PURPOSE: We designed the aft-multiple-slit (AMS) system to reduce scatter in cone-beam computed tomography (CBCT). As a preliminary study, we performed a Monte Carlo N-Particle Transport Code (MCNP) simulation to verify the effectiveness of this system. MATERIALS AND METHODS: The MCNPX code was used to build the AMS geometry. An AMS is an equi-angled arc to consider beam divergence. The scatter-reduced projection images were compared with the primary images only and the primary plus scatter radiation images with and without AMS to evaluate the effectiveness of scatter reduction. To obtain the full 2 dimensional (2D) projection image, the whole AMS system was moved to obtain closed septa of the AMS after the first image acquisition. RESULTS: The primary radiation with and without AMS is identical to all the slit widths, but the profiles of the primary plus scattered radiation varied according to the slit widths in the 2D projection image. The average scatter reduction factors were 29%, 15%, 9%, and 8% when the slit widths were 5 mm, 10 mm, 15 mm, and 20 mm, respectively. CONCLUSION: We have evaluated the scatter reduction effect of the AMS in CBCT imaging using the Monte Carlo (MC) simulations. A preliminary study based on the MCNP simulations showed a mount of scatter reduction with the proposed system.
Cone-Beam Computed Tomography

OBJECTIVE: CBCT has become popular for orthodontic diagnosis and treatment planning in recent times. The 3D pharyngeal airway space needs to be analysed using a 3D diagnostic tool. The aim of this study was to analyse the pharyngeal airway of different craniofacial morphology using CBCT. METHODS: The sample compromised 102 subjects divided into 3 groups (Class I, II, III) and 6 subgroups according to normal or vertical craniofacial patterns. All samples had CBCT (VCT, Vatech, Seoul, Korea) taken for orthodontic treatment. The pharyngeal airway was assessed according to the reference planes: aa plane (the most anterior point on the anterior arch of atlas), CV2 plane, and CV3 plane (most infero-anterior point on the body of the second & third cervical vertebra). The intergroup comparison was performed with one-way ANOVA and duncan test as a second step. RESULTS: The results showed the pharyngeal airway and anteroposterior width of group 2 (Class II) in aa plane, CV2 plane, CV3 plane were significant narrower than in group 3 (Class III). There was no significant difference between vertical and normal craniofacial patterns except for the anteroposterior pharyngeal width of Group 1 (Class I) in aa plane. CONCLUSIONS: Subjects with Class II patterns have a significantly narrower pharyngeal airway than those with Class III. However there was no difference in pharyngeal airway between vertical and normal craniofacial morphology.
Cone-Beam Computed Tomography

PURPOSE: To determine the accuracy of automated computer aided volumetry for simulated small pulmonary nodules at computed tomography using various types of phantoms MATERIALS AND METHODS: Three sets of synthetic nodules (small, calcified and those adjacent to vessels) were studied. The volume of the nodules in each set was already known, and using multi-slice CT, volumetric data for each nodule was acquired from the three-dimensional reconstructed image. The volume was calculated by applying three different threshold values using Rapidia(R) software (3D-Med, Seoul, Korea). RESULTS: Relative errors in the measured volume of synthetic pulmonary nodules were 17.3, 2.9, and 11.5% at -200, -400, and -600 HU, respectively, and there was good correlation between true volume and measured volume at -400 HU (r=0.96, p<0.001). For calcified nodules, relative errors in measured volume were 10.9, 5.3, and 16.5% at -200, -400, and -600 HU, respectively, and there was good correlation between true volume and measured volume at -400 HU (r=1.03, p<0.001). In cases involving synthetic nodules adjacent to vessels, relative errors were 4.6, 16.3, and 31.2 % at -200, -400, and -600 HU, respectively. There was good correlation between true volume and measured volume at -200 HU (r=1.1, p<0.001). CONCLUSION: Using computer-aided volumetry, the measured volumes of synthetic nodules correlated closely with their true volume. Measured volumes were the same at each threshold level, regardless of window setting.
Cone-Beam Computed Tomography ; Seoul

No abstract available.
Cone-Beam Computed Tomography* ; Dentistry*

Cone-Beam Computed Tomography ; Humans

ABSTRACT The main objective of this study was to ascertain and characterise different articles published in the field of dentistry based on cone beam computed tomography (CBCT) imaging technique. The search was performed using Scopus database to generate publications relevant to usage of CBCT in relation to dentistry. Additional data comprising of citation information, bibliographic information, abstract, keywords and other information was also included. Bibliometric pointers such as citation and documents, authors, journals and keywords were also investigated. About 411 research papers were available from 2004 and 2020 and were further analysed using VOSviewer 1.6.15. A gradual increase in the number of publications can be seen, however in 2018, highest number of papers was published. USA, Turkey and Brazil were the topmost countries making substantial contributions. The most productive organisation was University of Michigan School of Dentistry, USA. Journal of Dentomaxillofacial Radiology was the most preferred journals by authors. This is one of first bibliometric analysis that aims to identify different research articles published in the field of dentistry that focused on CBCT. This study will be helpful to the investigators who have just started CBCT based research by providing them with a general insight regarding research tendency along with source of possible associations among different authors and countries.
Bibliometrics ; Cone-Beam Computed Tomography

Assessing the condition of the alveolar bone before and after orthodontic treatment is important. Recently, cone-beam computed tomography has been widely accepted as a useful tool for orthodontic treatment. Moreover, using a three-dimensional (3D) structural analysis software enables gathering detailed information and quantifying data. The aim of this study was to introduce various quantitative analyses performed before and after orthodontic treatment by using a 3D structural analysis software for evaluating the morphological condition of the alveolar bone of a patient with gingival recession around the canines.
Cone-Beam Computed Tomography ; Gingival Recession ; Humans

PURPOSE: This study was performed to assess the compatibility of cone beam computed tomography (CBCT) synthesized cephalograms with conventional cephalograms, and to find a method for obtaining normative values for three-dimensional (3D) assessments. MATERIALS AND METHODS: The sample group consisted of 10 adults with normal occlusion and well-balanced faces. They were imaged using conventional and CBCT cephalograms. The CBCT cephalograms were synthesized from the CBCT data using OnDemand 3D software. Twenty-one angular and 12 linear measurements from each imaging modality were compared and analyzed using paired-t test. RESULTS: The linear measurements between the two imaging modalities were not statistically different (p>0.05) except for the U1 to facial plane distance. The angular measurements between the two imaging modalities were not statistically different (p>0.05) with the exception of the gonial angle, ANB difference, and facial convexity. CONCLUSION: Two-dimensional cephalometric norms could be readily used for 3D quantitative assessment, if corrected for lateral cephalogram distortion.
Adult ; Cephalometry ; Cone-Beam Computed Tomography ; Humans

The purpose of this clinical report was to show anatomical variations in permanent maxillary second molar using computed tomography (CT). This case report describes the application of CT to detect the unusual root anatomy of maxillary second molar with 2 separate palatal roots for successful endodontic treatment procedures. The use of cone beam computed tomography (CBCT) can overcome the limitation of the periapical standard radiography caused by the overlap of buccal and secondary palatal roots.
Cone-Beam Computed Tomography* ; Molar* ; Radiography

No abstract available.
Cone-Beam Computed Tomography ; Dentistry ; Radiography, Panoramic