scholarly journals Impacts of Thresholds of Gray Value for Cone-Beam Computed Tomography 3D Reconstruction on the Accuracy of Image Matching with Optical Scan

2020 ◽  
Vol 17 (17) ◽  
pp. 6375 ◽  
Author(s):  
Se-Won Park ◽  
Ra Gyoung Yoon ◽  
Hyunwoo Lee ◽  
Heon-Jin Lee ◽  
Yong-Do Choi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Image Registration ◽  
3D Reconstruction ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Dental Arch ◽  
Arch Model ◽  
3D Mesh ◽  
Optical Scan ◽  
Reconstruction Model

In cone-beam computed tomography (CBCT), the minimum threshold of the gray value of segmentation is set to convert the CBCT images to the 3D mesh reconstruction model. This study aimed to assess the accuracy of image registration of optical scans to 3D CBCT reconstructions created by different thresholds of grey values of segmentation in partial edentulous jaw conditions. CBCT of a dentate jaw was reconstructed to 3D mesh models using three different thresholds of gray value (−500, 500, and 1500), and three partially edentulous models with different numbers of remaining teeth (4, 8, and 12) were made from each 3D reconstruction model. To merge CBCT and optical scan data, optical scan images were registered to respective 3D reconstruction CBCT images using a point-based best-fit algorithm. The accuracy of image registration was assessed by measuring the positional deviation between the matched 3D images. The Kruskal–Wallis test and a post hoc Mann–Whitney U test with Bonferroni correction were used to compare the results between groups (α = 0.05). The correlations between the experimental factors were calculated using the two-way analysis of variance test. The positional deviations were lowest with the threshold of 500, followed by the threshold of 1500, and then −500. A significant interaction was found between the threshold of gray values and the number of remaining teeth on the registration accuracy. The most significant deviation was observed in the arch model with four teeth reconstructed with a gray-value threshold of −500. The threshold for the gray value of CBCT segmentation affects the accuracy of image registration of optical scans to the 3D reconstruction model of CBCT. The appropriate gray value that can visualize the anatomical structure should be set, especially when few teeth remain in the dental arch.

scholarly journals Effects of Exposure Parameters and Voxel Size for Cone-Beam Computed Tomography on the Image Matching Accuracy with an Optical Dental Scan Image: An In Vitro Study

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Hang-Nga Mai ◽  
Du-Hyeong Lee
Keyword(s):  
Computed Tomography ◽  
Image Registration ◽  
Cone Beam Computed Tomography ◽  
Image Matching ◽  
Cone Beam ◽  
Matching Accuracy ◽  
Tube Voltage ◽  
Voxel Size ◽  
Optical Scan ◽  
Tube Current

This study is aimed at assessing the effects of exposure parameters and voxel size for cone-beam computed tomography (CBCT) on the image matching accuracy with an optical dental scan image. CBCT and optical scan images of a dry human mandible were obtained. Different CBCT settings were used: tube voltage, 60, 80, and 100 kVp; tube current, 6 and 8 mA; and voxel size, 100, 200, and 300 μm. Image matching between the CBCT and optical scan images was performed using implant planning software by dental professionals ( n = 18 ). The image matching accuracy in each combination of CBCT settings was evaluated by assessing the linear discrepancy between the three-dimensionally reconstructed radiological image and the registered optical scan image using an image analysis software program. The Kruskal-Wallis test and a post hoc Mann–Whitney U test with Bonferroni correction were used to compare the accuracy of image registration between the groups ( α = 0.05 ). Overall, the image matching accuracy was not significantly different between tube voltage and current settings; however, significantly higher image registration errors were found at the combination of 100 kVp tube voltage/8 mA tube current ( F = 8.44 , P < 0.001 ). Changes in voxel sizes did not significantly interfere with the image registration results. No interaction was found among voltage, current, and voxel size in terms of image registration accuracy ( F = 2.022 , P = 0.091 ). Different exposure parameter settings in tube voltage and tube current did not significantly influence the image matching accuracy between CBCT and optical dental scan images; however, a high radiation dose could be inappropriate. The image matching accuracy was not significantly affected by changing the voxel sizes of CBCT.

scholarly journals Cone Beam Computed Tomography 3D Reconstruction of the Mandibular Condyle

2008 ◽  
Vol 78 (5) ◽  
pp. 880-888 ◽  
Author(s):  
Brian Schlueter ◽  
Ki Beom Kim ◽  
Donald Oliver ◽  
Gus Sortiropoulos
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
3D Reconstruction ◽  
Cone Beam Computed Tomography ◽  
Three Dimensional ◽  
Mandibular Condyle ◽  
Cone Beam ◽  
Low Density ◽  
Mineral Density ◽  
Linear Measurements

Abstract Objective: To determine the ideal window level and width needed for cone beam computed three-dimensional (3D) reconstruction of the condyle. Materials and Methods: Linear dimensions were measured with a digital caliper to assess the anatomic truth for 50 dry human mandibular condyles. Condyles were scanned with the i-CAT cone beam computed tomography (CBCT) and 3D-models were reconstructed. Three linear three-dimensional measurements were made on each of the 50 condyles at 8 different Hounsfield unit (HU) windows. These measurements were compared with the anatomic truth. Volumetric measurements were also completed on all 50 condyles, at 23 different window levels, to define the volumetric distribution of bone mineral density (BMD) within the condyle. Results: Significant differences were found in two of the three linear measurement groups at and below the recommended viewing window for osseous structures. The most accurate measurements were made within the soft tissue range for HU window levels. Volumetric distribution measurements revealed that the condyles were mostly comprised of low-density bone, and that condyles exhibiting significant changes in linear measurements were shown to have higher percentages of low-density bone than those condyles with little change from the anatomic truth. Conclusions: CBCT assessment of the mandibular condyle, using the 3D reconstruction, is most accurate when accomplished at density levels below that recommended for osseous examination. However, utilizing lower window levels which extend into the soft tissue range, may compromise one's capacity to view the bony topography.

scholarly journals Analysis of the correlation between dental arch and articular eminence morphology: a cone beam computed tomography study

2017 ◽  
Vol 124 (4) ◽  
pp. 420-431 ◽  
Author(s):  
Francielle Silvestre Verner ◽  
Gina Delia Roque-Torres ◽  
Laura Ricardina Ramírez-Sotello ◽  
Karina Lopes Devito ◽  
Solange Maria Almeida
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Dental Arch ◽  
Articular Eminence

scholarly journals Comparison of Online 6 Degree-of-Freedom Image Registration of Varian TrueBeam Cone-Beam CT and BrainLab ExacTrac X-Ray for Intracranial Radiosurgery

2016 ◽  
Vol 16 (3) ◽  
pp. 339-343 ◽  
Author(s):  
Jun Li ◽  
Wenyin Shi ◽  
David Andrews ◽  
Maria Werner-Wasik ◽  
Bo Lu ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Image Registration ◽  
Cone Beam Computed Tomography ◽  
Residual Error ◽  
Degree Of Freedom ◽  
Cone Beam ◽  
Patient Study ◽  
X Ray ◽  
Average Residual ◽  
Image Registrations

Purpose: The study was aimed to compare online 6 degree-of-freedom image registrations of TrueBeam cone-beam computed tomography and BrainLab ExacTrac X-ray imaging systems for intracranial radiosurgery. Methods: Phantom and patient studies were performed on a Varian TrueBeam STx linear accelerator (version 2.5), which is integrated with a BrainLab ExacTrac imaging system (version 6.1.1). The phantom study was based on a Rando head phantom and was designed to evaluate isocenter location dependence of the image registrations. Ten isocenters at various locations representing clinical treatment sites were selected in the phantom. Cone-beam computed tomography and ExacTrac X-ray images were taken when the phantom was located at each isocenter. The patient study included 34 patients. Cone-beam computed tomography and ExacTrac X-ray images were taken at each patient’s treatment position. The 6 degree-of-freedom image registrations were performed on cone-beam computed tomography and ExacTrac, and residual errors calculated from cone-beam computed tomography and ExacTrac were compared. Results: In the phantom study, the average residual error differences (absolute values) between cone-beam computed tomography and ExacTrac image registrations were 0.17 ± 0.11 mm, 0.36 ± 0.20 mm, and 0.25 ± 0.11 mm in the vertical, longitudinal, and lateral directions, respectively. The average residual error differences in the rotation, roll, and pitch were 0.34° ± 0.08°, 0.13° ± 0.09°, and 0.12° ± 0.10°, respectively. In the patient study, the average residual error differences in the vertical, longitudinal, and lateral directions were 0.20 ± 0.16 mm, 0.30 ± 0.18 mm, 0.21 ± 0.18 mm, respectively. The average residual error differences in the rotation, roll, and pitch were 0.40°± 0.16°, 0.17° ± 0.13°, and 0.20° ± 0.14°, respectively. Overall, the average residual error differences were <0.4 mm in the translational directions and <0.5° in the rotational directions. ExacTrac X-ray image registration is comparable to TrueBeam cone-beam computed tomography image registration in intracranial treatments.

3D reconstruction images of cone beam computed tomography applied to maxillofacial fractures: A case study and mini review

2018 ◽  
Vol 26 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Liyun Bai ◽  
Linlin Li ◽  
Kexin Su ◽  
Anthony Bleyer ◽  
Yuanyuan Zhang ◽  
...  
Keyword(s):  
Computed Tomography ◽  
3D Reconstruction ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Maxillofacial Fractures

scholarly journals Cone-beam computed tomography for assessment of palatal displaced canine position: A methodological study

2013 ◽  
Vol 84 (3) ◽  
pp. 459-466 ◽  
Author(s):  
Julia Naoumova ◽  
Heidrun Kjellberg ◽  
Reet Palm
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Vertical Position ◽  
Dental Arch ◽  
Linear Measurements ◽  
Precise Position ◽  
Angular Measurements ◽  
Mean Differences ◽  
Intraexaminer Reliability

ABSTRACT Objective: To assess the inter- and intraexaminer reliability of a measurement method for evaluation of eruption angles and position of palatal displaced canines (PDCs) with cone-beam computed tomography (CBCT) images and to test the validity of the measured angles on a dry skull. Materials and Methods: Twenty patients (eight boys, 12 girls; age 11.4 ± 1.2 years) were randomly chosen among 67 patients from a study evaluating the interceptive effect of extracting the deciduous canine in children with PDCs. In total, 60 images were analyzed, because each patient had three CBCT examinations (baseline, 6-month control, and endpoint). Two observers assessed the following measurements twice: mesioangular and sagittal angle, vertical position, canine cusp tip, and canine apex to dental arch. The validity of the angular measurements was tested against angular measurements on a dry skull using mathematical formulations. Results: The inter- and intraexaminer mean differences for angular and linear measurements were all low and statistically insignificant (P &gt; .05). The mean differences between the physical and 3D measurements were 0.5 ± 0.39 mm for the sagittal angle and 0.22 ± 0.19 mm for the mesioangular angle. Conclusions: Linear and angular measurements on CBCT images are accurate and precise and can be used to assess the precise position of a PDC.

scholarly journals Volume measurement of mandibular teeth pulp chamber as a prediction tool of gender and ethnicity in a Brazilian population

2020 ◽  
Vol 24 (1) ◽  
Author(s):  
Karolina Aparecida Castilho Fardim ◽  
Eurico Oliveira Junior ◽  
Rafael Rodrigues ◽  
Elaine Araújo ◽  
João Pedro Gomes ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Dental Arch ◽  
P Value ◽  
Forensic Dentistry ◽  
Pulp Chamber ◽  
Dental Tissues ◽  
Chamber Volume ◽  
Volumetric Assessment

Objective: Forensic dentistry has used some methods for the human identification process. However, there is a need to study characteristics that are able to perform identification more specifically, increasing accuracy. Considering the role of dental arch assessment in prediction of gender and ethnicity, the purpose of this study was to assess the volume of pulp chamber as a mean to obtain new forensic evidence. Material and methods: For this task, 1.190 cone beam computed tomography (CBCT) images were retrospectively selected and subdivided according to the population number, gender, age and ethnicity. All DICOM files were imported to the open-source software ITK-SNAP® (http://www.itksnap.org/pmwiki/pmwiki.php). The segmentation process was performed in all pulp chamber aiming to obtain pulp tissue´s volume. Results: As a result, the pulp chamber volume of mandibular canine teeth showed to be larger in white population than in non-white (P-value = 0.003) and in male individuals in comparison with female (P-value = 0.038). Conclusion: These results, however, must be confirmed by future studies with a larger sample size and by the assessment of other variables, including texture analysis and density of dental tissues. KEYWORDS Cone beam computed tomography; Ethnicity; Forensic dentistry; Gender; Pulp chamber volume; Volumetric assessment.

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