KR100542659B1 - Flow image acquisition and velocity field measuring device using ｒ-ｒａｙ beam - Google Patents

Abstract

The present invention is to combine the PIV / PTV velocity field measurement technology and the radiation x-ray in-line holography technology to quantitatively measure the flow information of the fluid in the invisible region or the opaque fluid inside the object. Is an accelerator for emitting an radiant light x-ray beam, a mechanical shutter mounted on the beam axis such that only the required amount of x-ray light can pass through the sample from the x-ray beam continuously emitted from the accelerator, and the x Micro-traverse installed on the beam axis to place the sample to be transmitted by the -ray beam, and the image of the visible x-ray wavelength while passing through the sample can be converted into a visible light band image A scintillator installed on the optical axis of the x-ray beam and a beam perpendicular to the beam axis to acquire an image of particles formed on the scintillator. Includes a CCD camera, a computer device installed to display images of the CCD camera on a monitor, and a PIV / PTV velocity field measurement technology capable of extracting quantitative flow information from two successive x-ray flow images. Characterized in that.

Description

Apparatus for acquiring the moving image and measuring the velocity field using ｘ-ｒａｙ beams {APPARATUS FOR MEASURING OF FLOW IMAGE AND VELOCITY FIELD USING FOR X-RAY BEAM}

1 is a conceptual diagram of a conventional PIV / PTV technique.

2 is a schematic diagram of a conventional in-line holography x-ray micro-imaging technique.

3 is a block diagram of a flow visualization and velocity field measuring apparatus using an x-ray beam according to the present invention.

Figure 4 is a view showing a particle image of the flow inside the Teflon tube obtained by the x-ray micro-imaging technique according to the present invention.

5 is a spatial distribution diagram of flow inner longitudinal velocity components obtained from particle images acquired using the PIV technique from FIG. 4 according to the present invention.

6 is a graph showing the main flow direction velocity component profile in any cross section of the velocity field results according to the present invention.

7 is a comparative view showing a difference in flow image according to the internal structure of the stem and contrast medium of the freesia flowers according to the present invention.

8 is a view showing a flow image in the thin bamboo inner conduit according to the present invention.

9 is a view showing a blood flow image in the rat ear according to the present invention.

<Description of the symbols for the main parts of the drawings>

One ; Accelerator 2; Mechanical shutter

3; Scintillator 4; CCD camera

5; Syringe pump 10; Microtubules (Teflon Tubes)

The present invention provides a flow image acquisition and velocity field using an x-ray beam that combines two different measurement techniques, PIV / PTV velocity field measurement technology and radiated x-ray in-line holography technology. Velocity field) Measuring apparatus, and more particularly relates to a flow image acquisition device using an x-ray beam capable of quantitatively measuring the flow information of the fluid in the invisible region or the opaque fluid inside the object.

The particle image velocity method, which obtains a quantitative velocity field by processing a flow image containing displacement information of particles in a flow, provides not only qualitative instant flow information but also excellent spatial resolution. It is a measurement technique that can extract quantitative velocity information with Two kinds of velocity field measurement techniques are used, particle image velocimetry (PIV) and particle tracking velocimetry (PTV). The PIV method calculates Fourier transform or direct correlation coefficient for the intensity distribution of scattering particle images in the interrogating window of the flow image to calculate the average velocity representative of the irradiation interval. In general, the PIV method is applied when the particle density is large and quantitative velocity information is calculated by extracting the representative velocity of the irradiation section. On the other hand, the PTV method extracts each particle position from several consecutively obtained flow images, and then obtains particle displacement information by tracking each particle. The PTV method provides Lagrangian velocity vectors of the particles, which are not representative speeds in the irradiation section of the PIV technique, and there is no directional ambiguity in the velocity measurement, while the image of each particle is relatively low. It is useful when having a particle density.

In-line holography of x-rays is a visualization method that uses phase contrast that occurs when an x-ray beam passes through an object. This method visualizes the inside of the object by the interference pattern represented by the phase difference at the boundary of the material, regardless of the composition of the material inside the object, and the absorption contrast using soft x-ray which is widely used in the medical field. X-ray images with much better spatial resolution than the method can be obtained. This advantage is possible because the x-ray beam of radiant light has better coherence and relatively higher energy level than soft x-ray. In the case of the in-line holography method applied in the present technology, the image of the three-dimensional structure inside the object is recorded as an interference phenomenon, but if the reconstruction process described in the optical holography technique is established, the three-dimensional space in the future You can get a video. It is also possible to acquire several x-ray images while rotating the object and tomography the three-dimensional structure of the object through the reproduction process.

The conventional PIV / PTV velocity field measurement technique and x-ray in-line holography technique are excellent technologies, but each has the following disadvantages. First of all, in the case of PIV / PTV velocity field measurement technique, it is possible to measure quantitative velocity for a given flow, but the measurement target must be transparent because the particle image in the flow cross section to be measured must be acquired by an image acquisition device such as a CCD camera. There is this. That is, it is impossible to measure internal flow or opaque fluid flow with PIV / PTV technology using white light or visible light such as laser. On the other hand, the x-ray in-line holography technique can visualize the opaque object by using the x-ray transmittance, but it is only effective for studying the structure of the object inside the solid object, Not suitable for observing the flow inside an object. Since there is no phase or density difference inside the flow, the same is true for either phase contrast, absorption contrast, or both. In addition, no attempt has been made to quantitatively measure the flow in an object using conventional x-ray imaging.

Therefore, the present invention is intended to solve such a disadvantage, and it is not only recently developed but also two different measurement techniques (PIV / PTV velocity field measurement technique and radiated light x-ray in-line holography). It is an object of the present invention to provide a flow image acquisition device using x-ray which can quantitatively measure the flow of fluid in an invisible region or the flow of an opaque fluid inside an object.

In order to achieve the above object, the present invention provides an accelerator that emits an x-ray beam of radiation and an amount of x-ray light required from the x-ray beam continuously emitted from the accelerator so that only the necessary amount of x-ray light can pass through the sample. A mechanical shutter installed in the apparatus, a micro-traverse installed on the beam axis so that the sample to be transmitted by the x-ray beam is placed, and an image of the x-ray wavelength visualized while passing through the sample. A scintillator installed on an optical axis of the x-ray beam so as to be converted into an image of a visible light band, a CCD camera installed perpendicular to the beam axis so as to acquire a particle image formed on the scintillator, and P device capable of extracting quantitative flow information from two x-ray flow images acquired continuously and a computer device installed to display images from a CCD camera on a monitor IV / PTV velocity field measurement technology.

According to the present invention, when the sample is a microtubule, it is characterized in that the syringe pump is connected to be installed to adjust the flow rate in the microtubule.

The above objects and various advantages of the present invention will become more apparent from the preferred embodiments of the invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

Figure 1 shows the basic principle of the PIV / PTV velocity field measurement technique using a conventional digital image processing. That is, the particle displacements obtained from the two particle images acquired between the time intervals Δt by continuously measuring the images of the particles placed in the flow between the short time intervals Δt and digitally processed them are determined by the time interval Δt. Divide into the instant velocity field.

On the other hand, Figure 2 is a schematic diagram of a conventional in-line holography (x-ray micro-imaging) technique, by using the radiation x-ray to detect the microstructure inside the object in the visible region (detection) Demonstrate imaging techniques that can be done. Here, the term 'micro-imaging' is referred to as 'micro-imaging' because the experimental equipment of the beam line that performs x-ray imaging in the in-line holography method of the accelerator is configured to observe the minute region. Writing. In other words, X-rays were used to transmit opaque flows (invisible region flows) that were not immediately visible, and in-line holography was used to visualize x-rays of transmitted invisible regions. . In-line holography is a technique that can visualize the inside of the specimen in a state in which the direction of the x-ray, the specimen, and the detector are arranged in the same direction as shown in FIG. 2. The x-ray imaging technique currently used in the human body in a hospital is to visualize the object by the absorption contrast (absorption contrast) the extent to which the x-ray is transmitted through the object. In the image (film) obtained by the absorption contrast method of x-ray, solids with high absorption rate such as bones are less exposed to the film and whiten. Comes out.

In-line holography of x-rays is a visualization method that uses phase contrast that occurs when an x-ray passes through an object. This method visualizes the inside of the object by the interference pattern represented by the phase difference at the boundary of the material, regardless of the composition of the material inside the object, and the absorption contrast using soft x-ray which is widely used in the medical field. X-ray images with much better spatial resolution than the method can be obtained. This advantage is possible because the x-ray beam of radiant light has better coherence and relatively higher energy level than soft x-ray. In the case of the in-line holography method applied in the present technology, the image of the three-dimensional structure inside the object is recorded as an interference phenomenon, but if the reconstruction process described in the optical holography technique is established, the three-dimensional space in the future You can get a video. It is also possible to acquire several x-ray images while rotating the object and tomography the three-dimensional structure of the object through the reproduction process.

The present invention combines these two measurement techniques (PIV / PTV velocity field measurement technique and radiated light x-ray in-line holography technique) to quantitatively measure the flow information of the fluid in the invisible region or the opaque fluid inside the object. .

In order to confirm the feasibility and reliability of the present technology, the velocity field of the opaque microtubular flow was measured using a combination of the accelerator x-ray micro-imaging technique and the PIV velocity field measurement technique.

 3 is a block diagram of a flow image acquisition and PIV velocity field measuring apparatus using an x-ray beam. First, as the x-ray beam from the accelerator 1 passes through the internal flow of the opaque microtube 10, phase contrast is generated by the internal structure of the microtube 10 and the flowing particles, which is a kind of crystal. Is directly reached to the scintillator (3). The scintillator 3 converts an image of an x-ray wavelength into an image of a visible light band. Particle images formed on the scintillator 3 are acquired by a CCD camera 4 equipped with a microscope, which is an x-ray particle image. At this time, the CCD camera 4 is configured perpendicular to the x-ray axis, in order to protect the CCD camera 4 from the x-ray.

If a mechanical shutter (2) is not installed, bubbles are generated inside a fluid or an object by a strong x-ray beam, which is found during the experiment.

In order to use the PIV velocity measurement technology, the double exposure technique is required. In this experiment, the mechanical shutter 2 (exposure time: 20 msec, delay time: 10 msec) and the CCD camera 4 are synchronized to obtain two x- Ray images were acquired continuously.

In this experiment, the size of the field of view was 1.5 mm x 1.5 mm and the fluid was flowed into the opaque Teflon tube 10 having an internal diameter of 0.75 mm while controlling the flow rate with a syringe pump (5). . The average flow velocity of the flow inside the microtubule 10 was about 4.91 mm / sec. As the following particles, alumina (Al ₂ O ₃ , density: 3.95 g / cm _³ , diameter: 3 μm) was used, and as a working fluid, glycerin (density: 1.26 g / cm ³ ) having a higher viscosity and density than water was used. The alumina was then subjected to gravity as little as possible. In the case of the liquid flow, the relatively large difference in density from the fluid such as bubbles or alumina was advantageous for obtaining a clear x-ray particle image, and the addition of contrast medium used in the hospital was more effective. FIG. 4 is an x-ray particle image inside a microtubule obtained by an x-ray micro-imaging technique. Particles of a flow inside the microtubule 10 made of an opaque teflon material obtained by using the penetrating power of the x-ray. Show the video.

FIG. 5 shows the spatial distribution of the flow longitudinal longitudinal component obtained from the acquired particle image, and the main flow direction inside the opaque microtubule obtained using the PIV technique from FIG. Shows the quantitative velocity field results of.

6 shows the main flow direction velocity profile in any cross section of the velocity field results. That is, the PIV velocity field obtained by the x-ray PIV technique shows a quantitative velocity distribution at a position along any horizontal line derived from FIG. 5. In this case, the velocity distribution has a symmetrical distribution with respect to the center of the microtubule and shows the well-developed flow of the tube flow. In addition, the more viscous effect increases as the tube approaches the outer wall, the flow rate gradually decreases and has the fastest velocity in the center. Where r ₀ is the diameter of the capillary tube and V ₀ is the maximum velocity

FIG. 7 (a) shows the basic structure of the catheter as a result of x-ray imaging of the vascular tissue of the stem of the freesia flower obtained by the present invention. Figure 7 (b) is an image when the contrast medium (contrast medium) is administered to the inside of the freesia stem, as the contrast agent flows along the conduit, the water pipe region becomes darker than the surroundings due to absorption contrast, the position of the internal conduit and the inside of the conduit You can see the flow more clearly. Here, the contrast agent refers to a substance that does not pass radiation such as barium injected to clearly see tissue structures such as blood vessels during x-ray examination in a hospital. 8 is an image of the inside of the thin bamboo branch was able to directly check the fluid flow flowing through the conduit (first ever). Here, the phase difference is large at the interface between the water part and the water part, so that a clear image of the flow of the liquid in the conduit can be obtained. Figure 9 shows the earlobe internal microvascular and blood images of live mice.

In the above description, it should be understood that those skilled in the art can only make modifications and changes to the present invention without changing the gist of the present invention as it merely illustrates a preferred embodiment of the present invention.

As described above, according to the present invention, a fluid image acquisition technique combining a transmission characteristic of x-ray and a digital image processing technique and a quantitative velocity field measurement technique based on an image may be used. Microfluidic flow can be analyzed. Therefore, the present invention can be applied to the visualization of bodily internal flow or measurement of quantitative velocity field, and to the fluid flow in which the interior is visible. It is also useful for the analysis of multiphase flows in which fluids with different phases are mixed.                     

The present invention can be further applied to flow analysis of an opaque fluid such as blood, flow analysis inside an invisible object, flow analysis in plants, insects, animals, and the human body.

Claims (5)

An accelerator that emits radiant light x-ray beams, A mechanical shutter mounted on the beam axis so that only the required amount of x-ray light can pass through the sample from the x-ray beam continuously radiated from the accelerator; A micro-traverse installed on the beam axis so that the sample to be transmitted by the x-ray beam is placed; A scintillator installed on the beam axis to change the visualized x-ray wavelength image into a visible light band while passing through the sample; A CCD camera installed perpendicular to the beam axis to acquire particle images formed on the scintillator; Comprising a computer device installed to display the image of the CCD camera on the monitor, Synchronize the mechanical shutter and the CCD camera to acquire two x-ray flow images in succession, and extract quantitative flow information from the two x-ray flow images acquired using PIV / PTV velocity field measurement technology. To do Flow image acquisition and velocity field measuring apparatus using x-ray beam. The method of claim 1, wherein when the sample is a microtubule, the syringe pump is connected to be installed to control the flow rate of the working fluid in the microtubule Flow image acquisition and velocity field measuring apparatus using x-ray beam. According to claim 2, wherein the microtubule working fluid to use the glycerin Flow image acquisition and velocity field measuring apparatus using x-ray beam. The method of claim 2, wherein the use of alumina particles as the following particles for the flow of the working fluid in the microtubules Flow image acquisition and velocity field measuring apparatus using x-ray beam. The method of claim 2, wherein the contrast medium is added to the working fluid in the microtubule Flow image acquisition and velocity field measuring apparatus using x-ray beam.

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