Monte Carlo Simulation on Dectecion Efficiency Distributions of γ Internal Contamination in the MIRD Phantom Lungs

In order to obtain detection e?ciencies of nine kinds of gamma rays emitted by isotopes deposited in lungs at various measurement geometry, Monte Carlo N-Particle Transport Code 5 (MCNP5) has been employed to for calculation. The results show that the detection e?ciency in different locations of lung is not completely accord with human body’s anatomy structure. The e?ciency decreases gradually from lower-right lung, to lower-left lung, and then to upper-left lung. When the location of detector is fixed, with the increase of energy, the detection e?ciency rises up firstly and then falls down.