The effect of voxel size on the measurement of mandibular thickness in cone-beam computed tomography

Abstract

Background: Cone-beam computed tomography (CBCT) is a new imaging technology that has
been widely used in implantology, oral and maxillofacial surgery and orthodontics. This method
provides 3-D images that are composed of voxel, which is the smallest image unit, and determines
image resolution. Smaller voxel is associated with the higher resolution and also greater radiation
exposure. This study was aimed to fi nd out the effect of voxel size on the measurement of
mandibular thickness.
Materials and Methods: Using voxel sizes of 0.30 mm and 0.15 mm, two CBCT protocols
(protocol 1: Field of view (FOV) of 15 cm, 85 kVp, 42 mAs, 0.15 mm voxel, 14 s scan time; protocol
2: FOV of 15 cm, 85 kVp, 10 mAs, 0.30 mm voxel, 14 s scan time) were carried out on 16 dry
human mandibles with permanent dentition. Mandibular thickness was measured at seven different
sites (midline region, bilateral canine regions, bilateral mental foramen regions and bilateral molar
regions). Analysis of variance was used for analysis of data using the Statistical Package for the Social
Sciences version 20 (SPSS Inc., Chicago, IL, USA). P < 0.05 considered to be statistically signifi cant.
Results: No statistically signifi cant differences were found between different protocols regarding
the mandibular thickness (P > 0.05).
Conclusion: Considering the insignifi cant differences of the mandibular thickness measurements
using different voxel sizes, it would be more reasonable to use 0.30 mm voxel size instead of
0.15 mm voxel size to avoid unnecessary radiation exposure.
Key Words: Cone-beam computed tomography, mandible, voxel