• The Journal of the Korean dental association
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• v.56 no.10
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• pp.538-547
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• 2018

ITK-SNAP (http://www.itksnap.org) and 3D Slicer (CMFreg extension module; www.slicer.org) are open-source softwares which can be used for superimposition of cone-beam CT images. For superimposition, segmentation of bone is done with ITK-SNAP, and then voxel based superimposition of CBCT images can be performed using 3D Slicer. 3D Slicer has various visualization modules which are not provided in common commercial programs. 'Models' module is used to visualize two overlapping three-dimensional images, and this allows various visualizations by changing view mode and color of the model. In addition, differences between two CBCT images can be represented in a color map using 'ShapePopulationViewer' module. This report introduces how to superimpose and visualize CBCT images using ITK-SNAP and 3D Slicer, and the usefulness and limitations of both softwares will be discussed in comparison with commercial softwares.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.271-274
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• 2001

미국의 National Library of Medicine에서 제공하는 Visible human 컬러영상을 이용하여, 신체 장기의 3차원 모델링 및 가시화 하기 위한 영역 분할 방법 연구가 활발히 진행되고 있다. 특히 다른 신체 장기 분할에 비해 뼈분할은 주위의 영역들과 모호한 경계를 지니고 있어 컬러영상만을 가지고 구분해 내기가 쉽지 않다. 이러한 문제점을 해결하기 위해 본 논문에서는 Visible human CT영상을 가지고 뼈 영역을 분할하고 분할 된 뼈 영역의 경계를 추출하여 그 경계를 컬러영상의 최적화된 위치로 변환해 최종적인 뼈 영역 분할을 시도한다. 제안된 방법은 Visible human 단면영상의 머리부분에 적용하여 좋은 결과를 얻음을 실험을 통해 효율성을 검증하였다.

• Annual Conference of KIPS
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• 2013.05a
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• pp.323-324
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• 2013

본 논문에서는 2차원 X-ray 영상을 이용하여 3차원 영상을 얻기 위한 전처리 과정으로 2차원 X-ray 영상에서 원하는 뼈 영상을 분할하기 위한 능동적 대퇴골 분할 기법에 대해 제안하고 구현하였다. X-ray 영상의 주된 화질 저하 요인인 잡음을 제거하고 에지 및 밝기 검출을 통하여 정확하고 빠른 뼈 영상 분할 기법을 구현하였고 대퇴골 영상을 통해 검증하였다. 이를 통해 최소한의 2차원 X-ray 영상을 이용하여 3차원 뼈 모델링을 구현하는데 필요한 뼈 영상을 획득하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.137-140
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• 2021

본 논문에서는 X-Ray 영상에서 발 뼈의 골절 영역을 분석 및 진단하기 위한 전단계로서 X-Ray 영상에서 뼈와 피부 영역을 분할하는 방법을 제안한다. 제안된 방법은 X-Ray 영상의 피부 영역과 발 뼈 영역을 분할하기 위해 가우시안 필터를 적용하여 DOG 영상을 생성한다. 그러나 기존의 가우시안 필터는 정적으로 적용되기 때문에 영상을 촬영하는 부위와 각도에 따라 영상의 특성이 달라지는 X-Ray 영상에 적용하기에 부적합하다. 따라서 부위와 각도에 따라 영상의 특성 변화에 민감하지 않는 동적 가우시안 필터를 제안한다. 실험 결과에서는 제안하는 동적 가우시안 필터와 기존의 정적인 가우시안 필터를 각각 적용하여 생성된 DOG 영상에 대해서 발 뼈 영역과 피부 영역을 분할하고, 효율성을 TPR과 특이도로 분석한 결과, 제안된 동적 가우시안 필터를 적용한 방법이 정적 가우시안 필터보다 평균적으로 TPR는 0.12%와 특이도는 평균적으로 0.36%가 개선된 것을 확인하였다.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.1
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• pp.89-102
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• 2019

Collagen can be used in building artificial skin replacements for treatment of burns and towards the reconstruction of bone as well as researching cell behavior and cellular interaction. The strength of collagen in connective tissue rests on the characteristics of collagen fibers. 3D confocal imaging of collagen fibers enables the characterization of their spatial distribution as related to their function. However, the image stacks acquired with confocal laser-scanning microscope does not clearly show the collagen architecture in 3D. Therefore, we developed a new method to reconstruct, visualize and characterize collagen fibers from fluorescence confocal images. First, we exploit the tensor voting framework to extract sparse reliable information about collagen structure in a 3D image and therefore denoise and filter the acquired image stack. We then propose to segment the collagen fibers by defining an energy term based on the Hessian matrix. This energy term is minimized by a min cut-max flow algorithm that allows adaptive regularization. We demonstrate the efficacy of our methods by visualizing reconstructed collagen from specific 3D image stack.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.10-14
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• 2013

Purpose: Due to developed simultaneous PET/MRI, it has become possible to obtain more anatomical image information better than conventional PET/CT. By the way, in the PET/CT, the linear absorption coefficient is measured by X-ray directly. However in case of PET/MRI, the value is not measured from MRI images directly, but is calculated by dividing as 4 segmentation ${\mu}-map$. Therefore, in this paper, we will evaluate the SUV's difference of attenuation correction PET images from PET/MRI and PET/CT. Materials and Methods: Biograph mCT40 (Siemens, Germany), Biograph mMR were used as a PET/CT, PET/MRI scanner. For a phantom study, we used a solid type $^{68}Ge$ source, and a liquid type $^{18}F$ uniformity phantom. By using VIBE-DIXON sequence of PET/MRI, human anatomical structure was divided into air-lung-fat-soft tissue for attenuation correction coefficient. In case of PET/CT, the hounsfield unit of CT was used. By setting the ROI at five places of each PET phantom images that is corrected attenuation, the maximum SUV was measured, evaluated %diff about PET/CT vs. PET/MRI. In clinical study, the 18 patients who underwent simultaneous PET/CT and PET/MRI was selected and set the ROI at background, lung, liver, brain, muscle, fat, bone from the each attenuation correction PET images, and then evaluated, compared by measuring the maximum SUV. Results: For solid $^{68}Ge$ source, SUV from PET/MRI is measured lower 88.55% compared to PET/CT. In case of liquid $^{18}F$ uniform phantom, SUV of PET/MRI as compared to PET/CT is measured low 70.17%. If the clinical study, the background SUV of PET/MRI is same with PET/CT's and the one of lung was higher 2.51%. However, it is measured lower about 32.50, 40.35, 23.92, 13.92, 5.00% at liver, brain, muscle, fat, femoral head. Conclusion: In the case of a CT image, because there is a linear relationship between 511 keV ${\gamma}-ray$ and linear absorption coefficient of X-ray, it is possible to correct directly the attenuation of 511 keV ${\gamma}-ray$ by creating a ${\mu}$map from the CT image. However, in the case of the MRI, because the MRI signal has no relationship at all with linear absorption coefficient of ${\gamma}-ray$, the anatomical structure of the human body is divided into four segmentations to correct the attenuation of ${\gamma}-rays$. Even a number of protons in a bone is too low to make MRI signal and to localize segmentation of ${\mu}-map$. Therefore, to develope a proper sequence for measuring more accurate attenuation coefficient is indeed necessary in the future PET/MRI.

• Journal of Biomedical Engineering Research
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• v.36 no.2
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• pp.43-47
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• 2015

Osteoarthritis is the most common chronic joint disease in the world. With its progression, cartilage thickness tends to diminish, which causes severe pain to human being. One way to examine the stage of osteoarthritis is to measure the cartilage thickness. When it comes to inter-subject study, however, it is not easy task to compare cartilage thickness since every human being has different cartilage structure. In this paper, we propose a method to assess cartilage defect using MRI inter-subject thickness comparison. First, we used manual segmentation method to build accurate atlas images and each segmented image was labeled as articular surface and bone-cartilage interface in order to measure the thickness. Secondly, each point in the bone-cartilage interface was assigned the measured thickness so that the thickness does not change after registration. We used affine transformation and SyGN to get deformation fields which were then applied to thickness images to have cartilage thickness atlas. In this way, it is possible to investigate pixel-by-pixel thickness comparison. Lastly, the atlas images were made according to their osteoarthritis grade which indicates the degree of its progression. The result atlas images were compared using the analysis of variance in order to verify the validity of our method. The result shows that a significant difference is existed among them with p < 0.001.

• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.259-266
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• 2003

Non-rigid registration between different modality images with shape deformation can be used to diagnosis and study for inter-patient image registration, longitudinal intra-patient registration, and registration between a patient image and an atlas image. This paper proposes a hierarchical registration method using bodily tissue based segmentation for registration between color images and CT images of the Visible Human leg areas. The cross-sectional color images and the axial CT images are segmented into three distinctive bodily tissue regions, respectively: fat, muscle, and bone. Each region is separately registered hierarchically. Bounding boxes containing bodily tissue regions in different modalities are initially registered. Then, boundaries of the regions are globally registered within range of searching space. Local boundary segments of the regions are further registered for non-rigid registration of the sampled boundary points. Non-rigid registration parameters for the un-sampled points are interpolated linearly. Such hierarchical approach enables the method to register images efficiently. Moreover, registration of visibly distinct bodily tissue regions provides accurate and robust result in region boundaries and inside the regions.

• Progress in Medical Physics
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• v.21 no.2
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• pp.153-164
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• 2010

To determine the clinical target volumes considering vascularity and cellularity of tumors, the software was developed for mapping of the analyzed biological clinical target volumes on anatomical images using regional cerebral blood volume (rCBV) maps and apparent diffusion coefficient (ADC) maps. The program provides the functions for integrated registrations using mutual information, affine transform and non-rigid registration. The registration accuracy is evaluated by the calculation of the overlapped ratio of segmented bone regions and average distance difference of contours between reference and registered images. The performance of the developed software was tested using multimodal images of a patient who has the residual tumor of high grade gliomas. Registration accuracy of about 74% and average 2.3 mm distance difference were calculated by the evaluation method of bone segmentation and contour extraction. The registration accuracy can be improved as higher as 4% by the manual adjustment functions. Advanced MR images are analyzed using color maps for rCBV maps and quantitative calculation based on region of interest (ROI) for ADC maps. Then, multi-parameters on the same voxels are plotted on plane and constitute the multi-functional parametric maps of which x and y axis representing rCBV and ADC values. According to the distributions of functional parameters, tumor regions showing the higher vascularity and cellularity are categorized according to the criteria corresponding malignant gliomas. Determined volumes reflecting pathological and physiological characteristics of tumors are marked on anatomical images. By applying the multi-functional images, errors arising from using one type of image would be reduced and local regions representing higher probability as tumor cells would be determined for radiation treatment plan. Biological tumor characteristics can be expressed using image registration and multi-functional parametric maps in the developed software. The software can be considered to delineate clinical target volumes using advanced MR images with anatomical images.

• Journal of Biomedical Engineering Research
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• v.31 no.6
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• pp.427-433
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• 2010

Although tracking methods are efficient and popular for vessel segmentation, they require a seed to initiate an instance of tracking. In this paper, a new method to detect new seeds for tracking of arterial segments from CT angiography (CTA) and to construct a vascular structure is proposed. The proposed algorithm is based on shape analysis of connected components in a volume of interest around a vessel segment which was already extracted by tracking. The eigenvalues of the covariance matrix are used as the shape features for detection. The experimental results on actual clinical data showed that the results totally revealed the arterial tree not hindered by bone or veins. In visual comparison to a method which combines registration and subtraction of both pre-contrast and post-contrast CT volumes, the proposed method produced comparable results to the reference method and were confirmed of its feasibility for clinical use of reducing the cost and burden of patients.