Organ doses in preterm and full-term neonates and infants - a retrospective study on 1,064 chest radiographs

Background Chest radiography is the most frequent X-ray examination performed in the neonatal period. However, commonly used dosimetric entities do not describe the radiation risk sufficiently. Objective The aim of this study was to investigate selected organ doses and total body dose of chest radiographs in preterm and full-term neonates and infants. Materials and methods In this retrospective study, we evaluated 1,064 chest radiographs of 136 preterm and 305 full-term babies with respect to field size and centering. We calculated the entrance dose from the dose-area product. Upper and lower field borders referred to the corresponding vertebrae. We calculated individual organ doses of the thyroid, the breast, the liver and active bone marrow for each chest radiograph using the neonatal PCXMC program, a Monte Carlo program for calculating patient doses in medical X-ray examinations. Results The median field size of chest radiographs ranged from 90 cm(2) in preterm neonates at birth to 290 cm(2) in full-term infants at the age of 6 months. Median values of entrance dose varied, depending on age, from 15 mu Gy to 25 mu Gy. The median organ doses ranged 1-20 mu Sv for the thyroid, 3-30 mu Sv for the breast, 2-20 mu Sv for the liver and 0.5-3.5 mu Sv for the bone marrow in preterm and full-term neonates and infants, respectively. Conclusion The analysis of chest radiographs in preterm and full-term neonates and infants revealed high variability in field size. By contrast, the entrance dose varied to a minor extent. Organ dose calculations using the PCXMC program might be a valuable tool to calculate the individual radiation risk in neonates and infants