Cynthia H. McCollough PhD, Presenter: Research grant, Siemens AG Research grant, General Electric Company

Theresa A Branham, Abstract Co-Author: Nothing to Disclose

Vincent Herlihy MD, Abstract Co-Author: Nothing to Disclose

Krista M Bush MA, Abstract Co-Author: Nothing to Disclose

Mythreyi Bhargavan, Abstract Co-Author: Nothing to Disclose

Robert K. Zeman MD, Abstract Co-Author: Nothing to Disclose

LaVonne Robbins , Abstract Co-Author: Nothing to Disclose

Dianna Cody PhD, Abstract Co-Author: Speaker, Medical Technology Management Institute, Milwaukee, WI

J. Thomas Payne, Abstract Co-Author: Nothing to Disclose

Doug Pfieffer, Abstract Co-Author: Nothing to Disclose

Thomas Ruckdeschel, Abstract Co-Author: Nothing to Disclose

Michael F. McNitt-Gray PhD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To assess the distribution of Volume CTDI (CTDIvol) values reported by sites undergoing ACR CT accreditation between 2002 and 2004.

Weighted CTDI (CTDIw) doses were measured by sites applying for ACR CT accreditation. Exposure or air kerma measurements, total beam collimation, and chamber correction factors were recorded in a provided Excel spreadsheet and CTDI values automatically calculated. The typical acquisition parameters for a site's adult head (head), pediatric abdomen (ped), and adult abdomen (body) examinations were used to calculate CTDIvol. For the ped exam, sites were instructed to assume the size and weight of a typical 5 year old, and doses were measured using the 16-cm phantom. The average and std. dev. of valid doses were calculated by year. The % of scanners reporting CTDIw values above reference values (head:60 mGy, ped: 25 mGy, body: 35 mGy) were recorded. Histogram analysis was performed to determine 75th and 90th %tiles of CTDIvol in order to determine U.S. actionable and maximum-accreditable dose values which take into account pitch.

Between Sept. 2002 and Dec. 2004, 829 scanners underwent the accreditation process (178 in 2002, 396 in 2003, 255 in 2004). CTDIvol values (ave±std) were 66.7±23.5, 57.8±16.6, 54.6±13.3, 58.4±17.7 (head), 17.2±9.7, 15.9±8.6, 14.0±7.0, 15.5±8.4 (ped), and 18.7±8.0, 19.2±8.6, 17.0±7.6, 18.4±8.3 (body) for 2002, 2003, 2004, and 2002-2004, respectively. In every case except adult body exams in 2003, both the average dose and the std. dev. fell for each consecutive year. Similarly, the 75th and 90th %tile values and the % of units with doses over the reference levels consistently fell. In 2004, 22.4, 6.9, and 2.8% of sites reported doses above reference levels, compared to 49.0, 15.0, and 4.7% in 2002.

From 2002 to 2004, average Accreditation Program doses have decreased by 12.1, 3.2, and 1.7 mGy (20.1, 12.8, and 4.9% of the reference values) for head, ped, and body exams, respectively.

Since the inception of the ACR Accreditation program, we have observed a consistent lowering of average U.S. CT doses for head, body, and pediatric body exams.

McCollough, C, Branham, T, Herlihy, V, Bush, K, Bhargavan, M, Zeman, R, Robbins , L, Cody, D, Payne, J, Pfieffer, D, Ruckdeschel, T, McNitt-Gray, M, et al, , Radiation Doses from the ACR CT Accreditation Program: Review of Data Since Program Inception and Proposals for New Reference Values and Pass/Fail Limits.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4430455.html