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X선관을 이용한 불투명한 물체 내부 유동의 정량적 가시화 연구
김국배(Guk Bae Kim),임남윤(Nam Yun Lim),류재춘(Jae Chun Ryu),임대현(Dae Hyun Yim),이형구(Hyung Koo Lee),이상준(Sang Joon Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
To diagnose circulatory diseases in the viewpoint of hemodynamics, we need to get quantitative hemodynamic information of blood flows related with the vascular diseases with high spatial resolution of tens micrometer and high temporal resolution in the order of millisecond. For investigating in-vivo hemodynamic phenomena, a new diagnosing technique combining medical radiography and PIV method was newly proposed and developed. This angiographic PIV technique consists of a medical X-ray tube, an X-ray CCD camera, a shutter module for double pulses of X-ray, and a synchronizer. The feasibility of the angiographic PIV technique was tested and quantitative flow velocity field distribution of a flow inside an opaque conduit was acquired by the developed system. It can be used for measuring flow phenomena of nontransparent fluids inside opaque conduits.
김국배(Guk Bae Kim),이상준(Sang Joon Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Conventional medical instruments for diagnosing vascular diseases such as an angiography and Doppler methods give rough information on the shape of blood vessels and point-wise blood speed. In this study, we developed a method called X-ray PIV technique for visualizing blood flow using a coherent synchrotron x-ray. Without any contrast agents or tracer particles, this X-ray PIV method can visualize the flow pattern of blood based on the diffraction and interference characteristics of blood cells. The quantitative velocity field information of blood flow inside an opaque tube was obtained by applying a 2-frame PIV (particle image velocimetry) algorithm to the x-ray images obtained. The velocity field data obtained are compared with various models for analyzing blood flows.
김국배(Guk Bae Kim),이상준(Sang Joon Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
Synchrotron X-ray micro-imaging method has been used to observe various dynamics of internal structures inside organisms, industrial devices, and so on. However, it is not suitable for this imaging system to observe dynamics of flows inside a structure because tracer matters, such as seeding particles, dyes typically used in conventional optical flow visualization methods, cannot be detectable under X-ray light source any more. On the other hand, PIV (particle image velocimetry) method, which has recently been accepted as a reliable quantitative flow visualization technique, can extract instantaneous velocity fields by applying digital image processing technique to pairs of consecutive particle images captured with a small time interval. In this study, we composed a synchrotron X-ray PIV system combining the PIV method into a synchrotron X-ray micro-imaging system. At first, peculiar optical characteristics of blood were investigated by enhancing speckle patterns with a synchrotron X-ray imaging method. This pattern enhancement can be explained by propagation-based phase contrast enhancement via sample-to-scintillator distance and by interference-based enhancement via sample thickness. In addition, we quantitatively visualized real blood flow inside a tube without any contrast media. The measured velocity field data show typical features of blood flow such as the yield stress and are well matched with the Casson’s hemorheologic model. The X-ray PIV method has a strong potential for visualizing blood samples non-invasively to obtain detailed flow information such as flow rate, spatial distributions of velocity, and shear stress.
이상준(Sang Joon Lee),김국배(Guk Bae Kim),김석(Seok Kim),김양민(Yang-Min Kim) 한국가시화정보학회 2005 한국가시화정보학회지 Vol.3 No.1
An x-ray PIV (Particle Image Velocimetry) technique was developed for measuring quantitative information on flows inside opaque conduits and/or opaque-fluid flows. To check the performance of the x-ray PIV technique developed, it was applied to a liquid flow in an opaque Teflon tube. To acquire xray images suitable for PIV velocity field measurements, the refraction-based edge enhancement mechanism was employed with seeding detectable tracer particles. The amassed velocity field data obtained were in a reasonable agreement with the theoretical prediction. The x-ray PIV technique was also applied to get velocity fields of blood flow and to measure size and velocity of micro-bubbles simultaneously, and to visualize the water refilling process in bamboo leaves. The x-ray PIV was found to be a powerful transmission-type flow imaging technique for measuring quantitative information of flows inside opaque objects and various opaque-fluid flows.
임대현(Dae-hyun Yim),김국배(Guk Bae Kim),김도일(Do-Il Kim),이형구(Hyong-Koo Lee),이상준(Sang Joon Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
A new medical X-ray PIV technique was developed using a conventional medical X-ray tube. To acquire images of micro-scale particles, the X-ray PIV system consists of an x-ray CCD camera with high spatial resolution, and a X-ray tube with small a focal spot. A new X-ray exposure control device was developed using a rotating disc shutter to make double pulses which are essential for PIV application. Synchronization methodology was also developed to apply the PIV technique to a conventional medical X-ray tube. In order to check the performance and usefulness of the developed X-ray PIV technique,it was applied to a glycerin flow in an opaque silicon tube. Tungsten particles which have high X-ray absorption coefficient were used as tracer particles. Through this preliminary test, the spatial resolution was found to be higher than ultrafast MRI techniques, and the temporal resolution was higher than conventional X-ray PIV techniques. By improving its performance further and developing more suitable tracers, this medical X-ray PIV technique will have strong potential in the fields of medical imaging or nondestructive inspection as well as diagnosis of practical thermo-fluid flows.