Typical calculations of radiation exposures in space approximate the composition of the human body by a single material, typically Aluminum or water. A further approximation is made with regard to body size by using a single anatomical model to represent people of all sizes. A comparison of calculations of organ dose and dose-equivalent is presented. Calculations are first performed approximating body materials by water equivalent thickness', and then using a more accurate representation of materials present in the body. In each case of material representation, a further comparison is presented of calculations performed modeling people of different sizes.