title: A Monte Carlo Simulation of the in vivo measurement of lung activity in the Lawrence Livermore National Laboratory torso phantom.
abstract: A torso phantom was developed by the Lawrence Livermore National Laboratory (LLNL) that serves as a standard for intercomparison and intercalibration of detector systems used to measure low-energy photons from radionuclides, such as americium deposited in the lungs. DICOM images of the second-generation Human Monitoring Laboratory-Lawrence Livermore National Laboratory (HML-LLNL) torso phantom were segmented and converted into three-dimensional (3D) voxel phantoms to simulate the response of high purity germanium (HPGe) detector systems, as found in the HML new lung counter using a Monte Carlo technique. The photon energies of interest in this study were 17.5, 26.4, 45.4, 59.5, 122, 244, and 344 keV. The detection efficiencies at these photon energies were predicted for different chest wall thicknesses (1.49 to 6.35 cm) and compared to measured values obtained with lungs containing (241)Am (34.8 kBq) and (152)Eu (10.4 kBq). It was observed that no statistically significant differences exist at the 95% confidence level between the mean values of simulated and measured detection efficiencies. Comparisons between the simulated and measured detection efficiencies reveal a variation of 20% at 17.5 keV and 1% at 59.5 keV. It was found that small changes in the formulation of the tissue substitute material caused no significant change in the outcome of Monte Carlo simulations.
authors.affiliation: Idaho State University, Nuclear Engineering and Health Physics, P.O. Box 8106, Pocatello ID 83209, USA. acharobe@isu.edu
authors.forename: Robert
authors.initials: R
authors.lastname: Acha
authors.forename: Richard
authors.initials: R
authors.lastname: Brey
authors.forename: Kevin
authors.initials: K
authors.lastname: Capello
mesh_terms: D006801:Humans; D007753:Laboratories; D008168:Lung / Q000528:radiation effects*; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011874:Radiometry / Q000295:instrumentation*; D060726:Torso