IMPACT OF RADIATION FIELD SIZE ON ABSORBED ORGAN DOSES IN NEONATES UNDERGOING CHEST RADIOGRAPHY IN AN ANTERIOR-POSTERIOR PROJECTION: A MONTE CARLO SIMULATION STUDY.

Electronic image cropping and poor collimation practices are used by some radiographers during paediatric radiography. Advantages of collimation should be investigated to disseminate convenient use among radiographers and create awareness. The aim of this study was to use Monte Carlo simulation to investigate the extent of the effect of collimation on the absorbed organ dose in neonates undergoing anterior-posterior chest examination. The minimum field size recommended by the European guidelines was calculated experimentally using a neonate phantom. A PCXMC version 2.0 simulation calculated the organ and effective doses at the minimum field size and at different field sizes. Increasing the field size by 1 cm in the head-to-feet direction increases the dose to the urinary bladder and prostate, whereas increasing the field size by 1 cm on all sides increases the dose to the upper limbs, ovaries, testicles and prostate. The use of an optimal field size reduces organ doses for neonates undergoing chest X-ray. Cropping X-ray images to reduce unnecessarily large field sizes results in unnecessary patient dosages and should be avoided. The primary beam should be restricted to expose only the area of interest, and image cropping should be discouraged.