A sourceless efficiency calibration method based on the coupling of Monte Carlo simulation and analytical calculation / 中国辐射卫生

Objective To establish a sourceless efficiency calibration method by coupling Monte Carlo simulation with analytical calculation. Methods Monte Carlo simulation was used to calculate the point-to-point detection efficiency of specific detectors to establish a detection efficiency grid. The detection efficiency of point source, disc, cylindrical, beaker, spherical, U-tube and Marlin cup samples was analyzed using numerical integration method after detection efficiency grid interpolation. Results The above coupling method was used for sourceless efficiency calibration. Within the energy range of 0.2–3 MeV, the relative deviation of calibration between coupling method and Monte Carlo simulation was mostly less than 10%, the maximum relative deviation was 18.06%, and the computation time was reduced by at least 86%. The above coupling method was used for sourceless efficiency calibration of an HPGe detector manufactured by ORTEC for point source detection, which was in good agreement with the experimental calibration, and the relative deviations were less than 10%. Conclusion This method can be generalized and used in the sourceless efficiency calibration of HPGe, LaBr3, and NaI detectors.

Numerical computation on the scaffolds models with regular square holes using nonlinear fluid-solid-coupling approaches / 医用生物力学

Objective The influencing parameters of solid and fluid computing fields for the scaffolds models with regular square holes were discussed by nonlinear fluid-solid-coupling approaches, the numerical computational results of which the models were regarded as both rigid body and non-linear elasticity were compared as well. Method one direct fluid-solid-coupling approach and two indirect fluid-solid-coupling approaches were adopted, and the calculating reliability of three kinds of fluid-solid coupling methods were verified. Results The solid-fluid-coupling computational results are obtained in light of 12 kinds of scaffolds which were constructed by 3 groups of square side length (50,100 and 150μm) and 4 groups of porosity (61%,65%,77% and 84%). The field parameters of those solid models including stress, strain and displacement and those fluid models including static pressure, velocity, wall shear stress and strain rate are achieved and compared.Conclusions A quiet difference between the results of porous scaffold models as a rigid body and that of non-linear elasticity. The different porosity with the same pore radius or the different pore radius with the same porosity effected the field parameters of solid models and fluid models in varying degrees.