Elizabeth H. Y. Du BA, BSc, Abstract Co-Author: Nothing to Disclose

Amdad Mustafa Ahmed MBCHB, FRCR, Abstract Co-Author: Nothing to Disclose

Savvas Nicolaou MD, Abstract Co-Author: Nothing to Disclose

Patrick McLaughlin FFR(RCSI), Presenter: Nothing to Disclose

Ultra-low-dose CT protocols at the authors’ institution result in a mean effective dose of 0.1 mSv, 0.2 mSv and 0.4 mSv in the chest, abdomen/thoracic spine and pelvis/lumbar spine, respectively. Similar exposure levels have been reported in the literature by McLaughlin et al. (Insights Imaging, Nov 2013) and Hanna et al. (J. Thorac. Cardiovasc. Surg., Jan 2014). We conducted a retrospective analysis of radiation exposure related to radiographic examinations of the chest, abdomen, thoracic spine, lumbar spine and pelvis in the ED of a level one trauma centre to determine the percentage of radiographs which exceeded mean exposure levels encountered at ultra-low-dose CT.

Ethics approval was obtained. A total of 1261 radiographic examinations were included in this study (255 chest, 252 abdominal, 251 thoracic spine, 251 lumbar spine and 252 pelvic). Dose area product values (DAP, dGy•cm2) for each image were obtained for all datasets, as was the examination indication and report findings. Individual DAPs were summed for multiple views to obtain a total DAP. Mean effective dose (MED, mSv) was calculated for each examination using published DAP-MED conversion factors (PA/lateral chest 0.012 mSv/dGy•cm2, AP chest 0.021 mSv/dGy•cm2, abdomen 0.026 mSv/dGy•cm2, thoracic spine 0.019 mSv/dGy•cm2, lumbar spine 0.021 mSv/dGy•cm2 and pelvis 0.029 mSv/dGy•cm2).

Mean and SD for the studies were: chest (0.061mSv, 0.107mSv), abdomen (1.025mSv, 1.152mSv), thoracic spine (1.124mSv, 1.045mSv), lumbar spine (1.074mSv, 1.087mSv) and pelvis (1.313mSv, 1.075mSv). MEDs for radiographs exceeded those for ultra-low-dose CT in 11% of chest, 96% of abdominal, 91% of thoracic spine, 81% of lumbar spine and 80% of pelvic examinations. Significant radiographic findings contributing to patient care were found in 32% of chest, 24% of abdominal, 22% of thoracic spine, 22% of lumbar spine and 35% of pelvic examinations.

This study demonstrates that a significant percentage of plain radiographs are performed at a greater radiation exposure than encountered in novel ultra-low-dose CT protocols, often with relatively low diagnostic yield. The context of our findings will be illustrated with clinical examples of ultra-low-dose CT images obtained in the ED at our institution.

We believe these findings will contribute to a paradigm shift as to how we best deliver ionizing radiation in the ED in future years.

Du, E, Ahmed, A, Nicolaou, S, McLaughlin, P, High-Dose Radiographic Examinations in the ED: Can We Justify Exposures in the Era of Ultra-Low-Dose CT?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14016637.html