• 대한치과교정학회지
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• 제51권4호
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• pp.231-240
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• 2021

Objective: This outcome analysis study evaluated the actual positions of the orthodontic miniplate and miniplate anchoring screws (MPASs) and the risk factors affecting adjacent anatomic structures after miniplate placement in the mandibular incisal area. Methods: Cone-beam computed tomographic images of 97 orthodontic miniplates and their 194 MPASs (diameter, 1.5 mm; length, 4 mm) in patients whose miniplates provided sufficient clinical stability for orthodontic treatment were retrospectively reviewed. For evaluating the actual positions of the miniplates and analyzing the risk factors, including the effects on adjacent roots, MPAS placement height (PH), placement depth (PD), plate angle (PA), mental fossa angle (MA), and root proximity were assessed using the paired t-test, analysis of variance, and generalized linear model and regression analyses. Results: The mean PDs of MPASs at positions 1 (P1) and 2 (P2) were 2.01 mm and 2.23 mm, respectively. PA was significantly higher in the Class III malocclusion group than in the other groups. PH was positively correlated with MA and PD at P1. Of the 97 MPASs at P1, 49 were in the no-root area and 48 in the dentulous area; moreover, 19 showed a degree of root contact (19.6%) without root perforation. All MPASs at P2 were in the no-root area. Conclusions: Positioning the miniplate head approximately 1 mm lower than the mucogingival junction is highly likely to provide sufficient PH for the P1-MPASs to be placed in the no-root area.

• Journal of Mechanical Science and Technology
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• 제14권1호
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• pp.1-10
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• 2000

This work shows that it is possible to obtain information about more than one parameter from acoustic field information. A variety of ultrasonic Lamb wave modes were utilized to reconstruct thickness and density of an isotropic plate. An image reconstruction of one parameter (thickness of a plate) was carried out for four cases, i.e., the lowest symmetrical and anti symmetrical modes, and the fastest symmetrical and anti symmetrical Lamb waves among multiple modes. For two parameter reconstructions (thickness and density), the image processing was performed using the lowest symmetrical and antisymmetrical modes simultaneously. In this work, a modified version of algebraic reconstruction technique (ART), which is a form of finite-series expansion method, was employed to reconstruct the ultrasonically computed tomographic images. Results from several sample geometries are presented.

• 대한치과교정학회지
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• 제43권4호
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• pp.178-185
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• 2013

Objective: To standardize the facial soft-tissue characteristics of South Korean adults according to gender by measuring the soft-tissue thickness of young men and women with normal facial profiles by using three-dimensional (3D) reconstructed models. Methods: Computed tomographic images of 22 men aged 20 - 27 years and 18 women aged 20 - 26 years with normal facial profiles were obtained. The hard and soft tissues were three-dimensionally reconstructed by using Mimics software. The soft-tissue thickness was measured from the underlying bony surface at bilateral (frontal eminence, supraorbital, suborbital, inferior malar, lateral orbit, zygomatic arch, supraglenoid, gonion, supraM2, occlusal line, and subM2) and midline (supraglabella, glabella, nasion, rhinion, mid-philtrum, supradentale, infradentale, supramentale, mental eminence, and menton) landmarks. Results: The men showed significantly thicker soft tissue at the supraglabella, nasion, rhinion, mid-philtrum, supradentale, and supraglenoid points. In the women, the soft tissue was significantly thicker at the lateral orbit, inferior malar, and gonion points. Conclusions: The soft-tissue thickness in different facial areas varies according to gender. Orthodontists should use a different therapeutic approach for each gender.

• Imaging Science in Dentistry
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• 제50권1호
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• pp.65-71
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• 2020

Ossifying fibroma is a slow-growing benign neoplasm that occurs most often in the jaws, especially the mandible. The tumor is composed of bone that develops within fibrous connective tissue. Some ossifying fibromas consist of cementum-like calcifications, while others contain only bony material; however, a mixture of these calcification types is commonly seen in a single lesion. Of the craniofacial bones, the mandible is the most commonly involved site, with the lesion typically inferior to the premolars and molars. Ossifying fibroma of the jaw shows a female predominance. Some reports of ossifying fibroma have been published in the literature; however, this report continues the research on this topic by detailing 3 types of ossifying fibroma findings on panoramic radiographs and cone-beam computed tomographic images of 4 patients. The radiographs of the presented cases could help clinicians understand the variations in the radiographic appearance of this lesion.

• Imaging Science in Dentistry
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• 제43권3호
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• pp.215-218
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• 2013

Periapical cemento-osseous dysplasia (PCOD) is a subtype of cemento-osseous dysplasia that usually occurs in middle-aged black women. This report described a case of a 45-year-old Iranian woman who was diagnosed with PCOD on the basis of cone beam computed tomographic (CBCT) findings. CBCT enabled detailed visualization of the bone changes. This report described the special radiographic characteristics of PCOD, including discontinuity of the lingual cortex on the CBCT sectional and three-dimensional images.

• Journal of Korean Neurosurgical Society
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• 제54권3호
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• pp.257-260
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• 2013

A 61-year-old woman with a very rare case of totally ossified large thoracic spinal metaplastic meningioma, showing progressing myelopathy is presented. Computed tomographic images showed a large totally ossfied intradural round mass occupying the spinal canal on T9-10 level. Magnetic resonance imaging revealed a large T9-10 intradural extramedullary mass that was hypointense to spinal cord on T1- and T2-weighted sequences, partial enhancement was apparent after Gadolinium administration. The spinal cord was severely compressed and displaced toward the right at the level of T9-10. Surgical removal of the tumor was successfully accomplished via the posterior midline approach and the histological diagnosis verified an ossified metaplastic meningioma. The clinical neurological symptoms of patient were improved postoperatively. In this article we discuss the surgical and pathological aspects of rare case of spinal totally ossified metaplastic meningioma.

• 대한의용생체공학회:의공학회지
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• 제9권2호
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• pp.153-158
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• 1988

A three-dimensional surface is reconstructed from contour information as identified on two-dimensional computed tomographic slices. Gradient operator with curvature constraint would be applied to extract the contour automatically, and backtracking is also adopted to reduce the tracking error. The surface between the consecutive slice is efficiently reconstructed using a triangular surface tiles. Hidden surface elimination, shading and parallel projection of the reconstructed surface are provied on the display screen.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 학술발표대회 논문집 제17권 2호
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• pp.239-242
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• 1998

본 논문에서는 횡파를 이용한 STAM 시스템을 이용하여 다층구조물에 대한 토모그라픽 영상을 복원함으로써 토모그라픽 영상의 분해능을 개선시키는 방법에 관하여 연구하였다. 먼저, STAM 시스템의 수조에서 초음파가 시료로 입사될 때 입사각도에 따라 발생되는 종파와 횡파에 대한 모드변환에 관하여 고찰하였다. 실험을 위하여 시료로 각 층이 서로 다른 패턴을 갖는 2층의 알루미늄을 가공하여 다층구조물을 제작하였으며, 시료에 횡파를 여기시키기 위하여 초음파변환기의 입사각을 18$^{\circ}$로 사각 입사시킬 수 있는 웨지를 가공하여 수조를 제작하였다. 본 실험에서는 동작주파수가 10MHz인 STAM 시스템을 이용하여 4중 프로젝션에 대한 토모그라픽 데이터를 영상처리하여 토모그라픽 영상을 복원하였으며 이를 기존의 종파를 이용한 토모그라픽 영상과 비교분석한 결과, 콘트라스트와 축방향 분해능이 향상되고 토모그라픽 영상을 복원할 수 있었다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.127-130
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• 1997

Phase-contrast(PC) methods have been used for quantitative measurements of velocity and volume flow rate. In addition, phase contrast cine magnetic resonance imaging (MRI) combines the flow dependent contrast of PC MRI with the ability of cardiac cine imaging to produce images throughout the cardiac cycle. In this method, the through-plane velocity has been encoded generally. However, the accuracy of the flow data can be reduced by the effect of flow direction, finite slice thickness, resolution, pulsatile flow pattern, and so on. In this study we calculated the error caused by misalignment of tomographic plane and flow directon. To reduce this error and encode the velocity for more complex flow, we suggested 3 directional velocity encoding method.

• Imaging Science in Dentistry
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• 제44권2호
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• pp.161-164
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• 2014

Mucoepidermoid carcinomas (MECs) arising within the jaws as primary central bony lesions are termed central MECs. Central MECs are extremely rare, comprising 2-3% of all mucoepidermoid carcinomas. We herein report a rare case of central MEC of the maxilla in a 52-year-old male whose plain radiographs showed a "ground glass" pattern and computed tomographic images, a hypodense mass with numerous calcifications. To the best of our knowledge, this is the first report of central MEC showing a "ground glass" appearance.