• Imaging Science in Dentistry
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• v.50 no.4
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• pp.299-307
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• 2020

Purpose: The diagnosis of chronic rhinosinusitis requires a comprehensive knowledge of the signs and symptoms of the disease and an accurate radiographic assessment. Computed tomography (CT) is the superior imaging modality for diagnosis of chronic rhinosinusitis. However, considering the lower dose and higher resolution of cone-beam computed tomography (CBCT) compared to CT, this study aimed to assess the agreement between the findings of CBCT and functional endoscopic sinus surgery (FESS). Materials and Methods: This descriptive prospective study evaluated 49 patients with treatment-resistant chronic rhinosinusitis who were candidates for FESS. Preoperative CBCT scans were obtained before patients underwent FESS. The agreement between the CBCT findings and those of FESS was determined using the kappa correlation coefficient. The frequency of anatomical variations of the paranasal sinuses was also evaluated on CBCT scans. Results: Significant agreement existed between pathological findings on CBCT scans and those of FESS, such that the kappa correlation coefficient was 1 for mucosal thickening, 0.644 for nasal deviation, 0.750 for concha bullosa, 0.918 for nasal polyp, 0.935 for ostiomeatal complex (OMC) obstruction, and 0.552 for infundibulum thickening. Furthermore, 95.9% of patients had 1 or more and 79.6% had 2 or more anatomical variations, of which nasal deviation was the most common (67.3%). Conclusion: Considering the significant agreement between the findings of CBCT and FESS for the detection of pathological changes in the paranasal sinuses, CBCT can be used prior to FESS to detect chronic rhinosinusitis and to assess anatomical variations of the OMC.

• Journal of Trauma and Injury
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• v.35 no.1
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• pp.12-18
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• 2022

Purpose: Pedicle screw fixation provides 3-column stabilization, multidimensional control, and a higher rate of interbody fusion. Although computed tomography (CT) is recommended for the postoperative assessment of pedicle screw fixation, its use is limited due to the radiation exposure dose. The purpose of this preliminary retrospective study was to assess the clinical usefulness of low-dose mobile cone-beam CT (CBCT) for the postoperative evaluation of pedicle screw fixation. Methods: The author retrospectively reviewed postoperative mobile CBCT images of 15 patients who underwent posterior pedicle screw fixation for spinal disease from November 2019 to April 2020. Pedicle screw placement was assessed for breaches of the bony structures. The breaches were graded based on the Heary classification. Results: The patients included 11 men and four women, and their mean age was 66±12 years. Of the 122 pedicle screws, 34 (27.9%) were inserted in the thoracic segment (from T7 to T12), 82 (67.2%) in the lumbar segment (from L1 to L5), and six (4.9%) in the first sacral segment. Although there were metal-related artifacts, the image of the screw position (according to Heary classification) after surgery could be assessed using mobile CBCT at all levels (T7-S1). Conclusions: Mobile CBCT was accurate in determining the location and integrity of the pedicle screw and identifying the surrounding bony structures. In the postoperative setting, mobile CBCT can be used as a primary modality for assessing the accuracy of pedicle screw fixation and detecting postoperative complications.

• Imaging Science in Dentistry
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• v.53 no.4
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• pp.325-333
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• 2023

Purpose: The objective of this study was to evaluate and compare the accuracy and image quality of root surface area (RSA) measurements obtained with various cone-beam computed tomography (CBCT) protocols, relative to the gold standard of micro-computed tomography (CT), in an in vitro setting. Materials and Methods: Four dry human skulls were scanned using 8 different protocols, with voxel sizes of 0.15 mm, 0.3 mm, and 0.4 mm. Three-dimensional models of the selected teeth were constructed using CBCT and microCT protocols, and the RSA was automatically measured by the image-processing software. The absolute difference in the percentage of the RSA(%ΔRSA) was calculated and compared across the 8 CBCT protocols using repeatedmeasures analysis of variance. Finally, image quality scores of the RSA measurements were computed and reported in terms of percent distribution. Results: No significant differences were observed in the %ΔRSA across the 8 protocols (P>0.05). The deviation in %ΔRSA ranged from 1.51% to 4.30%, with an increase corresponding to voxel size. As the voxel size increased, the image quality deteriorated. This decline in quality was particularly noticeable at the apical level of the root, where the distribution of poorer scores was most concentrated. Conclusion: Relative to CBCT protocols with voxel sizes of 0.15mm and 0.3mm, the protocols with a voxel size of 0.4 mm demonstrated inferior image quality at the apical levels. In spite of this, no significant discrepancies were observed in RSA measurements across the different CBCT protocols.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.3
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• pp.211-224
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• 2009

The objective of this study is to examine the condylar surfaces in order to find out the types, the incidence and common occurrence area of the osseous abnormalities of the condyles according to the age, genders and the purpose of CT taking, and to compare those between the groups for TMD diagnosis and the other groups. 3D CT images of 199 patients which were scanned with the $i-CAT^{TM}$ Cone Beam Computed Tomography were collected from Sanbon Dental Hospital of Wonkwang university and the MPR images were transfered to the TMJ mode to be showed serial sagittal images and coronal images. The images were macroscopically examined by three independent observers for the types and incidences of the osseous abnormalities, their common occurrence area and general shapes of the condyles. As a result, type F is most common ever than type N. The common occurrence area in sagittal images is antero-superior and superior area except for type D-C which were showed on postero-superior area commonly. In coronal images, latero-superior and superior area is most common except for type E which were present on mesio-superior and superior area most frequently. The osseous abnormalities of the condyles are more common in TMD diagnosis group except for type D-C, that is type N and type D-C are more common in the other groups. In this study, abnormalities of the condyles are classified into 6 types and it has a common occurrence area each. And TMD diagnosis group shows a tendency to have higher rate for osseous abnormalities except for type D-C.

• 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.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.6
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• pp.496-504
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• 2011

Introduction: This study compared the alveolar bone density of the mandible according to gender, age and position using Cone-beam computed tomography (CT). Materials and Methods: The maxillofacial CT scan data was obtained from 60 Korean patients. In addition, the alveloar bone density of 5 males and 5 females with normal occlusion aged from 10 to 70 years was measured at the buccal cortical bone, cancellous bone and lingual cortical bone, as well as at the position of the incisors, canines, premolars and molars. Results: The age-specific mean bone density was highest in patients in their third decade. The buccal cortical bone of the molars showed the highest bone density. Males in their fifties and sixties had a higher bone density in the cancellous bone in the region of the premolars and the buccal cortical bone of the molars, respectively, than females but there was no significant difference between males and females in the other parts. The cancellous bone density was highest in those in their twenties and thirties, and tended to decline up to their seventh decade. Conclusion: These results revealed a significantly different bone density according to gender, age and position in the Korean population. In addition, it is possible to predict the bone density based on these results.

• Progress in Medical Physics
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• v.24 no.4
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• pp.205-212
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• 2013

Recent developments of image guided radiation therapy (IGRT), especially the On Board Imaging (OBI) system and the cone beam CT (CBCT), enable the radiation treatment more accurate and reliable. IGRT is widely used in the radiation therapy as a standard of care. Use of IGRT is even expected to increase in the near future. IGRT is only beneficial to patients when it is used with proper considerations of safety and appropriateness of the techniques. Institutional procedure should be developed based on the clinical need and the deep understanding of the system before applying the new technique to the clinic. Comprehensive QA program should be established before to the clinic and imaging dose should be considered when preparing the departmental practice guidelines for IGRT.

• Imaging Science in Dentistry
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• v.38 no.3
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• pp.169-176
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• 2008

Purpose : To assess the diagnostic accuracy and value in an imaging technique field through the comparison of cone beam computed tomography and conventional panoramic radiography in assessing the topographic relationship between the mandibular canal and impacted third molars. Materials and Methods : Participants consisted of 100 patients offered the images through cone beam computed tomography and panoramic radiography. PSR-$9000^{TM}$ Dental CT system (Asahi Roentgen Ind. Co., Ltd, Japan) was used as the unit of cone beam computed tomography. CE-II (Asahi Roentgen Ind. Co., Ltd, Japan) and Pro Max (Planmeca Oy, Finland) were used as the unit of panoramic radiography. The images obtained through panoramic radiography were classified into 3 types according to the distance between mandibular canal and root of mandibular third molar. And they were classified into 4 types according to the proximity of radiographic feature. The images obtained through cone beam computed tomography based on the classification above were classified into 4 types according to the location between the mandibular canal and the root and were analyzed. And they were classified into buccal, inferior, lingual, and between roots, according to the location between mandibular canal and root. The data were statistically analyzed and estimated by $X^2$-test. Results : 1. There was no statistical significance according to 3 types (type I, type II, type III) through CBCT. 2. The results of 4 types (type A, type B, type C, type D) through CBCT were as high prevalence of CBCT 1 in type A, CBCT 2 in type B, CBCT 3 in type C, and CBCT1 in type D and those of which showed statistical significance (P value=0.03). 3. The results according to location between mandibular canal and root through CBCT recorded each 49, 25, 17, 9 as buccal, inferior, lingual, between roots. Conclusion : When estimating the mandibular canal and the roots through the panoramic radiography, it could be difficult to drive the views of which this estimation was considerable. Thus it is required to have an accurate diagnostic approaching through CBCT that could estimate the location between mandibular canal and roots.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.6
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• pp.492-498
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• 2009

We sought to evaluate the relationship between the mandibular canal and impacted mandibular third molars by using dental cone beam computed tomograph(CBCT) for third molar surgery. A total of 111 patients(177 teeth) offered the images through CBCT and panoramic radiography for the extraction of the mandibular third molars. In CBCT, the accurate relationship between the third molar and the mandibular canal were evaluated. In panoramic radiographies, we evaluated the impacted level and superimposition sign of the mandibular third molar with the mandibular canal, and also, the radiopacity of the white line in the canal. Data were statistically analyzed and estimated by $X^2$-test. In CBCT finding, high prevalence of contact between the mandibular canal and roots occured in the deep impacted third molars, narrowing mandibular canals, bending mandibular canals and cases where the radiopacity of white line of canals were "absence" on panoramic images. It showed statistical significance (P<0.05). When evaluating the mandibular canal and the roots through the panoramic radiography for third molar extraction, it could be difficult to diagnosis accurately. Thus, it is required to have an accurate diagnostic approach through CBCT that could evaluated the location between mandibular canal and root.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.2
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• pp.106-111
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• 2012

Purpose: The aim of this sturdy was to assess the prevalence and change in pathologic findings in the maxillary sinus by using preoperative and postoperative cone-beam computed tomography (CBCT). Methods: The subjects included 83 patients with maxillary sinus abnormalities who underwent orthognathic surgery between January 2010 to December 2010. The CBCT analyses were classified according to the thickness of maxillary sinus membrane; Normal (membrane thickness<2 mm), mucosal thickening (membrane thickness ${\geq}2mm$ and <6 mm), partial opacification (membrane thickness>6 mm but not complete), total opacification, and polypoidal mucosal thickening. The diameters of the maxillary sinus ostium on the coronal cross-sectional view were also calculated. Results: Out of 166 maxillary sinuses in 83 patients, 42 (25.3%) maxillary sinuses before surgery and 37 (22.3%) maxillary sinuses after surgery showed abnormalities. A decrease in the diameters of maxillary ostium was observed after surgery (P<0.05). However, there was no significant difference in mucosal thickness both, preoperatively and postoperatively. Conclusion: The orthognathic surgery didn't deteriorate the maxillary sinus abnormaility. Despite the low prevalence of sinus complications in orthognathic surgery, all the patients should be informed of the possibility of sinusitis that could require the surgical intervention before surgery.