Comparison of a heterogeneous child phantom with paediatric patients

In the optimisation of roentgen diagnostic procedures phantoms are often used for image quality assessment and/or dosimetry. In paediatric radiology phantoms are rare. In this work an anthropomorphic phantom for dosimetry simulating a one-year-old child is compared to real patients using clinical CT images of paediatric patients and Monte Carlo calculations of depth doses. The results indicate that the absorbed doses in paediatric patients are within 35% of the dose values received from measurements in the phantom and that effective dose calculated for the phantom should correspond within 20% to the effective dose for a paediatric patient. Between the lung tissue of the phantom and ICRU lung tissue of the same density, the calculated differences in absorbed dose are at most 9% for the energy spectra used (60 kV and 120 kV) and depths from 0 to 10 cm. Among lungs with different densities the differences in absorbed dose are larger. (Author)