Consideration of diagnostic reference levels for pediatric chest X-ray examinations

The use of diagnostic reference levels (DRLs) is currently recommended, and dose evaluation is considered to be important for establishing a Japanese radiological protection system in radiological medicine. Children, in particular, are sensitive to radiation, and their exposure levels must be taken into account. The DRL for the entrance surface dose (ESD) used in pediatric chest X-ray examinations in Japan is 0.2 mGy. However, the bodies of infants and young children show major changes with rapidly developing organs. Thus, the possibility that organ development may also be affected by radiation exposure should be taken into account. Therefore, radiological technologists must be conservative in setting radiographic conditions for pediatric examinations. The objective of this study was to evaluate the doses used in pediatric chest X-ray examinations at our hospital and compare them with the current DRLs, considering the assumption that setting conditions individually for different ages and subject thicknesses and performing more detailed dose evaluations will help reduce radiation exposure. The study was carried out to estimate the ESDs in 163 pediatric patients who underwent frontal or lateral chest X-ray examinations at our hospital. All doses were lower than 0.2 mGy, the dose recommended in the Japanese DRLs 2015. The doses showed a strong correlation with age, but a weaker correlation with subject thickness. These results suggest that instead of considering a common DRL for all children, the DRL should be evaluated on the basis of age.