Does the amount of tagged stool and fluid significantly affect the radiation exposure in low-dose CT colonography performed with an automatic exposure control?

• Published in: European radiology Vol. 21; no. 2; pp. 345 - 352
• Main Authors: Lim, Hyun Kyong, Lee, Kyoung Ho, Kim, So Yeon, Kim, Kil Joong, Kim, Bohyoung, Lee, Hyunna, Park, Seong Ho, Yanof, Jeffrey H., Hwang, Seung-sik, Kim, Young Hoon
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-02-2011; Springer Nature B.V
• Subjects: Abdomen; Adult; Aged; Aged, 80 and over; Barium; Body Burden; Body Fluids - chemistry; Colonography, Computed Tomographic - statistics & numerical data; Colorectal cancer; Diagnostic Radiology; Drug dosages; Enema; Feces - chemistry; Female; Gastrointestinal; Humans; Imaging; Internal Medicine; Interventional Radiology; Iodine; Iodine Compounds; Male; Medicine; Medicine & Public Health; Middle Aged; Neuroradiology; Patients; Pharmaceuticals; Preventive medicine; Prostheses; Radiation; Radiation Dosage; Radiation Protection; Radiology; Radiometry - statistics & numerical data; Republic of Korea - epidemiology; Risk Assessment; Risk Factors; Ultrasound; Republic of Korea; United States > US; Tagging; Radiation dose; Automatic exposure control; CT colonography
• ISSN: 0938-7994; 1432-1084
• DOI: 10.1007/s00330-010-1922-4

Objective
To determine whether the amount of tagged stool and fluid significantly affects the radiation exposure in low-dose screening CT colonography performed with an automatic tube-current modulation technique.
Methods
The study included 311 patients. The tagging agent was barium (
n
 = 271) or iodine (
n
 = 40). Correlation was measured between mean volume CT dose index (
CTDI
vol
) and the estimated
x
-ray attenuation of the tagged stool and fluid (
ATT
). Multiple linear regression analyses were performed to determine the effect of
ATT
on
CTDI
vol
and the effect of
ATT
on image noise while adjusting for other variables including abdominal circumference.
Results
CTDI
vol
varied from 0.88 to 2.54 mGy. There was no significant correlation between
CTDI
vol
and
ATT
(
p
 = 0.61).
ATT
did not significantly affect
CTDI
vol
(
p
 = 0.93), while abdominal circumference was the only factor significantly affecting
CTDI
vol
(
p
 < 0.001). Image noise ranged from 59.5 to 64.1 HU. The
p
value for the regression model explaining the noise was 0.38.
Conclusion
The amount of stool and fluid tagging does not significantly affect radiation exposure.