• Journal of the Korean Chemical Society
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• v.40 no.2
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• pp.135-138
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• 1996

• Imaging Science in Dentistry
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• v.34 no.1
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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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• v.50 no.1
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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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.486-492
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• 2015

Radiation source imaging system is essential for protecting of radiation leakage accidents and minimizing damages from the radioactive materials, and is expected to play an important role in the nuclear plant decommissioning area. In this study, the stereoscopic camera principle was applied to develop a new radiation imaging device technology that can extract the radiation three-dimensional position information. This radiation three-dimensional imaging device (K3-RIS) was designed as a compact structure consisting of a radiation sensor, a CCD camera, and a pan-tilt only. It features the acquisition of stereoscopic radiation images by position change control, high-resolution detection by continuous scan mode control, and stereoscopic image signal processing. The performance analysis test of K3-RIS was conducted for a gamma-ray source(Cs-137) in radiation calibration facility. The test result showed that a performance error with less than 3% regardless of distances of the objects.

• The Korean Journal of Nuclear Medicine
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• v.30 no.3
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• pp.372-378
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• 1996

In the case of $^{123}I$ from the $^{124}Te$(p,2n)reaction, the radionuclidic impurity is the high-energy gamma-emitting $^{124}I$, which interferes greatly with nuclear medicine images. The choice of a collimator can affect the quality of clinical SPECT images of [I-123]MIBG, [I-123] ${\beta}$-CIT, or [I-123]IPT. The tradeoffs that two different collimators make among spatial resolution, sensitivity, and scatter were studied by imaging a line source at 5cm, 10cm, 15cm distance using a number of plexiglass sheets between source and collimator, petri dish, two-dimensional Hoffman brain phantom, Jaszczak phantom, and three-dimensional Hoffman brain phantom after filling with $^{123}I$. (FWHM, FWTM, Sensitivity) for low-energy ultrahigh-resolution parallel - hole (LEUHRP) collimator and medium- energy general - purpose (MEGP) collimator were measured as (9.27mm, 61.27mm, $129CPM/{\mu}Ci$) and (10.53mm, 23.17mm, $105CPM/{\mu}Ci$), respectively. The image quality of two-dimensional Hoffman brain phantom with LEUHRP looked better than the one with MEGP. However, the image quality of Jaszczak phantom and three-dimensional Hoffman brain phantom with LEUHRP looked much worse than the one with MEGP because of scatter contributions in three-dimensional imaging situation. The results suggest that the MEGP is preferable to LEUHRP for three-dimensional imaging studies of [I-123]MIBG, [I-123] ${\beta}$-CIT, or [I-123]IPT.

• Korean Journal of Optics and Photonics
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• v.26 no.5
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• pp.249-254
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• 2015

In this paper we propose a binocular holographic three-dimensional (3D) imaging system using optical scanning holography. To realize a binocular 3D holographic imaging system, we could acquire the complex holograms of a real object after designing a holographic display system based on interpupillary distance and pupil size, and these holograms could be optically reconstructed following numerical signal processing with an amplitude spatial light modulator. The proposed binocular 3D holographic imaging system using optical scanning holography was verified experimentally.

• Journal of the Optical Society of Korea
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• v.19 no.3
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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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• v.41 no.2
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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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• v.15 no.1_2
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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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• v.11 no.2
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• pp.87-94
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• 2007

Purpose: The purpose of this study was to evaluate the usefulness of fast inversion recovery (FIR) and magnetization-prepared three dimensional gradient echo sequence (3D GRE) T1-weighted sequences for neonatal brain imaging compared with spin echo (SE) sequence in a 3T MR unit. Materials and Methods: T1-weighted axial SE, FIR and 3D GRE sequences were evaluated from 3T brain MR imaging in 20 neonates. The signal-to-noise ratio (SNR) of different tissues was measured and contrast-to-noise ratios (CNR) were determined and compared in each of the sequences. Visual analysis was carried out by grading gray-white matter differentiation, myelination, and artifacts. The Wilcoxon signed ranked test was used for evaluation of the statistical significance of CNR differences between the sequences. Results: Among the three sequences, the 3D GRE had the best SNRs. CNRs obtained with FIR and 3D GRE were statistically superior to those obtained with SE; these CNRs were better on the 3D GRE compared to the FIR. Gray to white matter differentiation and myelination were better delineated on the FIR and 3D GRE than the SE. However, motion artifacts were more commonly observed on the 3D GRE and flow-related artifacts of vessels were frequently seen on the FIR. Conclusion: FIR and 3D GRE are valuable alternative T1-weighted sequences to conventional SE imaging of the neonatal brain at 3T providing superior image quality.