• Imaging Science in Dentistry
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• v.30 no.1
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• pp.23-32
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• 2000

Purpose : The purpose of this study is to compare radiographic techniques for the diagnostic accuracy in the detection of osteophytes of the mandibular condyle. Material and Methods : A series of bone chips were placed at four locations on the condylar head of a dried human skull. Eight radiographic techniques such as panoramic, transcranial, infracranial, transorbital, reverse-Towne's, submentovertex, multidirectional tomographic and computed tomographic techniques were compared. Three oral radiologists were asked to rate the lesions by four stage score. The statistical analysis was performed by ANOVA test. Results: For the detection of lateral osteophyte, transcranial, infracranial, transorbital and reverse-Towne' s views showed superiority. Also, transcranial and infracranial views showed superiority for medial osteophyte. While for the detection of superior and anterior osteophyte, panoramic, transcranial, infracranial, transorbital views showed superiority. Lateral tomograph showed superiority for the detection of superior and anterior osteophyte, but it showed inferiority for lateral and medial osteophyte. And antero-posterior tomograph showed superiority for the detection of all osteophytes. Axial computed tomograph showed superiority for the detection of all osteophytes, and coronal computed tomograph showed superiority for lateral, medial and superior osteophytes. While reconstructed sagittal computed tomograph showed relatively superiority for the detection of anterior and superior osteophytes. Conclusion : The conventional radiographs can be used for the detection of bony changes of the mandibular condyle, and tomograph or computed tomograph can be used additionally when it is difficult to detect bony changes on conventional radiographs.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.697-698
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• 2012

• 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.

• Imaging Science in Dentistry
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• v.39 no.1
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• pp.41-49
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• 2009

Purpose: To detect the progression of experimentally induced periapical lesions on periapical radiograph and cone beam computed tomograph (CBCT) by quantitative analysis. Materials and Methods: After the removal of coronal pulps from premolars of two Beagle dogs, the root canals of premolars were exposed to oral environment during one week and then sealed for 70 days. Digital periapical radiographs and CBCTs were taken at baseline and every 7 days for 77 days after pulp exposure. We examined occurrence and areas of periapical bone resorption. Three comparative groups of CBCT radiographs were prepared by average projection of thin slabs with different bucco-lingual thicknesses (0.1, 3.0, and 8.0 mm) using a 3D visualization software. Radiographic densities were compensated by image normalization. Digital images were processed with mathematical morphology operations. The radiographic density and morphological features of periapical lesions were compared among three groups of CBCT in different time points. Results: In the CBCT group with 0.1 mm thickness, radiographic density (p<0.05) and trabecular bone area (p<0.01) were significantly decreased at the fifth week. However, in the CBCT groups with 3 mm and 8 mm thickness and periapical radiographs, none of densitometric and morphological features showed any significant differences in different time points. Radiographic density of periapical lesion showed increasing tendency at the eleventh week after pulp exposure. Conclusion: Radiographic detection of periapical lesions was possible at the fifth week after pulp contamination by quantitative method and was affected by buccolingual bone thickness.

• Imaging Science in Dentistry
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• v.38 no.2
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• pp.95-101
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• 2008

Purpose: To assess the positional relationship between the maxillary sinus floor and the apex of the maxillary first molar using cone beam computed tomograph (CBCT). Materials and Methods: CBCTs from 127 subjects were analysed. A total of 134 maxillary first molars were classified according to their vertical and horizontal positional relationship to the maxillary sinus floor and measured according to the distance between the maxillary sinus floor and the maxillary first molar. Results: Type III (The root projected laterally on the sinus cavity but its apex is outside the sinus boundaries) was dominated between 10 and 19 years and type I (The root apex was not in contact with the cortical borders of the sinus) was dominated (P<0.05) between 20 and 72 years on the vertical relationship between the maxillary sinus floor and the apex of the maxillary first molar. The maxillary sinus floor was located more at the apex (78.2%) than at the furcation (21.3%) for the palatal root. The distance from the root apex to the maxillary sinus floor confined to type I was increased according to the ages (P<0.05). Type M (The maxillary sinus floor was located between the buccal and the palatal root) was most common (72.4%) on the horizontal relationship between the maxillary sinus floor and the apex of the maxillary first molar. Conclusion: CBCT can provide highly qualified images for the maxillary sinus floor and the root apex of the maxillary first molar.

• Imaging Science in Dentistry
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• v.34 no.3
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• pp.159-164
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• 2004

Purpose: To compare alveolar bony height of pantomograph with bony height of thin slice, multiplanar reformatted (MPR) Computed Tomograph. Materials and Methods : Panoramic radiograms of 12 young adult patients had been taken by one radologic technitian and the measurements were corrected by magnification ratio (1.20). The slice thickness of Multi-detector Computed Tomography (CT) was at least 1mm for the accuracy. The raw CT datas were imported into the V-works 4.0 (CyberMed Corp., Seoul, Korea) and transformed to MPR images. Pantomographic measurements of alveolar bone were compared to CT values by average mean bony height measurements for the accuracy. Inter-, and Intra-observer variability was evaluated. Results : There was no significant differences between height measurement of pantomography and that of CT (P>0.05). There were no significant differences in either inter-or intra-observer measurements (P>0.05). Conclusion : Pantomography showed relatively high accuracy and precision in measuring alveolar bony height.

• Imaging Science in Dentistry
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• v.43 no.3
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• pp.197-200
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• 2013

Florid osseous dysplasia (FOD) is an uncommon, benign, cemento-osseous lesion of the jaws. The etiology of FOD is still unknown. It is often asymptomatic and may be identified on routine dental radiographs. The classic radiographic appearance of FOD is amorphous, lobulated, mixed radiolucent/radiopaque masses of cotton-wool appearance with a sclerotic border in the jaws. In our case the lesion was found incidentally on routine periapical radiographs taken for restored teeth and edentulous areas. For further and detailed examination, a panoramic radiograph and cone-beam computed tomograph (CBCT) were taken. The panoramic radiograph and CBCT revealed maxillary bilateral and symmetrical, non-expansile, well-defined, round, radiopaque masses in contact with the root of the maxillary right second molar and left first molar teeth. Our aim in presenting this case report was to highlight the importance of imaging in diagnosis of FOD.

• Health Policy and Management
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• v.28 no.2
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• pp.138-144
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• 2018

Background: Diagnostic imaging fee had been reduced in May 2011, but it was recovered after 6 months because of strong opposition of medical providers. This study aimed to analyze the behavior of medical providers according to fee changes. Methods: The National Health Insurance claims data between November 2010 and December 2012 were used. The number of exams per computed tomography was analyzed to verify that the fee changes increased or decreased the number of exams. Multivariate regression model were applied. Results: The monthly number of exams increased by 92.5% after fee reduction, so the diagnostic imaging spending were remained before it. But medical provider decreased the number of exams after fee return. After adjusting characteristic of hospitals, fee reduction increased the monthly number of exams by 48.0% in a regression model. Regardless type of hospitals and severity of disease, the monthly number of exams increased during period of fee reduction. The number of exams in large-scaled hospitals (tertiary and general hospital) were increased more than those of small-scaled hospitals. Conclusion: Fee-reduction increased unnecessary diagnostic exams under the fee-for-service system. It is needed to define appropriate exam and change reimbursement system on the basis of guideline.

• Smart Media Journal
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• v.9 no.3
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• pp.59-70
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• 2020

This paper presents a fully automatic tool to recognize the liver region from CT images based on a deep learning model, namely Multiple Filter U-net, MFUnet. The advantages of both U-net and Multiple Filters were utilized to construct an autoencoder model, called MFUnet for segmenting the liver region from computed tomograph. The MFUnet architecture includes the autoencoding model which is used for regenerating the liver region, the backbone model for extracting features which is trained on ImageNet, and the predicting model used for liver segmentation. The LiTS dataset and Chaos dataset were used for the evaluation of our research. This result shows that the integration of Multiple Filter to U-net improves the performance of liver segmentation and it opens up many research directions in medical imaging processing field.

• Imaging Science in Dentistry
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• v.39 no.2
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• pp.99-102
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• 2009

Adenomatoid odontogenic tumor (AOT) is a tumor of odontogenic epithelium with varying degrees of inductive changes in the connective tissue. The common radiographic appearance of AOT is a unilocular radiolucency associated with an unerupted tooth. Detectable radiopacities have been reported in many cases. We present a case of AOT in a 9-year old-female patient. Cystic lesion with numerous, punctuate radiopaque foci was observed on the anterior region of the mandible. These radiopacities were situated mostly on the buccal side of impacted tooth on the multi-planar images of cone beam computed tomograph. Characteristic duct like structures and amyloid like material were observed on histopathologic finding. (Korean J Oral Maxillofac Radiol2009; 39 : 99-102)