT PLANNING SYSTEM: SOFTWARE PARA EL CALCULO DOSIMETRICO DE ALTA PRECISION EN RADIOTERAPIA. (UNIVERSIDAD POLITECNICA DE VALENCIA) y SISTEMA DE PLANIFICACION DE TRATAMIENTOS EN RADIOTERAPIA BASADO EN EL METODO DE MOTE CARLO Y EL PROCESADO 3D DE IMAGENES MEDICAS (GENERALITAT VALENCIANA)Morató-Rafet, S.; Juste Vidal, BJ.; Miró Herrero, R.; Verdú Martín, GJ. (2017). VARIAN CLINAC 6 MeV Photon Spectra Unfolding using a Monte Carlo Meshed Model. EPJ Web of Conferences. 153(04012):1-7. https://doi.org/10.1051/epjconf/201715304012S171530401