Evaluation of skin absorbed doses during manipulation of radioactive sources: a comparison between the VARSKIN code and Monte Carlo simulations
The evaluation of skin doses during manipulation of radioactive sources can be a critical issue for which the most accurate calculation strategies available should be used. The aim of this work was to compare the results of the analytical approach used in VARSKIN with the simulation of radiation transport and interaction by Monte Carlo calculations in GAMOS (GEANT4-based Architecture for Medicine-Oriented Simulations), and to provide an accurate and versatile tool for the evaluation of skin doses from radionuclide sources of any realistic shape (e.g. cylindrical, parallelepiped), even in the presence of multiple interposed absorber layers. A set of 20 radionuclides (pure β, β–γ, Auger and γ emitters) from among the most frequently employed in nuclear medicine and laboratory practices were selected for comparison. We studied a point-like and a cylindrical source, in the presence of varying thicknesses of absorbing layers. We found a general agreement for most nuclides when the source was directly in contact with skin or in the presence of a thin layer of absorbing material. However, when the thickness of the absorber increased, significant differences were found for several nuclides. In these cases, the proposed method based on a dedicated Monte Carlo simulation could give more accurate results in a reasonable time, which could optimise accuracy when assessing skin doses in routine as well as incidental exposure scenarios.
Estimation of Radiation Exposure to Workers in Laboratory Accidents
The evaluation of the dose to the skin has not been a simple matter. For the most of radionuclide contaminants of concern, the dose to skin consisted of electron and photon. The contributions to the skin dose of these types of radiation depended on their energy distributions and the attenuation of the contamination. Radiation measurement instruments such as survey meters or personal dosimeters did not provide any useful information in the cases of accidents. It was therefore imperative to provide tolerable assessment of skin dose in case any worker accidentally got exposed. Previous studies of skin dose were mostly performed using computational dosimetry codes such as VARSKIN code and Monte Carlo simulations, but there has been rarely performed using laboratory data [1,4]. Exposure of hands and fingertips to relevant dose rates has been of great interest in the presence of high or moderate activities in university laboratories where operational radiation protection has not been usually optimized in terms of manipulation shields, tools and procedures. Radiation safety officers were therefore needed to estimate the potential exposure of given amounts of radionuclides and to assess skin doses from abnormal exposures that might occur under emergency situations. The objective of this study was to estimate skin dose, eye dose and equivalent dose to the occupational worker of Secondary Standard Dosimetry Laboratory (SSDL) of Nuclear Energy Commission (NEC) in Mongolia.
Explicit solutions for N-dimensional Schrödinger equations with position-dependent mass
With the consideration of spherical symmetry for the potential and mass function, one-dimensional solutions of nonrelativistic Schrodinger equations with spatially varying effective mass are successfully extended to arbitrary dimensions within the frame of recently developed elegant nonperturbative technique, where the BenDaniel-Duke effective Hamiltonian in one dimension is assumed like the unperturbed piece, leading to well-known solutions, whereas the modification term due to possible use of other effective Hamiltonians in one dimension and, together with the corrections coming from the treatments in higher dimensions, are considered as an additional term like the perturbation. Application of the model and its generalization for the completeness are discussed.