Xiang Li PhD, Presenter: 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

William Paul Segars PhD, Abstract Co-Author: Nothing to Disclose

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

To assess the dependence of organ dose and effective dose on body size (anteroposterior distance, truncal height, and weight) in pediatric chest radiography.

The study consisted of 42 pediatric patients (0-15 y.o.), for whom full-body computational models were created based on the patients’ clinical CT examinations. A Monte Carlo program was developed to simulate the organ dose received by each patient from an anteroposterior (AP) chest radiography examination taken in supine position on an x-ray examination table at 80 kVp and 100-cm source-to-image distance. Organ dose estimates were used to calculate effective dose. In-air dose was also estimated and multiplied by the area of the x-ray beam to obtain dose-area product (DAP). Organ dose and effective dose were normalized by DAP and correlated to several body size metrics (anteroposterior distance, truncal height, and weight) using nonlinear regress analysis.

For organs inside the primary radiation beam, DAP-normalized organ dose correlated strongly with AP distance and decreased with it following power-law relationships (correlation coefficient: r = -0.91, -0.95, -0.96 for breasts, lungs, and esophagus). For organs partially or completely outside of the primary radiation beam, similar relationships were found between DAP-normalized organ dose and truncal height (r = -0.93, -0.69, -0.97 for liver, stomach, and bladder), an indicator of the distances of these organs to the primary radiation field. For distributed organs, body weight correlated most strongly with DAP-normalized organ dose (r = -0.96, -0.98 for red marrow and bone surface). DAP-normalized effective dose also correlated most strongly with body weight (r = -0.98).

In pediatric chest radiography, organ dose and effective dose, when normalized by DAP, decrease with increasing patient size following power-law relationships, suggesting the feasibility of estimating patient-specific organ dose and cohort-specific effective dose based on simple body size measurements.

Digital radiography systems store DAP values in DICOM reports. DAP may be used together with body size measurements to estimate organ dose to facilitate dose monitoring and technique optimization.

Li, X, Samei, E, Segars, W, Frush, D, Pediatric Chest Radiography: Dependence of Organ Dose and Effective Dose on Body Size.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12026914.html