• 대한방사선기술학회지:방사선기술과학
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• 제34권1호
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• pp.27-33
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• 2011

과학 기술의 발달로 인해 의료 방사선 장비 또한 첨단화 되고 있으며 정확한 진단과 치료를 할 수 있게되어 의료의 질적 향상은 물론 양적인 면에서도 그 사용이 날로 증가하고 있는 추세이다. 특히 환자 피폭선량에 대부분을 차지하는 CT(Computed Tomography) 촬영의 건수는 크게 증가하고 있다. 치과 방사선 검사의 경우 정확한 병변 진단을 위한 CT 및 CBCT(Cone Beam Computed Tomography) 의 도입으로 과거에 비해 환자는 많은 선량을 받게 되었다. 본 연구에서는 인체 팬텀과 TLD-100H를 이용하여 치과 방사선 검사별 조직의 흡수선량을 측정하고 ICRP 60, 103에 따라 유효선량을 계산하였다. ICRP 60, 103에 따른 유효선량 값은 파노라마 검사의 경우 $5.1{\mu}Sv$, $29.5{\mu}Sv$, 세팔로 검사의 경우 $11.2{\mu}Sv$, $14.4{\mu}Sv$, 이며 CBCT는 상악골의 경우 $53.7{\mu}Sv$, $209.6{\mu}Sv$, 하악골은 $129{\mu}Sv$, $391.5{\mu}Sv$ 그리고 CT에서는 상악골의 경우 $93.3{\mu}Sv$, $139.5{\mu}Sv$이며 하악골은 $282.7{\mu}Sv$, $489.7{\mu}Sv$로 평가 되었다. CBCT 검사의 경우 유효선량은 CT 검사에 비해서는 적지만 파노라마 검사 및 세팔로 검사에 비해서는 높게 평가되었다.

• Imaging Science in Dentistry
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• 제49권2호
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• pp.131-137
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• 2019

Purpose: This study was designed to investigate the effects of voxel size, the oversampling technique, and the direction and area of measurement on modulation transfer function (MTF) values to identify the optimal method of MTF measurement. Materials and Methods: Images of the wire inserts of the SedentexCT IQ phantom were acquired, and MTF values were calculated under different conditions(voxel size of 0.1, 0.2, and 0.3 mm; 5 oversampling techniques; simulated pixel location errors; and different directions and areas of measurement). The differences in the MTF values across various conditions were evaluated. Results: The MTF 10 values showed smaller standard deviations than the MTF 50 values. Stable and accurate MTF values were obtained in the 0.1-mm voxel images. In the 0.3-mm voxel images, oversampling techniques of 11 lines or more did not show significant differences in MTF values depending on the presence of simulated location errors. MTF 10 values showed significant differences according to the direction and area of the measurement. Conclusion: To measure more accurate and stable MTF values, it is better to measure MTF 10 values in small-voxel images. In large-voxel images, the proper oversampling technique is required. MTF values from the radial and tangential directions may be different, and MTF values vary depending on the measured area.

• Imaging Science in Dentistry
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• 제41권4호
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• pp.143-150
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• 2011

Purpose : The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography (CBCT) images and bitewing images in detection of secondary caries. Materials and Methods : One hundred and twenty proximal slots of Class II cavities were randomly prepared on human premolar and molar teeth, and restored with amalgam (n=60) and composite resin (n=60). Then, artificial secondary caries lesions were randomly created using round steel No. 4 bur. The teeth were radiographed with a conventional bitewing technique and two CBCT systems; Pax-500ECT and Promax 3D. All images were evaluated by five observers. The area under the receiver operating characteristic (ROC) curve ($A_z$) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value<0.05). Results : The mean $A_z$ values for bitewing, Pax-500ECT, and Promax 3D imaging systems were 0.882, 0.995, and 0.978, respectively. Significant differences were found between the two CBCT systems and film (p=0.007). For CBCT systems, the axial plane showed the greatest $A_z$ value. Conclusion : Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries.

• 대한치과교정학회지
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• 제42권2호
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• pp.56-63
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• 2012

Objective: To identify the right and left difference of the facial soft tissue landmarks three-dimensionally from the subjects of normal occlusion individuals. Materials and Methods: Cone-beam computed tomography (CT) scans were obtained in 48 normal occlusion adults (24 men, 24 women), and reconstructed into 3-dimensional (3D) models by using a 3D image soft ware. 3D position of 27 soft tissue landmarks, 9 midline and 9 pairs of bilateral landmarks, were identified in 3D coordination system, and their right and left differences were calculated and analyzed. Results: The right and left difference values derived from the study ranged from 0.6 to 4.6 mm indicating a high variability according to the landmarks. In general, the values showed a tendency to increase according to the lower and lateral positioning of the landmarks in the face. Overall differences were determined not only by transverse differences but also by sagittal and vertical differences, indicating that 3D evaluation would be essential in the facial soft tissue analysis. Conclusions: Means and standard deviations of the right and left difference of facial soft tissue landmarks derived from this study can be used as the diagnostic standard values for the evaluation of facial asymmetry.

• 구강회복응용과학지
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• 제34권1호
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• pp.46-55
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• 2018

치조골의 흡수와 치주조직의 염증을 동반한 심한 치주질환 환자에서 임플란트를 통한 구강 회복은 임상적으로 어려움이 있다. 하지만 골 형태에 따른 적절한 임플란트 식립 위치를 선정한다면 불필요한 골 이식이나 연조직 수술을 최소로 할 수 있다. 최근에는 cone beam CT 촬영과 소프트웨어를 이용하여 환자의 해부학적 형태와 보철적인 위치를 고려하여 임플란트 식립 위치를 선정할 수 있게 되었고 3D printing 기술을 통해 제작된 surgical guide를 통해 계획된 위치로 정확한 수술이 가능하게 되었다. 본 증례는 70세 여성 환자로 심한 치주질환으로 인해 전악 치아의 발치가 필요하였으며 임플란트 지지 고정성 보철물로 전악 구강회복을 시행하였다. 수술 시에는 보철적인 위치를 고려한 surgical guide를 이용해 flapless 방식으로 임플란트를 식립하였고 수술 전에 CAD/CAM 방식으로 제작된 임시보철물을 즉시 부하하였다. 이후 맞춤형 지대주와 지르코니아를 이용한 보철물을 제작하였으며, 만족스러운 심미 및 기능 회복을 보였기에 보고하는 바이다.

• 한국방사선학회논문지
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• 제16권7호
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• pp.905-917
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• 2022

본 연구는 각각의 방사선 선량 조건을 나눠 검사할 때 MAR 기능의 사용과 영상 품질을 평가하기 위해 수행되었다. 실험을 위해 임플란트가 박힌 간단한 Periapical Phantom을 만들었고, CBCT 장비를 이용하여 선량 조건별로 MAR 기능의 유무에 따라 영상을 획득하고 실험에 임하였다. 본 연구에서는 Image J 프로그램을 이용하여 MEAN, SNR, 그리고 CNR 값들을 획득하였고, 통계 분석을 통해 Abutment of Implant 부분은 100 kVp, 8 mA 조건일 때, Center of Implant와 Apex of Implant 부분에서는 100 kVp, 9 mA 조건일 때 영상이 가장 정량적이고 적합한 값이었다. 따라서 방사선량이 증가하면 영상의 Pixel value, SNR, CNR 값이 상승해 화질이 향상되고, MAR 기능을 사용하면 Artifact가 줄어드는 것을 확인할 수 있었다.

• Journal of Oral Medicine and Pain
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• 제39권4호
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• pp.119-126
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• 2014

This review provides an overview of the most commonly used dental age estimation techniques which focus on radiological methods in Korean adults. The literature from 1995 through July 31, 2014, was searched, using PubMed, for publications in English language. In PubMed, the keywords 'tooth' OR 'dental' AND 'pulp' AND 'age estimation' were searched. Inclusion criteria was comprised of the following: the subjects were living adults and dental radiography (excluded computed tomography [CT] and cone-beam CT) was used to measure the pulpal size. Twenty articles that met the criteria were selected. The method of age estimation using dental radiographs for measuring pulp and tooth size was represented in all studies. The methods were assorted into three categories generally; Kvaal's, Ikeda's and Cameriere's methods. Those methods had certain limitations such as large error range and low correlation coefficient depending on populations, type of employed teeth and particular method. Various techniques and many studies have been published for age estimation from human teeth using dental radiographs, but those techniques showed various predictability and reliability. Therefore, future studies on larger samples with well-distributed age group using not only existing techniques but new techniques are necessary for deriving convincing results.

• Imaging Science in Dentistry
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• 제44권1호
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• pp.53-60
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• 2014

Purpose: This study was performed to investigate the incidence and configuration of the bifid mandibular canal in a Korean population by using cone-beam computed tomography (CBCT) imaging. Materials and Methods: CBCT images of 1933 patients (884 male and 1049 female) were evaluated using PSR-9000N and Alphard-Vega 3030 Dental CT units (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan). Image analysis was performed by using OnDemand3D software (CyberMed Inc., Seoul, Korea). The bifid mandibular canal was identified and classified into four types, namely, the forward canal, buccolingual canal, dental canal, and retromolar canal. Statistical analysis was performed by using the chi-squared test and one-way analysis of variance (ANOVA). Results: Bifid mandibular canals were observed in 198 (10.2%) of 1933 patients. The most frequently observed type of bifid mandibular canal was the retromolar canal (n=104, rate: 52.5%) without any significant difference among the incidence of each age and gender. The mean diameter of the accessory canal was 1.27 mm (range: 0.27-3.29 mm) without any significant difference among the mean diameter of each type of the bifid mandibular canal. The mean length of the bifid mandibular canals was 14.97mm(range: 2.17-38.8 mm) with only a significant difference between the dental canal and the other types. Conclusion: The bifid mandibular canal is not uncommon in Koreans and has a prevalence of 10.2% as indicated in the present study. It is suggested that a CBCT examination be recommended for detecting a bifid canal.

• 구강회복응용과학지
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• 제28권3호
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• pp.291-299
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• 2012

측두하악관절을 진단하기 위하여 선택할 수 있는 촬영 방법은 매우 다양하며, 모든 촬영법에는 제각각 장단점이 있으므로 모든 조건을 동시에 만족시키는 이상적인 하나의 촬영법은 없다. 그러므로 측두하악관절을 평가하기 위해서는 각 촬영법의 장단점을 파악하고 적절한 촬영법을 선택하여 다각적으로 분석해야 한다.

• Imaging Science in Dentistry
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• 제37권3호
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• pp.171-180
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• 2007

The role of radiographic imaging in determining the size, numbers and the position of implants is very important. To perform the implant procedure, the dentist needs to evaluate the bone pathology and bone density, and to know the precise height, width, and contour of the alveolar process, as well as its relationship to the maxillary sinus and mandibular canal. The author analyzed 3 implant cases for treatment planning with the cone beam CT. All axial, panoramic, serial and buccolingual-sectioned images of 3 cases with stent including vertical marker were taken by using Mercuray (Hitachi, Japan). When the curved line drawn intentionally did not include dot image of a vertical marker on the axial image of CBCT, the image of the vertical marker was deformed on its buccolingually sectioned image. There was wide discrepancy in inclination between the alveolar bone and tooth on buccolingually sectioned image.