Effects of Different Incident Direction on Organ-Absorbed Doses, Effective Doses, and Effective Dose Conversion Coefficients for Chest Radiography

Background:We aimed to evaluate the effects of different incident directions on organ-absorbed doses, effective doses, and effective dose conversion coefficients for chest radiography. Materials and Methods:We constructed an examination environment for chest radiography using a Monte Carlo simulation and estimated the organ-absorbed doses and effective doses for frontal anterior-posterior (AP), frontal posterior-anterior (PA), left lateral, and right lateral radiography.The effective dose conversion coefficients were calculated using the air kerma-area product.Results and Discussion: Some organs, such as the breast, showed more than a fivefold difference in the organ-absorbed dose between AP and PA radiography.In lateral radiography, there was a large difference in the organ-absorbed doses in the abdominal region.The effective dose was approximately 30% higher for AP radiography than for PA radiography.The effective dose conversion coefficients differed between AP and PA radiography.These findings are consistent with the anatomical arrangement of organs in the human body; nevertheless, they have not been explicitly reported in previous studies. Conclusion:It was suggested that using the PA direction of incidence in frontal radiography reduces the effective dose received by the patient.In addition, when estimating the effective dose using conversion coefficients, the estimated value may differ significantly due to differences in the direction of incidence, so the coefficients must be appropriately selected.