Patient-specific dose estimation for pediatric abdomen-pelvis CT

Xiang Li; Ehsan Samei; W. Paul Segars; Gregory M. Sturgeon; James G. Colsher; Donald P. Frush

doi:10.1117/12.813531

27 February 2009 Patient-specific dose estimation for pediatric abdomen-pelvis CT

Xiang Li, Ehsan Samei, W. Paul Segars, Gregory M. Sturgeon, James G. Colsher, Donald P. Frush

Proceedings Volume 7258, Medical Imaging 2009: Physics of Medical Imaging; 725804 (2009) https://doi.org/10.1117/12.813531
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States

Abstract

The purpose of this study is to develop a method for estimating patient-specific dose from abdomen-pelvis CT examinations and to investigate dose variation across patients in the same weight group. Our study consisted of seven pediatric patients in the same weight/protocol group, for whom full-body computer models were previously created based on the patients' CT data obtained for clinical indications. Organ and effective dose of these patients from an abdomen-pelvis scan protocol (LightSpeed VCT scanner, 120-kVp, 85-90 mA, 0.4-s gantry rotation period, 1.375-pitch, 40-mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated for the same CT system. The seven patients had effective dose of 2.4-2.8 mSv, corresponding to normalized effective dose of 6.6-8.3 mSv/100mAs (coefficient of variation: 7.6%). Dose variations across the patients were small for large organs in the scan coverage (mean: 6.6%; range: 4.9%-9.2%), larger for small organs in the scan coverage (mean: 10.3%; range: 1.4%-15.6%), and the largest for organs partially or completely outside the scan coverage (mean: 14.8%; range: 5.7%-27.7%). Normalized effective dose correlated strongly with body weight (correlation coefficient: r = -0.94). Normalized dose to the kidney and the adrenal gland correlated strongly with mid-liver equivalent diameter (kidney: r = -0.97; adrenal glands: r = -0.98). Normalized dose to the small intestine correlated strongly with mid-intestine equivalent diameter (r = -0.97). These strong correlations suggest that patient-specific dose may be estimated for any other child in the same size group who undergoes the abdomen-pelvis scan.

Citation Download Citation

Xiang Li, Ehsan Samei, W. Paul Segars, Gregory M. Sturgeon, James G. Colsher, and Donald P. Frush "Patient-specific dose estimation for pediatric abdomen-pelvis CT", Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 725804 (27 February 2009); https://doi.org/10.1117/12.813531

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