• 치위생과학회지
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• 제23권1호
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• pp.60-67
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• 2023

Background: In our study, a silver diamine fluoride (SDF) compound for the treatment of dental caries was synthesized to characterize its remineralization activity upon direct application to deciduous teeth. This study aimed to use microscopic computed tomography (microCT) and nanoindentation to evaluate whether SDF composite application could effectively arrest dental caries in five exfoliated primary molars. Methods: Carious teeth were extracted and visually examined using quantitative photofluorescence devices (Qraycam and QraypenTM). After performing microCT, the SDF composite was applied to the teeth according to the manufacturer's instructions. The researchers exchanged and precipitated the irritant saliva once daily for 1 week. The teeth were sectioned longitudinally through the centers of the mesial and distal surfaces, embedded, polished, and measured using nanoindentation. Thereafter, microCT was repeated. Statistical analyses were performed using GraphPad Prism software. Results: Following SDF composite application, a remineralized layer was observed on microCT images, and the hardness increased when measured using nanoindentation. We found that demineralized enamel presented with an increased number of irregular crystals in the deep carious lesion group compared with those in the shallow carious lesion group, resulting in a rougher surface. Conclusion: The SDF composite may be used for remineralization of early caries and cessation of advanced caries in primary molars.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8479-8486
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• 2015

본 연구는 Brain CT검사 시 영상에서 발생하는 선속경화현상의 원인과 감소방법을 알아보기 위하여 선속경화현상에 영향을 미치는 관전압, 관전류, 단면두께, 갠트리 각도, 기준선에 변화를 주었다. 사용한 장비로는 Somatom Sensation 16장비로 Bone opaque head phantom을 이용 영상영향인자에 변화를 주어 스캔하였고 획득한 영상 데이터를 이용하여, CT값 분석을 이용한 정량적 분석과 CT영상평가표를 이용한 정성적 평가를 시행하였다. 정량적 분석결과 관전압은 140kVp일 때 $31.56{\pm}2.89HU$로 측정되었고, 관전류의 경우 150mA에서 $-3.87{\pm}0.12HU$, 절편두께는 3mm에서 $2.29{\pm}0.78HU$로 측정되었으며 갠트리 각도에서 IOML이 $13.31{\pm}1.03HU$로 선속경화현상이 가장 적었다. 정성적 분석결과 대부분의 평가자들이 140kVp, 150mA, 3mm, IOML 또는 OML에서 스캔한 영상을 선속경화현상이 적게 발생한 영상으로 평가하였으며 모든 조건에서 변화 인자와 비교 시 통계학적으로 유의한 차이가 있었다.(P<0.05) 따라서, 임상적용 시 허용선량한도 범위 내에서 관전압은 높여주고 관전류는 영상 화질 저하에 영향을 미치지 않는 범위 내에서 낮게 설정하며, 절편두께는 해상도 저하를 고려하여 얇은 절편두께를 사용하고, 갠트리 각도는 IOML 또는 OML을 이용한다면 선속경화현상에 의해 발생되어지는 인공물을 최소화시켜 영상 판독자와 환자에게 보다 정확한 양질의 영상을 제공할 수 있을 것으로 사료된다.

• Journal of Chest Surgery
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• 제28권3호
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• pp.228-232
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• 1995

Computed tomography[CT is an effective technique for the evaluation of the thorax following blunt trauma. To evaluate multiply injured 30 patients who were diagnosed as hemothorax in emergency room, computed tomography of thorax was done. The thickness of slice was one centimeter and the entire pleural cavity from the apex to the costophrenic angle was included in the evaluation. Integration and addition of the hemothorax area for each CT slice was made and amount of blood in the pleural cavity was estimated. The slice which showed largest area of hemothorax was selected and the height and width of the hemothorax area were measured. The number of slices which showed radiographic evidence of hemothorax was counted. Regression analysis was done and measured amount of hemothorax, the height and width of the hemothorax area for each slice and number of slices were put as variables. And following equation was derived. V=108.3A-0.8B-7.4C+84.7 [R2=0.74 [ V: amount of hemothorax, A: height, B: width, C: number of slices Total amount of blood from thoracic drainage was compared to the measured amount by computed tomography and the relation between the two values was statistically significant.[p=0.001 In conclusion, quantitative estimation of size of hemothorax was possible by the above equation and the process was very helpful for determination policy of treatment of individual patient.

• Journal of Chest Surgery
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• 제27권10호
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• pp.833-837
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• 1994

Lung contusion due to blunt chest trauma is the most common lung injury and correlated with the clinical course and prognosis. Its diagnosis by CT[Computerized Tomogram] gives a more clear and understandable three dimensional view, by which we are able to measure the volume of the contused and entire lung. Other variables are arterial blood gas, number of rib fracture, presence of hemopneumothorax, sternal fracture and clavicle fracture, number of associated non-thoracic injuries, ventilator time and presence of pulmonary complication. Percentage[%] of lung contusion are expressed as mean $\pm$ standard deviation and data analysis was performed by means of multivariate repeated measures analysis of variance to detect significant differences in variables between positive thoracic injury group and negative group. The paired t-test was used. Differences of percentage of lung contusion between groups were assessed by one-way analysis of variance. Simple linear regression was used to perform correlation analysis in the number of rib fracture and ventilator time. A p value less than 0.05 was considered statistically significant. Pneumothorax and the number of associated other injuries affect the amount of lung contusion and pulmonary complication group has more contused lung volume. Arterial blood gas study shows no correlation with the amount of lung contusion statistically. The number of rib fracture correlated with the amount of lung contusion, which also correlated with ventilator time[r=0.56, p<0.05]. In conclusion, quantitative anlysis of lung contusion by CT predicts the clinical course and treatment such as ventilator care.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.103-105
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• 2002

Whole body stereotactic radiosurgery (WBSRS) technique is believed to be useful for the metastatic lesions as well as relatively small primary tumors in the trunk. Unlike stereotactic radiosurgery to intracranial lesion, inherent limitation on immobilization of whole body makes it difficult to achieve the reliable setup reproducibility. For this reason, it is essential to develop an objective and quantitative method of evaluating setup error for WBSRS. An evaluation technique using image registration has been developed for this purpose. Point pair image registrations with WBSRS frame coordinates were performed between two sets of CT images acquired before each treatment. Positional displacements could be determined by means of volumetric planning target volume (PTV) comparison between the reference and the registered image sets. Twenty eight sets of CT images from 19 WBSRS patients treated in Asan Medical Center have been analyzed by this method for determination of setup random error of each treatment. It is objective and clinically useful to analyze setup error quantitatively by image registration technique with WBSRS frame coordinates.

• 한국어류학회지
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• 제19권2호
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• pp.88-92
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• 2007

Marine birnavirus (MABV)에 무증상적으로 감염된 넙치 (Paralichthys olivaceus) 치어에 면역억제제의 일종인 Dexamathasone을 투여하였을 때 MABV의 감염강도에 영향을 미치는가를 조사하였다. Real time PCR 분석결과 dexamethasone을 투여한 그룹이 생리식염수를 주사한 그룹 및 no handling 그룹에 비해 유의적으로 낮은 Ct 값을 나타냈으며, 또한 semi-quantitative RT-PCR 분석결과에 있어서도 dexamethasone을 주사한 그룹이 대조구 그룹들에 비해 MABV 유전자가 유의적으로 높게 증폭되는 것으로 나타났다. 이러한 결과로부터 dexamethasone 투여가 넙치 치어에 감염된 MABV의 복제를 증가시킴을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권2호
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• pp.576-590
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• 2023

Machine learning is widely used in various academic fields, and recently it has been actively applied in the medical research. In the medical field, machine learning is used in a variety of ways, such as speeding up diagnosis, discovering new biomarkers, or discovering latent traits of a disease. In the respiratory field, a relative regional air volume change (RRAVC) map based on quantitative inspiratory and expiratory computed tomography (CT) imaging can be used as a useful functional imaging biomarker for characterizing regional ventilation. In this study, we seek to predict RRAVC using various regular machine learning models such as extreme gradient boosting (XGBoost), light gradient boosting machine (LightGBM), and multi-layer perceptron (MLP). We experimentally show that MLP performs best, followed by XGBoost. We also propose several relative coordinate systems to minimize intersubjective variability. We confirm a significant experimental performance improvement when we apply a subject's relative proportion coordinates over conventional absolute coordinates.

• Korean Journal of Radiology
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• 제24권10호
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• pp.1006-1016
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• 2023

Objective: Computed tomography (CT) is an established method for the diagnosis, staging, and treatment of multiple myeloma. Here, we investigated the potential of photon-counting detector computed tomography (PCD-CT) in terms of image quality, diagnostic confidence, and radiation dose compared with energy-integrating detector CT (EID-CT). Materials and Methods: In this prospective study, patients with known multiple myeloma underwent clinically indicated whole-body PCD-CT. The image quality of PCD-CT was assessed qualitatively by three independent radiologists for overall image quality, edge sharpness, image noise, lesion conspicuity, and diagnostic confidence using a 5-point Likert scale (5 = excellent), and quantitatively for signal homogeneity using the coefficient of variation (CV) of Hounsfield Units (HU) values and modulation transfer function (MTF) via the full width at half maximum (FWHM) in the frequency space. The results were compared with those of the current clinical standard EID-CT protocols as controls. Additionally, the radiation dose (CTDIvol) was determined. Results: We enrolled 35 patients with multiple myeloma (mean age 69.8 ± 9.1 years; 18 [51%] males). Qualitative image analysis revealed superior scores (median [interquartile range]) for PCD-CT regarding overall image quality (4.0 [4.0-5.0] vs. 4.0 [3.0-4.0]), edge sharpness (4.0 [4.0-5.0] vs. 4.0 [3.0-4.0]), image noise (4.0 [4.0-4.0] vs. 3.0 [3.0-4.0]), lesion conspicuity (4.0 [4.0-5.0] vs. 4.0 [3.0-4.0]), and diagnostic confidence (4.0 [4.0-5.0] vs. 4.0 [3.0-4.0]) compared with EID-CT (P ≤ 0.004). In quantitative image analyses, PCD-CT compared with EID-CT revealed a substantially lower FWHM (2.89 vs. 25.68 cy/pixel) and a significantly more homogeneous signal (mean CV ± standard deviation [SD], 0.99 ± 0.65 vs. 1.66 ± 0.5; P < 0.001) at a significantly lower radiation dose (mean CTDIvol ± SD, 3.33 ± 0.82 vs. 7.19 ± 3.57 mGy; P < 0.001). Conclusion: Whole-body PCD-CT provides significantly higher subjective and objective image quality at significantly reduced radiation doses than the current clinical standard EID-CT protocols, along with readily available multi-spectral data, facilitating the potential for further advanced post-processing.

• 보건의료산업학회지
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• 제3권2호
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• pp.87-94
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• 2009

The purpose of this study is to evaluate the relationship between osteoporotic postmenopausal women and its bone mineral density value by using the single energy quantitative CT. 1. Decreasing BMD with age is evident. There is a significant low BMD value in the osteoporotic women compared with the healthy subgroup. 2. BMD decrease from T12 to L4, except in healthy premenopausal women. 3. Relationship of spinal BMD expressed as average BMD of T12 through L4 Show strong correlation with mean BMD in all vertebral levels. 4. There are significantly different BMD value from T12 through L4 in subgroup 1, 2, 3 but there is no statistically significant difference between subgroup 2 and 3. Conclusion, There is a significant decreasing BMD with age but it is difficult to differentiate postmenopausal relatively healthy women from osteoporotic women by BMD.

• 대한소아치과학회지
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• 제49권1호
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• pp.65-75
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• 2022

본 연구의 목적은 유치의 치아우식증 검사를 위한 정량형광분석(quantitative light-induced fluorescence, QLF) 기술의 유효성을 평가하고, 우식병소의 부피와 QLF 분석결과 사이의 상관관계를 확인하는 것이다. 치아우식증 검사를 위해 53개의 교합면 및 72개의 인접면을 포함한 총 125개의 유구치 치면을 휴대용 QLF 장비를 이용해 조사하여 유구치의 치아우식증을 확인하였다. 또한 치아우식증을 분류하고 우식병소의 부피를 계산하기 위해 micro-CT 방사선 검사를 시행하였다. 상대적으로 낮은 수치를 보였던 인접면 우식에 대한 𝚫R average 결과를 제외하면, QLF 분석결과는 유치의 치아우식증 진단에 대해 충분한 수준의 정확성과 신뢰도를 보였다(민감도 0.75 - 0.94, 특이도 0.82 - 0.95, AUROC 0.88 - 0.98). Spearman 상관분석 결과에서는 𝚫F average 및 QS-Index와 우식병소 부피 사이에 통계적으로 유의한 높은 상관성을 확인할 수 있었다(r = 0.805 - 0.832, p < 0.001). QLF 기술을 이용한 치아우식증 검사는 어린이의 치아우식증 진단에 있어 방사선 노출에 대한 걱정 없이 안전하게 사용 가능하고, 신뢰할 만한 방법이 될 수 있을 것이다.