Objectives
To evaluate the distribution of metal artifacts from the exomass in small field-of-view
(FOV) cone beam computed tomography (CBCT) scans.
Study Design
An image phantom was scanned by using 3 CBCT units. Metal objects were positioned
in the exomass, and additional CBCT scans were obtained. Mean gray values were obtained
from 16 homogeneous areas and the standard deviation was calculated to quantify gray
level inhomogeneity according to distinct zones of the FOV: total area and outer,
inner, right, left, and mid-zones. The discrepancy between each zone and the total
area was calculated to compare different CBCT units. Mean gray, gray level inhomogeneity,
and discrepancy values were separately assessed by using analysis of variance (ANOVA)
and Tukey's test (α = 0.05).
Results
Overall, the mean gray values were significantly lower in the inner zone, and the
gray level inhomogeneity values were significantly higher in the inner and mid-zones
irrespective of the presence of metal objects in the exomass. The 3 CBCT units presented
significantly different discrepancy values in most conditions.
Conclusions
The distribution of metal artifacts from the exomass follows the inherent gray value
dispersion of CBCT images, with greater inhomogeneity in the inner zone of the FOV.
This is exacerbated when metal objects are in the exomass.
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Article info
Publication history
Published online: February 10, 2020
Accepted:
January 10,
2020
Received in revised form:
December 11,
2019
Received:
October 19,
2019
Identification
Copyright
© 2020 Elsevier Inc. All rights reserved.
