Analysis of linear measurement accuracy obtained by cone beam computed tomography (CBCT-NewTom VG)

Abstract

Objectives: the aim of this study was to evaluate linear measurement accuracy of CBCT Newtom VG (Quantitative Radiology, Verona, Italy) in vitro. CBCT is dedicated to dental and Maxillofacial imaging particularly for surgical and prosthetics implant planning in dentistry. Linear measurement accuracy is important in selection of implant type , size , orientation and number of implants.

Materials and methods: 22 anatomic landmarks in 4 dry skulls were marked by gutta – percha. 15 linear measurements were obtained using a digital caliper. These were considered as real measurements. Skulls were scanned at two settings: (a) voxel size 0.3mm (b) voxel size 0.15 mm High Resolution (HR). Radiographic distance measurement were made using the NNT viewer software in axial and coronal sections by three observers. The data were compared by mean difference, standard deviation and Intraclass Correlation Coefficient (ICC).

Results: Mean difference of real and radiographic measurements was -0.10 0.99 mm in axial sections,  -0.271.07 mm in coronal sections, +0.14 1.44mm in axial (HR) sections, 0.02 1.4mm in coronal (HR) sections. The ICC for CBCT measurements in axial sections was 0.9944, coronal sections 09941, axial (HR) sections 0.9935, coronal (HR) sections 0.9937. Statistical analysis showed high interobserver and intraobserver reliability.

Conclusions: CBCT is reliable in linear measurement in different image planes in maxillofacial area. Voxel size has no effect on accuracy of linear measurements, so by reducing radiation dose we can have images with the same dimensional accuracy.

Keywords: Cone Beam CT, Accuracy, Skull, Linear measurement