• 치과방사선
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• 제24권2호
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• pp.279-290
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• 1994

The purpose of this study was to compare the diagnostic accuracy of periapical radiographs and their digitized images for the detection of simulated interproximal carious lesions. A total of 240 interproximal surfaces was used in this study. The case sample was composed of 80 anterior teeth, 80 bicuspids and 80 molars which were prepared in order to distribute the surfaces from carious free to those containing simulated carious lesions of varying depths (0.5㎜, 0.8㎜, and 1.2㎜). The periapical radiographs were taken by paralleling technique and film used was Kodak Ektaspeed(E group). All radiographs were evaluated by five dentist to recognize the true status of simulated carious lesion. They were asked to give a score of 0, 1, 2, or 3. Digitized images were obtained using a commercial video processor(FOTOVIX Ⅱ- XS). And the computer system was 486 DX PC with PC Vision and frame grabber. The 17' display monitor had a resolution of 1280×1024 pixels(0.26㎜ dot pitch). But the one frame of the intraoral radiograph has a resolution of 700×480 pixels and each pixel has a grey level value of 256. All the radiographs and digital images were viewed under uniform subdued lighting in the same reading room. After a week the second interpretation was performed in the same condition. The detection of lesions on the monitor was compared with the finding of simulated interproximal carious lesions on the film images. The results were as follows: 1. When the scoring criteria was dichotomous ; lesion present and not present 1) The overall sensitivity, specificity and diagnostic accuracy of periapical radiographs and their digital images showed no statistically significant difference. 2) The sensitivity and specificity according to the region of teeth and the grade of lesions showed no statistically significant difference between periapical radiographs and their digital images. 2. When estimate the grade of lesions ; score 0, 1, 2, 3 1) The overall diagnostic accuracy was 53.3% on the intraoral films and 52.9% on digital images. There was no significant difference. 2) The diagnostic accuracy according to the region of teeth showed no statistically significant difference between periapical radiographs and their digital images. 3. The degree of agreement and reliability 1) Using gamma value to show the degree of agreement, there was similarity between periapical films and digital images. 2) The reliability of each twice interpretation of periapical films and digital images showed no statistically significant difference. In all cases P value was greater than 0.05, showing that both techniques can be used to detect the incipient and moderate interproximal carious lesions with similar accuracy.

• 대한소아치과학회지
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• 제49권4호
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• pp.442-452
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• 2022

이 연구의 목적은 파노라마 방사선사진에서 분석한 매복 상악 견치의 위치와 각도를 CBCT 영상에서 분석한 매복된 견치의 순구개측 위치, 인접 치아의 치근흡수와 비교 및 평가하는 것이다. 총 54명의 환자, 69개의 매복 상악 견치가 연구에 포함되었다. 파노라마 방사선사진에서 매복 상악 견치의 근원심 위치(구역 I - V)와 각도, 수직적 위치가 평가되었다. 순구개측 위치와 인접 치아의 치근흡수는 CBCT 상에서 평가되었다. 파노라마 방사선사진의 근원심 위치 분석에서 순측 매복은 구역 I에서 가장 많았다. 치열궁 내 매복은 구역 I과 II에서 가장 많았다. 구개측 매복은 구역 III, IV, V에서 가장 많았다. 파노라마 방사선사진에서 근심에 위치할수록 구개측에 매복되는 경향이 있었다. 인접 치아 치근흡수의 대부분은 구역 III, IV, V에서 발생했다. 수평 기준선에 대해 작은 각도를 가진 매복 견치는 구개측에 매복되고 인접 치아의 치근흡수를 일으키는 경향이 있었다. 파노라마 방사선사진에서 매복 상악 견치의 근원심 위치와 각도에 대한 분석은 매복 견치의 순구개측 위치와 인접 치아 치근흡수의 예측 가능성을 보여주었으며, 이는 CBCT 촬영에 대한 의사결정에 유용할 수 있다.

• Investigative Magnetic Resonance Imaging
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• 제12권2호
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• pp.153-160
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• 2008

목적: 소아성 대퇴골두 무혈성 괴사증의 추적 단순 X선 촬영술에서 대퇴 골단의 구형 모양을 유지하는 것을 기준으로 좋은 예후를 기대할 수 있는 환자를 찾는데에 자기공명영상이 진단당시 단순 X선 촬영술 보다 우월한지 여부를 알아보기 위함이 목적이다. 대상 및 방법: 소아성 대퇴골두 무혈성 괴사증을 가진 41명의 환자에서 48예의 대퇴 골두의 진단 당시 단순 X선 촬영술과 자기공명영상을 후향적으로 분석하였다. 대퇴 골두 침범은 초기 단순 X선 촬영술과 자기공명영상을 Catterall 분류를 이용하여 평가하였다. 최대 대퇴 골두 변형으로 결정되는 예후는 추적 단순 X선 촬영술에서 Stulberg 분류에 의해 평가되었다. 결과: 자기공명영상에서 Catterall 분류가 1보다 큰 경우에는 추적 단순 X선 촬영술에서 대퇴 골두 기형의 나쁜 예후(Stulberg class>2)를 보이는 환자를 발견하는 데에 100% 민감도 (14/14) 을 보였다. 단순 X선 촬영술에서는 57% (8/14)의 낮은 민감도를 보였다. 자기공명영상의 특이도는 21% (7/34)였고, 단순 X선 촬영술의 특이도인 32%(11/34)와 유의한 차이를 보이지 않았다. 결론: 자기공명영상에서 Catterall 분류1은 소아성 대퇴골두 무혈성 괴사증의 좋은 예후를 시사한다. 대퇴 골두의 더욱 광범위한 침범을 가진 환자들도 좋은 결과를 보일 수 있으나, 그들은 대퇴 골두의 구형 모양을 소실하고 수반되는 골관절염을 성인에서 보일 위험성이 있다. 자기공명영상은 좋은 예후를 가진 환자 집단을 파악하는데 단순 X선 촬영술보다 우월하다.

• Korean Journal of Radiology
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• 제24권6호
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• pp.541-552
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• 2023

Objective: Detection of pneumoperitoneum using abdominal radiography, particularly in the supine position, is often challenging. This study aimed to develop and externally validate a deep learning model for the detection of pneumoperitoneum using supine and erect abdominal radiography. Materials and Methods: A model that can utilize "pneumoperitoneum" and "non-pneumoperitoneum" classes was developed through knowledge distillation. To train the proposed model with limited training data and weak labels, it was trained using a recently proposed semi-supervised learning method called distillation for self-supervised and self-train learning (DISTL), which leverages the Vision Transformer. The proposed model was first pre-trained with chest radiographs to utilize common knowledge between modalities, fine-tuned, and self-trained on labeled and unlabeled abdominal radiographs. The proposed model was trained using data from supine and erect abdominal radiographs. In total, 191212 chest radiographs (CheXpert data) were used for pre-training, and 5518 labeled and 16671 unlabeled abdominal radiographs were used for fine-tuning and self-supervised learning, respectively. The proposed model was internally validated on 389 abdominal radiographs and externally validated on 475 and 798 abdominal radiographs from the two institutions. We evaluated the performance in diagnosing pneumoperitoneum using the area under the receiver operating characteristic curve (AUC) and compared it with that of radiologists. Results: In the internal validation, the proposed model had an AUC, sensitivity, and specificity of 0.881, 85.4%, and 73.3% and 0.968, 91.1, and 95.0 for supine and erect positions, respectively. In the external validation at the two institutions, the AUCs were 0.835 and 0.852 for the supine position and 0.909 and 0.944 for the erect position. In the reader study, the readers' performances improved with the assistance of the proposed model. Conclusion: The proposed model trained with the DISTL method can accurately detect pneumoperitoneum on abdominal radiography in both the supine and erect positions.

• Imaging Science in Dentistry
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• 제31권4호
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• pp.199-204
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• 2001

Purpose : To assess the relationship between soft tissue asymmetry and bone tissue asymmetry using the standardized photographs and the posteroanterior (PA) cephalometric radiographs in mandibular asymmetric patients. And to clarify that the lack of morphologic balance among different skeletal components can often be masked by compensatory soft tissue contributions. Methods: Experimental group consisted of 58 patients whose chief complaints were facial asymmetry, they were taken with standardized facial photographs and PA cephalometric radiographs. Control group consisted of 30 persons in the normal occlusion. The reproducibility of the facial photograph was confirmed by model test. The differences of fractional vertical heightand horizontal width from standardized facial photographs and PA cephalometric radiographs were compared and analyzed. Results: The difference of fractional vertical bone height was 0.63 and fractional vertical soft height was 0.58 in control group, 3.10 and 2.01 in asymmetric group, respectively. The difference of fractional horizontal bone width was 0.52 and fractional horizontal soft width was 0.70 in control group, 2.51 and 1.70 in asymmetric group, respectively. Both soft and bone tissue showed significant difference between control and asymmetric group (p<0.05). The difference of bone tissue was greater than that of soft tissue (p<0.05) in the experimental group but, not in control group. Conclusions: Soft tissue components may compensate for underlying skeletal imbalances.

• Imaging Science in Dentistry
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• 제33권4호
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• pp.199-205
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• 2003

Purpose: To compare the visibility of the mandibular canal at the different radiographic methods such as conventional panoramic radiographs, Vimplant multi planar reformatting (MPR)-CT panoramic images, Vimplant MPR-CT paraxial images and film-based DentaScan MPR-CT images. Materials and Methods: Data of 11 mandibular dental implant patients, who had been planned treatment utilizing both panoramic and MPR-CT examination with DentaScan software (GE Medical systems, Milwaukee, USA), were used in this study. The archived axial CT data stored on CD-R discs were transferred to a personal computer with 17' LCD monitor. Paraxial and panoramic images were reconstructed using Vimplant software (CyberMed Inc., Seoul, Korea). Conventional panoramic radiographs, monitor-based Vimplant MPR-CT panoramic images, monitor-based Vimplant MPR-CT paraxial images, and film-based DentaScan MPR-CT images were evaluated for visibility of the mandibular canal at the mental foramen, 1 cm, 2 cm, and 3 cm posterior to mental foramen using the 4-point grading score. Results: Vimplant MPR-CT panoramic, paraxial, and DentaScan MPR-CT images revealed significantly clearer images than conventional panoramic radiographs. Particularly at the region 1 em posterior to mental foramen, conventional panoramic radiographs showed a markedly lower percentage of 'excellent' mandibular canal images than images produced by other modalites. Vimplant MPR-CT and DentaScan MPR-CT images did not show significant difference in visibility of the mandibular canal. Conclusion: The study results show that Vimplant and DentaScan MPR-CT imaging systems offer significantly better images of the mandibular canal than conventional panoramic radiograph.

• Journal of Periodontal and Implant Science
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• 제28권4호
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• pp.797-809
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• 1998

The purposes of this study were to develop the computer program for the contrast and geometric correction in digital subtration radiography with the IDL (Interactive Data Language) and compare the results with this program for the correction of the non-standardized radiographs to those of standardized radiographs and those with "Emago" software, the commercial program for the correction. The procedures were written for the contrast correction and subtraction with the geometric correction, using IDL. 32 pairs of periapical radiographs of premolar and molar portion of two dry human mandibles were taken at two different occasions with XCP film holder(nonstandardized films) and another 32 pairs with customized XCP film holder(standardized films). Subtraction of standardized film pairs was performed. Subtraction after the contrast and geometric correction of non-standardized films was performed using the newly developed program and Emago software. Standard deviations of grey levels of the subtracted images by the newly developed program were compared with those of the standardized group and Emago-corrected group. Standard deviations of grey levels of new program-corrected group were much smaller than those of the Emago-corrected group (p<0.001) and slightly larger than those of standardized group (p<0.05). However, the difference was very minute. This study indicates that the newly developed program written with IDL may substitute the mechanical standardization for digital subtraction radiography.

• Journal of Yeungnam Medical Science
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• 제37권1호
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• pp.40-46
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• 2020

Background: Postoperative pain occurring after hip arthroplasty has become common since the expanded use of cementless femoral stems. The characteristic pain develop in the anterolateral thigh area. This study aimed to predict anterior thigh pain based on the measurements of postoperative anteroposterior (AP) and lateral (Lat) radiographs of the hip joint. Methods: The present study included 26 patients (29 hips) who underwent total hip replacement or bipolar hemiarthroplasty between March 2010 and May 2016, whose complete clinical information was available. AP and Lat radiographs of the affected hip were taken on the day of surgery and 1 and 6 months postoperatively. Patients with improper radiographs were excluded. The distance from the femoral stem to the nearest cortical bone in the distal region of the stem was measured. The patient group with a visual analog scale (VAS) score of ≥6 points was designated as patients with anterior thigh pain. Results: Sex, age, weight, height, body mass index, and bone mineral density in the lumbar spine and femur did not have a significant effect on postoperative VAS scores (p>0.05). Presence of contact between the femoral stem and cortical bone was associated with postoperative anterior thigh pain. Conclusion: Hip AP and Lat radiographs are usually taken to confirm fixation and alignment of the femoral stem after hip arthroplasty. The measurement method introduced in this study can be utilized for predicting anterior thigh pain after hip arthroplasty.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권6호
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• pp.658-665
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• 2000

Purpose : The present study was carried out to determine the diagnostic usefulness of bone scan for evaluating jaw bone extension of oral cancer. Materials and Methods : Medical records, preoperative bone scans, computerized tomographic (CT) scans, conventional radiographs, and findings of histopathologic sections of twenty patients who had been treated for oral malignant tumors by a resection of mandible and soft tissue at Chonnam University Hospital from January, 1994 to September, 1999 were analyzed. Results : In 13 cases which showed histopathologically positive, preoperative bone scans were positive in 12 (92.3%) and false negative in 1 (7.7%). Preoperative CT scans were positive in 9 (69.2%) and false negative in 4 (30.8%) of the 13 cases. Preoperative conventional radiographs were positive in 8 (61.5%) and false negative in 5 (38.5%) of the 13 cases. In 7 cases showing negative histopathologic findings, 1 (14.3%) was in CT scans and 2 (28.6%) were false positive in preoperative conventional radiographs. Conclusion : These results suggest that bone scan is more sensitive and reliable method for evaluating jaw bone extension of oral cancer than conventional radiographs or CT scans.

• Imaging Science in Dentistry
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• 제44권2호
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• pp.137-141
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• 2014

Purpose: This study was performed to investigate the interobserver agreement on the detection of carotid artery calcifications on panoramic radiographs. Materials and Methods: This study consisted of panoramic radiographs acquired from 634 male patients of the age of 50 years or older. Having excluded carotids of no diagnostic quality, 1008 carotids from the panoramic radiographs of the patients were interpreted by two oral and maxillofacial radiologists independently for the presence of carotid artery calcifications. Statistical analysis was used to calculate the interobserver agreement. Results: Interobserver agreement was obtained for 932 carotids (92.4%). Inconsistent interpretation of 76 carotids (7.5%) between the two observers was found. Cohen's kappa value was 0.688 (p<0.001). Conclusion: The probability of a match between the two observers was substantially high.