Body composition determinants of radiation dose during abdominopelvic CT.

Objectives: We designed a prospective study to investigate the in-vivo relationship between abdominal body composition and radiation exposure to determine the strongest body composition predictor of dose length product (DLP) at CT.

Methods: Following institutional review board approval, quantitative analysis was performed prospectively on 239 consecutive patients who underwent abdominopelvic CT. DLP, BMI, volumes of abdominal adipose tissue, muscle, bone and solid organs were recorded.

Results: All measured body composition parameters correlated positively with DLP. Linear regression (R = 0.77) revealed that total adipose volume was the strongest predictor of radiation exposure [B (95% CI) = 0.027(0.024-0.030), t=23.068, p < 0.001]. Stepwise linear regression using DLP as the dependent and BMI and total adipose tissue as independent variables demonstrated that total adipose tissue is more predictive of DLP than BMI [B (95% CI) = 16.045 (11.337-20.752), t=6.681, p < 0.001].

Conclusions: The volume of adipose tissue was the strongest predictor of radiation exposure in our cohort.

Main Message: • Individual body composition variables correlate with DLP at abdominopelvic CT. • Total abdominal adipose tissue is the strongest predictor of radiation exposure. • Muscle volume is also a significant but weaker predictor of DLP.