Radiologic imaging of the newborn inside the incubator. Part 3: Risk estimation

Introduction: Radiation risk strongly depends on the age at which exposure occurs; therefore, newborn and especially prematurely born babies are at highest risk for radiation-induced malignancies: risk of cancer induction is believed to be 2–3 times higher than that of the average population. Materials and Methods: In this work, cancer risk resulting from an exposure to ionising radiation is estimated using PCXMC 2.0, based on Monte Carlo simulation. For each of three incubators used at the AOU of Cagliari, organ doses and the effective dose received by the neonatal chest phantom (GAMMEX mod.610) are computed, in order to calculate REID (Risk of Exposure-Induced Death) and LLE (Loss of Life Expectancy) for female and male newborn. A model for representing neonatal chest phantom is defined in PCXMC; anatomic parameters, imaging geometry, beam conditions, exposure field, and incident air Kerma on the phantom (Ka,i)ph values (computed in a previous study) are configured as inputs. Moreover, diagnostic and exposure data (projection, source-to-image receptor distance, kV, mAs) of radiographs on 113 newborn (64 males and 49 females) have been collected for 8 months. Radiation risk (REID and LLE) for 4 newborn hospitalised is evaluated, relative to one or more exams. Results and Conclusions: As expected, for all the incubators REID increases with Ka,i; the values for the female newborn resulted much higher than the one for the male newborn. Moreover, REID increases with the number of radiographs performed. The same behaviour and results are observed for LLE. Exposure values and incubators configurations, proposed in a previous work for optimising images quality and radiation dose, also allow to minimise the radiation risk. Incubator features, such as attenuation and Focus to Skin Distance, have an impact not only on the image quality and the radiation dose but even on the cancer risk.