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Estimating Thyroid Doses From Modified Barium Swallow Studies

Bonilha, Heather Shaw1,2; Wilmskoetter, Janina1; Tipnis, Sameer V.3; Martin-Harris, Bonnie4; Huda, Walter5

doi: 10.1097/HP.0000000000000890

This study sought to obtain factors to convert entrance air kerma into thyroid doses for patients undergoing modified barium swallow studies. A commercial software package (PCXMC 2.0.1) was used to calculate patient thyroid doses from modified barium swallow studies, which were divided by the entrance air kerma to yield f thyroid ratios. Exposure in the lateral and posterior-anterior projections were considered where the thyroid was directly irradiated. Calculations were obtained for adult patients as well as children ranging from birth to 10 y old. The average value of f thyroid in a normal-sized adult was 0.63 ± 0.11 in the lateral projection and 0.18 ± 0.06 for an upper gastrointestinal posterior-anterior projection. Increasing the beam quality from the lowest (60 kV + 3 mm aluminum) to the highest (110 kV + 3 mm aluminum + 0.2 mm copper) values investigated nearly doubled the value of f thyroid from 0.42 to 0.79 in the lateral projection and quadrupled the value from 0.07 to 0.29 in the upper gastrointestinal posterior-anterior projection. Values of f thyroid decreased with increasing body mass index. Average values of f thyroid in 10 y olds were similar to those of adults but always increased as the age of the exposed child was reduced. The average f thyroid for newborns was 0.84, nearly one-third higher than the corresponding ratio for normal-sized adults.

1Health Sciences and Research, Medical University of South Carolina, 77 President Street, MSC 700, Charleston, SC 29425-2503;

2Department of Otolaryngology—Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425;

3Department of Radiology and Radiological Science, Medical University of South Carolina, 96 Jonathan Lucas Street, MSC 323, Charleston, SC 29425-3230;

4Communication Sciences and Disorders, Northwestern University, 70 Arts Circle Drive, Evanston, IL 60208;

5Department of Radiology, Dartmouth-Hitchcock Medical Center, 1 Medical Center Drive, Lebanon, NH 03766.

The authors declare no conflicts of interest.

For correspondence contact: Heather Shaw Bonilha, 77 President Street, MSC 700, Charleston, SC 29425, or email at

(Manuscript accepted 9 March 2018)

© 2018 by the Health Physics Society