Investigation of the effect of slice thickness and Kvp changes on the accuracy of linear measurements in CBCT: In vitro study

The accuracy of linear measurements in CBCT images is one of the critical parameters in treatment planning. Slice thickness and exposure parameters seem to affect the accuracy of linear measurements. In this study, we investigated the impact of the above factors on the accuracy of linear measurements in CBCT.

For the in vitro experiment, three dry human maxilla and mandibles were selected and the roots of their teeth were used as markers at the points of the anterior, premolars, and molars on both sides and placed in the desired locations. A digital caliper was used to measure its height and width prior to placement as the Gold Standard. For each location, the images were examined in slice thickness with dimensions of 0.5, 1, 2 and 3 mm and a kVp = 84 and a kVp = 90 and the results were then compared with Gold standard. The data were analyzed using the ANOVA test.

The results of this study showed that the effect of slice thickness, kvp, location and type of jaw were not significant for measuring the length of the marker (p>0.05) but about measuring the width of marker, in maxillary anterior and molar area and in mandibular premolar and molar area slice thickness was significant (p <0.05) and the effect of kVp was not significant (p >0.05). Similarly, the effects of slice thickness and kVp were also significant in the maxillary premolar area (p <0.05), whereas in the anterior mandibular area, the effect was not significant (p >0.05).

The accuracy of CBCT in measurement is very high although, for CBCT measurements to be as accurate as possible, it is desirable to use thinner slice thicknesses and higher voltages.