Sw. Covino et al., THE ACCURACY OF MEASUREMENTS OF 3-DIMENSIONAL COMPUTED-TOMOGRAPHY RECONSTRUCTIONS, Journal of oral and maxillofacial surgery, 54(8), 1996, pp. 982-990
Purpose: The purpose of this study was to evaluate the accuracy and re
producibility of linear measurements obtained from three-dimensional r
econstructions of computed tomography (CT) scans. Materials ana Method
s: Ten rectangular acrylic blocks were prepared with titanium molybden
um alloy (TMA) markers spaced from 1 to IO mm, respectively. A plastic
sphere was prepared with 10 sets of TMA markers spaced at variable in
tervals of 1 to 10 mm, Each object was scanned three times at 3-mm sli
ce thicknesses and 1.5 mm with 0.5 mm overlap slice thicknesses, as we
ll as positioned in the GT scanner in two different directions (perpen
dicular and parallel) to the scanning beam. Intermarker distances of t
he reconstructed objects were then measured using the measurement tool
of the MediCAD software and compared with measurements taken by hand
with a vernier caliper. Results. Using the 3-mm cut protocol, the data
indicated that inconsistency exists between intermarker distance in t
he scans when the rectangular objects were scanned parallel to the sca
nning beam. This finding was not seen using the 1.5-mm with 0.5-mm ove
rlap slice thickness protocol, The intermarker distances for objects s
canned perpendicular to the scanning beam were consistent but subject
to demagnification in the range of 17% to 20% for both scanning protoc
ols, Conclusion: The orientation of the object to the scanning beam an
d slice thickness protocol appear to have an impact on the accuracy an
d variability of linear measurements taken in the x, y, z axes.