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Proceedings Paper

Analysis of uncertainties in Monte Carlo simulated organ dose for chest CT
Author(s): John S. Muryn; Ashraf G. Morgan; W. Paul Segars; Chris L. Liptak; Frank F. Dong; Andrew N. Primak; Xiang Li
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Paper Abstract

In Monte Carlo simulation of organ dose for a chest CT scan, many input parameters are required (e.g., half-value layer of the x-ray energy spectrum, effective beam width, and anatomical coverage of the scan). The input parameter values are provided by the manufacturer, measured experimentally, or determined based on typical clinical practices. The goal of this study was to assess the uncertainties in Monte Carlo simulated organ dose as a result of using input parameter values that deviate from the truth (clinical reality). Organ dose from a chest CT scan was simulated for a standard-size female phantom using a set of reference input parameter values (treated as the truth). To emulate the situation in which the input parameter values used by the researcher may deviate from the truth, additional simulations were performed in which errors were purposefully introduced into the input parameter values, the effects of which on organ dose per CTDIvol were analyzed. Our study showed that when errors in half value layer were within ± 0.5 mm Al, the errors in organ dose per CTDIvol were less than 6%. Errors in effective beam width of up to 3 mm had negligible effect (< 2.5%) on organ dose. In contrast, when the assumed anatomical center of the patient deviated from the true anatomical center by 5 cm, organ dose errors of up to 20% were introduced. Lastly, when the assumed extra scan length was longer by 4 cm than the true value, dose errors of up to 160% were found. The results answer the important question: to what level of accuracy each input parameter needs to be determined in order to obtain accurate organ dose results.

Paper Details

Date Published: 18 March 2015
PDF: 11 pages
Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 941232 (18 March 2015); doi: 10.1117/12.2076067
Show Author Affiliations
John S. Muryn, Cleveland State Univ. (United States)
Ashraf G. Morgan, Cleveland State Univ. (United States)
Imaging Institute, The Cleveland Clinic (United States)
W. Paul Segars, Duke Univ. Medical Ctr. (United States)
Chris L. Liptak, Cleveland State Univ. (United States)
Frank F. Dong, Imaging Institute, The Cleveland Clinic (United States)
Andrew N. Primak, Siemens Medical Solutions USA, Inc. (United States)
Xiang Li, Cleveland State Univ. (United States)

Published in SPIE Proceedings Vol. 9412:
Medical Imaging 2015: Physics of Medical Imaging
Christoph Hoeschen; Despina Kontos, Editor(s)

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