Anum Sohail Minhas BS, Presenter: Nothing to Disclose

Olav Christianson, Abstract Co-Author: Nothing to Disclose

Donald P. Frush MD, Abstract Co-Author: Nothing to Disclose

Ehsan Samei PhD, Abstract Co-Author: Research Grant, Siemens AG Research Grant, General Electric Company Research Grant, Carestream Health, Inc Consultant, KUB Technologies, Inc

To determine the effect of an automated method to determine patient size in radiation dose estimation for pediatric body CT  

We retrospectively reviewed a CT database with all pediatric body scans performed at an academic medical center from 2007-2011 for patients under 18 years of age and randomly selected 150 examinations (50.0% male/female split) divided evenly between chest, abdomen, and abdomen/pelvis (50 scans each). These three groups were then further divided and analyzed by the following age groups: 0-<3, 3-<7, 7-<11, 11-<15, and 15-<18 years. Data was then generated using a fully automated investigational, institutionally developed and validated software program for SSDE determination (AAPM TG 204) whichuses patient dimensions obtained from the topogram. Conventional CTDI (also automatically retrieved using optical reader technology) and the SSDE modification of this CTDI were compared using statistical analysis including t-test.        

SSDE was greater than CTDI by 36% for body imaging when all age groups were combined. For all age groups and all three scan types SSDE was significantly greater than CTDI (p<0.001). Notably, this increase was greatest at younger ages and trended down as age increased (67% for 0-2 years, 45% for 3-6 years, 64% for 7-10 years, 35% for 11-14 years, and 20% for 15-17 years). SSDE was also highest compared to CTDI for abdominal imaging (51% increase) and lowest for abdominal/pelvis imaging (23% increase).

An automated method for SSDE determination based on the CT topogram provides a simple and effective method for calculating SSDE. This methodology can be applied to institutional or more broad registries for pediatric CT. Use of this method confirms that patient size is important in dose estimation and as predicted, there are greater discrepancies with traditional CTDI estimations at the younger ages (older children and teenagers are more accurately represented by traditional CTDI 32cm and 16cm methods). Dose estimation discrepancies are the greatest using SSDE for abdominal imaging and lowest for abdominal/pelvis imaging. These results can help establish more accurate diagnostic or performance reference levels, and can serve for institutional quality assurance and improvement roles.

Results using an automated SSDE determination provide more accurate and facile radiation dose estimations and reference ranges for pediatric body CT.

Minhas, A, Christianson, O, Frush, D, Samei, E, Radiation Dose-monitoring for Pediatric Body CT Comparing Traditional CTDI and Automated SSDE Methodology.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12030970.html