Evaluation of the linear and volumetric measuring changes in different positions in CBCT.

Abstract

The effect of head position on reproducibility of volumetric measurements on Cone-beam computed tomography (CBCT) scans has not been evaluated before. Thus, this study aimed to assess the changes in linear and volumetric measurements on CBCT scans in different positions of the respective object. In this experimental study, 16 balls were placed in containers and underwent CBCT in neutral position and 8 different altered positions. The horizontal and vertical diameters of each ball were measured by OnDemand software while the volume of each ball was quantified by ITK-Snap software. The reproducibility of linear and volumetric measurements in nine different positions was analyzed by the Cronbach's α. Paired t-test was applied to analyze the difference in volumetric and linear measurements of the balls in the anterior and posterior halves of the scans in neutral position versus the upward and downward tilts, and right and left halves of the scans in neutral position versus the right and left tilts. The Cronbach's α was found to be .982 and .933 for volumetric and linear measurements, respectively, indicating high reproducibility of the measurements. No significant difference was noted in the mean linear measurements on CBCT scans at different positions compared with neutral position. In volumetric measurements, maximum difference between neutral and the other positions was less than 1%. CBCT is a reliable modality for linear and volumetric measurements in different positions.