VARIATION OF ORGAN DOSES IN PEDIATRIC RADIOLOGY DUE TO PATIENT DIAMETER, CALCULATED WITH PHANTOMS OF VARYING VOXEL SIZE

The voxel type phantoms BABY and CHILD are used to quantify the depend ence of organ dose per exit dose conversion factors on patient diamete r in diagnostic paediatric radiology by variation of the voxel size in the relevant dimension. The results of Monte Carlo simulations of the five most frequent examinations, i.e. skull AP, thorax AP and PA, abd omen AP and pelvis AP, are presented for both phantoms. The organ dose s increase very differently with increasing patient diameter, dependin g on the phantom, the examination, the radiation quality and the relat ive position and percentage of the organ in the beam. Using these resu lts, phantom and examination specific organ dose scaling factors from 'standard patients' to patients with different diameters can be obtain ed.