Body composition determinants of radiation dose during abdominopelvic CT
Body composition determinants of radiation dose during abdominopelvic CT
Patrick D. McLaughlin 0 1 3 5 6
Liam Chawke 0 1 3 5 6
Maria Twomey 0 1 3 5 6
Kevin P. Murphy 0 1 3 5 6
Siobhán B. O'Neill 0 1 3 5 6
Sebastian R. McWilliams 0 1 3 5 6
Karl James 0 1 3 5 6
Richard G. Kavanagh 0 1 3 5 6
Charles Sullivan 0 1 3 5 6
Faimee E. Chan 0 1 3 5 6
Niamh Moore 0 1 3 5 6
Owen J. O'Connor 0 1 3 5 6
Joseph A. Eustace 0 1 3 5 6
Michael M. Maher 0 1 3 5 6
0 Department of Radiology, Cork University Hospital , Wilton, Cork , Ireland
1 Department of Radiology, University College Cork , Cork , Ireland
2 3350-950 West 10th Ave , Vancouver, BC V5Z 1M9 , Canada
3 Department of Emergency and Trauma Radiology, Vancouver General Hospital , Jim Pattison Pavilion North
4 Richard G. Kavanagh
5 Health Research Board Clinical Research Facility, University College Cork , Cork , Ireland
6 Department of Nephrology, Cork University Hospital , Cork , Ireland
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 (R2 = 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 (11.33720.752), t=6.681, p < 0.001]. Conclusions The volume of adipose tissue was the strongest predictor of radiation exposure in our cohort.
Tomography; X-ray computed; Radiation dosage; Intra-abdominal fat; Muscle; Skeletal; Body mass index
Introduction
At present there is a considerable research and industry drive
to reduce the radiation dose during CT scanning while
preserving image quality and diagnostic accuracy. To date, CT
dose reduction technology including automated tube current
modulation and iterative reconstruction have facilitated
reductions in CT dose to levels approximately 70–75% less than
what they were a decade ago. Larger reductions in dose are
conceivable with continued research and development and
more recent advances in CT technology have facilitated
significant dose reductions without sacrificing image quality
[
1–3
].
Differences in patient size and body weight challenge the
pathways of CT dose reduction. It is well recognised that
patients with a larger body habitus are exposed to significantly
larger doses of ionising radiation during abdominopelvic CT
when automated tube current modulation (ATCM) is
employed [
4–7
]. Previous studies have examined the
influence of variables such as body weight [6], body mass index
[
4
], patient cross-sectional area [
5, 7
] and patient AP diameter
[8] on imparted dose during abdominopelvic CT with ATCM.
However, the abdominal compartment houses many structures
of varying volume and density, which impact these indices.
These constituents include the solid abdominal organs, soft
tissue structures such as abdominal musculature and adipose
tissue and bony structures such as the lumbar spine and pelvis.
These structures all contribute to patient body weight, body
mass index and cross-sectional area and are therefore also
likely to contribute individually to the imparted dose during
abdominopelvic CT. Although one previous study found
an association between subjectively graded quantities of
abdominal fat and effective dose [
9
], we found no study
that has investigated the in-vivo relationship between
multiple abdominal body composition variables and radiation
dose during CT with ATCM. The authors believe that
further investigation of such factors, which may significantly
differ among individuals of similar weight, cross-sectional
area and BMI [
10
], may guide future methods of dose
optimisation in abdominopelvic CT and may allow
radiologists to refine examination technique and ATCM protocol
particularly in obese patients.
We therefore designed a prospective, cross-sectional study
with the following aims:
(1) To identify the body composition determinants of an
elevated dose length product during abdominopelvic CT.
(2) To determine which of the following parameters is the
strongest predictor of radiation dose at CT:
&
&
&
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Total abdominopelvic adipose tissue volume
Abdominopelvic muscle volume
Abdominopelvic bone volume
Solid organ volumes
Materials and methods
Following institutional review board approval, 239
consecutive patients who were referred for clinically indicated
a (...truncated)