Estimation of dose-area product-to-effective dose conversion factors for neonatal radiography using PCXMC

Dose-area product-to-effective dose (E) conversion factors for chest, abdomen and abdomen-chest neonatal radiographs were computed. Seven patient models in the Monte Carlo software, PCXMC, were defined, representing neonates ranging in weight from 0.5 to 6.0 kg. Conversion factors for a tube potential range of 50-80 kVp at two beam filtrations (3.0 mm Al and 3.0 mm Al+0.1 mm Cu) were calculated. For 133 neonatal radiographs, effective dose values determined using these conversion factors were compared with those obtained from PCXMC simulations customised for each radiograph. For a 3.0-kg newborn irradiated at 60 kVp/3.0 mm Al beam filtration, the conversion factors were 2.58, 1.90 and 1.91 μSv (mGy cm(2))(-1) for chest, chest-abdomen and abdomen radiographs, respectively. Average dose difference between the conversion factors and customised dose calculations was 16 %. Disagreement in effective dose was most strongly correlated with under-collimation in the lateral direction.