Organ dose assessment in pediatric fluoroscopy and CT via a tomographic computational phantom of the newborn patient

Of the various types of imaging modalities used in pediatric radiology, fluoroscopy and computed tomography (CT) have the highest associated radiation dose. While these examinations are commonly used for pediatric patients, little data exists on the magnitude of the organ and effective dose values for these procedures. Calculation of these dose values is necessary because of children's increased sensitivity to radiation and their long life expectancy for which to express radiation's latent effects. In this study, a newborn tomographic phantom has been implemented in a radiation transport code to evaluate organ and effective doses for newborn patients in commonly performed fluoroscopy and CT examinations.; Organ doses were evaluated for voiding cystourethrogram (VCUG) fluoroscopy studies of infant patients. Time-sequence analysis was performed for videotaped VCUG studies of five different patients. Organ dose values were then estimated for each patient through Monte Carlo (MC) simulations. The effective dose values of the VCUG examination for five patients ranged from 0.6 mSv to 3.2 mSv, with a mean of 1.8 +/- 0.9 mSv. Organ doses were also assessed for infant upper gastrointestinal (UGI) fluoroscopy exams. The effective dose values of the UGI examinations for five patients ranged from 1.05 mSv to 5.92 mSv, with a mean of 2.90 +/- 1.97 mSv.; MC simulations of helical multislice CT (MSCT) exams were also completed using, the newborn tomographic phantom and a stylized newborn phantom. The helical path of the source, beam shaping filter, beam profile, patient table, were all included in the MC simulations of the helical MSCT scanner. Organ doses and effective doses and their dependence on scan parameters were evaluated for newborn patients. For all CT scans, the effective dose was found to range approximately 1-13 mSv, with the largest values occurring for CAP scans. Tube current modulation strategies to reduce patient dose were also evaluated for newborn patients.; Overall, utilization of the newborn tomographic phantom in MC simulations has shown the need for and usefulness of pediatric tomographic phantoms. The newborn tomographic model has shown more versatility and realistic anatomical modeling when compared to the existing stylized newborn phantom. This work has provided important organ dose data for infant patients in common examinations in pediatric radiology.