Effect of Different Voxel Sizes on Accuracy of 2D and 3D Mandibular Linear Measurements Using CRANEX® 3D Cone Beam Computed Tomography Machine: Preclinical Study (original) (raw)
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Influence of voxel size on the accuracy of linear measurements taken in CBCT images
Clinical and Laboratorial Research in Dentistry, 2014
Cone-beam computed tomography (CBCT) has brought innovation to imaging examination methods, and has shown great potential in the maxillofacial area. The aim of this study was to evaluate the infl uence of different resolution values on the accuracy of linear measurements performed using a CBCT system. Methods: Seven pig mandibles were used in this study. Measurements were taken of the mesiodistal distance of the right and left fi rst molars. The mandibles were scanned using an iCAT CBCT apparatus and different voxel sizes, namely 0.125 and 0.25 mm. The images thus obtained were visualized using Xoran CT software, and the linear measurements were taken at different times by two examiners who used the software's electronic ruler. A digital caliper was used to perform the measurements on the anatomical specimens. The data were analyzed statistically. Results: The results indicated no statistically signifi cant difference between the measurements obtained by both examiners. As for the methods used in this study, no statistically signifi cant difference was observed between the measurements obtained with the digital caliper and those obtained using CBCT. Similarly, no signifi cant difference was observed between the measurements obtained using the different CBCT protocols. Conclusion: There is no signifi cant difference between linear measurements obtained from CBCT images with 0.125 or 0.25 mm voxel sizes. descrItores | Radiologia; Tomografi a Computadorizada de Feixe Cônico; Voxel.
Journal of applied oral science : revista FOB, 2014
The purpose of this study was to determine the accuracy and reliability of two methods of measurements of linear distances (multiplanar 2D and tridimensional reconstruction 3D) obtained from cone-beam computed tomography (CBCT) with different voxel sizes. Ten dry human mandibles were scanned at voxel sizes of 0.2 and 0.4 mm. Craniometric anatomical landmarks were identified twice by two independent operators on the multiplanar reconstructed and on volume rendering images that were generated by the software Dolphin®. Subsequently, physical measurements were performed using a digital caliper. Analysis of variance (ANOVA), intraclass correlation coefficient (ICC) and Bland-Altman were used for evaluating accuracy and reliability (p<0.05). Excellent intraobserver reliability and good to high precision interobserver reliability values were found for linear measurements from CBCT 3D and multiplanar images. Measurements performed on multiplanar reconstructed images were more accurate th...
Effect of voxel size on the accuracy of 3D reconstructions with cone beam CT
Dentomaxillofacial Radiology, 2012
Objectives: The various types of cone beam CT (CBCT) differ in several technical characteristics, notably their spatial resolution, which is defined by the acquisition voxel size. However, data are still lacking on the effects of voxel size on the metric accuracy of threedimensional (3D) reconstructions. This study was designed to assess the effect of isotropic voxel size on the 3D reconstruction accuracy and reproducibility of CBCT data. Methods: The study sample comprised 70 teeth (from the Institut d'Anatomie Normale, Strasbourg, France). The teeth were scanned with a KODAK 9500 3DH CBCT (Carestream Health, Inc., Marne-la-Vallée, France), which has two voxel sizes: 200 mm (CBCT 200 mm group) and 300 mm (CBCT 300 mm group). These teeth had also been scanned with the KODAK 9000 3DH CBCT (Carestream Health, Inc.) (CBCT 76 mm group) and the SCANCO Medical micro-CT XtremeCT (SCANCO Medical, Brü ttisellen, Switzerland) (micro-CT 41 mm group) considered as references. After semi-automatic segmentation with AMIRAH software (Visualization Sciences Group, Burlington, MA), tooth volumetric measurements were obtained. Results: The Bland-Altman method showed no difference in tooth volumes despite a slight underestimation for the CBCT 200 mm and 300 mm groups compared with the two reference groups. The underestimation was statistically significant for the volumetric measurements of the CBCT 300 mm group relative to the two reference groups (Passing-Bablok method). Conclusions: CBCT is not only a tool that helps in diagnosis and detection but it has the complementary advantage of being a measuring instrument, the accuracy of which appears connected to the size of the voxels. Future applications of such measurements with CBCT are discussed.
American Journal of Orthodontics and Dentofacial Orthopedics, 2010
Introduction: The aims of this study were to determine the linear accuracy of 3-dimensional surface models derived from a commercially available cone-beam computed tomography (CBCT) dental imaging system and volumetric rendering software and to investigate the influence of voxel resolution on the linear accuracy of CBCT surface models. Methods: Glass sphere markers were fixed on 10 dry mandibles. The mandibles were scanned with 0.40 and 0.25 voxel size resolutions in 3 sessions. Anatomic truth was established with 6 direct digital caliper measurements. The surface models were rendered by a volumetric rendering program, and the CBCT measurements were established as the mean of the 3 measurements. Results: The intraclass correlation coefficients between the physical measurements and the measurements of the CBCT images of 0.40 and 0.25 voxels were all more than 0.99. All CBCT measurements were accurate. There was no difference between the accuracy of the measurements between the 0.40 and 0.25 voxel size groups. The smallest detectable differences of the CBCT measurements were minimal, confirming the accuracy of the CBCT measurement procedure. Conclusions: The measurements on 3-dimensional surface models of 0.25 and 0.40 voxel size data sets made with the 3D eXam CBCT scanner (KaVo Dental GmbH, Bismarckring, Germany) and SimPlant Ortho Pro software (version 2.00, Materialise Dental, Leuven, Belgium) are accurate compared with direct caliper measurements. An increased voxel resolution did not result in greater accuracy of the surface model measurments.
Dentomaxillofacial Radiology, 2011
The aim of this study was to compare the linear and angular measurements made on two-dimensional (2D) conventional cephalometric images and three-dimensional (3D) cone beam CT (CBCT) generated cephalograms derived from a 3D volumetric rendering program. Methods: Pre-treatment cephalometric digital radiographs of 11 patients and their corresponding CBCT images were randomly selected. The digital cephalometric radiographs were traced using Vista Dent OC (GAC International, Inc Bohemia, NY) and by hand. CBCT and MaxilimH (Medicim, Sint-Niklass, Belgium) software were used to generate cephalograms from the CBCT data set that were then linked to the 3D hard-tissue surface representations. In total, 16 cephalometric landmarks were identified and 18 widely used measurements (11 linear and 7 angular) were performed by 2 independent observers. Intraobserver reliability was assessed by calculating intraclass correlation coefficients (ICC), interobserver reliability was assessed with Student t-test and analysis of variance (ANOVA). Mann-Whitney U-tests and Kruskal-Wallis H tests were also used to compare the three methods (P , 0.05). Results: The results demonstrated no statistically significant difference between interobserver analyses for CBCT-generated cephalograms (P , 0.05), except for Gonion-Menton (Go-Me) and Condylion-Gnathion (Co-Gn). Intraobserver examinations showed low ICCs, which was an indication of poor reproducibility for Go-Me and Sella-Nasion (S-N) in CBCTgenerated cephalograms and poor reproducibility for Articulare-Gonion (Ar-Go) in the 2D hand tracing method (P , 0.05). No statistical significance was found for Vista Dent OC measurements (P. 0.05). Conclusions: Measurements from in vivo CBCT-generated cephalograms from MaxilimH software were found to be similar to conventional images. Thus, owing to higher radiation exposure, CBCT examinations should only be used when the inherent 3D information could improve the outcome of treatment.
Accuracy of CBCT Measurements of a Human Skull
Journal of Digital Imaging, 2011
The purpose of this study is to assess the accuracy and reproducibility of cone-beam computed tomography (CBCT) measurements of a human dry skull by comparing them to direct digital caliper measurements. Heated gutta-percha was used to mark 13 specific distances on a human skull, and the distances were directly measured using a digital caliper and on CBCT images obtained with Iluma (3M Imtec, OK, USA) and 3D Accuitomo 170 (3D Accuitomo; J Morita Mfg. Corp., Kyoto, Japan) CBCT imaging systems. Iluma images were obtained at 120 kVp and 3.8 mA and reconstructed using voxel sizes of 0.2 and 0.3 mm 3 . Accuitomo images were obtained at 60 kVp and 2 mA and a voxel size of 0.250 mm 3 . In addition, 3-D reconstructions were produced from images obtained from both systems. All measurements were made independently by three trained observers and were repeated after an interval of 1 week. Agreement between observers and image type was assessed by calculating Pearson correlation coefficients, with a level of significance set at p<0.05. Pearson correlation coefficients between readings ranged from 0.995 to 1 for all image types. Correlations among observers were also very high, ranging from 0.992 to 1 for the first reading and from 0.992 to 1 for the second reading for the different image types. All CBCT image measurements were identical and highly correlated with digital caliper measurements. Accuracy of measurements of various distances on a human skull obtained from different CBCT units and image types is comparable to that of digital caliper measurements.
VALIDITY OF CONE BEAM COMPUTED TOMOGRAPHY VOXEL DENSITY VALUES: A REVIEW.
Introduction: voxel density value in CBCT is used regularly in many clinical aspects such as virtual implant planning. Many researchers studied factors affecting it and their significance. Most of the results obtained are contradicting and /or inconclusive. Objectives: to compile papers inquiring effect factors affecting voxel grey values and their significance. Methodology: internet search was done on two databases using MeSH terms. Resulting studies went through two level screening according to predetermined inclusion and exclusion criteria. Results: A total of 27 studies were included. Total number of factors, which were tested in the included papers, were eighteen. Conclusion:Significantly affecting factors are (FOV, mA, Objects position inside the FOV, Objects exo-mass, kVp, time between exposure, number of basis, adjacent air to the ROI).Insignificantly affecting factors are (exposure parameters, software, exposure dose, presence of teeth, presence of metallic post in or out the FOV). Inconclusive factors are (Machines model, voxel size, objects mass, receptor type, exposure time). Grey levels in CBCT which is known by Hounsfield Unit of CBCT is not reliable nor repeatable.