An Image Quality-informed Framework for CT Characterization
Rebecca Smith-Bindman1, Sophronia Yu1, Yifei Wang1
1From the Department of Radiology and Biomedical Imaging (R.S.B., S.Y., Y.W., M.D.K., P.C., R.C., J.L., C.S.), Department of Epidemiology and Biostatistics (R.S.B., A.B.), Philip R. Lee Institute for Health Policy Studies (R.S.B., A.B.), and Department of Medicine (A.B.), University of California San Francisco (UCSF), UCSF Mission Bay Campus, Mission Hall: Global Health and Clinical Sciences Building, 550 16th St, 2nd Floor, Box 0560, San Francisco, CA 94158; Department of Demography, University of California Berkeley, Berkeley, Calif (R.C.); Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany (D.B.); Department of Radiology and Biomedical Imaging, University of California Irvine, Irvine, Calif (B.B.); UCSF Medical School, San Francisco, Calif (A.A.C.); Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY (B.D.); Seymour, Paul, and Gloria Milstein Division of Cardiology, Department of Medicine, and Department of Radiology, Columbia University Irving Medical Center and New York-Presbyterian Hospital, New York, NY (A.J.E.); Department of Radiology and Public Health Sciences, Henry Ford Health System, Detroit, Mich (M.F.); Department of Nuclear Engineering and Radiological Science, University of Michigan, Ann Arbor, Mich (M.F.); Department of Medicine and Pediatrics (P.R.) and Department of Radiology (J.A.S.), University of California Davis Health, Sacramento, Calif; and Department of Radiology, University of Washington, Seattle, WA (A.C.W.).
Abstract:
Background Lack of standardization in CT protocol choice contributes to radiation dose variation. Purpose To create a framework to assess radiation doses within broad CT categories defined according to body region and clinical imaging indication and to cluster indications according to the dose required for sufficient image quality. Materials and Methods This was a retrospective study using Digital Imaging and Communications in Medicine metadata. CT examinations in adults from January 1, 2016 to December 31, 2019 from the University of California San Francisco International CT Dose Registry were grouped into 19 categories according to body region and required radiation dose levels. Five body regions had a single dose range (ie, extremities, neck, thoracolumbar spine, combined chest and abdomen, and combined thoracolumbar spine). Five additional regions were subdivided according to dose. Head, chest, cardiac, and abdomen each had low, routine, and high dose categories; combined head and neck had routine and high dose categories. For each category, the median and 75th percentile (ie, diagnostic reference level [DRL]) were determined for dose-length product, and the variation in dose within categories versus across categories was calculated and compared using an analysis of variance. Relative median and DRL (95% CI) doses comparing high dose versus low dose categories were calculated. Results Among 4.5 million examinations, the median and DRL doses varied approximately 10 times between categories compared with between indications within categories. For head, chest, abdomen, and cardiac (3 266 546 examinations [72%]), the relative median doses were higher in examinations assigned to the high dose categories than in examinations assigned to the low dose categories, suggesting the assignment of indications to the broad categories is valid (head, 3.4-fold higher [95% CI: 3.4, 3.5]; chest, 9.6 [95% CI: 9.3, 10.0]; abdomen, 2.4 [95% CI: 2.4, 2.5]; and cardiac, 18.1 [95% CI: 17.7, 18.6]). Results were similar for DRL doses (all P < .001). Conclusion Broad categories based on image quality requirements are a suitable framework for simplifying radiation dose assessment, according to expected variation between and within categories. © RSNA, 2021 See also the editorial by Mahesh in this issue.
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