WO2019124692A1

WO2019124692A1 - Single grid-based phase contrast x-ray imaging system and device

Info

Publication number: WO2019124692A1
Application number: PCT/KR2018/011870
Authority: WO
Inventors: 임현우; 이헌우; 서창우; 조효성
Original assignee: 연세대학교 원주산학협력단
Priority date: 2017-12-21
Filing date: 2018-10-10
Publication date: 2019-06-27
Also published as: KR101991813B1

Abstract

The present invention relates to a single grid-based phase contrast x-ray imaging device and the single grid-based phase contrast x-ray imaging device comprises an X-ray tube which irradiates X-rays, and a grid which are disposed at a distance on a straight line having a specimen between the X-ray tube and the grid; and a detector which is disposed at a distance on a straight line from the grid and detects an irradiated x-ray for the specimen, which is transmitted from the grid, wherein the x-ray tube, the specimen, the grid and, the detector may be disposed such that a first distance between the x-ray tube and the specimen, a second distance between the specimen and the grid, and a third distance between the grid and the detector are set to a distance which removes artifacts in generated X-ray image by using the detected X-ray.

Description

Single Grid-Based Phase-Phase X-ray Imaging Systems and Devices

The present invention relates to a single lattice-based phase contrast x-ray imaging system and apparatus capable of removing artifacts from a single lattice-based phase-contrast x-ray image.

Imaging technology using the phase information of a sample is a key element of the latest X-ray imaging science. This attracts the attention of many researchers as a promising tool to significantly improve x-ray imaging performance in the medical and industrial sectors. Conventionally, in connection with phase-sensitive x-ray imaging techniques, a radio-based imaging technique (see, for example, A. Burvall, U. Lundstrøm, P. Takman, D. Larsson, H. Hertz, Opt. 2011) 10359.), analyzer-based imaging techniques (for example, C. Parham, Z. Zhong, D. Connor, L. Chapman, E. Pisano, Acad. Radiol. .), A document relating to a crystal interferometer and a grating-based imaging technique has been reported.

Among these conventional techniques, the lattice-based imaging technique is a new and precise phase-sensing imaging technique capable of simultaneously recovering absorption, scattering (or rockstone) and differential phase contrast images at high resolution and sensitivity using existing X-ray tubes and detectors Proven. However, this technique has the drawbacks of requiring a high precision grid, high sensitivity to the array of experimental equipment, and limited speed by analytical grid scanning.

As an attempt to overcome the disadvantages of the conventional lattice-based imaging technique as described above, recently, in the paper [H. Wen, E. Bennett, M. Hegedus, S. Carroll, IEEE Trans. on Med. Imaging 27 (8) (2008) 997. A single-grid based phase-contrast x-ray imaging technique has been proposed. In the above technique, a conventional lattice with a large lattice spacing and a large area is used.

Figure 1 is a schematic representation of a conventional single-grid based phase-contrast x-ray imaging (PCXI) system.

Referring to FIG. 1, for example, in a conventional single-grid-based PCXI system, an X-ray grid is placed between an X-ray tube and a detector, It can be placed in front of the grid. As shown in FIG. 1, when the X-ray irradiated from the X-ray tube passes through the specimen, the transmitted wavefront is distorted as it is refracted by the refractive index difference of the specimen structure, and its intensity can be modulated by the periodic lattice pattern. In other words, the wavefront before the x-ray passes through the specimen is undistorted, whereas the wavefront after the x-ray passes through the specimen is distorted so that the x-rays transmitted from the grating are refracted Refracted x-rays and unrefracted x-rays are present. Also, since the grating serves as a frequency modulator for the Fourier component of the sample, the phase information can be reconstructed using a Fourier processing technique.

However, since the phase information reconstructed by the conventional single-lattice-based PCXI system is damaged by moire fringe and wraparound aliasing, which are two main artifacts that damage the reconstructed image, Through the grid-based PCXI system, it is difficult to obtain high-quality images with two major artifacts removed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a single lattice-based phase contrast X-ray imaging system and apparatus capable of effectively removing artifacts from a single lattice-based phase-contrast X-ray image.

The present invention has been made to solve the problems of the conventional art described above, and it is an object of the present invention to provide a high-quality image which effectively removes two main artefacts moire fringe and wraparound aliasing in a single lattice-based phase- Based phase-contrast x-ray imaging apparatus capable of acquiring a single-grid-based phase-contrast X-ray imaging apparatus.

It is to be understood, however, that the technical scope of the embodiments of the present invention is not limited to the above-described technical problems, and other technical problems may exist.

According to a first aspect of the present invention, there is provided a single-grid-based phase-contrast X-ray imaging apparatus comprising: an X-ray tube and a grating for irradiating X-rays placed on a straight line with a distance therebetween; And a detector disposed at a distance on a straight line from the grating and detecting an irradiated x-ray for the specimen transmitted from the grating, wherein the x-ray tube, the specimen, the grating, A first distance between the specimens, a second distance between the specimen and the grating, and a third distance between the grating and the detector are set to a distance such that artifacts in the x-ray image generated using the detected x- Respectively.

As a technical means to achieve the above object, a single-grating-based phase-contrast X-ray imaging system according to the second aspect of the present invention comprises: a single grating-based phase-contrast X-ray imaging apparatus according to the first aspect; And an image output device for outputting an image generated using the X-ray detected by the single-grid-based phase-contrast X-ray imaging apparatus.

According to a third aspect of the present invention, there is provided a single-grating-based phase-contrast X-ray imaging method, comprising the steps of: Disposing a grating at a distance between the specimens on a straight line, and placing the detector at a distance on a straight line from the grating; Irradiating the sample with an X-ray; And a step of detecting an irradiated X-ray on the specimen transmitted from the grating, wherein in the arranging step, the X-ray tube, the specimen, the grating, 1 distance, a second distance between the specimen and the grating, and a third distance between the grating and the detector are set to a distance such that artifacts in the x-ray image generated using the x-ray detected through the detector are removed .

The above-described task solution is merely exemplary and should not be construed as limiting the present disclosure. In addition to the exemplary embodiments described above, there may be additional embodiments in the drawings and the detailed description of the invention.

According to an embodiment of the present invention, there is provided an X-ray tube, a specimen, a grating, and a detector such that the first distance, the second distance, and the third distance are set to distances for removing artifacts in the X- The arrangement of the single grating-based phase-contrast X-ray imaging apparatus can acquire a high-quality image in which two main artefacts moire fringe and wraparound aliasing are effectively removed.

We place the grid at an angle and arrange the specimen so that the first distance, the distance between the x-ray tube and the specimen, is short (ie, the specimen is positioned as close to the x-ray tube as possible between the x-ray tube and the detector) X-ray images generated by using the detected X-rays can be used to acquire images with high contrast while simultaneously removing artifacts, thereby improving the efficiency and quality of medical image diagnosis.

However, the effects obtainable here are not limited to the effects as described above, and other effects may exist.

FIG. 1 is a schematic diagram of a conventional single-grating-based phase-contrast X-ray imaging system.

Figure 2 is a schematic representation of a simplified Fourier process in a single grid-based PCXI for retrieving absorbance, scattering and differential phase contrast images in a single original image of the examined sample.

3 is a view showing an example of a moire pattern formed by two sets of parallel lines.

4 is a view showing an example in which a wide angle phenomenon is formed.

FIG. 5 is a diagram schematically illustrating the configuration of a single-grating-based phase-contrast X-ray imaging apparatus according to an embodiment of the present invention.

FIG. 6 is a graph illustrating a theoretical curve for a critical pixel size expressed as a function of the grating line density when the third distance is fixed at 55 cm, for example, in a single grating-based phase-contrast imaging apparatus according to an embodiment of the present invention .

FIG. 7 is a graph illustrating the relationship between the spacing of the gratings expressed as a function of the first distance and the focal length size of the x-ray tube when the third distance is fixed at 55 cm, for example, in the single grid- Fig.

8 is a schematic view of an x-ray grating used in an experimental example of the present invention and a photograph of an actual x-ray grating.

Figure 9 shows a raw image of anchovy taken at 20 kV _P with a horizontal grating and a raw image taken with a tilted grating.

10 is a diagram showing a two-dimensional Fourier spectrum of each of the raw images of FIG. 9 having a horizontal grid and a slanted grid.

Figure 11 is a set of PCXI results retrieved from a raw image of anchovy applied with a horizontal grid and a tilted grating, showing absorption, scattering and differential phase contrast images.

12 is a graph showing the characteristics of each of the absorption image, the scattered image, and the differential phase difference image obtained according to the change of the first distance.

13 is a diagram for comparing the characteristics of the fusion images obtained by combining the single absorption image and the absorption image with the color scattering image.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when an element is referred to as being "connected" to another element, it is intended to be understood that it is not only "directly connected" but also "electrically connected" or "indirectly connected" "Is included.

It will be appreciated that throughout the specification it will be understood that when a member is located on another member "top", "top", "under", "bottom" But also the case where there is another member between the two members as well as the case where they are in contact with each other.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

In this paper, we propose a new technique to remove moire fringe and wraparound aliasing, which are artifacts that damage reconstructed images in single-grid phase-contrast x-ray imaging (PCXI) We propose the arrangement structure of X-ray tube, specimen, grating and detector in lattice-based phase-contrast X-ray imaging apparatus.

Before describing the present invention in detail, the Fourier processing technique used in the PCXI based on a single grid and the artifacts related thereto will be described first, and hereafter, the present invention will be described in detail.

The Fourier processing technique used in the PCXI based on a single grid is exemplified in [H. Wen, E. Bennett, M. Hegedus, S. Rapacchi, Radiology 251 (3) (2009) 910. Hereinafter,

Figure 2 shows a simplified Fourier process in a single grid-based PCXI for retrieving the absorption, scattering and differential phase-contrast images in a single raw image of the examined sample Fig.

Referring to FIG. 2, a Raw image of the bare grid,

) And a grid image (Raw image of the sample with grid,

Are obtained, Fast Fourier Transform (FFT) can be performed on each of the acquired images. Thereafter, in the Fourier domain for each of the acquired images, the areas surrounding the primary maximum value and the first harmonic maximum are passed through a band pass filter (e.g., a Hann filter) Respectively, and the main image (

, Primary image (ie, reconstructed absorption image, absorption image), and first harmonic image

Inverse FFT and image normalization using a grid image may be applied to obtain a first harmonic image, and the main image and the first harmonic image may satisfy Equation (1).

[Equation 1]

here,

Wow

Represents the main image and the first harmonic image of the specimen taken with the grid, respectively.

Wow

Represent the main image and the first harmonic image of the lattice, respectively. At this time, in order to restore the phase information,

) And the first harmonic image

) Can be calculated through the following equation (2).

&Quot; (2) "

here,

(Amplitude,

) And angles (Angle,

) Components represent a reconstructed scattering image and a differential phase-contrast image, respectively.

Figure 2 shows three types of interactions (i. E., Absorption, scattering, differential phase difference) used as contrast mechanisms in a single lattice-based PCXI. Referring to this, the incident x-ray beam profile (assuming that the x-ray beam has a Gaussian shape, for example) is attenuated and laterally displaced by the absorption and refraction characteristics of the sample, And is broadened by small-angle scattering due to the microstructure of the specimen. Here, phase-contrast imaging can provide a high contrast between materials with different refractive indices, whereas scattering images can be obtained by conventional radiography It is possible to provide information on the microstructure which can not be visualized.

The following description of artifacts is as follows.

There are moire fringes and wraparound aliasing in artifacts that damage the reconstructed image. The moire pattern can be more easily understood with reference to Fig. 3, and the wide angle phenomenon can be more easily understood with reference to Fig.

Referring to FIG. 3, a moire fringe refers to an interference artifact generated by interaction between a digital detector and periodic lattice streaks. That is, the moire pattern can be used in a variety of digital video and computer graphics techniques to produce an opaque pattern with transparent gaps (e.g., a grid pitch

(For example, a pattern corresponding to a detector pitch), but different patterns having similar pitches (e.g.,

Which is often seen when the image is superimposed or rotated on a pattern (e.g.

In Fig. 3 (a), two sets are arranged side by side (i.e.,

= 0 [deg.]), And (b) represents one set (e.g., a detector interval) in which one set of two sets

As shown in FIG. here,

Denotes an angle at which the grating is inclined, that is, a grid angle,

Represents the moire angle of the moire pattern.

In digital radiography, moiré patterns typically occur as a digital detector improperly samples grid shadows (i.e., when a fixed grid with a digital detector is used, the grid shadow is improperly sampled by detector pixels ), Which causes strong vibrations in the grid shadows.

The angle of the moire pattern can be defined theoretically to satisfy the following equation (3).

&Quot; (3) "

here,

The angle of the moire pattern,

(Which may be expressed as a grid frequency)

(In other words, the angle between the grating and the detector, the grid angle), the angle at which the grating is inclined with respect to the detector

Represents the sampling frequency of the detector, and m and n represent integers satisfying the condition of the above-mentioned equation (3).

According to this, when the grating is tilted at a certain angle, the moire pattern can be separated from the main harmonics frequency of the grating frequency. In consideration of this, in a single grating-based phase-contrast X-ray imaging apparatus according to an embodiment of the present invention to be described later, by arranging gratings at specific angles, the moire pattern can be effectively separated from the main harmonic frequency of the grating frequency. An explanation of the formation theory of moire patterns is given in [M. Gauntt and G. Barnes, A novel technique to suppress grid line artifacts, Med. Phys. 33, 1654-1667 (2006)), and a detailed description thereof will be omitted below.

On the other hand, the wide angle phenomenon refers to an artifact generated by the spectral overlap of adjacent harmonic maximum values in the Fourier spectrum when the lattice is placed. That is, the wide angle phenomenon is caused by the spectrum overlap of the adjacent harmonic maximum in the Fourier spectrum. The wraparound aliasing can be more easily understood with reference to FIG.

4 is a view showing an example in which a wide angle phenomenon is formed.

Referring to FIG. 4, when a sample is taken with a grating in PCXI, the original Sample spectrum of the sample is copied at the harmonic maximum of the grating spectrum, which is modulated by the grating as shown in FIG. 4 (a) Spectral overlap in the sample spectrum modulated by grid. In other words, wide-angle phenomena can occur when the copied spectra overlap in the frequency domain.

In this case, when the x-ray image is taken, the sample spectrum is smoothed (or the band is limited, Band-limited) by increasing the focal spot size or magnifying the object magnification The wide angle phenomenon can be suppressed as shown in (b) of FIG. In other words, by increasing the focal spot size or by enlarging the object magnification (ie magnification), spectral separation can be achieved without overlap between the spectra in the sample image modulated by the grating and the sample spectra in which the band is limited So that the wide angle phenomenon can be suppressed.

Hereinafter, a single-grid-based phase-contrast X-ray imaging apparatus according to an embodiment of the present invention will be described in detail with reference to the above-described contents. More specifically, in the following description, a single-grid-based phase-contrast X-ray imaging apparatus capable of effectively removing an artifact in a single-grid-based phase-contrast X-ray imaging technique for recovering an elastic scattering signal from a single original image using a Fourier- Will be described in detail.

In order to demonstrate the feasibility of the arrangement structure of a single-grating-based phase-contrast X-ray imaging apparatus according to an embodiment of the present invention, in one experiment example of the present invention, 200-lines / inch grid strip density and a microfocus X-ray tube in the case of the X-ray tube 1

Ray tube having the focal size of the detector 4 is used, and as the CMOS type flat plate detector 49.5

Lt; RTI ID = 0.0 > of < / RTI >

FIG. 5 is a diagram schematically showing the configuration of a single-grid-based phase-contrast X-ray imaging apparatus 10 for artifact removal according to an embodiment of the present invention (hereinafter referred to as 'apparatus 10' for convenience of explanation).

Referring to FIG. 5, the apparatus 10 may include an X-ray tube 1, a sample 2, a grid 3, and a detector 4.

The x-ray tube 1 can irradiate the x-ray (x-ray) toward the sample 2.

The grating 3 can transmit the irradiated X-rays to the specimen 2. The grating 3 may serve as a frequency modulator for the Fourier component of the sample 2. Accordingly, the phase information of the sample 2 can be reconstructed using a Fourier processing technique.

Further, the grating 3 may be a linear grating, but is not limited thereto. Further, the grating 3 can be arranged at an inclined angle, and a description thereof will be described later in more detail.

The x-ray tube 1 and the lattice 3 can be arranged at a distance on a straight line with the sample 2 interposed therebetween.

The detector 4 can be arranged at a distance on the straight line from the grating 3 to detect the irradiated x-rays against the specimen 2 transmitted from the grating 3. The detector 4 may be, for example, a flat plate detector, but is not limited thereto.

In the present apparatus 10, the distance between the x-ray tube 1 and the specimen 2 is the first distance

, And the distance between the specimen 2 and the lattice 3 is defined as the second distance

, And the distance between the grating 3 and the detector 4 is defined as the third distance

). &Lt; / RTI >

At this time, the X-ray tube 1, the sample 2, the lattice 3 and the detector 4 in the present apparatus 10 are arranged such that the first distance, the second distance and the third distance are detected through the detector 4 Ray image generated by using the X-ray can be removed. That is, in the present apparatus 10, the X-ray tube 1, the sample 2, the lattice 3 and the detector 4 are arranged so as to have a first distance to a third distance for removing artifacts in the X- .

Specifically, the first arrangement condition of the present device 10 for effective artifact removal is such that the pixel size of the detector 4 (i.e., the first harmonic peak, otherwise referred to as the first harmonic peak)

Of the grating appearing on the surface of the detector (4)

(In other words, the period of the grid shadow

/ RTI > of < / RTI > Accordingly, the first distance, the second distance, and the third distance can be set to satisfy the following equation (4).

&Quot; (4) "

here,

Represents the pixel size of the detector 4.

(In other words, the period of the grid shadow)

).

The first distance, which is the distance between the x-ray tube 1 and the specimen 2,

The second distance, which is the distance between the specimen 2 and the lattice 3,

Represents the third distance, which is the distance between the lattice 3 and the detector 4.

FIG. 6 is a graph illustrating a function of a grid strip density (in other words, a function of a grating frequency) when a third distance is fixed at 55 cm in a single grid-based phase-contrast X-ray imaging apparatus according to an embodiment of the present invention. And the theoretical curve for the critical pixel size.

Referring to FIG. 6, in the present device 10, for example, the sum of the first distance to the third distance (that is,

+

) May be set to 100 cm, and the third distance may be set to 55 cm.

At this time, in order to use the lattice 3 having a lattice line density of 200-lines / inch applied in an experimental example of the present invention, the pixel size of the maximum detector satisfying the expression (4) is 94

Lt; / RTI > In other words, the threshold pixel size for a 200-lines / inch grid for the application of a grating 3 with a grating line density of 200-lines /

Lt; / RTI > Meanwhile, in one experimental example of the present invention, for example, 49.5

A detector 4 having a pixel size of < / RTI >

The second arrangement condition of the device 10 for effective artifact removal is that the size of the x-ray tube 1 is adjusted so that the lattice 3 can be clearly seen in the detector 4

) May be set to be smaller than the period of the grating shadow (in other words, the grating blur due to the focus size of the x-ray tube). In other words, the ratio of the spacing of the grating 3 to the focus size (

) Can be set to be smaller than the spacing of the gratings so that the gratings in the detector are clearly visible. Accordingly, the first distance, the second distance, and the third distance can be set to satisfy the following equation (5).

&Quot; (5) "

here,

(3) < / RTI >

) And the focus size of the x-ray tube 1 (

), &Lt; / RTI >

The first distance,

The second distance,

Represents the third distance.

On the other hand, the above-described wide angle phenomenon can be suppressed when the magnification of the sample (differently expressed as the magnification of the object) is sufficiently large as shown in Equation (6) below, which can lead to the condition of Equation (7). Here, the degree of enlargement of the sample is sufficiently large that the sample 2 is disposed between the x-ray tube 1 and the detector 4 as close as possible to the x-ray tube 1, which means that one distance is set short.

In other words, in order to suppress the wide angle phenomenon, in the present apparatus 10, the ratio of the interval of the grating and the focus size may be set to satisfy the following Equation 7 in consideration of the magnification of the sample according to the first distance, The enlarged view can be set to satisfy the following expression (6).

&Quot; (6) "

here,

Represents the magnification of the sample (in other words, the magnification of the object)

Represents the focus size of the x-ray tube,

Is the period of the lattice shadow (in other words, the spacing of the lattice

). Also,

The first distance,

The second distance,

Represents the third distance.

&Quot; (7) "

here,

(3) < / RTI >

) And the focus size of the x-ray tube 1 (

), &Lt; / RTI >

The first distance,

The second distance,

Represents the third distance.

According to this, the ratio of the distance between the gratings 3 and the focus size of the x-ray tube 1 (

The upper limit value and the lower limit value can be set.

FIG. 7 is a graph illustrating the relationship between the spacing of the gratings expressed as a function of the first distance and the focal length size of the x-ray tube when the third distance is fixed at 55 cm, for example, in the single grid- (

FIG. 4 is a diagram showing a zone of tolerance of the present invention.

Referring to FIG. 7, in one experimental example of the present invention, the ratio of the spacing of the gratings to the focus size of the x-ray tube

) And 0.43 for a given ratio of 0.43,

May be set to be not larger than 16.3 cm to satisfy the above-mentioned Equations (5) and (7).

According to this, the apparatus 10 can allow the first arrangement condition to allow the first harmonic maximum to be sufficiently sampled, and the second arrangement condition to allow the grating 3 to be clearly So that it can be seen. The apparatus 10 further includes a first distance to a third distance L3 for satisfying the conditions of the equations (4) to (7) above for the X-ray tube 1, the sample 2, the lattice 3, It is possible to acquire an image in which the wide angle phenomenon, which is one of artifacts, is removed.

On the other hand, the moiré pattern can theoretically be removed from the image when the grid shadow and the frequency of the detector match exactly. However, in practice, it is almost impossible to precisely match the grating shadow and detector frequency due to the manufacturing tolerances of the grating structure. In consideration of this, in the present apparatus 10, by arranging the grating 3 at a specific angle, the moire pattern can be effectively separated from the first harmonic maximum value.

That is, in the present apparatus 10, the grating 3 can be arranged so as to have a predetermined angle so that the moiré pattern is effectively separated from the first harmonic maximum. At this time, the lattice 3 can be arranged to be inclined at a predetermined angle in the right direction, for example, with respect to the lattice 3 facing the x-ray tube 1 on the basis of Fig. Here, the predetermined angle may mean, for example, any angle of 20 to 30 degrees. However, it is preferable that the predetermined angle is set to 27.8 degrees.

In order to demonstrate the feasibility of the arrangement structure of a single grating-based phase-contrast imaging apparatus according to one embodiment of the present application, as described above, in one experimental example of the present invention, 55

Ray tube 1 having a focal spot size of 200-lines / inch, a grating 3 having a grating line density of 200-lines / inch, 49.5

A flat type detector 4 of CMOS type having a pixel size of the pixel type can be applied. Also, in one experiment example of the present invention, the first distance, the second distance, and the third distance may be set to 15 cm, 30 cm, and 55 cm, respectively. The distance between the X-ray tube 1 and the detector 4 may be set to 100 cm. Further, the x-ray tube 1 used in the experimental example of the present application was 20

, And 1 mAs, respectively.

8 is a schematic view (a) of an x-ray grating 3 used in an experimental example of the present invention and a photograph (b) of an actual x-ray grating 3. Fig.

Referring to FIG. 8 (a), the lattice 3 having a lattice line density of 200-lines / inch used in an experimental example of the present invention has a thickness of lead or lead strip

25

, And the thickness (or spacing) of the lattice space

102

, And the height h of the lattice plate is 510

Lt; / RTI > Accordingly,

The

Due to 127

Lt; / RTI > In addition, the lattice used in one experimental example of the present invention

And a grating ratio of 5: 1.

Referring to FIG. 8 (b), the lattice 3 used in one experimental example of the present invention can be manufactured by a precise sawing process together with a carbon-fiber plate as an example. In addition, the grating 3 used in one experimental example of the present invention was produced by precisely aligning grooves with microcontrol diamond blades rotating at about 30,000 rpm during the manufacturing process, and pouring lead compounds in a liquid state into the grooves It can be a grid with accurate grid strips.

Figure 9 shows a horizontal grid (i.e.,

= 0 °) and an anchovy top image taken at 20 kV _P and a tilted grating (ie,

= 27.8 [deg.]). The drawing on the right in Fig. 9 shows an enlarged image with respect to the area A on the left side.

Referring to FIG. 9, it can be seen that Moire appears on the screen due to subsampling to reduce the size of the published picture in the raw image captured with the horizontal grid. On the other hand, in the image taken with the inclined grid, it can be seen that the grid shadow is clearly displayed on the screen without moire.

Figure 10 is a two-dimensional (2D) Fourier spectrum of each of the raw images of Figure 9 with a horizontal grid and a tilted grid.

Referring to FIG. 10, the Fourier spectrum includes several harmonics of the lattice frequency and corresponding moiré components. The symmetric impulse-like bursts indicated by the arrows in FIG. 10 may be the result of the near periodicity of the moire pattern. Referring to FIG. 10, in the case of a tilted grating, the moiré component is well separated from a window of a band-pass filter (window to which a band-pass filter is applied), whereas in the case of a horizontal grating, Can not be separated well.

11 is a complete set of PCXI results retrieved from a raw image of anchovy applied with a top image and a bottom image and showing absorption, scattering and differential phase-contrast, Fig.

11, in Fig. 11, the distance from the x-ray tube to the specimen

Is the distance from the specimen to the grid

Is 30 cm, and the distance from the lattice to the detector

Is set to 55 cm,

Lt; RTI ID = 0.0 >

= 55

/ 127

0.43 may fall within the allowable range as shown in FIG.

11, in the case of the horizontal grating, since the first harmonic maximum (in other words, the first harmonic peak) in which moire components are separated is still included (see FIG. 10A), the scattering and differential It can be confirmed that all results are obtained irrespective of phase difference images.

On the other hand, referring to the bottom view of FIG. 11, in the case of a tilted lattice, the moiré component is well separated from the first harmonic maximum (see FIG. 10 (b) Can be removed.

11, it can be seen that the intestines of the anchovy are clearly visible in the scattered image as compared with the absorbed image.

Because x-ray scattering radiography visualizes small angular scattering of the x-rays at air-tissue interfaces, the air-tissue interface is reduced and replaced by connective tissue X-ray scattering can be more strongly reduced in the field of destroyed anchovies. This results in a positive effect of increasing the contrast of the anchovy field.

FIG. 12 is a diagram showing the characteristics of each of an absorption image (left), a scattering image (center), and a differential phase-contrast image (right) obtained according to a change in the first distance. At this time, in Fig. 12,

Are images of the three characteristics obtained when 10 cm, 15 cm, 20 cm and 35 cm, respectively.

Based on the description with reference to Fig. 7 described above, it can be seen that the layout of the present apparatus 10 when the first distance is 10 cm and 15 cm belongs to the allowable area, whereas when 20 cm and 35 cm It can be said that it does not belong to the allowable area.

Referring to FIG. 12, in the scattered image and the differential phase contrast image obtained when the first distance is 20 cm and 35 cm, the edges of the anchovy structure in particular are more severely affected with the first distance due to the spectrum overlap of adjacent harmonic peaks , And it can be confirmed that most of them are high frequency components of the first harmonic peak (or first harmonic peak) separated.

On the other hand, since the absorbed image is retrieved from the primary peaks that do not include lattice modulation, it can be confirmed that it is not affected by the first distance. 12, it can be confirmed that the experimental result according to one experimental example of the present application agrees well with the theoretical prediction.

13 is a diagram for comparing characteristics between a single absorbance image (a) and a fusion image (i.e., absorption + scattering) (b) obtained by combining an absorption image and a coloring scattering image.

13, since the influence of the absorption and the small angular scattering phenomenon is different in principle, the fusion image shown in FIG. 13 is a complementary image that can provide much richer information about the existing specimen than the image of the existing radiography Can be used as an authentication mechanism.

The single-grid-based phase-contrast X-ray imaging system according to one embodiment of the present invention includes a single grid-based phase-contrast X-ray imaging apparatus 10 and a single-grid-based phase-contrast X-ray imaging apparatus 10, And a video output device for outputting an image.

Here, the single-grid-based phase-contrast X-ray imaging apparatus means the same apparatus as the single-grid-based phase-contrast X-ray imaging apparatus 10 described above, and thus a duplicated description will be omitted.

In addition, the video output device may be, for example, a device such as a desktop PC, a monitor, and a portable terminal device, but is not limited thereto and various video output devices can be applied.

In addition, the single-grid-based phase-contrast X-ray imaging method according to an embodiment of the present invention is characterized in that the X-ray tube for irradiating X-rays in the single-grid-based phase-contrast X-ray imaging apparatus 10 described above and the distance on a straight line (Step 1) of disposing the detector at a distance from the grating in a straight line (step 1), irradiating the sample with the x-ray through the x-ray tube (step 2), and irradiating the irradiated sample with the x- (Step 3) through a detector.

In addition, in the step of placement (step 1), the x-ray tube, the specimen, the grating and the detector are positioned such that the first distance between the x-ray tube and the specimen, the second distance between the specimen and the grating, Ray image generated by using the X-ray detected through the X-ray detector.

Here, the single grid-based phase-contrast X-ray imaging apparatus means the same apparatus as the single-grid-based phase-contrast X-ray imaging apparatus 10 described above. Therefore, Can be equally applied to a description of a single-grating-based phase-contrast x-ray imaging method.

It will be understood by those of ordinary skill in the art that the foregoing description of the embodiments is for illustrative purposes and that those skilled in the art can easily modify the invention without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims

A single-grating-based phase-contrast x-ray imaging apparatus,

X-ray tubes and lattices for irradiating x-rays placed at a distance on a straight line with the sample in between; And

A detector disposed at a distance on a straight line from the grating to detect an irradiated X-ray on the specimen transmitted from the grating,

Lt; / RTI >

The x-ray tube, the specimen, the grating and the detector,

A first distance between the x-ray tube and the specimen, a second distance between the specimen and the grating, and a third distance between the grating and the detector are such that artifacts in the x-ray image generated using the detected x- Wherein the single grid-based phase-contrast x-ray imaging device is arranged to set a distance to the first grid-based phase-contrast x-ray imaging device.
The method according to claim 1,

Wherein the grating is a linear grating and is tilted.
The method according to claim 1,

Wherein the detector is a flat plate detector,

Wherein the detector pixel size is set not to be greater than 1/3 of the spacing of the grating appearing on the surface of the detector.
The method of claim 3,

Wherein the first distance, the second distance, and the third distance are set to satisfy the following equation (1): " (1) "

[Equation 1]

here,
The pixel size of the detector,
Lt; RTI ID = 0.0 >
The first distance,
The second distance,
Represents the third distance.
The method according to claim 1,

Wherein a ratio of the spacing and the focal spot size of the grating is set to be smaller than the spacing of the grating.
6. The method of claim 5,

Wherein the first distance, the second distance, and the third distance are set to satisfy: < EMI ID = 2.0 >

&Quot; (2) "

here,
The focus size,
Lt; RTI ID = 0.0 >
The first distance,
The second distance,
Represents the third distance.
6. The method of claim 5,

Wherein the ratio of the spacing and focus size of the grating is set to satisfy Equation (3) in view of the magnification of the sample according to the first distance;

&Quot; (3) "

here,
The focus size,
Lt; RTI ID = 0.0 >
The first distance,
The second distance,
Represents the third distance.
8. The method of claim 7,

Wherein the sample magnification is set to satisfy Equation (4): " (4) "

&Quot; (4) "

here,
Is a sample magnification,
The period of the grid shadow,
The focus size,
The first distance,
The second distance,
Represents the third distance.
In a single-grating-based phase-contrast x-ray imaging system,

9. A single-grating-based phase-contrast X-ray imaging apparatus as claimed in any one of claims 1 to 8; And

An image output device for outputting an image generated by using the X-ray detected by the single grid-based phase-contrast X-ray imaging apparatus,

Based phase-contrast x-ray imaging system.
In a single-grating-based phase-contrast x-ray imaging method,

A single-grating-based phase-contrast X-ray imaging apparatus according to any one of claims 1 to 8, wherein an X-ray tube and a grating for irradiating an X-ray are arranged at a distance from each other with a distance therebetween and a distance on a straight line from the grating Placing a detector;

Irradiating the sample with an X-ray; And

Detecting an irradiated X-ray on the specimen transmitted from the grating,

Lt; / RTI >

In the arranging step,

Wherein the x-ray tube, the specimen, the grating and the detector have a first distance between the x-ray tube and the specimen, a second distance between the specimen and the grating, and a third distance between the grating and the detector, Ray image generated by using the X-ray detected through the X-ray detector is removed.