The comparison of two MCNP models used for prompt gamma in vivo detection of cadmium and mercury

In vivo detection of trace elements is one of the most important research areas at the Medical Physics and Applied Radiation Sciences Department at McMaster University. Prompt gamma neutron activation analysis (PGNAA) used for detection of cadmium and mercury takes place simultaneously at two different experimental sites; the McMaster Nuclear Reactor (MNR) and the 238Pu/Be neutron source site. This particular study consists of two parts. In the first part the water phantoms (125mL) were used in MCNP simulations. The water phantoms were doped with different concentrations of Cd, Hg and HCl. This is done in order to compare the (n, γ) prompt gamma reaction rate; in fact, the rate of neutron capture by the nuclides of interest; 113Cd, 199Hg and 35Cl. The second part involves, the neutron and photon dosimetry calculations that were performed for both sites using MCNP compatible body builder software developed in Los Alamos. The output of this program is the actual MCNP geometry description for various human anthropomorphic phantoms (different sex and ages). This phantom geometry output is incorporated into the original MCNP geometry and the dosimetry calculations were performed for various organs at risk.