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

OBJECTIVE: This study investigated whether it is possible to use a two-dimensional (2D) standard in three-dimensional (3D) analysis, by comparing the angles and lengths measured from a midsagittal projection in 3D cone-beam computed tomography (CBCT) with those measured by 2D lateral cephalometric radiography (LCR). METHODS: Fifty patients who underwent both LCR and CBCT were selected as subjects. CBCT was reoriented in 3 different methods and the measuring-points were projected onto the midsagittal plane. Twelve angle values and 8 length values were measured on both LCR and CBCT and compared. RESULTS: Repeated measures analysis of the variance revealed statistically significant differences in 7 angular and 5 linear measurements among LCR and 3 types of CBCT (p < 0.05). Of these 12 measurements, multiple comparisons showed that 6 measurements (ANB, AB to FH, IMPA, FMA, Co-Gn, Go-Me) were not significantly different in pairwise comparisons. LCR was significantly different from 3 types of CBCT in 3 angular (SN to FH, interincisal angle, FMIA) and 2 linear (S-Go, Co-ANS) measurements. The CBCT method was similar for all measurements, except for 1 linear measurement, i.e., S-N. However, the disparity between the mean values for all parameters was within the range of clinical measurement error. CONCLUSIONS: 3D-CBCT analysis, using midsagittal projection, is a useful method in which the 2D-LCR normative values can be used. Although the measurements changed with reorientation, these changes were not clinically significant.
Cone-Beam Computed Tomography* ; Humans ; Radiography

No abstract available.
Cone-Beam Computed Tomography ; Dental Pulp Cavity

The use of computed tomography for dental procedures has increased recently. Cone beam computed tomography (CBCT) systems have been designed for imaging hard tissues of the dentomaxillofacial region. CBCT is capable of providing high resolution in images of high diagnostic quality. This technology allows for 3-dimensional representation of the dentomaxillofacial skeleton with minimal distortion, but at lower equipment cost, simpler image acquisition and lower patient dose. Because this technology produces images with isotropic sub-millimeter spatial resolution, it is ideally suited for dedicated dentomaxillofacial imaging. In this paper, we provide a brief overview of cone beam scanning technology and compare it with the fan beam scanning used in conventional CT and the basic principles of currently available CBCT systems.
Cone-Beam Computed Tomography* ; Humans ; Radiography ; Skeleton