• Tunnel and Underground Space
• /
• v.27 no.5
• /
• pp.333-342
• /
• 2017

In this study, the heterogeneity of internal structure of various igneous rocks acquired in Korea was quantified and correlated with the seismic velocity and the point load strength. Three-dimensional X-ray Computed Tomography (CT) was used to obtain information on the internal structure of the rock specimen, and the representative unit length (LR) was calculated by applying a statistical technique to the CT images. We also proposed an estimation equation to predict the mechanical properties of rocks from the relationship between LR, acoustic velocity and point load strength. In the proposed method, it is shown that the characterization of internal structure of rocks could be utilized as an indirect index to account for the mechanical behavior of rocks by substituting physical laboratory testing for non-destructive test.

• Journal of Biomedical Engineering Research
• /
• v.29 no.5
• /
• pp.364-370
• /
• 2008

Recent development in large area flat-panel x-ray detector technology enables clinical application of digital tomosyntesis. Unlike conventional motion tomography using x-ray films, flat-panel x-ray detectors provide projection images in digital formats so that tomographic images can be synthesized in a more flexible way. For the digital tomosynthesis, precise movements of the x-ray source and the x-ray detector with respect to a fulcrum point are necessary. In this study, we apply the digital tomosynthesis technique to the flat-panel detector based micro-CT in which the flat-panel detector and the x-ray source rotate together on a circular arc. The experimental results suggest that flat-panel detector based 3D CTs can be used for digital tomosynthesis in the clinical environment.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.4
• /
• pp.370-374
• /
• 2009

In this paper, we presents a new cone beam computerized tomography (CB CT) system for the reconstruction of 3 dimensional dynamic images. The system using cone beam has less the exposure of radioactivity than fan beam, relatively. In the system, the reconstruction 3-D image is reconstructed with the radiation angle of X-ray in the image processing unit and transmitted to the monitor. And in the image processing unit, the Three Pass Shear Matrices, a kind of Rotation-based method, is applied to reconstruct 3D image because it has less transcendental functions than the one-pass shear matrix to decrease a time of calculations for the reconstruction 3-D image in the processor. The new system is able to get 3~5 3-D images a second, reconstruct the 3-D dynamic images in real time.

• Journal of Biomedical Engineering Research
• /
• v.25 no.2
• /
• pp.97-102
• /
• 2004

We developed an x-ray cone-beam micro computed tomography (micro-CT) system for small-animal imaging. The micro-CT system consists of a 2-D flat-panel x-ray detector with a field-of-view (FOV) of 120${\times}$120 mm2, a micro-focus x-ray source, a scan controller and a parallel image reconstruction system. Imaging performances of the micro-CT system have been evaluated in terms of contrast and spatial resolution. The minimum resolvable contrast has been found to be less than 36 CT numbers at the dose of 95 mGy and the spatial resolution about 14 lp/mm. As small animal imaging results, we present high resolution 3-D images of rat organs including a femur, a heart and vessels. We expected that the developed micro-CT system can be greatly used in biomedical studies using small animals.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.9
• /
• pp.45-55
• /
• 2020

X-ray computed tomography (CT) is very useful for the quantitative evaluation of internal structures, particularly defects in rock samples, such as pores and fractures. In situ CT allows 3D imaging of a sample subjected to various external treatments such as loading and therefore enables observation of changes that occur during the loading process. We reviewed state-of-the-art of in situ CT applications for geomaterials. Two triaxial cells made using relatively low density but high strength materials were developed aimed at in situ CT scanning during hydro-mechanical laboratory testing of rocks. Preliminary results for in situ CT imaging of granite and sandstone samples with diameters ranging from 25 mm to 50 mm show a resolution range of 34~105 ㎛ per pixel pitch, indicating the feasibility of in situ CT observations for internal structural changes in rocks at the micrometer scale. Potassium iodide solution was found to improve the image contrast, and can be used as an injection fluid for hydro-mechanical testing combined with in situ CT scanning.

• Conservation Science in Museum
• /
• v.22
• /
• pp.15-26
• /
• 2019

This study was focused on the three-dimensional convergence modeling that can multilaterally analyze internal and external shapes of the Sam-Chongtong Hand Canon by optical precision scanning optimized for acquiring the surface shape and X-ray CT scanning used for obtaining the internal shape. First, the scanning results were converted by compatible extension, after which three-dimensional deviation analysis was conducted to verify mutual conformities. Accordingly, most (56.98%) deviations between the two scanning models was found be ±0.1mm. This result did not influence registration and merging based on the ICP algorithm. The merged data exhibited the external surface color, detailed shapes, internal width, and structure of the hand canon. The three-dimensional model based on optical surface scanning and X-ray CT scanning can be used for traditional technique interpretation as well as digital documentation of cultural heritage. In the future, it will contribute to deliver accessible scientific information of exhibits for visitors.

• Journal of the Korean Society of Radiology
• /
• v.16 no.7
• /
• pp.969-974
• /
• 2022

In order to maximize dynamic range and to minimize image lag in digital X-ray imaging, diminishing residual parasitic capacitance in photodiode in pixels is critically necessary. These requirements are more specifically requested in dynamic X-ray imaging with high frame rate and low image lag for industrial 2D/3D automated X-ray inspection and medical CT imaging. This study proposes duoPIX^TM X-ray imaging sensor for the first time that is composed of reset thin film transistor, readout thin film transistor and photodiode in a pixel. To verify duoPIX^TM X-ray imaging sensor, designing duoPIX^TM pixel and imaging sensor was executed first then X-ray imaging sensor with 105 ㎛ pixel pitch, 347 mm × 430 mm imaging area and 3300 × 4096 pixels (13.5M pixels) was fabricated and evaluated by using module tester and image viewer specifically for duoPIX^TM imaging sensor.

• Korean Journal of Bronchoesophagology
• /
• v.1 no.1
• /
• pp.82-93
• /
• 1995

Three-dimensional reconstruction of computed tomographic image(3D CT) is a well-established imaging modality which has been investigated in various clinical settings. It is commonly performed in case of congenital or developmental abnormalities, and traumatic fracture of skull and face that requires reconstruction of osseous structure. However reporting the 3D CT in laryngeal or tracheal stenosis is rare and its results are obscure. The authors performed 3D CT in six cases of tracheal stenosis and found diagnostic value of 3D CT. A Comparision of diagnostic information obtained from plain X-ray, 2D CT and 3D CT has performed in total six cases of tracheal stenosis. Surgical treatment of the tracheal stenosis was following in these cases : tracheal end to end anastomosis In 1 case, laryngotracheal end to end anastomosis in 2 cases. 3D CT information was compared with operative finding. In two of six cases, satisfactory information was not obtained from 3D CT in evaluating an exact stenosis of trachea. Future, it will be helped in evaluating of tracheal stenosis by 3D CT.

• 전기의세계
• /
• v.38 no.8
• /
• pp.9-18
• /
• 1989

초음파 CT는 시기적으로 가장 빨리 X-ray CT와 함께 연구되어 왔으나 인체내의 투과성, 난반사, 긴파장등에 의해 실용화가 아직은 요원하다. 초음파 CT는 크게 Time of flight (TOF)CT, Attenuation CT, Reflection CT, Diffraction CT등으로 나눌수 있다. 초기에는 TOF CT, Attenuation CT의 연구가 주로 이루어 졌으나 투과의 문제로 인하여 실제로는 유방의 진단에 국한되고 있다. Reflection CT는 초음파의 특성상 실용화가 가장 쉬우나 Transducer 크기등의 문제로 연구가 지연되고 있다. Diffraction CT는 모든 초음파 CT의 특성을 갖고 있으며 현재에 실용화는 요원한 실정이다. KAIST에서는 TOF CT와 Reflection CT의 특징을 결합한 초음파 CT를 연구 발표한 바 있다. 3-D Image은 지금까지의 초음파진단장치에서 표시하는 2-D Image가 갖고 있는 제반의 문제들을 극복하기 위해 현재 KAIST에서 활발히 연구가 진행중에 있다.

• Archives of Craniofacial Surgery
• /
• v.13 no.2
• /
• pp.111-118
• /
• 2012

Purpose: The nasal bone fracture is known as the most common facial fracture, with the postoperative results and the patient's satisfaction known to be lower than other facial fractures. The patient's satisfaction is firstly related to the accurate comprehension of the spatial relationship in the fractured nasal bone and secondly to the accurate reduction based on accurate comprehension. The aim of this study is to evaluate the objective usefulness of the three-dimensional (3D) imaging. Methods: The survey was conducted on 10 randomly selected cases of nasal bone fractures among the 46 cases with 3D computed tomography (CT) during the past one year. It was requested upon 4 plastic residents and 4 plastic surgeons to draw 3D aspect of fractured nasal bone directly on the printed photos of cadaver nasal bone, based on simple X-ray and two-dimensional (2D) CT. They were compared with the real fractured nasal bone aspects based on the 3D image and marked the difference in the 10-point scale of 0 to 10. Results: The average score of the 4 residents was 1.62 and that of the 4 surgeons was 4.47 out of 10 by simple X-ray. The average score of the 4 residents was 5.67 and that of the 4 surgeons was 7.25 out of 10 by 2D CT. Conclusion: It was surmised that the precise analysis and accurate comprehension of the spatial relationship of the fractured nasal bone using the 3D image, as based on the 2D CT images, can produce more favorable satisfaction levels in the patients.