• Imaging Science in Dentistry
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• 제34권1호
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• pp.13-18
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• 2004

Purpose : This study was to evaluate the influence of slice thickness of computed tomography (CT) and rapid protyping (RP) type on the accuracy of 3-dimensional medical model. Materials and Methods: Transaxial CT data of human dry skull were taken from multi-detector spiral CT. Slice thickness were 1, 2, 3 and 4 mm respectively. Three-dimensional image model reconstruction using 3-D visualization medical software (V-works /sup TM/ 3.0) and RP model fabrications were followed. 2-RP models were 3D printing (Z402, Z Corp., Burlington, USA) and Stereolithographic Apparatus model. Linear measurements of anatomical landmarks on dry skull, 3-D image model, and 2-RP models were done and compared according to slice thickness and RP model type. Results: There were relative error percentage in absolute value of 0.97, 1.98,3.83 between linear measurements of dry skull and image models of 1, 2, 3 mm slice thickness respectively. There was relative error percentage in absolute value of 0.79 between linear measurements of dry skull and SLA model. There was relative error difference in absolute value of 2.52 between linear measurements of dry skull and 3D printing model. Conclusion: These results indicated that 3-dimensional image model of thin slice thickness and stereolithographic RP model showed relative high accuracy.

• Imaging Science in Dentistry
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• 제50권1호
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• pp.15-22
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• 2020

Purpose: This study was conducted to objectively and subjectively compare the accuracy and reliability of 2-dimensional(2D) photography and 3-dimensional(3D) soft tissue imaging. Materials and Methods: Facial images of 50 volunteers(25 males, 25 females) were captured with a Nikon D800 2D camera (Nikon Corporation, Tokyo, Japan), 3D stereophotogrammetry (SPG), and laser scanning (LS). All subjects were imaged in a relaxed, closed-mouth position with a normal smile. The 2D images were then exported to Mirror^® Software (Canfield Scientific, Inc, NJ, USA) and the 3D images into Proplan CMF^® software (version 2.1, Materialise HQ, Leuven, Belgium) for further evaluation. For an objective evaluation, 2 observers identified soft tissue landmarks and performed linear measurements on subjects' faces (direct measurements) and both linear and angular measurements on all images(indirect measurements). For a qualitative analysis, 10 dental observers and an expert in facial imaging (subjective gold standard) completed a questionnaire regarding facial characteristics. The reliability of the quantitative data was evaluated using intraclass correlation coefficients, whereas the Fleiss kappa was calculated for qualitative data. Results: Linear and angular measurements carried out on 2D and 3D images showed excellent inter-observer and intra-observer reliability. The 2D photographs displayed the highest combined total error for linear measurements. SPG performed better than LS, with borderline significance (P=0.052). The qualitative assessment showed no significant differences among the 2D and 3D imaging modalities. Conclusion: SPG was found to a reliable and accurate tool for the morphological evaluation of soft tissue in comparison to 2D imaging and laser scanning.

• 한국정보통신학회논문지
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• 제19권2호
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• pp.486-492
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• 2015

방사선 영상장치는 방사능 누출사고의 조기처리 및 확산 피해 최소화에 필수적인 장비이며, 가까운 미래에 빅마켓으로 성장될 원전폐로 분야에서도 중요한 역할을 담당할 것으로 예상된다. 현재까지 개발된 방사선 영상장치는 방사선 오염원의 위치를 방향 정보만으로 탐지하여 가시화하고 있고 방사선원의 거리 측정은 불가능한 실정이다. 본 논문에서는 스테레오 카메라 원리를 적용하여 방사선원의 3차원 위치정보를 추출할 수 있는 새로운 기법의 방사선 3차원 영상장치의 구현에 대해 연구하였다. 한 대의 방사선 센서와 CCD 카메라, 그리고 팬틸의 컴팩트한 구성으로 설계된 방사선 3차원 영상장치(K3-RIS)는 위치변환 제어에 의한 스테레오 방사선 영상 취득과 연속모드 제어 및 고속 스테레오 영상정보처리 기능이 특징이다. 개발한 장치의 기능검증을 위해 감마 방사선원(Cs-137)을 대상으로 실험을 수행한 결과 선원간의 거리와 무관하게 3% 이하의 거리측정 오차를 확인하였다.

• 대한핵의학회지
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• 제30권3호
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• pp.372-378
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• 1996

목적 : 본 연구의 목적은 Te-124 반응으로 생산된 I-123을 이용하여 표지된 방사의약품을 이용할 때 저에너지용 조준기와 중에너지용 조준기가 SPECT에 미치는 영향을 비교 평가하는 것이다. 방법 : I-123을 채운 선선원을 이용 선선원과 조준기 사이에 풀렉시 유리판을 넣고 조준기로부터 선선원까지의 거리 5cm, 10cm, 15cm에서 영상을 얻었다. 비슷한 방법으로 I-123을 채운 패트리 접시, 2차원 호프만 모형, 3차원 제젝 모형, 3차원 호프만 모형을 영상화하였다. 서로 다른 조준기에서의 장단점을 보기 위해 공간해상도, 예민도, 산란성등의 특성이 비교되었다. 결과 : LEUHRP와 MEGP 대한 FWHM, FWTM, 그리고 예민도는 각각 (9.27mm, 61.27mm, $129CPM/{\mu}Ci$) 그리고 (10.53mm, 23.17mm, $105CPM/{\mu}Ci$)였다. 2차원 호프만 뇌 모형의 영상질은 LEUHRP가 MEGP보다 우수하였다. 그러나 3차원 제젝모형과 호프만 모형에서의 영상질은 MEGP가 LEUHRP보다 우수하였으며 그 이유는 3차원 영상 조건에서의 산란영향 때문인 것으로 생각된다. 결론 : 이상의 결과로 보아 [I-123]MIBG, [I-123]${\beta}$-CIT, 또는 [I-123]IPT의 3차원 영상 검사를 위하여 MEGP가 LEUHRP보다 우수한 영상을 제공할 것으로 생각된다.

• 한국광학회지
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• 제26권5호
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• pp.249-254
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• 2015

본 논문에서는 광 스캐닝 홀로그래피를 이용한 양안식 3차원 홀로그래픽 영상 시스템을 제안하였다. 양안식 3차원 홀로그래픽 영상 시스템을 구현하기 위하여 사람의 두 눈 사이의 거리와 동공의 크기를 고려하여 양안식 3차원 홀로그래픽 디스플레이 시스템을 설계한 뒤 실제 물체의 홀로그램 정보를 획득하였고 수치적인 신호 처리 후 세기 형태의 공간 광 변조기를 이용하여 광학적인 방법으로 복원하였다. 이를 통하여 광 스캐닝 홀로그래피를 이용한 양안식 3차원 홀로그래픽 영상 시스템의 구현 가능성을 실험적으로 확인하였다.

• Journal of the Optical Society of Korea
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• 제19권3호
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• pp.248-254
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• 2015

In this paper we propose an improved version of the computational integral imaging reconstruction (CIIR) for visualizing a partially occluded object by utilizing an image inpainting technique. In the proposed method the elemental images for a partially occluded three-dimensional (3D) object are recorded through the integral imaging pickup process. Next, the depth of occlusion within the elemental images is estimated using two different CIIR methods, and the weight mask pattern for occlusion is generated. After that, we apply our image inpainting technique to the recorded elemental images to fill in the occluding area with reliable data, using information from neighboring pixels. Finally, the inpainted elemental images for the occluded region are reconstructed using the CIIR process. To verify the validity of the proposed system, we carry out preliminary experiments in which faces are the objects. The experimental results reveal that the proposed system can dramatically improve the quality of a reconstructed CIIR image.

• Imaging Science in Dentistry
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• 제41권2호
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• pp.79-84
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• 2011

Purpose : The aim of the present study was to investigate the disagreement of cephalometric analysis depending on the reference determination of midsagittal plane on three-dimensional computed tomography. Materials and Methods : A total of 102 young women with class III dentofacial deformity were evaluated using three-dimensional computed tomography. The cranial and facial midsagittal planes were defined and the amounts of jaw deviation were calculated. The amounts of jaw deviation were compared with paired t-test (2-tailed) and Bland-Altman plot was drawn. Results : The landmark tracing were reproducible ($r{\ge}.978$). The jaws relative to the cranial midsagittal plane were 10-17 times more significantly deviated than to the facial midsagittal plane (P<.001). Bland-Altman plot demonstrated that the differences between the amounts of jaw deviation from two midsagittal planes were not normally distributed versus the average of the amounts of jaw deviation from two midsagittal planes. Conclusion : The cephalometric analyses of facial asymmetry were significantly inconsistent depending on the reference determination of midsagittal plane. The reference for midsagittal plane should be carefully determined in three-dimensional cephalometric analysis of facial asymmetry of patients with class III dentofacial deformity.

• Journal of applied mathematics & informatics
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• 제15권1_2호
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• pp.425-434
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• 2004

Pattern recognition in three dimensional image is highly sensitive to assigned value and formation of voxels (pixels for two dimension case). However, occurred while digital imaging, digitization error leads to unpredictable noises in image data. Skeletonization, a powerful tool of pattern recognition, is sensitively dependent on boundary formation. Without successful controlling of the noises, the results of skeletonization can not be allowed as a stable solution. To minimize the effect of noises affecting to boundary formation, we developed a robust processing method useful in skeletonization technique for pattern recognition. Finally, we provide rigorous test results achieved throughout simulation on analytic three dimensional image.

• Investigative Magnetic Resonance Imaging
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• 제11권2호
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• pp.87-94
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• 2007

목적: 3T 장비의 신생아 뇌자기공명영상에서 T1 강조 고속 역전회복기법 (fast inversion recovery, FIR)과 자기화 삼차원 경사에코기법, (magnetization-prepared three dimensional gradient echo sequence, 3D GRE)을 스핀에코기법 (SE)과 비교하여 유용성을 알아보는 데 있다. 대상 및 방법: 20명의 신생아에서 T1 강조 SE, FIR, 그리고 3D GRE의 신호소음비 (SNR)와 대조소음비 (CNR)를 측정하고 시각적으로 회백질-백질 구별, 수초화 인식, 인공음영 발생을 점수화하여 비교하였다. 각 영상기법의 CNR 비교에는 Wilcoxon signed ranked test를 사용하였다. 결과: 세가지 영상기법 중 3D GRE가 가장 우수한 SNR을 보였고 CNR은 FIR과 3D GRE 모두 SE보다 우수하였으며 FIR보다 3D GRE가 더 우수하였다. 회백질-백질의 구분과 수초화 유무 역시 스핀에코보다 FIR과 3D GRE에서 더 잘 보였다. 그러나 3D GRE는 움직임에 의한 인공음영이 많았고 FIR에서 혈류에 의한 혈관의 고신호강도가 자주 발견되었다. 결론: 3T 장비에서 신생아 뇌영상을 얻을 때 FIR과 3D GRE 기법은 SE보다 좋은 T1 강조영상을 제공할 것으로 기대된다.

• Investigative Magnetic Resonance Imaging
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• 제23권1호
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• pp.1-16
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• 2019

Dynamic contrast enhanced (DCE) magnetic resonance (MR) imaging plays an important role in non-invasive detection and characterization of primary and metastatic lesions in the liver. Recently, efforts have been made to improve spatial and temporal resolution of DCE liver MRI for arterial phase imaging. Review of recent publications related to arterial phase imaging of the liver indicates that there exist primarily two approaches: breath-hold and free-breathing. For breath-hold imaging, acquiring multiple arterial phase images in a breath-hold is the preferred approach over conventional single-phase imaging. For free-breathing imaging, a combination of three-dimensional (3D) stack-of-stars golden-angle sampling and compressed sensing parallel imaging reconstruction is one of emerging techniques. Self-gating can be used to decrease respiratory motion artifact. This article introduces recent MRI technologies relevant to hepatic arterial phase imaging, including differential subsampling with Cartesian ordering (DISCO), golden-angle radial sparse parallel (GRASP), and X-D GRASP. This article also describes techniques related to dynamic 3D image reconstruction of the liver from golden-angle stack-of-stars data.