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OP 61
Title
RELIAbILITy OF VOXEL GRAy VALuES IN CONE bEAM COMPuTED TOMOGRAPHy
Authors
A. PARSA 1 , N. IbRAHIM 1 , b. HASSAN 1 , A. MOTRONI 2 , P. VAN DER STELT 1 , D. WISMEIJER 3
Affiliations
1 Academic Center for Dentistry Amsterdam (ACTA)-Department of general and specialized
dentistry, Amsterdam, THE NETHERLANDS, 2 Applied Medical Imaging Research Group (AMIRG
), Milan, ITALY, 3 Academic Center for Dentistry Amsterdam (ACTA)-Department of oral implantology
and prosthodontics, Amsterdam, THE NETHERLANDS
Body
Objectives:The aim of this ex-vivo study was to assess the reliability of cone beam computed
tomography (CBCT) voxel gray values measurements using Hounsfield units (HU) derived from
multi-slice computed tomography (MSCT) as a clinical reference (gold) standard.
Methods: Ten partially edentulous human mandibular cadavers were scanned by two types of
CT modalities: multi-slice CT (Philips, Best, the Netherlands) and cone beam CT (NewTom 5G,
Verona, Italy). The analysis of the data was performed using 3Diagnosys software (v3.1,
3diemme, Italy). On MSCT scans, eight regions of interest (ROI) designating the site for
pre-operative implant placement were selected in each mandible. The datasets from both CT
systems were matched using a 3D registration algorithm. The mean voxel gray values of the
region around the implant sites were compared between MSCT and CBCT.
Results: Significant differences between the mean gray values obtained by CBCT and HU by
MSCT were found. In all the selected ROIs, CBCT showed higher mean values than MSCT. A
strong correlation (R=0.968) between mean voxel gray values of CBCT and mean HU of MSCT
was determined.
Conclusions: Voxel gray values from CBCT deviate from actual HU units. However, a strong
linear correlation exists, which may permit deriving actual HU units from CBCT using linear
regression models.
Keywords
Cone-Beam Computed Tomography, Bone Density, Dental Implants
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