• 한국방사선학회논문지
• /
• 제8권4호
• /
• pp.147-153
• /
• 2014

디지털 Mammography영상에서 압축률에 따른 화질의 특성에 대해 정량적 평가와 정성적평가를 실시하였다. ACR Accreditation phantom을 대상으로 JPEG2000, JPEG 압축알고리즘을 적용하여 압축한 후 Detection Score를 측정하여 압축률에 상관없이 10점 인정기준을 충족하였다. 또한 실제미세병소 영상을 선정하여 압축을 실시하여 확대율에 따른 진단능의 변화를 측정하여 20:1 이상 압축 후 50% 이상 확대 시 진단능에 영향을 미칠 수 있음을 알 수 있었다. 또한, 정량적 평가방법인 PSNR, RMSE, MAE, SSIM등을 측정하여 압축률에 따른 원본영상과의 차이점은 비교적 허용 가능한 오차범위 내의 값이 측정되었다. 또한 MTF 측정을 통해 Full Field Digital Mammography 영상의 화질이 진단에 적합한 영상임을 알 수 있었다.

• 한국멀티미디어학회논문지
• /
• 제18권6호
• /
• pp.701-709
• /
• 2015

Image stitching method is a technique for obtaining an high-resolution image by combining two or more images. In X-ray image for clinical diagnosis, the size of the imaging region taken by one shot is limited due to the field-of-view of the equipment. Therefore, in order to obtain a high-resolution image including large regions such as a whole body, the synthesis of multiple X-ray images is required. In this paper, we propose a rapid stitching method of digital X-ray images using template-based registration. The proposed algorithm use principal component analysis(PCA) and k-nearest neighborhood(k-NN) to determine the location of input images before performing a template-based matching. After detecting the overlapping position using template-based matching, we synthesize input images by alpha blending. To improve the computational efficiency, reduced images are used for PCA and k-NN analysis. Experimental results showed that our method was more accurate comparing with the previous method with the improvement of the registration speed. Our stitching method could be usefully applied into the stitching of 2D or 3D multiple images.

• 한국컴퓨터정보학회논문지
• /
• 제21권11호
• /
• pp.17-21
• /
• 2016

Heterogeneity assessment of tumor in oncology is important for diagnosis of cancer and therapy. The aim of this study was performed assess heterogeneity tumor region in PET image using texture analysis. For assessment of heterogeneity tumor in PET image, we inserted sphere phantom in torso phantom. Cu-64 labeled radioisotope was administrated by 156.84 MBq in torso phantom. PET/CT image was acquired by PET/CT scanner (Discovery 710, GE Healthcare, Milwaukee, WI). The texture analysis of PET images was calculated using occurrence probability of gray level co-occurrence matrix. Energy and entropy is one of results of texture analysis. We performed the texture analysis in tumor, liver, and background. Assessment textural features of region-of-interest (ROI) in torso phantom used in-house software. We calculated the textural features of torso phantom in PET image using texture analysis. Calculated entropy in tumor, liver, and background were 5.322, 7.639, and 7.818. The further study will perform assessment of heterogeneity using clinical tumor PET image.

• Nuclear Engineering and Technology
• /
• 제51권6호
• /
• pp.1610-1615
• /
• 2019

Positron emission tomography (PET)/magnetic resonance (MR) scanning has the advantage of less additional exposure to radiation than does PET/computed tomography (CT). In particular, MR based attenuation correction (MR AC) can greatly affect the image quality of PET and is frequently obtained using various MR sequences. Thus, the purpose of the current study was to quantitatively compare the image quality between MR non-AC (MR NAC) and MR AC in PET images with three MR sequences. Percent image uniformity (PIU), percent contrast recovery (PCR), and percent background variability (PBV) were estimated to evaluate the quality of PET images with MR AC. Based on the results of PIU, 15.2% increase in the average quality was observed for PET images with MR AC than for PET images with MR NAC. In addition, 28.6% and 71.1% improvement in the average results of PCR and PBV respectively, was observed for PET images with MR AC compared with that with MR NAC. Moreover, no significant difference was observed among the average values using three MR sequences. In conclusion, the current study demonstrated that PET with MR AC improved the image quality and can be help diagnosis in all MR sequence cases.

• 대한방사선기술학회지:방사선기술과학
• /
• 제42권4호
• /
• pp.285-290
• /
• 2019

Magnetic resonance imaging is a technique specialized in soft tissue imaging with high contrast resolution without in vivo ionization and has been widely used in various clinical settings. In particular, the recent increase in social stress factors has been used in the diagnosis of pituitary adenoma, the incidence increases rapidly. Recently, due to the development of magnetic resonance imaging, it is possible to diagnose micro pituitary adenoma, but despite the use of contrast medium, there has been a difficulty in diagnosing the pituitary adenoma due to its small size and noise. In order to solve this problem, a proposed method of separating signal components image and noise components image from a measured image is applied, and the improvement of diagnostic efficiency is attempted by removing noise. As a result, it was confirmed that the image quality was improved as a whole by applying SNR for 30 subjects data. It is expected that this study will be useful as a pre-processing method for improving the image quality and developing diagnostic indicators of pituitary adenoma.

• 대한건축학회논문집:구조계
• /
• 제35권11호
• /
• pp.163-170
• /
• 2019

Most of the current crack investigation work consists of visual inspection using simple measuring equipment such as crack scale. These methods involve the subjection of the inspector, which may lead to differences in the inspection results prepared by the inspector, and may lead to a large number of measurement errors. So, this study proposes an image-based crack detection method to enhance objectivity and efficiency of concrete crack investigation. In this study, YOLOv2 was used to determine the presence of cracks in the image information to ensure the speed and accuracy of detection for real-time analysis. In addition, we extracted shapes of cracks and calculated quantitatively, such as width and length using various image processing techniques. The results of this study will be used as a basis for the development of image-based facility defect diagnosis automation system.

• 한국멀티미디어학회논문지
• /
• 제24권2호
• /
• pp.178-185
• /
• 2021

Three-dimensional high-resolution magnetic resonance imaging (MRI) provides fine-level anatomical information for disease diagnosis. However, there is a limitation in obtaining high resolution due to the long scan time for wide spatial coverage. Therefore, in order to obtain a clear high-resolution(HR) image in a wide spatial coverage, a super-resolution technology that converts a low-resolution(LR) MRI image into a high-resolution is required. In this paper, we propose a super-resolution technique through filter learning based on information on the surrounding gradient information in 3D space from 3D MRI images. In the learning step, the gradient features of each voxel are computed through eigen-decomposition from 3D patch. Based on these features, we get the learned filters that minimize the difference of intensity between pairs of LR and HR images for similar features. In test step, the gradient feature of the patch is obtained for each voxel, and the filter is applied by selecting a filter corresponding to the feature closest to it. As a result of learning 100 T1 brain MRI images of HCP which is publicly opened, we showed that the performance improved by up to about 11% compared to the traditional interpolation method.

• 한국콘텐츠학회논문지
• /
• 제11권11호
• /
• pp.185-193
• /
• 2011

결핵은 환자를 미리 발견하여 치료함으로서, 질병의 전파를 차단하여 새로운 감염자가 발생을 최소화하고, 결핵을 조기에 예방 및 진단하는 것이 중요하다. 그러므로 현재 의학에서는 디지털 의료영상을 활용하여 질병진단의 보조 수단으로서 컴퓨터자동진단시스템이 응용되고 있다. 본 연구에서 주성분 분석(PCA)과 질감분석(Texture features)의 알고리즘을 이용하여 결핵의 질병을 자동으로 판별 및 인식하였으며, 그 기준에 따라 디지털 흉부 방사선영상에서 컴퓨터자동진단의 실용화를 위한 선행연구를 하였다. 실험결과는 주성분분석을 이용한 병변 인식률은 전문의의 질병에 대한 판독률보다 낮게 나타났지만, 질감분석의 인식률은 전문의 판독결과보다 높은 병변 인식률을 나타내었다. 그러므로 제안하는 알고리즘을 활용한 컴퓨터자동진단시스템은 임상의사에게 부가적인 보조 수단으로서 예비판독 단계의 정보를 제공하여 질병의 조기진단 및 예방이 가능할 것으로 사료된다.

• 한국통신학회:학술대회논문집
• /
• 한국통신학회 2006년도 하계종합학술발표회 논문 초록집
• /
• pp.443-443
• /
• 2006

• 대한자기공명의과학회:학술대회논문집
• /
• 대한자기공명의과학회 2000년도 제5차 추계학술대회
• /
• pp.35-36
• /
• 2000