• Journal of the Korean Academy of Esthetic Dentistry
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• v.28 no.1
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• pp.4-17
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• 2019

Nowadays, Cone-Beam CT is widely supplied in dental clinics, the distribution rate in south korea is highly ranked worldwidely. Recently, The number of Cone-Beam CTs reached 10 thousands according to national healthcare system report. Also, dental manufacturers released many kinds of In-house 3D digital printers, the distribution rate of which rises rapidly in dental clinics. Accordingly, using Cone-Beam CT data and Intraloral scan data, the application of implant guide surgery is widespread in a unit of private clinic. Through the previous articles, the latest methods of computer-guided implant surgery are reviewed, and also the considerations for precise and reliable guide surgery are summarized.

• Journal of Oral Medicine and Pain
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• v.47 no.3
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• pp.156-160
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• 2022

Temporomandibular joint (TMJ) ankylosis is a condition in which condylar movement is restricted because of fibrous or bony union between the mandibular condyle and temporal bone. TMJ ankylosis is most often caused by trauma, followed by systemic or local infection, and secondary to unknown causes. Diagnostic imaging plays a vital role in diagnosing TMJ ankylosis and establishing a treatment plan. Computed tomography (CT) or cone beam computed tomography (CBCT) is currently the imaging technique of choice to accurately demonstrate preoperative ankylosing masses and other surgically important findings, such as the shape of the mandibular condyle and the pathological changes in the joint. The osseous changes in the mandibular condyle are easily identified in the coronal and sagittal sections of CT or CBCT images. This report describes the case of a middle-aged woman who developed TMJ ankylosis of the left TMJ while undergoing repeated treatment for TMJ disease. We report the findings observed on radiographic and CBCT images through continuous observation.

• The korean journal of orthodontics
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• v.39 no.1
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• pp.6-17
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• 2009

Objective: The purpose of this study was to evaluate the possibility of using a digital model and cone beam computed tomograph(CBCT) image for model analysis. Methods: Model analyses of CBCT images, plaster models, and digital models of 20 orthodontic patients with a permanent dentition with no proximal metal restorations, were compared. Results: The average differences of tooth size measurements were 0.01 to 0.20 mm, and the average difference of arch length discrepancy measurements were 0.41 mm in the maxilla and 0.82 mm in the mandible. The difference in Bolton discrepancy measurements was 0.17 mm for the anterior region and 0.44 mm overall but with no statistically significant difference. When comparing CBCT images with plaster models, the average differences in tooth size measurements were -0.22 to 0.01 mm, and the average differences in arch length discrepancy measurements were 0.43 mm in the maxilla and 0.32 mm in the mandible. Difference in Bolton discrepancy measurements were 0.35 mm in the anterior region and 1.25 mm overall. CBCT images showed significantly smaller overall Bolton discrepancy measurements. Conclusions: Although there were statistically significant differences in some model analysis measurements, the ranges of measurement errors of the digital model and CBCT images were clinically acceptable. Therefore, a digital model and CBCT image can be used for model analysis.

• Imaging Science in Dentistry
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• v.52 no.2
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• pp.171-179
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• 2022

Purpose: The aim of this study was to assess the accuracy of cone-beam computed tomographic (CBCT) images obtained using different voxel sizes in measuring trabecular bone microstructure in comparison to micro-CT. Materials and Methods: Twelve human skull bones containing posterior-mandibular alveolar bone regions were analyzed. CBCT images were obtained at voxel sizes of 0.075mm(high: HI) and 0.2mm(standard: Std), while microCT imaging used voxel sizes of 0.06 mm (HI) and 0.12 mm (Std). Analyses were performed using CTAn software with the standardized automatic global threshold method. Intraclass correlation coefficients were used to evaluate the consistency and agreement of paired measurements for bone volume (BV), percent bone volume (BV/TV), bone surface (BS), trabecular thickness (TbTh), trabecular separation (TbSp), trabecular number (TbN), trabecular pattern factor(TbPf), and structure model index (SMI). Results: When compared to micro-CT, CBCT images had higher BV, BV/TV, and TbTh values, while micro-CT images had lower BS, TbSp, TbN, TbPf, and SMI values (P<0.05). The BV, BV/BT, TbTh, and TbSp variables were higher with Std voxels, whereas the BS, TbPf, and SMI variables were higher with HI voxels for both imaging methods. For each imaging modality and voxel size evaluated, BV, BS, and TbTh were significantly different(P<0.05). TbN, TbPf, and SMI showed statistically significant differences between imaging methods(P<0.05). The consistency and absolute agreement between micro-CT and CBCT were excellent for all variables. Conclusion: This study demonstrated the potential of high-resolution CBCT imaging for quantitative bone morphometry assessment.

• Imaging Science in Dentistry
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• v.40 no.3
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• pp.115-121
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• 2010

Purpose : The purpose of this study was to accurately analyze the radiographic characteristics of dentigerous cyst (DC) with multiplanar images of cone beam computed tomography (CBCT). Materials and Methods : Thirty eight radiographically and histopathologically proven cases of DCs were analyzed with panoramic radiograph and CBCT, retrospectively. The radiographic CT pattern, symmetry of radiolucency around the unerupted tooth crown, ratio of long length to short length, degree of cortical bone alternation, effects on adjacent tooth, and cyst size were analyzed. Relative frequencies of these radiographic features were evaluated. In order to compare the CBCT features of DC with those of odontogenic keratocyst (OKC), 9 cases of OKCs were analyzed with the same method radiographically. Results : DCs consisted of thirty unilocular cases (79.0%), seven lobulated cases (18.4%) and one multilocular case (2.6%). Eight were asymmetric (21.0%) and thirty were symmetric (79.0%). Maxillary DC showed rounder shape than mandibular DC (L/S ratio; maxilla 1.32, mandible 1.67). Alternations of lingual cortical bone (14 cases, 48.2%) were more frequent than those of buccal side (7 cases, 24.1%). CBCT images of DC showed definite root resorption and bucco-lingual tooth displacement. These findings were hardly observed on panoramic radiographs of DCs. Comparison of CBCT features of DC with those of OKC showed several different features. Conclusions : CBCT images of DC showed various characteristic radiographic features. Therefore, CBCT can be helpful for the diagnosis of DC radiographically.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1157-1164
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• 2023

This study measures the additional dose for each treatment area using kV X-ray based OBI (On-Board Imager) and CBCT (Cone-Beam CT), which have excellent spatial resolution and contrast, and evaluates the adequacy and stability of radiation management aspects of IGRT. The subjects of the experiment were examined with OBI and CBCT attached to a linear accelerator (Clinac IX), and ring-shaped Halcyon CBCT under imaging conditions for each treatment area, and the dose at the center was measured using an ion chamber. OBI single fraction dose was measured as 0.77 mGy in the head area, 3.04 mGy in the chest area, and 7.19 mGy in the pelvic area. The absorbed doses from the two devices, Clinac IX CBCT and Halcyon CBCT, were measured to be similar in the pelvic area, at 70.04 mGy and 70.45 mGy. and in chest CBCT, the Clinac IX absorbed dose (70.05 mGy) was higher than the Halcyon absorbed dose (21.01 mGy). The absorbed dose to the head area was also higher than that of Clinac IX (9.08 mGy) and Halcyon (5.44 mGy). In kV X-ray-based IGRT, additional radiation exposure due to photoelectric absorption may affect the overall volume of the treatment area, and caution is required.

• Imaging Science in Dentistry
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• v.37 no.3
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• pp.165-170
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• 2007

Purpose: To estimate the shape of root and pulp canal using a dental cone beam computed tomography (CBCT) and to evaluate the accuracy of imaging reformation. Materials and Methods: CBCT images were obtained with incisors, premolars, and molars as the destination by using PSR $9000N^{TM}$ Dental CT system (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan) and i-CAT (Imaging Sciences International, Inc, USA) cone beam CT unit that have different kind of detector and field of view, and compared these with the shape and the size of actual root and root canal. Results: When the measuring value of cone beam computed tomography concerning to each root's bucco-lingual diameter and mesio-distal diameter was compared with the value of the actual root, it reveals an error range $-0.49{\sim}+0.63$ mm at PSR900N and $-0.97{\sim}+1.14$ mm at i-CAT (P>0.05). It was possible to identify and measure PSR$9000N^{TM}$ Dental CT system to the limit $0.48{\pm}0.06mm$ (P>0.05) and i-CAT CBCT to the limit $0.86{\pm}0.09mm$ (P<0.05) on estimating the size and the shape of root canal. Two kinds of CBCT images revealed the useful reproducibility to estimate the shape of root, but there was the difference to estimate the shape of root according to apparatus. The reproducibility of root shape in the image of three-dimensions at PSR 900N is low such as 0.65 mm in a case of minute root canal. Conclusions: CBCT images revealed higher accuracy of the imaging reformation for root and pulp and clinically CBCT is a useful diagnostic tool for the assessment of root and canal. However, there are different qualities of imaging reformation according to CBCT apparatus and limitation of reproducibility for minute root canals.

• The Journal of the Korean dental association
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• v.48 no.10
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• pp.724-728
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• 2010

Accurate analysis of facial asymmetry prior to any orthognathic or orthodontic treatment plan is essential in ensuring good treatment result. Dental CBCT (Cone-beam Computed Tomography) provides as actual three-dimensional measurements of distance and angle without any radiographic magnification as medical CT provides, while its field of view is limited to the oral and maxillofacial area. CBCT is a useful tool for the diagnosis of facial asymmetry. The coordinates of facial landmarks are obtained from the 3D reconstruction software which enables the establishment of perpendicular planes and the identification of the landmarks. Then, the bilateral discrepancies of the landmarks are obtained as spherical polar coordinates which can show the amount of asymmetry and its direction. A method of 3D analysis of facial asymmetry using CBCT is introduced in this report.

• Imaging Science in Dentistry
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• v.44 no.2
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• pp.121-128
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• 2014

Purpose: The present study was performed to compare the planning of implant placement based on panoramic radiography (PAN) and cone-beam computed tomography (CBCT) images, and to study the impact of the image dataset on the treatment planning. Materials and Methods: One hundred five partially edentulous patients (77 males, 28 females, mean age: 46 years, range: 26-67 years) seeking oral implant rehabilitation were referred for presurgical imaging. Imaging consisted of PAN and CBCT imaging. Four observers planned implant treatment based on the two-dimensional (2D) image data-sets and at least one month later on the three-dimensional (3D) image dataset. Apart from presurgical diagnostic and dimensional measurement tasks, the observers needed to indicate the surgical confidence levels and assess the image quality in relation to the presurgical needs. Results: All observers confirmed that both imaging modalities (PAN and CBCT) gave similar values when planning implant diameter. Also, the results showed no differences between both imaging modalities for the length of implants with an anterior location. However, significant differences were found in the length of implants with a posterior location. For implant dimensions, longer lengths of the implants were planned with PAN, as confirmed by two observers. CBCT provided images with improved scores for subjective image quality and surgical confidence levels. Conclusion: Within the limitations of this study, there was a trend toward PAN-based preoperative planning of implant placement leading towards the use of longer implants within the posterior jaw bone.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.742-749
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• 2009

The use of cone-beam computed tomography(CBCT) has been proposed for guiding the delivery of radiation therapy. A kilovoltage imaging system capable of radiography, fluoroscopy, and cone-beam computed tomography(CT) has been integrated with a medical linear accelerator. A standard clinical linear accelerator, operating in arc therapy mode, and an amorphous-silicon (a-Si) with an on-board electronic portal imager can be used to treat palliative patient and verify the patient's position prior to treatment. On-board CBCT images are used to generate patient geometric models to assist patient setup. The image data can also, potentially, be used for dose reconstruction in combination with the fluence maps from treatment plan. In this study, the accuracy of Hounsfield Units of CBCT images as well as the accuracy of dose calculations based on CBCT images of a phantom and compared the results with those of using CT simulator images. Phantom and patient studies were carried out to evaluate the achievable accuracy in using CBCT and CT stimulator for dose calculation. Relative electron density as a function of HU was obtained for both planning CT stimulator and CBCT using a Catphan-600 (The Phantom Laboratory, USA) calibration phantom. A clinical treatment planning system was employed for CT stimulator and CBCT based dose calculations and subsequent comparisons. The dosimetric consequence as the result of HU variation in CBCT was evaluated by comparing MU/cCy. The differences were about 2.7% (3-4MU/100cGy) in phantom and 2.5% (1-3MU/100cGy) in patients. The difference in HU values in Catphan was small. However, the magnitude of scatter and artifacts in CBCT images are affected by limitation of detector's FOV and patient's involuntary motions. CBCT images included scatters and artifacts due to In addition to guide the patient setup process, CBCT data acquired prior to the treatment be used to recalculate or verify the treatment plan based on the patient anatomy of the treatment area. And the CBCT has potential to become a very useful tool for on-line ART.)