JP6287813B2 - Radiation phase contrast imaging device - Google Patents

Description

  The present invention relates to a radiation phase difference imaging apparatus capable of imaging an internal structure of an object using a phase difference of radiation transmitted through the object.

  2. Description of the Related Art Conventionally, various devices have been devised as radiation imaging apparatuses for imaging an internal structure of an object by transmitting radiation to the object. As a general thing of such a radiography apparatus, a projected image of radiation is captured by irradiating an object with radiation and passing the object through. In such a projected image, shading appears according to the ease of passing radiation, and this represents the internal structure of the object.

  With such a radiation imaging apparatus, only an object having a property of absorbing radiation to some extent can be imaged. For example, living soft tissue hardly absorbs radiation. Even if such a tissue is photographed with a general device, the projection image shows almost nothing. Thus, when attempting to image the internal structure of an object that does not absorb radiation, a general radiographic apparatus has a theoretical limit.

  Thus, a radiation phase difference imaging apparatus has been devised that images the internal structure of an object using the phase difference of transmitted radiation. Such an apparatus uses Talbot interference to image the internal structure of an object.

  Talbot interference will be described. The radiation source 53 in FIG. 11 emits radiation in phase. When the radiation passes through the phase grating 55 having a saddle shape, an image of the phase grating 55 appears on a projection plane separated from the phase grating 55 by a predetermined distance (Talbot distance). This image is called a self-image. The self-image is generated only at a position where the projection plane is separated from the phase grating 55 by the Talbot distance, and is not simply a projection image of the phase grating 55. The self-image is composed of interference fringes generated by light interference. The reason why the self-image of the phase grating 55 appears at the Talbot distance is that the phases of the radiation generated from the radiation source 53 are aligned. When the phase of radiation is disturbed, the self-image that appears in the Talbot distance is also disturbed.

  The radiation phase contrast imaging apparatus images the internal structure of an object using the disturbance of the self-image. Assume that an object is placed between the radiation source and the phase grating 55. Since this object hardly absorbs radiation, most of the radiation incident on the object is emitted to the phase grating 55 side.

  That's not the case if the radiation was completely passing through the object. The phase of the radiation changes while passing through the object. The radiation emitted from the object passes through the phase grating 55 with its phase changed. When this radiation is observed on the projection plane placed at the Talbot distance, the self-image of the phase grating 55 is disturbed. The degree of disturbance of the phase grating 55 represents a change in the phase of radiation.

  The extent to which the phase of the radiation transmitted through the object changes specifically depends on where the radiation has passed through the object. If the object has a homogeneous configuration, the change in the phase of the radiation is the same everywhere in the object. However, in general, an object has some internal structure. If radiation is transmitted through such an object, the phase change will not be the same.

  Therefore, if the phase change is known, the internal structure of the object can be known. The change in phase can be known by observing the self-image of the phase grating 55 at the Talbot distance. Observation of the self-image is performed with a radiation detector placed at the Talbot distance (see, for example, Patent Document 1).

International Patent Publication No. 2009104560

However, the conventional radiation phase contrast imaging apparatus has the following problems.
That is, it is difficult to obtain a clear fluoroscopic image with the conventional radiation phase contrast imaging apparatus. This is because the radiation energy used for imaging cannot be optimized.

  The energy of the radiation emitted from the radiation source of the radiation phase contrast imaging apparatus is not limited. For example, if the energy of the radiation emitted from the radiation source is too low, the radiation is absorbed in the object and is difficult to transmit. Such low energy radiation is not suitable for imaging. This is because in order to know the internal structure of the object, it is necessary to observe the disturbance of the self-image caused by the radiation passing through the object.

  However, if the energy of the radiation emitted from the radiation source is too high, the phase of the radiation is not easily affected by the object, and the radiation passes through as it is without interacting with the object. Such high energy radiation is not suitable for imaging. This is because in order to know the internal structure of the object, it is necessary to observe the disturbance of the self-image caused by the radiation passing through the object. Thus, when performing radiation phase contrast imaging, there is radiation energy suitable for imaging. The optimum energy for shooting varies depending on the subject. In order to obtain a clear fluoroscopic image, it may be better to change the energy of the radiation and re-shoot.

  In the first place, in the conventional apparatus, the radiation energy is set to one, and the configuration of the phase grating, the separation distance from the detection element, and the like are set in accordance with that. Therefore, the conventional apparatus is not configured to repeat imaging while changing the radiation energy.

  However, based on the principle of Talbot interference, it is not impossible to repeat imaging with different radiation energies even with conventional devices. However, it is extremely troublesome to perform such shooting in the conventional apparatus. The Talbot distance varies depending on the energy of the radiation. Therefore, the distance from the phase grating 55 to the position where the self-image appears changes depending on the energy of the radiation. In order to repeat imaging with different radiation energies, the distance between the phase grating 55 and the radiation detector must be adjusted each time the radiation energy is changed.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a radiation phase difference imaging apparatus that can easily perform imaging of an object using radiation of a plurality of energies. is there.

The present invention has the following configuration in order to solve the above-described problems.
That is, in the radiation phase contrast imaging apparatus according to the present invention, a radiation source that irradiates high-energy radiation and low-energy radiation, and an absorber that extends in one direction that absorbs radiation are arranged in a direction orthogonal to one direction. In addition, a grating that causes Talbot interference by transmitting radiation, a high-energy radiation detection surface that detects a self-image of the grating related to high-energy radiation, and a self-image of the grating related to low-energy radiation are detected. A radiation source, a grating, and a radiation source such that the projection of the subject moves on the detection surface while maintaining the positional relationship between the radiation source, the grating, and the detection unit. a position changing unit for changing the relative position between the imaging system and the subject constituted by the detection unit, from the results detector detects radiation with high energy radiation detection surface The self-image generator 1 images the second self-image based on the result of detecting the radiation on the low-energy radiation detection surface, and the high-energy radiation imaged by the self-image generator. The first perspective image or the first small-angle scattered image of the subject is generated from the first self-image and the second self-image of the low-energy radiation imaged by the self-image generation unit is generated. And a fluoroscopic image generation unit that generates a fluoroscopic image or a second small-angle scattered image .

[Operation / Effect] According to the present invention, it is possible to provide a radiation phase difference imaging apparatus capable of easily imaging an object using radiation of a plurality of energies. That is, the configuration of the present invention includes a dual energy output type radiation source and a detection unit having a high energy radiation detection surface and a low energy radiation detection surface, and imaging with high energy radiation and imaging with low energy radiation. The two types of shooting can be performed. If shooting is performed so that the subject is scanned while changing the relative position between the imaging system and the subject, two types of shooting can be completed at once.
Further, if the self-image generation unit individually images a self-image for high-energy radiation and a self-image for low-energy radiation, a self-image can be reliably generated for each of different radiation conditions.
Further, if the fluoroscopic image generation unit individually generates a fluoroscopic image for high-energy radiation and a fluoroscopic image for low-energy radiation, it is possible to reliably generate a fluoroscopic image for each of different radiation conditions.

In the above-described radiation phase contrast imaging apparatus, the grating is one grating having a portion through which high-energy radiation is transmitted and a portion through which low-energy radiation is transmitted, and the detection unit has a high-energy radiation detection surface. The distance from the grid to the grid and the distance from the low-energy radiation detection surface to the grid are different from each other, and the distance from the high-energy radiation detection surface to the grid of the detector is set based on the Talbot distance corresponding to the high-energy radiation It is more desirable that the distance from the low energy radiation detection surface to the grating is set based on the Talbot distance corresponding to the low energy radiation .

  [Operation / Effect] The above-described configuration is more specifically shown in the present invention. The Talbot distance, which indicates the distance from the lattice to the position where the self-image appears, varies depending on the energy of the radiation. If the distance from the high-energy radiation detection surface to the grating and the distance from the low-energy radiation detection surface to the grating are set independently, the distance from the detection surface to the grating can be reliably set to the Talbot distance for radiation of different energies. Can be set to

  In the above-mentioned radiation phase contrast imaging apparatus, it is more desirable that the position changing unit is moved in a state where the positional relationship between the high energy radiation detection surface and the low energy radiation detection surface is maintained.

  [Operation / Effect] The above-described configuration is more specifically shown in the present invention. If the detector is moved while maintaining the positional relationship between the high-energy radiation detection surface and the low-energy radiation detection surface, the subject can be scanned with the distance from the detection surface to the grid reliably maintained at the Talbot distance. It can be carried out.

Further, in the above-described radiation phase difference imaging apparatus, the self-image generation unit arranges images that are narrow in the moving direction when changing the relative position between the imaging system and the subject and arranged in the moving direction in chronological order, It is more desirable to image the first self-image and the second self-image.

Further, in the above-described radiation phase difference imaging apparatus, the position changing unit includes the radiation source, the grating, and the radiation source, the grating, and the radiation source, the grating, It is more desirable to change the relative position between the imaging system constituted by the detection unit and the subject.

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  ADVANTAGE OF THE INVENTION According to this invention, the radiation phase difference imaging apparatus which can image | photograph the object easily using the radiation of several energy can be provided. That is, the configuration of the present invention includes a dual energy output type radiation source and a detection unit having a high energy radiation detection surface and a low energy radiation detection surface, and imaging with high energy radiation and imaging with low energy radiation. The two types of shooting can be performed. If shooting is performed so that the subject is scanned while changing the relative position between the imaging system and the subject, two types of shooting can be completed at once.

1 is a functional block diagram illustrating an overall configuration of a device according to Embodiment 1. FIG. FIG. 3 is a schematic diagram illustrating movement of the imaging system according to the first embodiment. 3 is a plan view illustrating the configuration of a phase grating according to Embodiment 1. FIG. 3 is a plan view illustrating a configuration of a detection surface according to Embodiment 1. FIG. 6 is a schematic diagram illustrating two detection surfaces of the FPD according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a self-image generation unit according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a self-image generation unit according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a self-image generation unit according to Embodiment 1. FIG. FIG. 3 is a schematic diagram illustrating a perspective image according to the first embodiment. FIG. 3 is a schematic diagram illustrating a perspective image according to the first embodiment. It is a schematic diagram explaining the apparatus which concerns on a conventional structure.

  Next, modes for carrying out the invention will be described with reference to examples. X-rays in the examples correspond to the radiation of the present invention. In addition, FPD in an Example is the abbreviation for a flat panel detector. The radiation phase contrast imaging apparatus of the present invention can take an image of the subject M with little radiation absorption, and thus is suitable for fluoroscopy of a substrate for industrial use and for fluoroscopy of a breast for medical use.

  A radiation phase contrast imaging apparatus according to the present invention will be described. FIG. 1 shows the overall configuration of a photographing apparatus 1 according to the present invention. As shown in FIG. 1, the imaging apparatus 1 includes a mounting table 2 on which a subject M is mounted, an X-ray source 3 that is provided above the mounting table 2 and that irradiates an X-ray beam that spreads in a pyramid shape, and an X-ray source 3, and an FPD 4 that detects X-rays transmitted through the subject M on the mounting table 2. A phase grating 5 that causes Talbot interference is provided at a position between the FPD 4 and the mounting table 2. The X-ray source 3 corresponds to the radiation source of the present invention, and the FPD 4 corresponds to the detection unit of the present invention. The phase grating 5 corresponds to the grating of the present invention.

  The imaging apparatus 1 is a radiation imaging apparatus that uses Talbot interference. Therefore, the X-ray source 3 is configured to output an X-ray beam that spreads radially in phase. The distance between the phase grating 5 and the FPD 4 is set to the Talbot distance. With this setting, the self-image of the phase grating 5 appears on the detection surface for detecting the X-rays of the FPD 4. There are two detection surfaces in the present invention, and their functions are different. Details of this point will be described later.

  The self-image generation unit 11 generates self-images P0a and P0b in which the self-image of the phase grating 5 is captured based on the output of the FPD 4. That is, the self-image generating unit 11 is configured to handle the detection data detected on the two detection surfaces of the FPD 4 as independent ones and generate two types of self-image images P0a and P0b. The generated self-images P0a and P0b are output to the perspective image generation unit 12. The perspective image generation unit 12 generates perspective images P1a and P1b in which the phase difference of the X-ray generated in the subject M is imaged based on each of the self-image images P0a and P0b of the phase grating 5.

  As shown in FIG. 2, the imaging system moving mechanism 13 is configured to move the X-ray source 3, the FPD 4, and the phase grating 5 with respect to the mounting table 2 while maintaining the mutual positional relationship. The X-ray source 3, the FPD 4, and the phase grating 5 can be moved in a direction parallel to the mounting table 2 by the imaging system moving mechanism 13. The imaging system moving mechanism 13 is configured so that the projection of the subject M moves linearly on the detection surface of the FPD 4 while the positional relationship between the X-ray source 3, the phase grating 5, and the FPD 4 is maintained. And the relative position of the subject M is changed. The imaging systems 3, 4, and 5 include an X-ray source 3 that irradiates X-rays, a phase grating 5 in which absorption lines 5 a extending in one direction that absorb radiation are arranged in a direction orthogonal to one direction, and radiation The detection elements to be detected are configured by an FPD 4 that detects a self-image of the phase grating 5 caused by Talbot interference on a detection surface arranged in rows and columns. The imaging system moving mechanism 13 moves the FPD 4 while maintaining the positional relationship between a high energy X-ray detection surface 4b and a low energy X-ray detection surface 4a described later. The absorption line 5a corresponds to the absorber of the present invention, and the imaging system moving mechanism 13 corresponds to the position changing unit of the present invention.

  In the case of the first embodiment, the relative position of the subject M with respect to the imaging systems 3, 4, and 5 is changed by moving the imaging systems 3, 4, and 5 without moving the subject M. The imaging system movement control unit 14 is provided for the purpose of controlling the imaging system movement mechanism 13.

  The X-ray source control unit 6 is provided for the purpose of controlling the X-ray source 3. During imaging, the X-ray source control unit 6 controls the X-ray source 3 so as to repeatedly output the X-ray beam in a pulse shape. Each time the X-ray source 3 outputs an X-ray beam, the FPD 4 detects X-rays that have passed through the subject M and the phase grating 5 on the mounting table 2 and sends detection data to the self-image generation unit 11. As described above, the apparatus of the present invention is configured to generate a self-image by continuously shooting X-ray imaging.

  The continuous shooting of X-ray imaging is realized by the X-ray source control unit 6 and the imaging system movement control unit 14 cooperating with each other. That is, by cooperation of both, the width of the high energy X-ray detection surface 4a in the short direction of the high energy X-ray detection surface 4a (longitudinal direction in FIG. The operation of moving the imaging systems 3, 4, and 5 by the corresponding movement amount and the operation of irradiating the X-ray beam are repeated. Therefore, if continuous shooting is continued, the position of the subject M on the FPD 4 moves by the width in the short direction of the high energy X-ray detection surface 4a. As described above, the X-ray source control unit 6 according to the first embodiment is configured so that the imaging system moving mechanism 13 moves the projection of the subject M on the detection surface by the width in the short direction of the high energy X-ray detection surface 4a. The radiation source 3 is irradiated with radiation. Note that the width in the short direction of the high energy X-ray detection surface 4a matches the width in the short direction of the low energy X-ray detection surface 4b.

  FIG. 3 illustrates the phase grating 5. The phase grating 5 is shaped so that the projection of the X-ray beam is reflected over the entire detection surface of the FPD 4. Accordingly, the phase grating 5 has a rectangular shape in which the moving direction of the imaging systems 3, 4, 5 is the vertical direction and the direction orthogonal to the moving direction is the horizontal direction, like the detection surface of the FPD 4.

  The phase grating 5 has a plurality of absorption lines 5a extending linearly to absorb X-rays. The absorption lines 5a are arranged at a predetermined pitch in a direction orthogonal to the extending direction. The absorption line 5a extends in the moving direction of the imaging systems 3, 4, and 5.

  The main control unit 21 shown in FIG. 1 is provided for the purpose of comprehensively controlling the units 6, 11, 12, and 14. The main control unit 21 is constituted by a CPU, and realizes each unit by executing various programs. In addition, each of these units may be divided and executed by an arithmetic device in charge of them. Each unit can access the storage unit 27 as necessary. The console 25 is provided for the purpose of inputting operator instructions. The display unit 26 is provided for the purpose of displaying a fluoroscopic image.

<Characteristic configuration of the present invention>
Subsequently, a characteristic configuration of the present invention will be described. The present invention is characterized by the X-ray source 3, the FPD 4, the self-image generation unit 11, and the perspective image generation unit 12.

<Characteristic Configuration of the Present Invention: Dual Energy Output Type X-ray Source>
One characteristic configuration of the present invention is that the X-ray source 3 simultaneously outputs X-rays having different energies. That is, the X-ray source 3 outputs, for example, a low energy X-ray (long wavelength X-ray) having an energy of 8.5 kev and a high energy X-ray (short wavelength X-ray) having an energy of 22 kev, for example. . Since the low-energy X-ray and the high-energy X-ray are emitted in different directions, the X-ray source 3 does not output an X-ray with different energy overlapped. The difference in energy between the X-rays output from the X-ray source 3 is derived from the fact that the wavelengths of the output X-rays are different. The X-ray source 3 of the present invention simultaneously irradiates high energy X-rays and low energy X-rays.

  The phase grating 5 has a portion through which low energy X-rays pass and a portion through which high energy X-rays pass. The two parts do not overlap. Moreover, the pitch of the absorption line of the phase grating 5 can be made the same between the two parts, or can be made different.

<Characteristic configuration of the present invention: FPD having two detection surfaces>
As shown in FIG. 1, the detection surface of the FPD 4 includes a low energy X-ray detection surface 4a for detecting low energy X-rays and a high energy X-ray detection surface 4b for detecting high energy X-rays. . FIG. 4 illustrates the low energy X-ray detection surface 4 a of the FPD 4. On the low energy X-ray detection surface 4a of the FPD 4, detection elements each having a rectangular shape of 20 μm long × 20 μm wide are arranged vertically and horizontally. The vertical direction of the detection element coincides with the moving direction of the imaging systems 3, 4, 5 realized by the imaging system moving mechanism 13. The low energy X-ray detection surface 4a of the FPD 4 has a rectangular shape in which the moving direction of the imaging systems 3, 4 and 5 is the vertical direction and the direction orthogonal to the moving direction is the horizontal direction. The low energy X-ray detection surface 4a has a width of 20 cm in the vertical direction and a width of 2 cm in the horizontal direction. The sizes of these detection elements and detection surfaces can be changed as appropriate.

  The high energy X-ray detection surface 4b has the same configuration as the low energy X-ray detection surface 4a described in FIG. Next, the positional relationship between the two detection surfaces 4a and 4b will be described. The two detection surfaces 4 a and 4 b are arranged in a direction in which the horizontal direction coincides with the moving direction of the imaging systems 3, 4, and 5. As described above, the FPD 4 of the present invention detects the high-energy X-ray detection surface 4b that detects the self-image of the phase grating 5 related to the high-energy X-ray and the self-image of the phase grating 5 related to the low-energy X-ray. And a low energy X-ray detection surface 4a.

  As shown in FIG. 5, the X-ray energy irradiated by the X-ray source 3 is different from that incident on the low energy X-ray detection surface 4a and that incident on the high energy X-ray detection surface 4b. That is, in the X-ray source 3, low energy X-rays indicated by diagonal lines in FIG. 5 are incident on the low energy X-ray detection surface 4a, and high energy X rays indicated by hatching in FIG. 5 are incident on the high energy X-ray detection surface 4b. Operates so that the line is incident. When X-rays are incident on the detection surfaces 4a and 4b, the self-image of the phase grating 5 due to Talbot interference is reflected on the detection surfaces 4a and 4b.

  There are conditions for the self-image of the phase grating 5 to appear on the detection surfaces 4a and 4b. That is, the distance between the detection surfaces 4a and 4b and the X-ray source 3 must be the Talbot distance. This Talbot distance varies depending on the wavelength of the X-ray. That is, the Talbot distance has a property of shortening as the wavelength of X-rays becomes longer. Therefore, according to the configuration of the present invention, as shown in FIG. 1, the low energy X-ray detection surface 4a is positioned closer to the phase grating 5 than the high energy X-ray detection surface 4b. That is, the two detection surfaces 4a and 4b are both separated from the phase grating 5 by the Talbot distance. However, since the target X-ray wavelength is different between the two detection surfaces 4a and 4b, the two detection surfaces 4a and 4b are arranged as shown in FIG.

  Therefore, the distance from the high energy X-ray detection surface 4b to the phase grating 5 of the FPD 4 is different from the distance from the low energy X-ray detection surface 4a to the phase grating 5. That is, the distance between the phase grating 5 and the low energy X-ray detection surface 4a is optimized for low energy X-rays, and the distance between the phase grating 5 and the high energy X-ray detection surface 4b is high energy X-rays. Optimized for lines. Therefore, low energy X-rays generated by the X-ray source 3 pass through the phase grating 5 and project a self-image of the phase grating 5 on the low energy X-ray detection surface 4a. Similarly, high-energy X-rays generated by the X-ray source 3 pass through the phase grating 5 and project a self-image of the phase grating 5 on the high-energy X-ray detection surface 4b.

  Thus, FPD4 of Example 1 is comprised from two detector units, the detector unit which has the low energy X-ray detection surface 4a, and the detector unit which has the high energy X-ray detection surface 4b. The relative positions of these detector units do not change during imaging. The outputs of these detector units are independent of each other.

<Characteristic Configuration of the Present Invention: Self-Image Generation Unit that Generates Two Self-Images>
The output of the FPD 4 related to the low energy X-ray detection surface 4 a and the output of the FPD 4 related to the high energy X-ray detection surface 4 b are output to the self-image generation unit 11. The self-image generating unit 11 generates the self-image image P0a based on the output of the FPD 4 related to the low energy X-ray detection surface 4a, while the self image image based on the output of the FPD 4 related to the high energy X-ray detection surface 4b. P0b is generated. The self-images P0a and P0b of each other include a self-image of the same phase grating 5.

  Here, consider a case where the subject M is placed on the mounting table 2 as shown in FIG. In this case, the low-energy X-rays indicated by the oblique lines in FIG. 5 and the high-energy X-rays indicated by the hatching in FIG. 5 enter the detection surfaces 4a and 4b through different portions of the subject M, respectively. Therefore, in the state as shown in FIG. 5, imaging for low-energy X-rays can be performed only for one part Ma of the subject M through which low-energy X-rays pass, and imaging for high-energy X-rays is performed for high-energy X-rays. This means that it can be performed only for one portion Mb of the subject M through which X-rays pass.

  In view of this, the configuration of the present invention is devised so that imaging for low-energy X-rays and imaging for high-energy X-rays can be performed for the entire subject. That is, the photographing of the self-image in the present invention is executed by continuously emitting X-rays while the imaging systems 3, 4, and 5 are moved with respect to the subject M. FIG. 6 shows that the imaging systems 3, 4, and 5 are moving during shooting. As the imaging systems 3, 4 and 5 are moved, the low energy X-ray detection surface 4a and the high energy X-ray detection surface 4b approach the subject M in this order and move away from the subject M in this order. FIG. 7 shows a state where the low energy X-ray detection surface 4a and the high energy X-ray detection surface 4b pass through one end of the subject M. On the left side of FIG. 7, one end of the subject M is imaged by the low energy X-ray detection surface 4a. On the right side of FIG. 7, one end portion of the subject M is imaged by the high energy X-ray detection surface 4b. In this way, one end of the subject M is photographed by each of the detection surfaces 4a and 4b.

  The self-image generation unit 11 generates two self-images P0a and P0b based on the detection result of the X-rays shot continuously while the imaging systems 3, 4, and 5 are moved. The self-image generating unit 11 receives the detection result of the low energy X-rays irradiated every time the X-rays are irradiated from the FPD 4, and forms a strip-like image narrow in the moving direction of the imaging systems 3, 4, 5. Is generated. Then, as shown in FIG. 8, the self-image generation unit 11 displays the entire area of the subject M by arranging and connecting a plurality of generated strip-like images in the moving direction of the imaging systems 3, 4, 5 in the time series of the shooting. The embedded self-image image P0a is generated. However, what is actually reflected in the self-image P0a is not the subject M itself but the self-image of the phase grating 5 disturbed by the subject M.

  Similarly, the self-image generation unit 11 receives the detection result of the high energy X-rays irradiated every time the X-rays are irradiated from the FPD 4, and the strips narrow in the moving direction of the imaging systems 3, 4, 5. Image is generated. Then, the self-image generation unit 11 arranges the plurality of generated strip-shaped images in the moving direction of the imaging systems 3, 4, 5 and joins them together in the time-series order of shooting, and the self-image image P 0 b in which the entire area of the subject M is reflected. Is generated. The state in which the self-image image P0b is generated at this time is the same as that in FIG. However, what is actually reflected in the self-image P0b is not the subject M itself but the self-image of the phase grating 5 disturbed by the subject M.

  As described above, the self-image generation unit 11 generates the self-image image P0a for the entire subject based on the detection result of the low energy X-ray detection surface 4a, and the entire subject region based on the detection result of the high energy X-ray detection surface 4b. A self-image image P0b for is generated. The self-image P0a represents the disturbance of the self-image of the phase grating observed when low energy X-rays are applied to the subject M, and the self-image image P0b applies high-energy X-rays to the subject M. This shows the disturbance of the self-image of the phase grating observed at the time. As described above, the self-image generation unit 11 images the self-image from the result of the FPD 4 detecting the X-rays with the high-energy X-ray detection surface 4b, and the FPD 4 detects the X-rays with the low-energy X-ray detection surface 4a. The self image is imaged from the result.

<Characteristic Configuration of the Present Invention: Perspective Image Generating Unit that Generates Two Perspective Images>
The self-image generation unit 11 sends the self-image images P0a and P0b to the fluoroscopic image generation unit 12. The perspective image generation unit 12 generates a perspective image P1a in which a perspective image of the subject M is reflected based on the self-image image P0a, and a perspective image P1b in which a perspective image of the subject M is reflected based on the self-image image P0b. Is generated. As described above, the perspective image generation unit 12 generates a perspective image of the subject M from the self-image related to the high-energy X-rays imaged by the self-image generation unit 11 and the low-energy image captured by the self-image generation unit 11. A perspective image of the subject M is generated from the self-image related to X-rays. Each of the generated perspective images P1a and P1b is displayed side by side on the display unit 26.

  9 and 10 schematically show perspective images P1a and P1b obtained when a spherical subject M is photographed. Such a subject M has a property that the peripheral portion easily passes X-rays and the center portion easily absorbs X-rays.

  FIG. 9 shows how the fluoroscopic image P1a is generated. The fluoroscopic image P1a is a result of imaging the subject M with low energy X-rays. The perspective image P1a clearly shows the inside of the subject M in the peripheral portion of the subject M. Low energy X-rays are suitable for imaging a portion of a subject that easily passes through X-rays. However, it cannot be said that the central part of the subject M shown in the fluoroscopic image P1a is clear. This is because low energy X-rays may not be transmitted through the center of the subject M. The apparatus of the present invention visualizes how much the phase of the X-ray that has passed through the subject M has changed. Therefore, clear imaging of the inside of the subject cannot be performed unless X-rays sufficiently pass through the subject M.

  FIG. 10 shows how the perspective image P1b is generated. The fluoroscopic image P1b is a result of imaging the subject M with high-energy X-rays. In the perspective image P1b, the inside of the subject M is clearly reflected in the center of the subject M. High energy X-rays are suitable for imaging a portion of a subject that is difficult to pass through X-rays. However, it cannot be said that the peripheral portion of the subject M shown in the fluoroscopic image P1b is clear. This is because high-energy X-rays have passed through the periphery of the subject M. The apparatus of the present invention visualizes how much the phase of the X-ray that has passed through the subject M has changed. Therefore, if the phase of the X-ray passing through the subject M has not changed sufficiently, clear imaging inside the subject cannot be performed.

  According to the apparatus of the present invention, it is possible to accurately know the state inside the subject M by comparing two fluoroscopic images P1a and P1b having different photographing conditions. That is, the fluoroscopic image P1a may be referred to if the internal structure of the peripheral part of the subject M is known, or the fluoroscopic image P1b may be referred to if the internal structure of the central part of the subject M is known.

  As described above, according to the present invention, it is possible to provide an X-ray phase difference imaging apparatus capable of easily imaging an object using X-rays having a plurality of energies. That is, the configuration of the present invention includes the dual energy output type X-ray source 3 and the FPD 4 provided with the high energy X-ray detection surface 4b and the low energy X-ray detection surface 4a. Two types of imaging, that is, imaging with energy X-rays, can be performed. If shooting is performed so that the subject M is scanned while changing the relative position between the imaging system and the subject M, two types of shooting can be completed at once.

  Since the present invention can also be applied to a fluoroscopic image using small angle scattering, first, small angle scattering will be briefly described. When X-rays are applied to an object, a phenomenon occurs in which the traveling direction of some X-rays in the object is changed. Such a phenomenon is called X-ray scattering. Of the X-ray scattering, the scattering in which the traveling direction hardly changes is called small-angle scattering. Such X-rays related to small-angle scattering are detected by the FPD 4 and reflected in the self-image images P0a and P0b generated by the self-image generation unit 11. The perspective image generation unit 12 can extract a component related to small angle scattering from each of the self-image images P0a and P0b to generate a small angle scattered image. There are two small-angle scattered images generated at this time, an image generated based on the self-image image P0a and an image generated based on the self-image image P0b.

  When considering the phenomenon of small-angle scattering, it is easy to understand if the structures that make up the interior of the subject are considered as particles. It is thought that small-angle scattering occurs when X-rays hit this particle. Small-angle scattered X-rays generated by applying low-energy X-rays to a subject are derived from particles having a relatively large diameter among particles constituting the subject. On the other hand, small-angle scattered X-rays generated by applying high-energy X-rays to the subject are derived from particles having a relatively small diameter among the particles constituting the subject. As described above, when the wavelength of the X-ray used for capturing the small angle scattered image is changed, the image reflected in the small angle scattered image is changed. A small-angle scattered image taken by shining low-energy X-rays on the subject is a reflection of large-diameter particles that make up the interior of the subject, and small-angle scatters taken by shining high-energy X-rays on the subject. The image is a photograph of particles having a small diameter constituting the inside of the subject.

  According to the configuration of the present invention, imaging using low energy X-rays and imaging using high energy X-rays can be performed at the same time in one scan, so two small angle scatterings with different imaging targets can be performed. Images can be acquired simultaneously. That is, from the self-image image P0a related to low-energy X-rays, a small-angle scattered image in which large-diameter particles constituting the inside of the subject are captured, and from the self-image image P0a related to high-energy X-rays, A small-angle scattered image in which particles having a small diameter constituting the inside of the subject are captured can be generated.

  The present invention is not limited to the above-described configuration, and can be modified as follows.

  (1) According to the above-described embodiment, the imaging system moving mechanism 13 is configured to move the X-ray source 3 together with the FPD 4 and the phase grating 5, but the present invention is not limited to this. By configuring the imaging system moving mechanism 13 so that the FPD 4 and the phase grating 5 are moved along an arc locus so as not to change the positional relationship between the X-ray source 3, the FPD 4 and the phase grating 5, The relative position may be changed. Alternatively, the relative position between the subject M and the imaging system may be changed by moving the mounting table 2 without moving the imaging systems 3, 4, and 5.

  (2) According to the above-described configuration, the subject M is placed between the X-ray source 3 and the phase grating 5, but the present invention is not limited to this configuration. The mounting table 2 and the subject M may be mounted between the phase grating 5 and the FPD 4.

  (3) According to the above-described embodiment, the X-ray source 3 simultaneously irradiates low energy X-rays and high energy X-rays, but the present invention is not limited to this configuration. The X-ray source 3 may be configured to alternately irradiate low energy X-rays and high energy X-rays.

  (4) According to the above embodiment, the low energy X-ray detection surface 4a and the high energy X-ray detection surface 4b are arranged with the same pitch, but the present invention is not limited to this configuration. You may comprise so that the pitch of a detection element may be changed between the detection surfaces 4a and 4b.

  (5) According to the above-described embodiment, the low energy X-ray and the high energy X-ray pass through the same phase grating 5, but the present invention is not limited to this configuration. The pitch of the absorption line comprising the low energy X-ray phase grating 5 through which the low energy X-ray passes and the high energy X-ray phase grating 5 through which the high energy X-ray passes, and constituting the low energy X-ray phase grating 5 And the pitch of the absorption lines constituting the high energy X-ray phase grating 5 may be mutually changed.

  (6) In the above-described configuration in which the phase grating 5 having different absorption line pitches is provided, the Talbot distance associated with the low energy X-ray and the Talbot distance associated with the high energy X-ray can be set to coincide with each other. In this case, the distance from the low energy X-ray detection surface 4a to the phase grating 5 and the distance from the high energy radiation detection surface 4b to the phase grating 5 are the same.

  (7) According to the above-described embodiment, the FPD 4 is configured to directly observe the self image, but the present invention is not limited to this configuration. An arrangement may be adopted in which an absorption grating is disposed so as to cover the detection surfaces 4a and 4b, and moire generated between the self-image and the absorption grating is observed on the detection surfaces 4a and 4b.

(8) Although the above-mentioned X-ray source 3 is a dual energy output type, the present invention is not limited to this configuration. Instead of this, the X-ray source 3 of the present invention can be configured to output broadband X-rays. Since such an X-ray source 3 outputs X-rays of various wavelengths, monochromatic X-rays are not incident on the low energy radiation detection surface 4a and the high energy radiation detection surface 4b. However, the wavelength of the X-ray that can participate in the generation of the self-image is determined according to the distance from the phase grating 5 to the detection surfaces 4a and 4b. Therefore, according to the present invention, it is low-energy X-rays having a specific wavelength that captures a self-image on the low-energy radiation detection surface 4a, and it is certain that a self-image is captured on the high-energy radiation detection surface 4b. Energy X-rays having a wavelength of
Thus, the fluoroscopic images P1a and P1b described with reference to FIGS. 9 and 10 can be acquired without using the dual energy output type X-ray source 3. The wavelength of the X-ray self-image that appears on the detection surfaces 4a and 4b is determined not only by the distance between the phase grating 5 and the detection surfaces 4a and 4b, but also by the pitch of the absorption lines 5a arranged on the phase grating 5. It depends on. Therefore, the wavelength of the X-ray that generates the self-image can be selected by appropriately changing the distance between the phase grating 5 and the detection surfaces 4a and 4b and the pitch of the absorption lines 5a of the phase grating 5.

3 X-ray source (radiation source)
4 FPD (detector)
4a Low energy radiation detection surface 4b High energy radiation detection surface 5 Phase grating (grating)
11 Self-image generator (self-image generator)
12 perspective image generation unit (perspective image generation unit)
13 Imaging system moving mechanism (position changing unit)

Claims (5)

A radiation source that emits high and low energy radiation;
A grating that absorbs radiation and extends in one direction is arranged in a direction orthogonal to one direction, and causes Talbot interference by transmitting radiation;
A detection unit comprising a high-energy radiation detection surface for detecting a self-image of the grating related to high-energy radiation and a low-energy radiation detection surface for detecting a self-image of the grating related to low-energy radiation;
An imaging system including the radiation source, the grating, and the detection unit so that the projection of the subject moves on the detection surface while maintaining the positional relationship among the radiation source, the grating, and the detection unit; A position changing unit for changing a relative position with respect to the subject ;
The detection unit images a first self-image from the result of detecting radiation on the high-energy radiation detection surface, and the detection unit generates a second self-image from the result of detection of radiation on the low-energy radiation detection surface. A self-image generation unit for imaging;
Low energy imaged by the self-image generation unit while generating a first fluoroscopic image or a first small-angle scattered image of the subject from the first self-image related to high-energy radiation imaged by the self-image generation unit A radiation phase difference imaging apparatus, comprising: a perspective image generation unit configured to generate a second perspective image or a second small-angle scattered image of a subject from the second self-image related to the radiation of The radiation phase difference imaging apparatus according to claim 1,
The grating is one grating having a portion through which high energy radiation is transmitted and a portion through which low energy radiation is transmitted;
The distance from the high energy radiation detection surface of the detection unit to the grating is different from the distance from the low energy radiation detection surface to the grating, and the detection unit has the distance from the high energy radiation detection surface to the grating. Is set based on the Talbot distance corresponding to the high energy radiation, and the distance from the low energy radiation detection surface to the grating is set based on the Talbot distance corresponding to the low energy radiation. A radiation phase contrast imaging apparatus. In the radiation phase contrast imaging apparatus according to claim 1 or 2,
A radiation phase difference imaging apparatus, wherein the position changing unit moves the detection unit while maintaining a positional relationship between the high energy radiation detection surface and the low energy radiation detection surface. In the radiation phase contrast imaging apparatus according to any one of claims 1 to 3,
  The self-image generating unit arranges the narrow self-aligned images in the moving direction when changing the relative position between the imaging system and the subject in time-sequential order and joins the first self-image and A radiation phase difference imaging apparatus for imaging the second self-image. In the radiation phase contrast imaging apparatus according to any one of claims 1 to 4,
The position changing unit includes the radiation source, the grating, and the detection unit so that the projection of the subject translates on the detection surface while maintaining the positional relationship of the radiation source, the grating, and the detection unit. A radiation phase difference imaging apparatus, wherein a relative position between an imaging system constituted by the object and the subject is changed.

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