Effect of density on absorbed doses in a mouse voxel phantom

Mohammadi, A.; Kinase, Sakae   

The accurate dosimetry for murines such as mice is necessary since they are widely used in preclinical evaluations of new radiopharmaceuticals. Dose of organs in these animals can be evaluated in a voxel mouse phantom, which has a realistic anatomy, by Monte Carlo methods. Dose of each organ depends on density of that organ and the other organs around. In this study, we evaluated the effect of bones and lungs density on photon and electron absorbed fractions (AFs) and S values for I and Y nuclides in major organs and whole body of the Digimouse phantom. Source was considered to be distributed uniformly in the whole body of the mouse phantom. AFs and S values were evaluated by Monte Carlo methods in homogeneous and heterogeneous Digimouse phantoms. The density of skeleton and lungs in homogeneous phantom were changed to make the heterogeneous phantom. From the results it was found that the density changes affected on AFs and S values of all organs specially the heart however the effect in whole body was really much smaller than each individual organ. It shows that whole body dose is not sufficiently good as a quantity for accurate dosimetry.