• Progress in Medical Physics
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• v.2 no.2
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• pp.183-192
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• 1991

Ophthalmoscopy following the intravenous injection of fluorescein has gained great diagnostic importance in ophthalmology. This technique provides sequential evaluation of the anatomic and physiologic status of the choroidal and retinal vasculature. In order to detect the changes between fluorescein ocular fundus image frames, the direct subtraction of the two frames is inadequate because of geometric distortions and background gray level differences in two images. In this study, a scheme for the correction of the geometric distortions is proposed. Precise control point coordinate values for transformation functions are manually determined after the process including a series of blood vessel detection and thinning, and one frame is mapped to another, and then a geometric distortion corrected image is obtained. When the corrected image is used in interframe change detections, a sucessful result is ensured.

• Journal of Korea Multimedia Society
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• v.12 no.8
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• pp.1073-1081
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• 2009

In this paper, we proposed new method to enhance choroidal vessels by suppressing retina vessels brightness. It is well-known that CNV(choroidal neovascularization) is related with sight loss. The main feature of CNV is the occurrence of new vessels in choroid. Unfortunately, because retina vessels brightness is stronger than choroidal vessels brightness in ICGA(indocynanine green angiography) image, so that the choroidal vessels were hardly recognized. Therefore, for correct diagnosis, the choroidal vessels must be enhanced in ICGA image. The proposed enhancement method consists of 3 strategies. First, the retina vessels were detected by multi scale enhancement technique, hysteresis thresholding, KNN(Kth-nearest neighbor) classification method. And then, a retina vessel mask was generated from detection result. Next, the brightness of retina vessels was suppressed by the proposed conditional region erosion method and mask region until the mask region was vanished. Finally, the brightness of choroidal vessel was enhanced on processed image. Through an experiment, we had confirmed that the proposed method was robust and efficient.

• Journal of the Korea Computer Graphics Society
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• v.23 no.1
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• pp.49-55
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• 2017

Computed tomographic angiography (CTA) is widely used in the diagnosis and treatment of coronary artery disease because it shows not only the whole anatomical structure of the cardiovascular three-dimensionally but also provides information on the lesion and type of plaque. However, due to the large size of the image, there is a limitation in manually extracting coronary arteries, and related researches are performed to automatically extract coronary arteries accurately. As the coronary artery originate from the ascending aorta, the ascending aorta and ostium should be detected to extract the coronary tree accurately. In this paper, we propose an automatic segmentation for the ostium as a starting structure of coronary artery in CTA. First, the region of the ascending aorta is initially detected by using Hough circle transform based on the relative position and size of the ascending aorta. Second, the volume of interest is defined to reduce the search range based on the initial area. Third, the refined ascending aorta is segmented by using a two-dimensional geodesic active contour. Finally, the two ostia are detected within the region of the refined ascending aorta. For the evaluation of our method, we measured the Euclidean distance between the result and the ground truths annotated manually by medical experts in 20 CTA images. The experimental results showed that the ostia were accurately detected.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.4
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• pp.249-254
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• 2007

This paper describes a technique for detecting the boundary of the optic disk in digital image of the retina using inward and outward curve evolution. Optic disk boundary offers medical information about glaucoma progresses. For accurate boundary detection, image inpainting based on PDE removes blood vessels crossing the optic disk. For removing noises and preserving boundary of optic disk in image inpainting process, the anisotropic diffusion filtering is developed. After pre-processing, the optic disk boundary is determined using inward and outward curve evolution. Experimental results show that blurring effect of original region and optic disk boundary is reduced considerably. By the proposed method, we can detect correct disk boundary compare to conventional method.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.229-230
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• 2015

신생혈관 형성은 기존에 존재하는 혈관으로부터 새로운 혈관을 형성하는 기작으로 정상 세포에서 상처 치유, 세포의 발생 및 성장에 관여한다고 알려져 있다. 더 중요한 것은 이 기작이 암의 성장 및 전이에서도 매우 중요한 역할을 하고 있다는 사실이다. 특히, 엔지오제닌(Angiogenin)이 신생혈관형성을 촉진하는 것으로 알려져있다. 이러한 주요 물질을 최신 바이오칩 기술 중 하나인 액적 기반 미세유체 시스템을 활용하여 1 나노리터 수준의 시료 내에 존재하는 엔지오제닌을 정량하는 기술을 개발함으로써 현재 일반적으로 사용되고 있는 정량 기술에 비해 시간뿐만 아니라 비용을 절감할 수 있음을 보여주었다. 이외에도 본 연구에서 개발한 액적 기반 미세유체 시스템 기술은 수은과 같은 중금속의 검출도 가능하기 때문에 환경 센서로의 활용 가능성을 보여준다.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.12 no.1
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• pp.42-62
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• 2008

Objectives: It is well known that some parameters of the photoplethysmogram (PPG) acquired by time domain contour analysis can be used as markers of vascular aging. But the previous studies that have been performed for frequency domain analysis of the PPG to date have provided only restrictive and fragmentary information. The aim of the present investigation was to determine whether the harmonics extracted from the PPG using a fast Fourier transformation could be used as an index of vascular aging. Methods: The PPG was measured in 600 recruited subjects for 30 second durations, To grasp the gross age-related change of the PPG waveform, we grouped subjects according to gender and age and averaged the PPG signal of one pulse cycle. To calculate the conventional indices of vascular aging, we selected the 5-6 cycles of pulse that the baseline was relatively stable and then acquired the coordinates of the inflection points. For the frequency domain analysis we performed a power spectral analysis on the PPG signals for 30 seconds using a fast Fourier transformation and dissociated the harmonic components from the PPG signals. Results: A final number of 390 subjects (174 males and 216 females) were included in the statistical analysis. The normalized power of the harmonics decreased with age and on a logarithmic scale reduction of the normalized power in the third (r=-0.492, P<0.0001), fourth (r=-0.621, P<0.0001) and fifth harmonic (r=-0.487, P<0.0001) was prominent. From a multiple linear regression analysis, Stiffness index, reflection index and corrected up-stroke time influenced the normalized power of the harmonics on a logarithmic scale. Conclusions: The normalized harmonic power decreased with age in healthy subjects and may be less error prone due to the essential attributes of frequency domain analysis. Therefore, we expect that the normalized harmonic power density can be useful as a vascular aging marker.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1378-1380
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• 2015

본 논문은 흉부 CT 영상을 활용하여 폐결절을 자동으로 검출하는 알고리즘에 관한 연구내용을 담고 있다. 폐 결절 자동 검출을 위해 폐 CT 영상 내에 있는 객체를 검출하고, 검출된 객체의 특징들 중, 이동성 및 기하학적 특징을 가지고 폐혈관과 폐결절을 구분하였다. 실험한 영상은 폐결절이 있는 26명의 원광대학교 병원 환자의 흉부 CT 영상을 사용하였으며, 그 결과 96.15%의 정확도와 3.54 False Positves / Scan이 발생하였다.

• Journal of Biomedical Engineering Research
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• v.20 no.5
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• pp.567-572
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• 1999

혈관내 맥검출 센서인 MPX2300DT1을 요골동맥상에서 무침습적으로 맥파를 검출할 수 있도록 실리콘 고무를 부착하여 맥진 센서로 활용하였다. 또한 추의 무게에 의해 압력을 조절하여 그것에 따른 맥파의 변화를 볼 수 있는 맥진 시스템을 제작하였다. 맥진 센서의 압력에 따른 출력전압의 선형성을 확인하였으며 추의 무게에 따른 맥파의 진폭과 주기 변화를 조사하였다.

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.399-406
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• 2019

This study aims to find geometric parameters that the radiologist can change from time to time to reduce dose in angiography examinations. Depending on the geometric characteristics, the values calculated by effective dose were compared, while filming in fluoroscopy mode and Digital subtraction angiography, respectively. The study found that the lower the dose was in FPS mode, the lower the dose was reduced to 30-40%. Doses according to the X-ray angle were measured highest in AP View and lower as the angle went in the head direction. The greater the FOV, the higher the dose was 1.2-1.6 times, and the closer the distance between the X-ray tube and the table, the greater the dose was about 10%. Source-image intensifier distance (SID) get longer to 100 mm, dose of each fluoroscopy and Digital subtraction angiography increase up to 25-30%. In conclusion, various geometric characteristics in angiography examinations are parameters that can be applied by radiographers as frequently as possible, and appropriate geometric properties can be considered and applied in various situations, resulting in appropriate dose reduction.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.482-483
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• 2008

본 연구는 수면 중 무구속적 방식으로 에어 베개에 부착한 PPG 센서에서 호흡 및 심박을 검출하는 방법을 제안하였다. 본 연구에서 사용된 반사형 PPG 센서는 광원이 피부로 투과되어 혈관의 이완 및 수축 정도를 측정할 수 있다. 반사형 PPG 센서로부터 하드웨어 모듈을 통과한 생체 신호는 AD 변환되어 PC로 전송된다 PPG에서 검출된 분당 심박 수는 전송된 신호의 밸리점간의 시간 간격을 이용하여 추출하며 호흡 신호는 밸리점의 크기를 연결하여 추출하였다. 검출된 호흡 신호와 기준 호흡 신호간의 상관성을 확인하기 위해 기준신호로 호흡과 심박을 동시에 측정하여 그 결과를 분석하였다. PPG 센서로부터 획득한 심박 및 호흡 신호는 기준신호들과 높은 상관성을 가지며 호흡시 발생하는 움직임과 호흡 속도에 영향을 받는다는 것을 알 수 있었다.