Aims and objectives
Nowadays the radiation burden of the population is mostly an estimation based on general conversion factors (e.g.
from Dose Area Product to effective dose) for a reference normal sized patient.
However the prevalence of obesity nearly tripled since 1975 [1] and in 2008 over 50% of the European populationwas overweight [2].
The aim of this study was to examine the effect of Body Mass Index (BMI) and Water Equivalent Diameter (WED) on organ dose conversion factors in the case of conventional chest Posterior-Anterior (PA) radiology...
Methods and materials
In this study,
we have calculated dose conversion factors from voxel models made from the Computed Tomography (CT) scan of patients.
We opted for total body CT scans,
such that all organs of importance can theoretically be included in the study,
even though the current focus was chest PA imaging.
Voxel phantoms: Forty patients (20 female,
20 male) of different Body Mass Index (BMI),
who underwent a CT exam from head to thighs,
were selected.
The Water Equivalent Diameter (WED) [3] of every patient was...
Results
The BMI and WED of the selected patients are shown in a boxplot inFig. 3.All evaluated conversion factors were normally distributed according to the D'Agostino & Pearson omnibus normality test.
Significant linear correlations were observed between the dose conversion factors and BMI,
respectively WED,
for both genders for the red bone marrow(Fig. 4),lung(Fig. 5),heart(Fig. 6)and breast(Fig. 7).
The p-values are shown in Table 1.The conversion factors are decreasing with increasing BMI and WED (Fig. 4,
Fig. 5,Fig. 6,
Fig. 7).This can be explained by the...
Conclusion
The body size,
in terms of BMI or WED,
has an influence on the dose conversion factors of a conventional chest PA examination for the organs in the field of view,
except for the thyroid.
Other studies found similar results regarding the influence of the BMI or weight [6-8].
Using the automatic exposure control (AEC) during a radiological examination will increase the exposure of overweight patients to maintain sufficient image quality.
However our study showed that the organ dose conversion factors decrease with increasing patient...
Personal information
An Dedulle
Qaelum NV
Department of Imaging and Pathology,
University of Leuven
The PhD research of An Dedulle is supported by the Flanders Innovation & Entrepreneurship agency [grant number HBC.2016.0233].
The work was conducted in cooperation with Qaelum and the University of Leuven.
Gaston Geenslaan 9
3001 Leuven,
Belgium
e-mail:
[email protected]
References
1.
http://www.who.int/mediacentre/factsheets/fs311/en/,
accessed on 13/12/2017
2.
http://www.euro.who.int/en/health-topics/noncommunicable-diseases/obesity/data-and-statistics,
accessed on 13/12/2017
3.
Use of Water Equivalent Diameter for Calculating Patient Size and Size-Specific Dose estimates (SSDE) in CT,
AAMP task group 220.
American Association of Physicists in Medicine, 2014
4.
Zhang,
G.; Pauwels,
R.; Marshall,
N.; Shaheen,
E.; Nuyts,
J.; Jacobs,
R.
& Bosmans,
H.
Development and validation of a hybrid simulation technique for cone beam CT: application to an oral imaging system.
Physics in Medicine and Biology, 2011,
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Zhang,
G.; Marshall,
N.;...
