Evaluation of organ doses in CT examinations with an infant anthropomorphic phantom

Purpose: The increase in the frequency of CT examinations over the past decade has raised concerns about radiation doses and the possible detriment to the health of children. The estimation of accurate dose levels and radiation risks requires organ doses for paediatric patients in CT examinations and the dose evaluation appropriate for various child body sizes depending on the age. However, details of CT doses for children, especially infants, have not been reported. The aim of this study is to evaluate organ doses in infant CT examinations at child medical facilities and compare the doses for infants with those for adult and 6-year-child patients.Method: Dose measurements in infant CT examinations were performed with two types of 64 multi-detector row CT scanners in each medical facility. The doses were measured with 170 photoluminescence glass dosemeters set in various organ positions within a 1-year-old child anthropomorphic phantom and organ doses were evaluated from these measurement values.Results: Organ doses for brain and lens in head CT protocols used routinely for infants were 26-37mGy. The dose variations among CT scanners were caused by the differences in the types of CT scanners and scan conditions such as mAs and pitch factor etc. The doses for tissues or organs within scan ranges in a chest CT and abdominal-pelvic CT protocol were approximately 10mGy. The infant CT doses were 1/2 to 1/3 of adult CT doses and were similar to CT doses evaluated with a 6-year-old anthropomorphic phantom for the same type of CT scanner.Conclusions: Organ doses in infant CT examinations could be obtained in this study. The dose data would be useful for the evaluation of dose levels and radiation risks for infants and would also lead to the optimization of scan protocols.International Conference on Radiation Protection in Medicin