Impact of contrast agents on organ dosimetry in paediatric diagnostic fluoroscopy: the upper gastrointestinal series

<i>Objective.</i>Barium and iodinated contrast media are ubiquitous with upper gastrointestinal (UGI) series examinations performed on paediatric patients. The present study quantifies the impact of contrast media on organ absorbed and detriment-weighted doses for UGI examinations.<i>Approach.</i>A paediatric radiologist and a medical physicist created reference imaging fields for four complete UGI series examinations encompassing the newborn and 1-year-old female for both normal and abnormal disease states. Monte Carlo radiation transport simulations were performed for these four cases, with and without contrast media, using the international commission on radiological protection's voxel-based reference computational phantoms.<i>Main results.</i>Estimates of detriment-weighted dose and absorbed doses to the colon, heart wall, kidneys, lungs, small intestine wall, spleen, stomach wall, thymus, thyroid, and remainder tissues are reported. For fields with contrast media the organ absorbed doses and detriment-weighted dose decreased by up to 50% and 26%, respectively, with the dose for the complete examination, i.e. not per field, decreasing by up to 26% for organs impacted by the presence of contrast media.<i>Significance.</i>Overall, relative doses were shown to decrease for simulations that included contrast media due to selective absorption of the x-ray beam by the contrast media. This study, however, did not investigate the effects of the automatic brightness control which could result in organ absorbed doses increasing due to compensation by the fluoroscopy machine when contrast media is present in the field.