DiscussionThe results of this study

Discussion
The results of this study demonstrate that by switching to a PA
projection a mean reduction in effective dose of 19.8% is achievable
(range ¼ 17.9%e22.8% across the 70 kVp to 110 kVp range). Similar
reductions (mean, range) in the absorbed dose to the stomach
(70.4%, 66.9%e74.0%), colon (61.1%, 56.6%e68.3%), remainder tissues
(33.2%, 29.3%e36.0%), testes (15.9%, 8.7%e24.7%) and ovaries
(7.3%, 3.7%e22.8%) are also achievable. Dose reductions can be
explained by the fact that the radiosensitive organs are closer to the
anterior surface than the posterior surface and, therefore, in the PA
projection they lie further away from the beam entrance surface
when compared to an AP projection. As previously stated Tsuno
and Shu (1990) confirmed this and added that the abdominal
structures are well protected by the filtering process from the
posterior musculature and spine.5