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U.S. Diagnostic Reference Levels and Achievable Doses for 10 Adult CT Examinations

Kalpana M. Kanal, PhD, FACR, FAAPM, FSCBTMR, University of Washington, Seattle, WA
Priscilla F. Butler, MS, FACR, FAAPM, American College of Radiology, Reston, VA
Updated November 2017 | Download PDF

Using data from the American College of Radiology’s Dose Index Registry, the world’s largest registry of dose information, Kanal et al have established U.S. national dose levels for the 10 most common adult CT examinations based on patient size. The study establishes patient-size based diagnostic reference levels (DRLs) and achievable doses (ADs) for the 10 most common CT head, neck and body examinations. A summary table of ADs and DRLs for median size patients is presented below. Except for head and brain without contrast, all exams used water-equivalent diameter as an indicator of patient size. For head and brain without contrast, lateral thickness was used.

Healthcare facilities can use this information to effectively compare their patient doses to national benchmarks, optimize their exam protocols so that dose is commensurate with the size of the patient, and help avoid unnecessary radiation exposure.


  1. Kanal KM, Butler PF, Sengupta D, et al. U.S. Diagnostic Reference Levels and Achievable Doses for 10 Adult CT Examinations, Radiology 2017;284(1):120–133.

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