Pediatric Radiology
November 2015, Volume 45, Issue 12, pp 1771-1780
First online: 04 July 2015
Patient-specific dose calculations for pediatric CT of the chest, abdomen and pelvis
Susan D. Kost , Nicholas D. Fraser, Diana E. Carver
, David R. Pickens, Ronald R. Price,Marta Hernanz-Schulman
, Michael G. Stabin
Abstract
Background
Organ dose is essential for accurate estimates of patient dose from CT.
Objective
To determine organ doses from a broad range of pediatric patients undergoing diagnostic chest–abdomen–pelvis CT and investigate how these relate to patient size.
Materials and methods
We used a previously validated Monte Carlo simulation model of a Philips Brilliance 64 multi-detector CT scanner (Philips Healthcare, Best, The Netherlands) to calculate organ doses for 40 pediatric patients (M:F = 21:19; range 0.6–17 years). Organ volumes and positions were determined from the images using standard segmentation techniques. Non-linear regression was performed to determine the relationship between volume CT dose index (CTDIvol)-normalized organ doses and abdominopelvic diameter. We then compared results with values obtained from independent studies.
Results
We found that CTDIvol-normalized organ dose correlated strongly with exponentially decreasing abdominopelvic diameter (R2 > 0.8 for most organs). A similar relationship was determined for effective dose when normalized by dose-length product (R2 = 0.95). Our results agreed with previous studies within 12% using similar scan parameters (e.g., bowtie filter size, beam collimation); however results varied up to 25% when compared to studies using different bowtie filters.
Conclusion
Our study determined that organ doses can be estimated from measurements of patient size, namely body diameter, and CTDIvol prior to CT examination. This information provides an improved method for patient dose estimation.