Analytical formulas of surface emitted energy spectra of alpha flat source.

The analytical formulas of the surface emitted energy spectra of an alpha infinite flat source are derived, using the derived formulas of the distribution of residual range of alpha particles, considering the different thicknesses of the source and the absorbing layer. Utilizing these formulas, the typical residual range distributions and the energy spectra of alpha particles have been calculated and shown in figures. The variation tendency of the calculated spectrum is in good agreement with the measured spectrum.

An improved method of nasal swab analysis for assessing alpha internal radioactive contaminants.

When responding to nuclear and radiological emergencies, rapid and on-site detections of possible internal radioactive contaminants are required for early dose estimation and medical triage. Nasal swab analysis is an effective method to provide valuable information for early and fast estimates of alpha radionuclide inhalation intakes and resultant doses. In this study, to improve the quality of nasal swab measurements, a specialised double-detector alpha counter was designed. Various parameters including swab materials, sample pre-preparation, angle-dependence and vacuum dependence were investigated to optimise the reliability and convenience of the nasal swab method. An improved procedure of direct nasal swab measurement was eventually established, which could be used to obtain early data for initial dose assessment during the first response of nuclear and radiological emergencies.

Microdosimetric calculation of spherical cells and ellipsoidal red blood cells in an extremely low frequency electromagnetic field / 军事医学

Objective To calculate the electric field intensity and transmembrane voltage of spherical cells and ellipsoi -dal red blood cells ( RBC) in an extremely low frequency electromagnetic field .Through this calculation , we can provide reference to the search for interaction targets and mechanics between the extremely low frequency electromagnetic field and organisms.Methods The Finite Element Method was used in the numerical computation for the spherical cell model and the ellipsoidal RBC model .Results The electric field intensity of the two types of cells on the cellular membrane was both significantly higher than the applied electric field strength , and the values of the induced field strength and transmembrane voltage varied with the direction of the electric field periodically .Conclusion The cell shape and direction of the applied electric field are not the main determinants of the cellular membrane electric field intensity and the transmembrane voltage compared with electromagnetic parameters .The distribution of the electric field intensity and transmembrane voltage are re-lated to the direction of the applied electric field.

An efficiency calibration method without a radioactive source using BOMAB phantom and Monte Carlo simulation for Inspector 2000 gamma spectroscopy system / 中华放射医学与防护杂志

Objective To establish an efficiency calibration method without a radioactive source for Inspector 2000 gamma spectroscopy system.Methods At the fwst step,geometry parameters of the detector were properly specified by comparisons of FEPE(Full Energy Peak Efficiency)between Monte Carlo(MC)calculations and the average measured values of HPGe and NaI detectors using point sources(137 Cs).The differences between calculations and measurements were generally within ±10% for gamma rays.Then,Monte Carlo simulation was used to evaluate the counting efficiency of Nal(TI)and HPGe detectors for BOMAB phantoms.Corresponding efficiency curves and functions were fitted.Results The counting efficiency received from the fitted efficiency functions had a good agreement with those from MC simulation.The bias for Nal detector ranged from-19% to 18%,while the bias for HPGe detector ranged from-11% to 17%.The above errors were totally acceptable in the on-site deployment during nuclear and radiological emergency events.Conclusions Monte Carlo method is simple,time and laborsaving in determing the counting efficiency of gamma spectroscopy system.