JPWO2008102632A1 - X-ray bandpass filter, X-ray irradiation system, and X-ray imaging system - Google Patents

Abstract

The present invention provides a band-pass filter that can extract X-rays having a desired wavelength from X-rays having a wavelength of 1 mm or less, and is compatible with various X-ray imaging. The X-ray bandpass filter includes an X-ray refracting lens that refracts X-rays, and an X-ray shield having a slit or hole provided at a position where X-rays of a desired wavelength refracted by the X-ray refracting lens are condensed. And a member.

Description

  The present invention relates to an X-ray bandpass filter, an X-ray irradiation system, and an X-ray imaging system.

Conventionally, it has been considered to extract X-rays having a desired wavelength using a band-pass filter (see, for example, Patent Document 1) that transmits only light in a predetermined wavelength range. For example, when a band-pass filter provided with a multilayer reflector is used, it is possible to extract X-rays having a desired wavelength from soft X-rays having a wavelength exceeding 1 wavelength. However, a multilayer film reflecting mirror that reflects X-rays having a wavelength of 1 mm or less has not been manufactured. Therefore, for X-rays with a wavelength of 1 mm or less, a bandpass filter formed based on a material having a K edge on the wavelength side lower than the desired wavelength, not the bandpass filter using the multilayer reflector described above. Is used.
JP 2006-23602 A

  However, since practical materials having a K edge are limited, the center wavelength of the bandpass is also limited. If this center wavelength does not match the desired wavelength, it does not make sense as a filter. Furthermore, the present situation is that there is no steep filter performance unlike the band-pass filter in multilayer reflection today.

  An object of the present invention is to provide a band-pass filter that can extract X-rays having a desired wavelength from X-rays having a wavelength of 1 mm or less and can cope with various X-ray imaging.

The X-ray bandpass filter according to the invention described in claim 1 is:
An X-ray refractive lens that refracts X-rays;
And an X-ray shielding member having a slit or a hole provided at a position where X-rays having a desired wavelength refracted by the X-ray refraction lens are condensed.

The invention described in claim 2 is the X-ray bandpass filter according to claim 1,
The X-ray shielding member is arranged such that a slit or a hole of the X-ray shielding member is positioned at a position where X-rays of the wavelength refracted by the X-ray refractive lens are condensed for each of a plurality of different desired wavelengths. It is characterized by being movable.

The invention according to claim 3 is the X-ray bandpass filter according to claim 1 or 2, wherein
The lens diameter D of the X-ray refracting lens and the width d of the slit or hole in a direction parallel to the direction having the refractive power of the X-ray refracting lens orthogonal to the optical axis of the X-ray refracting lens are expressed by the following formula (1). It is characterized by satisfying.

d ≦ D / 2 (1)
The invention according to claim 4 is the X-ray bandpass filter according to any one of claims 1 to 3,
X-rays incident on the X-ray refractive lens are substantially parallel X-rays;
The slit or hole of the X-ray shielding member is located in the vicinity of a focal position of an X-ray having a desired wavelength refracted by the X-ray refracting means.

The invention according to claim 5 is the X-ray bandpass filter according to any one of claims 1 to 3,
X-rays incident on the X-ray refractive lens are X-rays irradiated from an X-ray source having a focal diameter α,
The distance R1 between the focal position of the X-ray source and the lens center of the X-ray refractive lens, the distance R2 between the lens center of the X-ray refractive lens and the slit or hole of the X-ray shielding member, and the slit or hole The width d satisfies the following formula (2).

d ≧ R2 / R1 × α (2)
An X-ray irradiation system according to the invention of claim 6
X-ray bandpass filter according to any one of claims 1 to 5,
The X-ray bandpass filter has an X-ray source that emits X-rays.

The invention according to claim 7 is the X-ray irradiation system according to claim 6,
The X-ray source has an X-ray generator for generating characteristic X-rays;
The X-ray bandpass filter sets a peak wavelength of the characteristic X-ray to a desired wavelength.

An X-ray imaging system according to the invention of claim 8
The X-ray irradiation system according to claim 6 or 7,
And an X-ray image detector for detecting X-rays irradiated from the X-ray source and passing through the slits or holes of the X-ray shielding member.

The invention described in claim 9 is the X-ray imaging system according to claim 8,
A subject table for placing the subject;
A first diffraction grating that produces a Talbot effect by diffracting X-rays irradiated from the X-ray source through the object table;
A second diffraction grating that diffracts the X-rays diffracted by the first diffraction grating,
The X-ray image detector detects X-rays diffracted by the second diffraction grating.

The invention according to claim 10 is the X-ray imaging system according to claim 9,
The half width of the wavelength distribution of the X-rays irradiated by the X-ray source is ¼ or less of the peak wavelength of the X-rays.

The invention according to claim 11 is the X-ray imaging system according to claim 8,
X-ray optical means for narrowing X-rays generated from the X-ray source so as to have a dot-shaped or striped X-ray irradiation dose distribution discretely arranged on the X-ray image detection surface of the X-ray image detector When,
It is characterized by comprising deformation equivalent amount detecting means for detecting a deformation equivalent amount corresponding to the discretely arranged dot-like or striped deformation based on the detection result of the X-ray image detector.

The invention described in claim 12 is the X-ray imaging system according to claim 11,
The X-ray optical means is an X-ray refractive lens group in which a plurality of second X-ray refractive lenses are arranged in the X-ray optical axis direction.

The invention according to claim 13 is the X-ray imaging system according to claim 11 or 12,
The X-ray optical means is periodically arranged so that each of the plurality of second X-ray refractive lenses forms dots or stripes of the X-ray dose distribution on a plane perpendicular to the X-ray optical axis direction. X-ray refractive lens array.

The invention described in claim 14 is the X-ray imaging system according to claim 13,
The focal diameter of the X-ray source is a, the arrangement period of the second X-ray refractive lens in the direction orthogonal to the X-ray optical axis direction is p, the center of the X-ray source and the center of the second X-ray refractive lens And the distance between the lens center of the second X-ray refractive lens and the X-ray image detection surface of the X-ray detector is R4, the following equation (3) is satisfied. .

a × R4 <p × (R3 + R4) (3)
The invention described in claim 15 is the X-ray imaging system according to any one of claims 11 to 14,
The X-ray optical means is a discrete dot so that X-rays emitted from the X-ray source in the absence of a subject may straddle at least two adjacent pixels among the plurality of pixels of the X-ray detector. It is characterized by narrowing to a X-ray dose distribution in the form of stripes or stripes.

The invention described in claim 16 is the X-ray imaging system according to claim 16,
The X-ray detector includes differential phase image calculation means for calculating a differential phase image based on a value corresponding to a ratio between an output difference between the two adjacent pixels and an output sum.

The invention described in claim 17 is the X-ray imaging system according to claim 16,
The detection result of the X-ray detector based on X-rays emitted from the X-ray source without the subject and the X-rays based on X-rays transmitted from the X-ray source through the subject with the subject present A differential phase image calculating means for calculating the differential phase image based on a result of comparison with the detection result of the line detector is provided.

The invention described in claim 18 is the X-ray imaging system according to any one of claims 15 to 17,
Absorption image calculation means for calculating an absorption image based on a value corresponding to the output sum between the two adjacent pixels in the X-ray detector is provided.

The invention described in claim 19 is the X-ray imaging system according to any one of claims 15 to 17,
An absorption image including a phase edge effect from a value corresponding to the output sum between the two adjacent pixels in the X-ray detector and a value corresponding to a ratio between the output difference between the two adjacent pixels and the output sum. It is characterized by comprising an edge absorption image calculation means for calculating.

The invention according to claim 20 is the X-ray imaging system according to claim 16 or 17,
A phase difference image calculating unit that integrates the differential phase image calculated by the differential phase image calculating unit to calculate a phase difference image is provided.

  According to the invention described in claim 1, X-rays having a desired wavelength pass through slits or holes provided at positions where the X-rays having that wavelength are condensed, but X-rays having a shorter wavelength than the desired wavelength. The position where light is collected is farther from the X-ray refractive lens than the position of the slit or hole, and X-rays having a wavelength longer than the desired wavelength are closer to the X-ray refractive lens than the position of the slit or hole. Position. In any case, since the ratio of shielding by the X-ray shielding member with respect to the ratio of passing through the slits or holes increases as compared with X-rays having a desired wavelength, it can function as an X-ray bandpass filter.

  In addition, the bandpass center wavelength is not limited like a bandpass filter using a material having a K edge on the lower wavelength side than the desired wavelength, and an X-ray refraction lens, an X-ray shielding member, and their arrangement Can be made to function as an X-ray bandpass filter having the desired wavelength as the center wavelength of the bandpass. Thereby, X-rays having a desired wavelength can be extracted even with X-rays having a wavelength of 1 mm or less.

  According to the second aspect of the present invention, with one X-ray bandpass filter, for each of a plurality of different desired wavelengths, the X corresponds to the position where the long X-ray is condensed. By positioning the slit or hole of the line shielding member, it can function as a bandpass filter having the wavelength as the center wavelength.

  According to the third aspect of the present invention, the shielding characteristic on the longer wavelength side than the desired wavelength can be sharpened, and a good bandpass filter characteristic can be obtained. For example, the X-ray refracting lens has a function of condensing only in one direction intersecting the X-ray traveling direction, and the slit is formed so that the X-ray shielding member transmits X-rays having a desired wavelength collected in the one direction. If there is, the position of the slit depends on the optical performance of the X-ray refracting lens, but in principle, X-rays having a wavelength longer than √2 times the desired wavelength spread beyond the lens diameter of the X-ray refracting lens. Since the slit size is less than half of the lens diameter, it is shielded by more than half. Further, the X-ray refracting lens has a function of condensing in both biaxial directions perpendicular to the X-ray traveling direction and perpendicular to each other, and the X-ray shielding member collects X-rays having a desired wavelength collected in the biaxial direction. In the case where there is a hole so as to transmit, the X-ray having a wavelength of √2 times or more of the desired wavelength is in principle X-ray refracting lens, although it depends on the optical performance of the X-ray refracting lens at the slit position. Since the slit size is less than half of the lens diameter, 3/4 or more is shielded.

  According to the invention described in claim 4, since the incident X-ray is substantially parallel X-ray, the length of the X-ray refraction lens in the X-ray traveling direction is longer than that of the diffuse X-ray from the X-ray source. Can be made to function as an X-ray bandpass filter with the desired wavelength as the center wavelength of the bandpass.

  According to the invention described in claim 5, for example, even if an X-ray source having a focal diameter α as used in general X-ray imaging is used, it depends on the optical performance of the X-ray refractive lens. However, in principle, X-rays having a desired wavelength that have entered the lens aperture D of the X-ray refractive lens are not shielded by the X-ray shielding member, but are transmitted through the slits or holes of the X-ray shielding member. It can function as an X-ray bandpass filter with the wavelength as the center wavelength of the bandpass.

  According to the invention described in claim 6, the X-ray bandpass filter is incident on the lens aperture D of the X-ray refractive lens in principle, depending on the optical performance of the X-ray refractive lens. Since the X-ray of the desired wavelength is not shielded by the X-ray shielding member, it functions as an X-ray bandpass filter having the desired wavelength as the center wavelength of the bandpass while passing through the slit or hole of the X-ray shielding member. A monochromatic X-ray can be irradiated using an X-ray source having a focal diameter α as generally used.

  According to the invention described in claim 7, the X-ray bandpass filter depends on the optical performance of the X-ray refractive lens, but in principle, the peak of characteristic X-rays irradiated from the X-ray source. Since it functions as an X-ray bandpass filter having the wavelength as the center wavelength of the bandpass, X-rays with higher monochromaticity can be irradiated.

  According to the invention described in claim 8, for example, X-ray imaging is performed by irradiating monochromatic X-rays using an X-ray source having a focal point diameter α as generally used. Therefore, the influence of beam hardening is reduced in X-ray imaging that is relatively inexpensive and has good monochromaticity.

  In addition, even if the detection amount is used quantitatively, the low quantitative amount of the detection amount due to the instability of the X-ray source and the effect of different beam hardening for each subject cannot be suppressed, and the detection amount From this ratio, quantitative data can be obtained.

According to the invention described in claim 9, an image usable for medical diagnosis / biological diagnosis can be obtained by the Talbot interferometer method. According to the invention described in claim 10, X having good monochromaticity can be obtained. The image becomes more useful for medical diagnosis and biological diagnosis by the Talbot interferometer method.

  According to the invention described in claim 11, since the deformation equivalent amount can be detected by one X-ray optical means, it is easy even when compared with a Talbot interferometer method that requires at least two diffraction gratings. A phase image can be detected with a simple configuration. Further, since refraction is used for detection instead of interference, the X-ray source does not require coherence. This makes it possible to capture high-contrast boundaries between different tissues with large density differences and between gas and tissues, even with tissues that have less X-ray absorption than the Talbot interferometer method. It becomes.

  According to the invention of claim 12, since the X-ray optical means is an X-ray refractive lens group in which a plurality of X-ray refractive lenses are arranged in the X-ray optical axis direction, The shape does not have to be sharp, easy to create, and can ensure durability.

  According to the invention of claim 13, the X-ray optical means periodically causes the plurality of X-ray refracting lenses to form dots or stripes on a plane perpendicular to the X-ray optical axis direction. Since the X-ray refracting lens array is provided side by side, each X-ray refracting lens may be about several times the pixel size of the captured image. For this reason, it is easy to create and the X-rays that have passed through the subject can be narrowed down into dots or stripes with a simpler configuration.

  Further, even if there is a problem with the X-ray refractive lens, it is possible to identify the dots or stripes formed by the X-ray refractive lens from the detection result of the X-ray detector. The refractive lens can be easily specified.

  According to the invention described in claim 14, since the subject can be arranged so as to satisfy the relationship of Expression (3), by arranging the subject so as to satisfy the relationship of Expression (3), X A highly discriminating image can be obtained as a phase image based on the X-ray refractive index difference in the subject on the line image detection surface.

  According to the invention as set forth in claim 15, the X-rays transmitted through the subject are formed into discrete dots in such a manner as to straddle two adjacent pixels among a number of pixels of the X-ray detector by the X-ray optical means. Alternatively, the phase image can be detected with a simple configuration as compared with a Talbot interferometer method that requires at least two diffraction gratings. Further, since refraction is used for detection instead of interference, the X-ray source does not require coherence. This makes it possible to capture high-contrast boundaries between different tissues with large density differences and between gas and tissues, even with tissues that have less X-ray absorption than the Talbot interferometer method. It becomes.

  According to the sixteenth aspect of the present invention, the differential phase image can be calculated from the discrete dot-like or stripe-like displacement due to the X-rays passing through the subject.

  According to the invention of claim 17, the detection result of the X-ray detector based on the X-rays irradiated from the X-ray source in the absence of the subject and the transmission of the subject from the X-ray source in the presence of the subject Since the calculation is based on the comparison result with the detection result of the X-ray detector based on the X-ray, the differential phase image with high accuracy can be calculated.

  According to the eighteenth aspect of the present invention, the absorption image calculation means can calculate the absorption image based on a value corresponding to the output sum between two adjacent pixels.

  According to the invention of claim 19, the absorption image calculation means corresponds to the ratio between the value corresponding to the output sum between two adjacent pixels and the output difference between the two adjacent pixels and the output sum. An absorption image including a phase edge effect can be calculated from the value.

  According to the invention of claim 20, since the phase image calculating means integrates the differential phase image to calculate the phase difference image, it is possible to calculate the phase difference image together with the differential phase image by one shooting. it can.

It is sectional drawing of embodiment of an X-ray band pass filter. It is a block diagram which shows the control structure of the X-ray imaging system in 1st embodiment. It is a side view which shows the principal part structural example of the X-ray imaging apparatus which comprises the X-ray imaging system in 1st embodiment. It is a perspective sectional view of the diffraction grating holding structure in the first embodiment, and the first diffraction grating and the second diffraction grating held by the structure. It is a principal part perspective view explaining the X-ray transmission in the X-ray imaging apparatus in 1st embodiment. It is II sectional drawing in FIG. 5 of the 1st diffraction grating of 1st embodiment. It is II-II sectional drawing in FIG. 5 of the 2nd diffraction grating of 1st embodiment. It is explanatory drawing explaining the positional relationship of the X-ray tube of a X-ray imaging apparatus in 1st embodiment, a to-be-photographed object, a 1st diffraction grating, a 2nd diffraction grating, and an X-ray detector. It is a data flow diagram showing the flow of the X-ray imaging method performed with the X-ray imaging system in 1st embodiment. It is a side view which shows the modification of the X-ray imaging apparatus in 1st embodiment. It is explanatory drawing which shows the structural example of the X-ray imaging system in 2nd embodiment. It is explanatory drawing which shows schematic structure of the X-ray refractive lens array with which the X-ray imaging system in 2nd embodiment is equipped. It is sectional drawing of the X-ray refractive lens with which the X-ray refractive lens array in 2nd embodiment is equipped. It is explanatory drawing showing the state which the edge part vicinity of the other stripe approached when one stripe straddled two adjacent pixels of the X-ray detector with which the X-ray imaging system in 2nd Embodiment was equipped. It is a block diagram which shows the control structure of the imaging device main-body part with which the X-ray imaging system in 2nd embodiment is equipped. It is a figure showing the irradiation condition of the X-ray at the time of imaging | photography with the X-ray imaging system in 2nd embodiment. It is explanatory drawing showing the displacement based on the presence or absence of the to-be-photographed object which appears on the X-ray detector in 2nd embodiment. It is a data flow diagram showing the flow of a calculation process of a differential phase image, a phase difference image, an absorption image, and an absorption image having a phase edge effect, which is executed by the control device according to the second embodiment. It is explanatory drawing which shows the modification of the X-ray refractive lens in embodiment of an X-ray band pass filter. It is explanatory drawing which shows the modification of the X-ray refractive lens in embodiment of an X-ray band pass filter. It is explanatory drawing which shows the modification of the X-ray refractive lens array in 2nd embodiment. It is explanatory drawing which shows the modification of the X-ray refracting lens in 2nd embodiment. It is explanatory drawing showing the X-ray refractive lens array in 3rd embodiment. It is explanatory drawing showing the displacement of the dot revealed by the X-ray refractive lens array in 3rd embodiment. It is explanatory drawing which shows the X-ray imaging system in 4th embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray imaging apparatus 3 Console 11 Support base 12 X-ray irradiation apparatus 13 Subject stand 14 X-ray detector 15 1st diffraction grating 16 2nd diffraction grating 31 Control apparatus 33 Display apparatus 40 X-ray band pass filter 41 X-ray refraction Lens 42 X-ray shielding member 46 Slit 100 X-ray imaging system 122 X-ray tube H Subject

  Hereinafter, an X-ray bandpass filter according to the present invention and an X-ray imaging system using the same will be described with reference to the drawings.

  The best mode column for carrying out the invention indicates a mode that the inventor recognizes as the best for carrying out the invention, and is used in the scope of the invention and in the claims. There are also expressions that seem to be asserted or defined at first glance, but these are only expressions that specify the form that the inventor recognizes as the best, and are used in the scope of the invention and in the claims. It is not intended to identify or limit the terminology used.

[Embodiment of X-ray bandpass filter]
The X-ray bandpass filter 40 is provided at an X-ray refraction lens 41 that refracts X-rays emitted from the X-ray tube 122 and a position where X-rays having a desired wavelength refracted by the X-ray refraction lens 41 are condensed. And an X-ray shielding member 42 having a slit 46.

  The X-ray refracting lens 41 is disposed along the optical axis direction of X-rays on the X-ray image detection surface side from the X-ray tube 122. As a result, as will be described later, the X-rays incident on the X-ray refractive lens 41 are refracted and collected.

  FIG. 1 is a cross-sectional view of the X-ray refractive lens 41. A plurality of lenses 43 are arranged in the X-ray refraction lens 41 along the optical axis of X-rays emitted from the X-ray tube 122. Each lens 43 is formed such that a concave curved surface 44 having a parabolic cross section recessed toward the X-ray tube 122 and a concave curved surface 45 having a parabolic cross section recessed toward the X-ray detector 14 face each other. In addition, since the refractive index is slightly lower in the presence of the substance than in the vacuum or the atmosphere, the X-rays are refracted in a direction slightly approaching the optical axis by these concave curved surfaces 44 and 45. . Since a plurality of lenses are arranged along the optical axis of the X-ray, the light is condensed toward the optical axis, and the X-ray having a desired wavelength is condensed toward the slit 46.

  The case where the X-ray refractive lens as described above is used, for example, a composite X-ray refractive lens in which 75 X-ray refractive lenses having a diameter of 157 μm and a minimum parabolic radius of 19.625 μm are arranged in the X-ray traveling direction. For example, 20 KeV parallel X-rays, that is, 0.6 X wavelength parallel X-rays can be incident on the compound X-ray refracting lens and condensed at a position of about 20 cm from the lens tip.

  If the parallel X-ray is 40 KeV (wavelength 0.3 mm), the difference in refractive index with respect to air will be ¼ times that of 20 KeV (wavelength 0.6 mm) parallel X-ray. Therefore, the condensing position is about 80 cm from the lens tip.

  When the parallel X-ray is 10 KeV (wavelength 1.2 mm), the difference in refractive index with respect to air is four times that of 20 KeV (wavelength 0.6 mm) parallel X-ray. The condensing position is about 4 to 5 cm from the lens tip.

The X-ray shielding member 42 is formed of a material that shields X-rays such as lead. The X-ray shielding member 42 is disposed on the X-ray detection surface side (downward) of the X-ray refracting lens 41, and a slit 46 is formed at a position facing the lens 41. Therefore, when viewed from the X-ray detection surface, the position of the slit 46 becomes the center of the irradiated X-ray with respect to the refraction direction by the X-ray refraction lens 41.
The X-ray shielding member 42 is arranged at a position where the slit 46 is arranged at a position where X-rays having a desired wavelength (for example, a peak wavelength of characteristic X-rays) are collected among the X-rays condensed on the X-ray refractive lens 41. Is controlled to be.

  That is, the X-ray shielding member 42 is held by the X-ray shielding member holding portion 47 guided by the guide member 48 in a direction parallel to the optical axis direction of the X-ray, and the X-ray shielding member holding portion 47 is held by the guide member. While being guided by 48 in a direction parallel to the optical axis direction of the X-ray, it is moved and stopped by a driving member (not shown) so as to be positioned at a predetermined position, thereby Among them, the slit 46 is controlled to be disposed at a position where X-rays having a desired wavelength (for example, a peak wavelength of characteristic X-rays) are condensed.

  For example, when a compound X-ray refracting lens in which 75 X-ray refracting lenses having a diameter of 157 μm and a minimum parabolic radius of 19.625 μm are arranged in the X-ray traveling direction as described above is used, the tip of the lens If a slit with an aperture width of 78.5 μm is provided at a position about 20 cm from the center, 20 KeV (wavelength 0.6 mm) X-rays condensed at this position pass through this slit and are condensed at a position about 80 cm from the tip of the lens. A large proportion of 40 KeV (wavelength 0.3 mm) X-rays and 10 KeV (wavelength 1.2 mm) X-rays collected at a position of about 4 to 5 cm from the lens tip are blocked by the slit.

  In this way, for each of a plurality of different desired wavelengths, the X-ray shielding member can be moved so that the slit or hole of the X-ray shielding member is positioned at the position where the X-rays of the wavelength refracted by the X-ray refractive lens are condensed. Therefore, it can function as a bandpass filter with the wavelength as the center wavelength.

  Thus, for example, when the subject is thin, long-wavelength X-rays with high contrast can be irradiated, and when the subject is thick, short-wavelength X-rays that can obtain the necessary amount of X-ray transmission can be irradiated. By irradiating X-rays with the optimum wavelength for the thickness of the subject, or irradiating X-rays with different wavelengths, and taking the difference image, an image that emphasizes the bone part of the subject or soft tissue It is possible to obtain an enhanced image and various applications.

  Then, the width d of the slit 46 in the direction parallel to the direction having the refractive power of the X-ray refractive lens 41 orthogonal to the optical axis of the X-ray refractive lens 41, the lens diameter D of the X-ray refractive lens 41, the X-ray tube 122. , The distance R1 between the focal position of the X-ray tube 122 and the lens center of the X-ray refractive lens 41, and the distance R2 between the lens center of the X-ray refractive lens 41 and the slit 46 of the X-ray shielding member 42 are as follows. By satisfying the formulas (1) and (2), it is possible to efficiently extract X-rays having a desired wavelength more efficiently.

d ≦ D / 2 (1)
d ≧ R2 / R1 × α (2)
Further, in the present embodiment, the X-ray refraction lens 271 provided with the concave curved surface 272 having a parabolic cross section has been described as an example. However, the shape of the lens is not limited to this as long as it refracts X-rays. For example, as shown in FIG. 19, a lens 271A (see Japanese Patent Application Laid-Open No. 2001-337197) formed on opposing surfaces and refracting X-rays by means of concave curved surfaces 274 and 275 having a parabolic cross section. As shown in FIG. 20, a lens 271B (Japanese Patent Publication No. 2003-505679) that refracts X-rays by an opposed stepped surface 276, and an X-ray refractive lens having a curved surface 77 having a circular cross section as shown in FIG. An X-ray refractive lens group 9a formed by arranging a plurality of 71b in the X-ray optical axis direction (see Japanese Patent Application Laid-Open Nos. 2002-131488 and 2526409) A plurality of X-ray refraction lens having a curved surface of an elliptical shape, X-rays optical axis direction forming the X-ray refracting lens group by arranging (see U.S. Pat. No. 6,718,009) and the like.

  As described above, according to the present embodiment, X-rays having a desired wavelength pass through the slit 46 provided at a position where the X-rays having the wavelength are collected. The condensing position is farther from the X-ray refractive lens 41 than the slit 46, and the X-ray having a longer wavelength from the desired wavelength is closer to the X-ray refractive lens 41 than the slit 46. In any case, since the ratio of shielding by the X-ray shielding member 42 with respect to the ratio of passing through the slit 46 is increased as compared with X-rays having a desired wavelength, even the above configuration functions as an X-ray bandpass filter.

  Further, unlike a bandpass filter using a substance having a K edge on the lower wavelength side than the desired wavelength, the center wavelength of the bandpass is not limited, and the X-ray refractive lens 41, the X-ray shielding member 42, Can be made to function as an X-ray bandpass filter having the desired wavelength as the center wavelength of the bandpass. Thereby, X-rays having a desired wavelength can be extracted even with X-rays having a wavelength of 1 mm or less.

  Further, the slits 46 of the X-ray shielding member 42 are positioned at positions corresponding respectively to positions where X-rays having different desired wavelengths are collected by one X-ray bandpass filter 40, so that a plurality of different desired It can function as a band-pass filter with the wavelength as the center wavelength.

  Further, the shielding characteristic on the longer wavelength side than the desired wavelength can be sharpened, and a good bandpass filter characteristic can be obtained.

  Further, since the incident X-rays are substantially parallel X-rays, the length of the X-ray refraction lens 41 in the X-ray traveling direction can be made relatively shorter than the diffusion X-rays from the X-ray tube 122, and the desired wavelength. Can be made to function as an X-ray bandpass filter with the center wavelength of the bandpass.

For example, even if an X-ray tube 122 with a focal diameter α as used in general X-ray imaging is used, depending on the optical performance of the X-ray refractive lens 41, in principle, The X-ray having a desired wavelength that has entered the lens aperture D of the X-ray refracting lens 41 is not shielded by the X-ray shielding member 42 but passes through the slit 46 of the X-ray shielding member 42, and the desired wavelength is changed to the bandpass. It can function as an X-ray bandpass filter with a center wavelength.
[First embodiment]
An embodiment of an X-ray imaging system according to the present invention will be described with reference to FIGS.

  FIG. 2 is a diagram showing a control configuration of the X-ray imaging system in the present embodiment. FIG. 3 shows a configuration example of an X-ray imaging apparatus applied to the X-ray imaging system in the present embodiment.

  As shown in FIG. 2, the X-ray imaging system 100 controls the X-ray imaging apparatus 1 that performs X-ray imaging of the subject H and the X-rays irradiated to the subject H by controlling each part of the X-ray imaging apparatus 1. And a console 3 that performs image processing of an X-ray image acquired by irradiating or irradiating X-rays.

  As shown in FIG. 3, the X-ray imaging apparatus 1 includes a support base 11 fixed to a floor surface with a bolt or the like. The support base 11 includes a support member 111 that extends in a direction perpendicular to the floor surface, and an upper portion of the support member 111 has an X-ray optical axis direction that is substantially vertical from above to below. An X-ray irradiation unit 12 that irradiates X-rays is provided. A transmission port 70 is provided below the X-ray irradiation unit 12, and an X-ray bandpass filter 40 for extracting X-rays having a predetermined wavelength from the X-rays irradiated from the X-ray irradiation unit 12 is arranged. It is installed. A subject table 13 that supports the subject H from below is disposed at a position below the X-ray irradiating unit 12 in the X-ray optical axis direction. An X-ray detector 14 that detects X-rays emitted from the X-ray irradiation unit 12 and transmitted through the subject H is provided at a position below the subject table 13 in the X-ray optical axis direction. In addition, a first diffraction grating 15 and a second diffraction grating 16 (see FIG. 1 and the like) are integrally held between the subject table 13 and the X-ray detector 14 and configured separately from the subject table 13. A diffraction grating holding structure 17 is provided.

  The X-ray irradiation unit 12 includes a high voltage generation source 121 that generates a high voltage, and an X-ray tube 122 as an X-ray source that generates X-rays when a high voltage is applied by the high voltage generation source 121. Is provided. The X-ray irradiation unit 12 includes an X-ray source control unit 123, and the high voltage generation source 121 and the X-ray tube 122 are connected to the X-ray source control unit 123, respectively. The X-ray source control unit 123 controls the high voltage generation source 121 and the X-ray tube 122 based on a control signal from the control device 31 (see FIG. 2) of the console 3.

  The X-ray tube 122 is an X-ray source that irradiates the X-ray detector 14 with X-rays via the first diffraction grating 15 and the second diffraction grating 16. A Coolidge X-ray tube widely used in destructive inspection facilities and a rotating anode X-ray tube can be mentioned. In the rotary anode X-ray tube, X-rays are generated when an electron beam emitted from the cathode collides with the anode. This is incoherent (incoherent) like natural light, and is not divergent X-rays but divergent light. If the electron beam continues to hit the place where the anode is fixed, the anode is damaged by the generation of heat. Therefore, in the normally used X-ray tube 122, the anode is rotated to prevent the life of the anode from being reduced.

  By causing the electron beam to collide with a surface of a certain size of the anode, the generated X-rays are emitted toward the subject H from the plane of the certain size of the anode. The size of the plane of the anode where X-rays are generated as viewed from the irradiation direction (subject direction) is called a real focus (focus). The focal diameter (μm) can be measured by the method specified in (2) Measurement of focal dimension by slit camera method in 7.4.1 Focus test of JIS Z 4704-1994. Note that it is needless to say that the optional selection conditions in this measurement method can be measured with higher accuracy by selecting the conditions that give the highest accuracy in consideration of the measurement principle according to the properties of the X-ray irradiation unit 12. Yes.

  Here, as the anode (target), molybdenum, rhodium, or the like whose characteristic X-ray peak is easy to understand is used. This anode is the X-ray generating part according to the present invention.

  The X-ray source preferably has a half-value width of the wavelength distribution of the X-ray to be irradiated that is not more than 0.1 times the peak wavelength of the X-ray. It is not limited to 122, and a microfocus X-ray source may be used.

  In the present embodiment, it is assumed that the X-ray irradiation unit 12 has sufficient spatial coherence that can generate a Talbot effect to be described later when the first diffraction grating 15 is irradiated with X-rays. For example, the focal diameter (μm) is about 30 microns, and the spatial coherence at a position of about 5 meters or more from the X-ray irradiation unit 12 corresponds to that.

  The X-ray bandpass filter 40 is the X-ray bandpass filter described in the embodiment as the X-ray bandpass filter of the present invention. In this embodiment, the X-ray source and the bandpass filter 40 described above are used. In combination with the X-ray irradiation system.

  The subject table 13 is held by a holding member 18 held on the support base 11 and is fixed to the support member 111 so as to be substantially parallel to the floor surface. A portion of the holding member 18 that contacts the subject table 13 is provided with a buffer member 19 that absorbs and relieves shocks and vibrations. The subject table 13 is held by the holding member 18 via the buffer member 19. Yes.

  The subject table 13 includes the first diffraction grating 15, the first diffraction grating 15, the first diffraction grating 15, and the first diffraction grating 15 in the horizontal direction, at least because the subject is supported on the subject table 13 and in the direction away from the subject supported on the subject table 13. The shape protrudes from the two diffraction gratings 16 and the diffraction grating holding structure 17, and the subject may contact the first diffraction grating 15, the second diffraction grating 16, and the diffraction grating holding structure 17. Is reduced.

  As a material of the buffer member 19, for example, hard rubber or various resins can be applied, but the material of the buffer member 19 is not limited thereto.

  The X-ray detector 14 includes a panel 141, a detector power supply unit 142, a detector communication unit 143, a detector control unit 144, and the like. The panel 141, the detector power supply unit 142, the detector communication unit 143, and the detector control unit 144 are each connected to a bus in the X-ray detector 14.

  The panel 141 is disposed on the surface of the X-ray detector 14 (the surface facing the subject H), and outputs X-ray image data based on the X-rays emitted from the X-ray irradiation unit 12 and transmitted through the subject H. Is.

  In the present embodiment, the panel 141 is a two-dimensional image sensor, and the X-ray detector 14 reads a signal based on the X-ray irradiation amount for each of a number of pixels arranged two-dimensionally on the panel 141 to obtain X-ray image data. FPD (flat panel detector) that acquires Each pixel (not shown) of the panel 141 is arranged in a matrix at a pitch of 70 to 150 μm, for example.

  The detector power supply unit 142 supplies power to each unit disposed in the X-ray detector 14. The detector power supply unit 142 is provided with, for example, a capacitor that can be charged and can handle power consumed during photographing. The configuration of the detector power supply unit 142 is not limited to that shown here.

  The detector communication unit 143 transmits / receives a signal to / from the console 3 via the interface 34 (referred to as “I / F” in FIG. 2) of the console 3, and transmits X-ray image data to the console 3. It is a functional part that can be used. In general, the X-ray imaging apparatus 1 is, for example, an X-ray imaging room covered with an X-ray shielding member such as a lead plate (a metal member having a property of suppressing transmission of radio waves or a property of reflecting radio waves). The console 3 is provided in an X-ray control room (not shown) in which an operator such as an X-ray engineer waits. For this reason, when the detector communication unit 143 transmits and receives signals wirelessly, a radio repeater (not shown) is provided in the X-ray imaging room, and signals are transmitted to and from the console 3 via the radio repeater. Is configured to be able to transmit and receive.

  The detector control unit 144 controls each unit provided in the X-ray detector 14 based on the control signal received by the detector communication unit 143. Specifically, the detector control unit 144 reads a signal based on the X-ray irradiation amount detected for each pixel of the panel 141, and detects X-ray image data obtained as a result of the reading by detector communication. To the console 3 via the unit 143.

  The diffraction grating holding structure 17 is, for example, a member formed in a frame shape as shown in FIG. 4. The first diffraction grating 15 is held on one surface of the diffraction grating holding structure 17, and the other A second diffraction grating 16 is held on the surface. The diffraction grating holding structure 17 is fixed to the support member 111 of the support base 11 via the buffer member 171 so that the first diffraction grating 15 and the second diffraction grating 16 are arranged substantially parallel to the floor surface. .

  The buffer member 171 is formed of, for example, hard rubber or various resins as with the buffer member 19, but the material forming the buffer member 171 is not limited thereto.

  As described above, the diffraction grating holding structure 17 has a separate structure from the subject table 13, and the diffraction grating holding structure 17 and the subject table 13 buffer the force and vibration applied to the subject table 13. Buffer means 19 and 171 are arranged, respectively. As a result, even when a force is applied to the subject table 13 or a vibration occurs due to the subject H moving, the positional relationship between the first diffraction grating 15 and the second diffraction grating 16 held by the diffraction grating holding structure 17. Thus, there is no influence such as the occurrence of a shift.

  In the present embodiment, as shown in FIG. 5, the X-rays irradiated from the X-ray irradiation unit 12 and transmitted through the subject H pass through the first diffraction grating 15 and the second diffraction grating 16 and pass through the X-ray detector 14. The Talbot interferometer is constituted by the X-ray irradiator 12, the first diffraction grating 15, and the second diffraction grating 16. The conditions for configuring the Talbot interferometer will be described later.

  6 is a cross-sectional view of the first diffraction grating 15 taken along the line II in FIG.

  As shown in FIGS. 5 and 6, the first diffraction grating 15 includes a substrate 151, a plurality of diffractive members 152 arranged on the substrate 151, and an adjacent diffractive member 152 so as to embed each other. A holding member 153 for holding the member 152 is provided, and a Talbot effect to be described later is generated by diffracting X-rays transmitted through the subject table 13 and the subject H held thereon. The substrate 151 is made of, for example, glass. Note that a surface of the substrate 151 on which the diffraction member 152 is disposed is a diffraction grating surface 153.

  Each of the plurality of diffraction members 152 is a linear member extending in one direction (for example, the vertical direction in FIG. 5 in the present embodiment) orthogonal to the X-ray irradiation direction irradiated from the X-ray irradiation unit 12. .

  The thickness of each diffraction member 152 is substantially equal. For example, in the case of an absorption type diffraction grating, it is preferably 10 μm or more and 100 μm or less, and in the case of a phase type diffraction grating, it is preferably 1 μm or more and 10 μm or less.

  Further, the arrangement interval (grating period) d1 (see FIG. 5) of the plurality of diffraction members 152 is constant, that is, the arrangement intervals of the plurality of diffraction members 152 are equal intervals, and an interval of 2 μm or more and 10 μm or less is preferable.

  As a material constituting the plurality of diffraction members 152, a material having excellent X-ray absorption is preferable, and for example, a metal such as gold, silver, or platinum can be used. The diffractive member 152 is formed by, for example, plating or vapor-depositing these metals on the substrate 151.

  The diffractive member 152 changes the phase velocity of the X-rays irradiated to the diffractive member 152. The diffractive member 152 is (1/3) × π or more (2/3) with respect to the irradiated X-rays. ) × π or less (particularly, (3/8) × π or more and (5/8) × π or less, ideally (1/2) × π)) is formed so-called phase type diffraction grating It is preferable that The X-ray does not necessarily have to be monochromatic, and may have an energy width (that is, a wavelength spectrum width) in a range that satisfies the above conditions.

  7 is a cross-sectional view of the second diffraction grating 16 taken along the line II-II in FIG.

  As shown in FIGS. 5 and 7, the second diffraction grating 16 includes a substrate 161 and a plurality of diffraction members 162, similarly to the first diffraction grating 15. Note that a surface of the substrate 161 on which the diffraction member 162 is disposed is a diffraction grating surface 163.

  Note that the distance between the diffraction members 162 of the second diffraction grating 16 (grating period) and the width of each diffraction member 162 are the same as the distance between the diffraction members 152 of the first diffraction grating 15 (grating period) and each diffraction member 152. The width is the same.

  The second diffraction grating 16 is held by the diffraction grating holding structure 17 in such an arrangement that the extending direction of the diffraction member 162 coincides with the extending direction of the diffraction member 152 of the first diffraction grating 15. The image contrast is formed by diffracting the X-rays diffracted by one diffraction grating 15. The second diffraction grating 16 is desirably an amplitude type diffraction grating in which the diffraction member 162 is made thicker, but may have the same configuration as the first diffraction grating 15. For example, in the case of an absorption type diffraction grating, the thickness is preferably 20 μm or more and 200 μm or less, and in the case of a phase type diffraction grating, it is preferably 1 μm or more and 10 μm or less.

  Next, the conditions under which the X-ray tube 122, the hole or slit 46 of the X-ray shielding member 42, the first diffraction grating 15 and the second diffraction grating 16 constitute a Talbot interferometer will be described.

First, due to the coherence of X-rays, when the slit 46 provided in the X-ray shielding member 42 extends in a direction perpendicular to the diffractive member, the focal diameters a and X of the X-ray tube 122 in a direction substantially perpendicular to the diffractive member. The distance L from the actual focal point of the ray tube 122 to the first diffraction grating 15 is set, but otherwise, as shown in FIG. 8, the hole or slit 46 of the X-ray shielding member 42 in a direction substantially perpendicular to the diffraction member. , A distance L from the hole or slit 46 of the X-ray shielding member 42 to the first diffraction grating 15 (see FIG. 8), and a distance Z ₁ from the first diffraction grating 15 to the second diffraction grating 16 (FIG. 8). (See FIG. 8), when the distance Z ₂ from the second diffraction grating 16 to the X-ray detector 14 (see FIG. 8) and the peak wavelength λp of the X-ray to be irradiated are given, the distance d ₁ ( 6) and the second diffraction grating 16 Distance _{d 2} of the folding member 162 (see FIG. 7), it is preferable to satisfy each formula (4) and (5).

d ₁ <(L / a) × λp (4)
d ₂ <{(L + Z ₁ ) / a} × λp (5)
Further, the distance Z ₁ between the first diffraction grating 15 and the second diffraction grating 16 is based on the following formula (6) in any natural number m, assuming that the first diffraction grating 15 is an absorption diffraction grating. It is ideal to satisfy the conditions indicated by

Z ₁ = m × (d ₁ ² / λp) (6)
Actually, it is preferable that the condition represented by the following formula (7) is satisfied in any natural number m.

(M−1 / 8) × (d ₁ ² / λp) ≦ Z ₁ ≦ (m + 1/8) × (d ₁ ² / λp) (7)
Further, the distance Z ₁ between the first diffraction grating 15 and the second diffraction grating 16 can be expressed by the following formula (8) in any natural number m, assuming that the first diffraction grating 15 is a phase type diffraction grating. It is ideal to satisfy the conditions indicated by

Z ₁ = (m + 1/2) × (d ₁ ² / λp) (8)
Actually, it is preferable that the condition represented by the following formula (9) is satisfied in any natural number m.

(M-5 / 8) × (d ₁ ² / λp) ≦ Z ₁ ≦ (m−3 / 8) × (d ₁ ² / λp) (9)
In the above formulas (6) to (9),
λp: X-ray peak wavelength Z ₁ irradiated from the X-ray irradiation unit: distance from the first diffraction grating 15 to the second diffraction grating 16 (see FIG. 8)
d ₁ : spacing between the diffraction members of the first diffraction grating 15 (see FIG. 6)
It is.

  Here, the Talbot effect means that when a plane wave passes through a diffraction grating, in the case of a phase type diffraction grating, a self-image of the diffraction grating is formed at a distance given by the expression (4) or (6). is there. However, if the distance satisfies the above formula (5) or (7), the following phenomenon occurs sufficiently, although slightly blurred.

  In the case of the present embodiment, the X-rays irradiated from the X-ray tube 122 pass through the subject H, causing a phase shift of the X-rays due to the subject H. Therefore, the wavefront of the X-rays incident on the first diffraction grating 15 Is distorted. Therefore, the self-image of the first diffraction grating 15 is deformed depending on it. Subsequently, the X-ray passes through the second diffraction grating 16. As a result, the superposition of the deformed self-image of the first diffraction grating 15 and the second diffraction grating 16 causes an image contrast in the X-ray. This image contrast is generally moiré fringes and can be detected by the X-ray detector 14. The generated moire fringes are modulated by the subject H. The amount of modulation is proportional to the angle at which the X-ray is bent by the refraction effect of the subject H. Therefore, by analyzing the moiré fringes detected by the X-ray detector 14, the subject H and its internal structure can be detected.

The ratio between the interval L and the grating period d1 of the first diffraction grating 15 is such that the X-ray detector 14 can detect moire fringes (or differential phase difference images and phase difference images obtained by analyzing moire fringes). The ratio of the interval (L + Z ₁ ) to the grating period d ₂ of the second diffraction grating 16 is ideal for adjusting the fringe interval only by the minute angle θ as will be described later. That is, satisfying the following formula (10) is ideal for adjusting the stripe interval only by the minute angle θ, as will be described later.
d ₁ / L = d ₂ / (L + Z ₁ ) (10)
Note that the diffraction members 152 and 52 of the first diffraction grating 15 or the second diffraction grating 16 are relatively rotated by a small angle θ around a virtual axis passing through the X-ray tube 122 and the X-ray detector 14. Assume that they are placed. The interval between the generated moire fringes varies depending on the magnitude of θ. If there is no subject H, the moire fringe spacing is given by d ₃ / θ. Here, d ₃ is a distance obtained by projecting the distance between the diffractive members 152 of the first diffraction grating 15 from the center of the X-ray tube 122 onto the X-ray detection surface (that is, the X-ray detector 14). The distance between the diffraction members 162 of the diffraction grating 16 is the distance projected from the center of the X-ray tube 122 onto the X-ray detection surface (that is, the X-ray detector 14).

  If a mechanism for changing the minute angle θ (for example, a mechanism for rotating one of the first diffraction grating 15 and the second diffraction grating 16 relative to the other) is provided, the moire fringes are adjusted as preferable for observation. It becomes possible to do. Further, if the minute angle θ is adjusted to be substantially zero, moire fringes do not appear in portions other than the portion corresponding to the subject H (that is, in the non-modulated portion). As a result, only the absorption contrast due to the subject H appears in the obtained X-ray image.

If it is not necessary to obtain an X-ray image with only absorption contrast while the first diffraction grating and the second diffraction grating are arranged at predetermined positions, the condition of the above equation (10) need not be satisfied, and X-ray detection can be performed. D ₁ , d ₂ , and θ may be appropriately selected so that the spacing between the stripes that can be detected by the device 14 is obtained.

The ratio between the interval L and the grating period d ₁ of the first diffraction grating 15 is such that the X-ray detector 14 detects a moire fringe (or a differential phase difference image or a phase difference image obtained by analyzing the moire fringe). To the extent possible (preferably close to the ratio of the spacing (L + Z ₁ ) to the grating period d ₂ of the second diffraction grating 16)
To be close to the ratio of the interval (L + Z ₁ ) to the grating period d ₂ of the second diffraction grating 16 means that the change in fringes generated by the X-ray detector 14 can be detected. When the pixel pitch P ₃ of the line detector 14 is satisfied, the following equation (11) is satisfied.
[1- (d ₁ / L) × {(L + Z ₁ + Z ₂ ) / P ₃ })] × (d ₁ / L) ≦ d ₂ / (L + Z ₁ ) ≦ [1+ (d ₁ / L) × {( L + Z ₁ + Z ₂ ) / P ₃ }] × (d ₁ / L)
(11)
In this embodiment, the diffraction grating holding structure 7 holds the first diffraction grating 15 so as to be movable in a direction parallel to the diffraction grating surface 43 and intersecting the extending direction of the diffraction member 152. At one end of the first diffraction grating 15, a piezoelectric actuator 20 (hereinafter simply referred to as “actuator”) that deforms when a voltage is applied is provided.

  The actuator 20 operates in accordance with an instruction signal from the console 3, and the first diffraction grating 15 is substantially parallel to the diffraction grating surface 43 of the first diffraction grating 15 and intersects the extending direction of the diffraction member 152. Drive means for moving in the direction.

  When the actuator 20 is driven, the first diffraction grating 15 is translated relative to the second diffraction grating 16.

  The console 3 shown in FIG. 2 includes a control device 31 including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (all not shown).

  The control device 31 includes an input device 32 for inputting an imaging preparation instruction, an imaging instruction, and instruction contents, a display device 33 for displaying an X-ray image, and an interface 34 connected to each part of the X-ray imaging apparatus 1. An image storage unit 35 that stores image information, a console power supply unit 36 that supplies power to each unit of the console 3, and the like are connected via a bus.

  As the input device 32, for example, an X-ray irradiation request switch, a touch panel, a mouse, a keyboard, a joystick, or the like can be used. X-ray imaging conditions such as irradiation time, X-ray imaging control conditions such as imaging timing, imaging region, imaging method, image processing conditions, image output conditions, X-ray detector selection information (a plurality of imaging devices are connected to the console 3 In the case of the order selection information, subject ID, and the like.

  The display device 33 is, for example, a CRT (Cathode Ray Tube) display, a liquid crystal display, or the like. The display device 33 is controlled by the control device 31 of the console 3 so that characters such as X-ray imaging conditions and image processing conditions, and X-rays are displayed. Display an image.

  The image storage unit 35 temporarily stores X-ray image data received from the X-ray detector 14 via the interface 34 and stores image-processed X-ray image data. As the image storage unit 35, a hard disk that is a large-capacity and high-speed storage device, a hard disk array such as a RAID (Redundant Array of Independent Disks), a silicon disk, or the like can be used.

  The console power supply unit 36 supplies power to each unit constituting the console 3 from an external power supply or an internal power supply.

  A control program and various processing programs for controlling each part of the X-ray imaging system 100 are stored in the internal storage device of the control device 31, and the CPU cooperates with the control program and the various processing programs to perform X-rays. The operation of each part of the imaging system 100 is comprehensively controlled to perform X-ray image imaging.

  For example, the control device 31 controls the X-ray source control unit 123 of the X-ray imaging apparatus 1 so as to adjust the voltage supplied from the high voltage power supply 121 to the X-ray tube 122. Then, the high voltage power supply 121 supplies a predetermined voltage to the X-ray tube 122, the X-ray tube 122 irradiates the subject H with X-rays, and the X-ray dose incident on the X-ray detector 14 is set in advance. When the X-ray dose is reached, the high-voltage power supply 121 stops supplying high voltage to the X-ray tube 122, and the X-ray source 2 stops X-ray irradiation.

  In the present embodiment, the control device 31 reads the signal from the panel 141 in the X-ray detector 14 and moves from the X-ray tube 122 when the movement of the first diffraction grating 15 by the actuator 20 is stopped. The X-ray source control unit 123 is controlled to perform the X-ray irradiation.

  Whether or not the movement of the first diffraction grating 15 by the actuator 20 is stopped is detected from the output of the acceleration sensor fixed to the first diffraction grating 15 also by detecting the voltage applied to the actuator 20, for example. This can also be determined by detecting from the output of the speed sensor that detects the movement of the first diffraction grating 15.

  In addition, the control device 31 operates the detector control unit 144 of the X-ray detector 14 to start reading a signal based on the X-ray irradiation amount detected for each pixel of the panel 141, and obtains the result of the reading. The X-ray image data thus received is transmitted to the console 3 via the detector communication unit 143.

  In addition, the control device 31 operates the actuator 20 to move the first diffraction grating 15 by a predetermined amount.

  In the present embodiment, the first diffraction grating 15 is translated relative to the second diffraction grating 16 by the actuator 20 as described above. The direction of the first diffraction grating 15 is substantially parallel to the diffraction grating surface 43 of the first diffraction grating 15 and is substantially orthogonal to the extending direction of the diffraction member 152.

  As the first diffraction grating 15 translates relative to the second diffraction grating 16, the moire fringes move, and the movement distance (translation distance) of the first diffraction grating 15 is the grating of the first diffraction grating 15. When reaching one period, the moire fringe image is restored. In the present embodiment, the control device 31 performs X-ray imaging a plurality of times while translating the first diffraction grating 15 by, for example, an integral part of one period of the grating period of the first diffraction grating 15. ing.

  That is, when the first X-ray imaging is performed, the control device 31 operates the actuator 20 to move the first diffraction grating 15 relative to the second diffraction grating 16 by 1 / integer of one period of the grating period. The second shot is taken. Thereafter, the control device 31 operates the actuator 20 to translate the first diffraction grating 15 further in the same direction by an integral number of one cycle of the diffraction member 152 to perform the third imaging. The photographing and the movement of the first diffraction grating 15 are repeated a plurality of times.

  Note that the control device 31 is adapted to acquire the movement amount information of the actuator 20 and obtain movement amount information for obtaining movement amount information regarding the movement amount of the first diffraction grating 15 by each actuator 20 during a plurality of imaging operations. It is designed to function as a means.

  Note that the amount of movement by which the first diffraction grating 15 is moved by the actuator 20 may be set as a default in advance, or may be arbitrarily set by the operator as appropriate.

  In the present embodiment, the X-ray detector 14 or the control device 31 corrects the offset / gain characteristics of each pixel unique to the X-ray detector 14. Then, for the X-ray image whose offset / gain characteristics have been corrected, the control device 31 transmits the subject H, the first diffraction grating 15 and the second diffraction grating 16 and detects the X-ray detected by the X-ray detector 14. Analyze line image contrast (moire fringes). Thereby, the control apparatus 31 calculates a differential phase image and a phase difference image based on the radiation dose of each pixel acquired from the X-ray detector 14. Further, the control device 31 acquires an absorption image based on the difference in the X-ray absorption rate of the subject H as necessary.

  That is, in the present embodiment, as described above, X-ray imaging is performed a plurality of times while the first diffraction grating 15 is translated relative to the second diffraction grating 16, and the control device 31 It functions as a differential phase image acquisition means for obtaining a differential phase image from a plurality of X-ray images obtained by X-ray imaging and the movement amount information of the first diffraction grating 15.

  Further, the control device 31 functions as a phase difference image acquisition unit that obtains a phase difference image from a plurality of X-ray images obtained by a plurality of X-ray images and movement amount information of the first diffraction grating 15.

  Hereinafter, a method of calculating the differential phase image, the phase difference image, and the absorption image will be described.

  First, the differential phase image is a distribution image of an angle at which X-rays are bent by the refraction effect by the subject H, and the control device 61 detects the X-ray detector 14 by using a so-called fringe scanning method described below. The X-ray image in which the moire fringes appear (hereinafter referred to as “stripe image”) can be converted into a differential phase image.

  In the fringe scanning method, imaging is performed while one of the first diffraction grating 15 and the second diffraction grating 16 is translated relative to the other. In this embodiment, the first diffraction grating 15 is replaced with the second diffraction grating 15. 16 is translated relative to 16.

  As the first diffraction grating 15 moves, the moire fringes move, and when the translational distance (movement amount) reaches one cycle of the diffraction member 152, the fringe image is restored. In the fringe scanning method, such a change in the fringe image is recorded while moving the first diffraction grating 15 by an integral number of one cycle of the diffraction member 152, and the differential phase image ψ ( x, y). (X, y) is a coordinate indicating the position of the pixel. The fringe image I (x, y) is generally given by the following equation (12), where the amount of movement is ξ.

Here, Ak (k = 0, 1,...) Is a constant determined by the shape of the first diffraction grating 15. Δ (x, y) represents the contribution of contrast generated regardless of the subject H due to distortion, manufacturing error, and arrangement error of the first diffraction grating 15. d is the period of the diffraction member 152 to be moved, and Z ₁ is the distance between the first diffraction grating 15 and the second diffraction grating 16. Now, it is assumed that M striped images are acquired by performing M times of X-ray imaging while changing ξ at step d / M (M: integer). If the term of k> N is sufficiently small and can be ignored in the equation (12), the following equation (13) is satisfied if M is selected so as to satisfy M> N + 1.

arg [] means extraction of declination. Ip (x, y) is the value of equation (12) when ξ = pd / M. d and Z ₁ are known, and Δ (x, y) can be obtained in advance by performing the same measurement when there is no subject (ie, ψ (x, y) = 0). Therefore, ψ (x, y) can be obtained from the above.

  The control device 61 generates a differential phase image and outputs the differential phase image to the display device 9 when outputting the differential phase image, and calculates the phase difference image by integrating the differential phase image when outputting the phase difference image. And output to the display device 9.

  Next, the phase difference image is an image representing the phase shift itself by integrating the differential phase image, and the phase difference image Φ (x, y) and the differential phase image ψ (x, y) are: It is related by the following formula (14).

  Here, x corresponds to the direction in which the first diffraction grating 15 is translated by the fringe scanning method. Thus, the phase difference image Φ (x, y) is given by integrating the differential phase image ψ (x, y) along the x axis.

  The phase difference image Φ (x, y) is given by the following formula (15), where n (x, y, z) is the refractive index distribution of the subject.

  When X-rays pass through the object, an X-ray image corresponding to the difference in X-ray absorption rate of the object is formed and detected by the X-ray detector 14. The image obtained by this is called an absorption image.

  Note that any of these imaging methods can be sufficiently used according to the purpose of the imaging, and the control device 61 can output the differential phase image φ (x, y) when the differential phase image is output. ) Is generated and output to the display device 9. When the phase difference image is output, the differential phase image is integrated to calculate the phase difference image Φ (x, y) and output to the display device 9. it can.

  In addition, when a plurality of types of images (differential phase image, phase difference image, absorption image) are acquired by photographing, the control device 61 stores these plurality of types of images in association with each other in the image storage unit 35. It is like that.

  Here, an outline of a process for obtaining a differential phase image, a phase difference image, and an absorption image will be described with reference to the data flow diagram of FIG.

  First, the X-ray imaging 521 is performed by a series of X-ray imaging 521 of the same subject based on the imaging instruction signal from the control device 31, and the X-ray detector detects a plurality of fringe images IM (x, y) or a single image. This is a process for obtaining one striped image I (x, y).

  In the offset gain correction 522, an X-ray detector applies an X-ray detector to a plurality of stripe images IM (x, y) or a single stripe image I (x, y) obtained by a series of X-ray imaging 521 of the same subject. This is a process of correcting the offset / gain for each pixel in order to correct the variation in characteristics of each pixel unique to the line detector.

  The subject-dependent defect region specifying process 537 is obtained from a plurality of striped images IM (x, y) or a single striped image I (x, y) obtained by a series of X-ray imaging 521 of the same subject and corrected for offset gain. This is a process of specifying an area that exceeds the normal stripe width and has no image data as a subject-dependent defect area. Such a subject-dependent defect region is a region in which the image data value at the X-ray detector becomes 0 even if the subject has a large X-ray absorption, even if it is a striped X-ray transmission region by a diffraction grating.

  The ID assigning process 523 in the X-ray detector is obtained by a series of X-ray imaging 521 of the same subject, and a plurality of fringe images IM (x, y) or a single fringe image I (x, y) is a process in which the X-ray detector assigns an imaging ID common to a series of X-ray imaging 521 of the same subject. The storage process 523 is a process of temporarily storing a plurality of striped images IM (x, y) or a single striped image I (x, y) given a common shooting ID.

  As described above, the differential phase image calculation processing 525 performs a movement amount ξ corresponding to each fringe image from a plurality of temporarily stored fringe images IM (x, y) or a single fringe image I (x, y). This is a process for obtaining a differential phase image according to the differential phase image Δ (x, y) when there is no subject, that is, according to the photographing conditions. In the present embodiment, the differential phase image obtained in this way is called an original differential phase image.

  The original differential phase image storage process 526 is a process for temporarily storing the obtained original differential phase image.

  The defect correction process 527 is a process for correcting a defect peculiar to the X-ray detector for an area other than the subject-dependent defect area for the temporarily stored original differential phase image. If there is a defective pixel, the original differential phase image is interpolated from data around the defective pixel. When there is a linear defect, interpolation processing is performed on the original differential phase image from the data of the line adjacent to the defect line. In this way, defect correction is performed on the original differential phase image, and a defect-corrected differential phase image is output.

  The pixel number / gradation number reduction process 528 is a process for improving the response by displaying an image, transmitting image data, and the like at the time of diagnosis / inspection while reducing the amount of image data stored by the storage unit. For example, up to 12-bit gradation, for example, 14-bit gradation until the number-of-pixels / gradation-number reduction processing 528, after performing dynamic range compression processing, the number of gradations is reduced to 8-bit gradation, For example, the average value of 2 × 2 pixels is a value of one pixel, and the number of pixels is reduced. By this processing, a differential phase image with the number of pixels and the number of gradations reduced can be obtained.

  The order ID assigning process 529 is a process for assigning an order ID to the pixel number / gradation number decreasing differential phase image based on the correspondence between the order ID and the photograph ID from the photograph ID. The reason why the order ID is assigned after completion of various image processes is that order information may be created after X-ray imaging.

  The differential phase image storage process 530 is a process of long-term storage of the differential phase image that has been assigned the order ID and has the reduced number of pixels and gradations.

  The integration process 531 is a process of integrating the temporarily stored original differential phase image as described above. By this integration processing, an original phase difference image is obtained.

  The original phase difference image storing process 532 is a process for temporarily storing the obtained original phase difference image.

  The defect correction process 533 is a process for correcting defects peculiar to the X-ray detector with respect to the temporarily stored original phase difference image.

  If there is a defective pixel, the constant of the pixel column data ahead of the defective pixel in the integration direction with respect to the original phase difference image is minimized by using, for example, the least square method. Is added.

  When there is a linear defect in the integration direction, interpolation processing is performed on the original differential phase image from data of a line adjacent to the defect line.

  On the other hand, when a linear defect in the direction perpendicular to the integration direction completely crosses the X-ray detector, the data of the pixel column in the integration direction beyond the linear defect is sequentially obtained by, for example, the least square method. In addition, a constant that minimizes the difference from data of adjacent pixel columns is added or subtracted. After that, a constant that minimizes the data difference between the pixel columns adjacent to the linear defect is used by using, for example, the least square method so that the step is not conspicuous before and after the linear defect in the integration direction. Add to all pixels ahead of the line defect in the integration direction.

  In addition, when a linear defect in a direction perpendicular to the integration direction does not completely cross the X-ray detector or there is a subject-dependent defect region, the linear defect or the subject-dependent defect region is a region that is not related to integration. A constant that minimizes the data difference is added to the data of the pixel column in the boundary area by using, for example, the least square method or the like for the data of the pixel column adjacent thereto. After that, by determining the data of the pixel column adjacent to the pixel column to which the constant is added, for example, a least square method is used so that the step is not conspicuous before and after the linear defect in the integration direction. Using this, the pixel data ahead of the integration direction from the linear defect or subject-dependent defect area is determined.

  Thus, the defect correction method is greatly different between the differential phase image and the phase difference image. Then, a defect-corrected phase difference image is obtained by the defect correction processing 533.

  The pixel number / gradation number reduction process 534 is a process for improving the response by displaying an image, transmitting image data, etc. at the time of diagnosis / inspection while reducing the amount of image data stored by the storage unit. For example, up to 12-bit gradation or more, for example, 14-bit gradation until the number-of-pixels / gradation-number reduction process 534, after performing dynamic range compression processing, the number of gradations is reduced to 8-bit gradation, For example, the average value of 2 × 2 pixels is a value of one pixel, and the number of pixels is reduced. By this processing, a phase difference image with a reduced number of pixels and gradations is obtained.

  The order ID assigning process 535 is a process for assigning an order ID to the pixel number / gradation number decreasing phase difference image based on the correspondence between the order ID and the photograph ID from the photograph ID. In this way, a differential obtained from a plurality of fringe images IM (x, y) or a single fringe image I (x, y) obtained by a series of X-ray imaging 521 of the same subject and corrected for offset gain. The same order ID as that of the phase difference image is given.

  The phase difference image saving process 536 is a process for long-term saving the phase difference image having the number of pixels and the number of gradations assigned the order ID.

  The moire removal processing 541 according to the shooting conditions removes stripes from a plurality of striped images IM (x, y) or a single striped image I (x, y) to which a temporarily stored common shooting ID is assigned. This is the process of calculating the absorption image. For example, with respect to the period d of the diffractive member 152 to be moved, X-ray imaging is performed M times while changing the moving amount ξ by a certain amount of step d / M (M: integer), and M stripe images IM (x , Y), even if they are simply summed, the fringes cancel each other and an absorption image is obtained. In other cases, the moire fringes by the diffraction grating are also a kind of moire fringes, so that an absorption image can be obtained by removing the moire fringes by the moire removal processing. As such moire removal processing, simple smoothing processing for averaging in units of pixels sufficiently large with respect to the moire cycle, frequency processing for suppressing frequency components above the moire frequency, frequency processing for suppressing frequency components near the moire frequency, etc. However, it is not limited to these. In addition, the influence of moire fringes due to the diffraction grating can be suppressed by a known moire removal process, but the influence of moire fringes may be suppressed by an unknown moire removal process. The moire processing method is preferably selected according to the shooting conditions.

  Note that it is preferable that the sampling frequency fs by the X-ray detector satisfies the following expression (13) with respect to the frequency fm of the moire fringes by the diffraction grating because the beat component after removing the moire fringes can be reduced.

fm ≦ 0.4 × fs (16)
Thus, an original absorption image is obtained by the moire removal processing 541 according to the imaging conditions. The original absorption image storage process 542 temporarily stores the obtained original absorption image.

  The defect correction process 543 is a process for correcting a defect peculiar to the X-ray detector for an area other than the subject-dependent defect area for the temporarily stored original absorption image. If there is a defective pixel in a region other than the subject-dependent defective region, the original absorption image is interpolated from data around the defective pixel. If there is a linear defect in an area other than the subject-dependent defect area, interpolation processing is performed on the original absorption image from data of a line adjacent to the defect line. In this way, defect correction is performed on the original absorption image, and a defect-corrected absorption image is output.

  The pixel number / gradation number reduction process 544 is a process for improving the response by displaying an image, transmitting image data, and the like at the time of diagnosis / inspection while reducing the amount of image data stored by the storage unit. For example, until the number of pixels / gradation number reduction processing 544, after performing a dynamic range compression process on a gradation of 12 bits or more, for example, a 14 bit gradation, the number of gradations is reduced to 8 bits, For example, the average value of 8 × 8 pixels is a value of one pixel, and the number of pixels is reduced. Since the absorption image obtained in this way has fewer fine components than the stripe interval, the number of pixels corresponding to the stripe interval in both the vertical and horizontal directions is greatly reduced. Also good. By this processing, an absorption image having a reduced number of pixels and gradations is obtained.

  The order ID assigning process 545 is a process for assigning an order ID to the absorption image with the reduced number of pixels and the number of gradations based on the correspondence between the order ID and the photograph ID from the photographing ID. In this way, differential phase images and phase differences obtained from a plurality of fringe images IM (x, y) or a single fringe image I (x, y) obtained by a series of X-ray imaging 521 of the same subject. The same order ID as the image is assigned.

  The absorption image storage process 546 is a process for long-term storage of the reduced number of pixels / tones to which the order ID is assigned.

  In this way, an absorption image can be obtained from an X-ray image obtained by the Talbot interferometer system that obtains an image related to a good X-ray phase, so that an X-ray phase such as an X-ray phase differential image or a phase difference image can be obtained. The image related to the image and the absorption image corresponding to this image are obtained from the same one time or a series of images, not separate images.

  The order ID is an ID unique to the order of X-ray imaging, and is assigned so as not to overlap with the IDs of other orders for each X-ray imaging order on the console.

  Further, in the above-described embodiment, a workflow in which an order ID is issued at the time of X-ray imaging or, if issued, is obtained by a series of X-ray imaging 521 of the same subject in the ID assignment processing 523 in the X-ray detector, Although the shooting ID is assigned to the plurality of fringe images IM (x, y) or the single fringe image I (x, y) corrected for offset gain, an order ID may be assigned instead. In this case, the order ID assigning processes 529, 535, and 545 are not necessary.

  As described above, according to the present embodiment, X-rays having a desired wavelength pass through the slit 46 provided at a position where the X-rays having the wavelength are collected. The condensing position is farther from the X-ray refractive lens 41 than the slit 46, and the X-ray having a longer wavelength from the desired wavelength is closer to the X-ray refractive lens 41 than the slit 46. In any case, since the ratio of shielding by the X-ray shielding member 42 with respect to the ratio of passing through the slit 46 is increased as compared with X-rays having a desired wavelength, even the above configuration functions as an X-ray bandpass filter.

  In the present embodiment, the FPD has been described as an example of the X-ray detector 14, but the X-ray detector 14 is not limited to this. Besides the FPD, for example, a cassette containing a stimulable phosphor sheet can be used as the X-ray detector 14.

  In the present embodiment, the case where the X-ray bandpass filter 40 has one X-ray refractive lens 41 has been described as an example. However, as shown in FIG. 10, the X-ray bandpass filter 40A includes a plurality of X-ray filters. You may have the refractive lens 41a. In this case, the plurality of X-ray refracting lenses 41 a are arranged below the X-ray tube 122 so as to have a radial shape centering on the X-ray tube 122. A plurality of slits 46a of the X-ray shielding member 42 are formed so as to face the lower end portions of the respective X-ray refractive lenses 41a.

  Further, in the present embodiment, the case where the X-ray having the desired wavelength is allowed to pass by forming the slit 46 in the shielding member 42 is described as an example, but the slit 46 may be a hole.

The X-ray source may be a synchrotron radiation light source other than the X-ray tube 122 illustrated in this embodiment. In the synchrotron radiation source, hard X-rays are easily generated by inserting a thin X-ray target into the electron storage ring. Since the synchroton radiation source has a thin target, multiple scattering does not occur, and the radiation concentrates sharply forward. The generation of heat is due to the generation of secondary electrons and characteristic X-rays. However, if the target is thin, these radiations are not absorbed by the target and are not converted into heat. Furthermore, if the target is thin, electrons that have not been scattered or decelerated continue to circulate around the storage ring and collide with the target again, resulting in high generation efficiency.
[Second Embodiment]
FIG. 11 shows a configuration example of the X-ray imaging system 200 in the second embodiment. The X-ray imaging system 200 includes an X-ray tube 202 that emits X-rays toward the subject H, an X-ray detector 203 that detects X-rays emitted from the X-ray tube 202 and transmitted through the subject H, and an X-ray. X-rays having a predetermined wavelength from X-rays irradiated from the X-ray tube 202 between the holding unit 204 and the X-ray tube 202 between the holding unit 204 and the X-ray tube 202 are held between the tube 202 and the X-ray detector 203. An X-ray bandpass filter 240 for taking out and an imaging apparatus main body 205 for controlling these parts are provided.

  Examples of the X-ray tube 202 include a Coolidge X-ray tube widely used in medical sites and nondestructive inspection facilities, and a rotating anode X-ray tube. In the rotary anode X-ray tube, X-rays are generated when an electron beam emitted from the cathode collides with the anode. This is incoherent (incoherent) like natural light, and is not divergent X-rays but divergent light. If the electron beam continues to hit the place where the anode is fixed, the anode is damaged by the generation of heat. Therefore, in an X-ray tube that is usually used, the anode is rotated to prevent the anode from being shortened. An electron beam is made to collide with a surface of a certain size of the anode, and the generated X-rays are emitted toward the subject H from the plane of the certain size of the anode. The size of the plane of the anode where X-rays are generated as viewed from the irradiation direction (subject direction) is called a real focus (focus). The focal diameter a (μm) can be measured by a method defined in (2) Measurement of focal dimension by slit camera method in 7.4.1 Focus test of JIS Z 4704-1994. Needless to say, the optional selection conditions in this measurement method can be measured with higher accuracy by selecting the conditions that give the highest accuracy in consideration of the measurement principle in accordance with the properties of the X-ray source.

  A power supply unit 221 (see FIG. 15) for applying a tube voltage and a tube current is connected to the X-ray tube 202.

  The X-ray detector 203 detects the X-rays emitted from the X-ray tube 202 and transmitted through the subject H with the X-ray image detection surface 232, so that the X-ray detector 203 is based on the X-ray irradiation amount for each of the two-dimensionally arranged pixels. An FPD (flat panel detector) that acquires a signal. That is, the X-ray detector 203 is a two-dimensional image sensor arranged on the X-ray image detection surface 232. The pixels 231 of the X-ray detector 203 are arranged in a matrix at a pitch of 70 to 150 μm, for example.

  The holding unit 204 includes a support unit 206 that supports the subject H on the surface on the X-ray tube 202 side, and an X-ray refractive lens array (X-ray optical unit) 207 disposed on the X-ray detector 203 side of the support unit 206. And are stored. The X-ray refractive lens array 207 narrows X-rays transmitted through the subject H to a striped X-ray dose distribution so as to straddle two adjacent pixels 231 among the many pixels 231 of the X-ray detector 203. It has become.

  The X-ray bandpass filter 240 is provided at a position where an X-ray refracting lens 241 that refracts X-rays irradiated from the X-ray tube 202 and an X-ray having a desired wavelength refracted by the X-ray refracting lens 241 is condensed. And an X-ray shielding member 242 having a slit 246.

  A plurality of X-ray refracting lenses 241 are arranged in front of the X-ray tube 202 in the X-ray irradiation direction so as to have a radial shape centering on the X-ray tube 202. Thereby, the X-rays incident on each X-ray refractive lens 241 become substantially parallel X-rays. The shape of the X-ray refractive lens 241 is the same as that of the X-ray refractive lens 41 of the first embodiment.

  The X-ray shielding member 242 is formed of a material that shields X-rays such as lead. The X-ray shielding member 242 is disposed in front of the X-ray irradiation direction of the X-ray refracting lens 241, and a slit 246 is formed at a position facing each lens 241. The X-ray shielding member 242 is arranged at a position where the slit 246 is arranged at a position where X-rays having a desired wavelength (for example, a peak wavelength of characteristic X-rays) are collected among the X-rays condensed on the X-ray refractive lens 241. Has been determined to be.

  12A and 12B are explanatory views showing a schematic configuration of the X-ray refractive lens array 207. FIG. 12A is a front view, and FIG. 12B is a cross-sectional view taken along line AA of FIG. As shown in FIG. 12, the X-ray refracting lens array 207 includes a number of X-ray refracting lenses (second X-ray refracting lenses) having a light collecting power in the horizontal direction on the paper surface of FIG. Lens) 271 is arranged along the horizontal direction at a predetermined period. A plurality of X-ray refractive lenses 271 are stacked in the X-ray optical axis direction. As a result, an X-ray refractive lens group 209 in which a plurality of X-ray refractive lenses 271 are arranged in the X-ray optical axis direction is formed.

  FIG. 13 is a cross-sectional view of one X-ray refractive lens 271. The X-ray refracting lens 271 has a concave curved surface 272 that is recessed toward the X-ray tube 202 side, and X-rays are refracted by the concave curved surface 272. Thereby, each X-ray refracting lens 271 collects the incident X-rays and forms stripes of the X-ray irradiation amount distribution on the X-ray image detection surface 232. As described above, the X-rays are condensed by the X-ray refractive lens array 207, and the striped X-ray irradiation amount discretely arranged on the X-ray detection surface 232, that is, on the X-ray image detector 203. Distribution.

  Here, the installation location of each part will be described. The focal diameter of the X-ray tube 202 is a, the array period of the X-ray refractive lens array 207 in the direction orthogonal to the X-ray optical axis direction is p, and the optical axis of the X-ray tube 202 The distance between the center in the direction and the center in the optical axis direction of the X-ray refractive lens array 207 is R3, and the distance between the lens center in the optical axis direction of the X-ray refractive lens array 207 and the X-ray image detection surface 232 in the X-ray detector 203 When the interval is R4, an X-ray tube 202, an X-ray refractive lens array 207, and an X-ray detector 203 are arranged so as to satisfy the following expression (3).

a × R4 <p × (R3 + R4) (3)
Accordingly, the geometrical sharpness on the X-ray image detection surface 232 due to the focal diameter a of the X-ray tube 122 is an image on the X-ray image detection surface 232 of the X-ray refraction lens 271 with the X-ray tube 202 as the projection center. Since this is smaller than the arrangement period of the X-rays, it falls within the two pixels adjacent to the stripe of the X-ray irradiation distribution by the X-ray refractive lens array 207 and does not significantly affect the pixels adjacent to the adjacent stripe. An image is obtained.

  And while satisfy | filling said Formula (3), as shown in FIG. 11, the stripe S of the X-ray irradiation distribution formed by each X-ray refracting lens 271 spans between the two adjacent pixels 231 in the X-ray detector 203. In addition, an X-ray tube 202, an X-ray refractive lens array 207, an X-ray detector 203, and a subject H are arranged.

  When the X-ray refracting lens array 207 having a condensing function only in the uniaxial direction shown in FIG. 12 is used, (2) Measurement of focal size by the slit camera method in 7.4.1 Focus test of JIS Z 4704-1994 It is preferable that the expression (3) is satisfied, where a (μm) is the focal diameter measured in the arrangement direction of the X-ray refractive lens array 207 by the method defined in the above.

Here, “the stripe S of the X-ray irradiation amount distribution spans between two adjacent pixels” means that a minute region having an irradiation amount that is half or more of the minute region having the maximum irradiation amount in each stripe is referred to as a stripe region. as shown in FIG. 14 (a), in the refraction direction X by the X-ray refraction lens means, fringe area _{S n} is 2 pixels _P n adjacent to the direction X, _m, have across the _{P n + 1, m} In addition, it is within the two pixels P _{n, m} and P _{n + 1, m} and does not extend to the pixels adjacent to the adjacent stripe region S _{n + 2} . This is because an X-ray shielding plate having a slit having a width of 1/3 or less of the pixel size of the X-ray detector in the refraction direction X by the X-ray refractive lens means is 1/3 or less of the pixel size of the X-ray detector. Measurement can be performed by irradiating X-rays under the same conditions as normal X-ray irradiation conditions in the absence of a subject by shifting by a predetermined amount.

On the other hand, as shown in FIG. 14 (b), two adjacent pixels _P n, _{m, P n + 1,} spans one stripe _{S n} to _m, further, other fringe _{S n + 2} is the pixel _{P n + 1, m} When straddling, it does not correspond to “the stripe S of the X-ray dose distribution spans between two adjacent pixels”.

  As shown in FIG. 15, the photographing apparatus main body 205 includes a control device 251 configured by a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). An X-ray detector 203 and a power supply unit 221 are connected to the control device 251 via a bus 252. The control device 251 also includes an input device 224 that includes a keyboard and touch panel (not shown) for inputting shooting conditions, a position adjustment switch for adjusting the position of the holding unit 204, a CRT display, a liquid crystal display, and the like. The display device 225 or the like is connected.

  The ROM of the control device 251 stores a control program and various processing programs for controlling each part of the X-ray imaging apparatus 100, and the CPU cooperates with the control program and various processing programs to obtain an X-ray image. The operation of each part of the imaging apparatus 100 is comprehensively controlled to perform X-ray image imaging.

  For example, the imaging apparatus main body 205 applies a tube voltage and a tube current to the X-ray tube 202 by the power supply unit 221 to irradiate the subject H with radiation, and the amount of radiation incident on the X-ray detector 203 is determined in advance. When the set radiation dose is reached, the power supply unit 221 stops the radiation irradiation from the X-ray tube 202.

  Then, the X-ray detector 203 or the control device 251 corrects variations in offset / gain characteristics of each pixel unique to the X-ray detector 203. Thereafter, with respect to the X-ray image with the offset / gain characteristics corrected, the control device 251 detects the difference between the reference value and the output difference / detection detected by each of the two adjacent pixels 231 in which the stripe S is formed when the subject H is transmitted. The output sum is compared, and a deformation equivalent amount corresponding to the deformation of the stripe S due to the transmission through the subject H is detected. This reference value is the output difference / output sum of the radiation dose detected by each of the two adjacent pixels 231 of the X-ray image when X-ray irradiation is performed when the subject H is not present, and is stored by the control device 251. It is a reference value. That is, the control device 251 is a deformation equivalent amount detection unit according to the present invention. The control device 251 calculates a differential phase image, an absorption image, an absorption image having a phase edge effect, and a phase difference image based on the radiation dose and deformation equivalent amount of each pixel 231 acquired from the X-ray detector 203. That is, the control device 251 is a differential phase image calculation unit, an absorption image calculation unit, a phase difference image calculation unit, and an edge absorption image calculation unit according to the present invention.

  Hereinafter, a method for calculating each image will be described.

  First, FIG. 16 is a diagram illustrating an X-ray irradiation state at the time of imaging. As shown in FIG. 16, when a distance is provided between the subject H and the X-ray detector 203, the X-ray image enlarged with respect to the life size by the X-rays irradiated from the X-ray tube 202 is converted into the X-ray detector. 203 is detected.

  Here, if the inclination angle of the X-ray due to the transmission through the subject H is α and the wavelength of the X-ray is λ, the X-ray phase shift φ of the subject H is expressed by Expression (17).

φ (x, y) = (2π / λ) × ∫δ (x, y, z) dz (17)
Here, δ is a coefficient related to the phase, and is calculated from the complex refractive index n = 1−δ−iβ (β: coefficient related to absorption) of the subject H.

  The relationship between the angle α and the phase shift φ is expressed by Expression (18).

(Α _x , α _y ) = (λ / 2π) × Δφ (x, y) (18)
If either α _x or α _y is detected from the relationship of the equation (18), the X-ray phase shift φ is obtained by integrating it.

  An image based on the radiation detection amount of each pixel 231 before integration is a differential phase image, and an image based on a value obtained by integrating the differential phase image is a phase difference image.

  Specifically, the control device 251 outputs two adjacent pixels 231 in the X-ray detector 203 in order to obtain the displacement amount of the fringes S caused by the transmission of the X-rays through the subject H when the differential phase image is output. The deformation equivalent amount is obtained based on the value corresponding to the ratio between the output difference of the radiation dose and the output sum, and the differential phase image is calculated by passing through the LUT indicating the relationship between the deformation equivalent amount and the differential phase amount. And output to the display device 225.

  In addition, when outputting the phase difference image, the control device 251 calculates the phase difference image by integrating the differential phase image and outputs the phase difference image to the display device 225.

  In addition to the differential phase image calculation method described above, the detection result of each pixel 231 of the X-ray detector 203 based on the X-rays emitted from the X-ray tube 202 without the subject H and the subject H exist. The displacement of the fringes S caused by the X-rays passing through the subject H based on the comparison result with the detection results of the respective pixels 231 of the X-ray detector 203 based on the X-rays passing through the subject H from the X-ray tube 202 in the state. It is also possible to obtain the quantity and calculate the differential phase image.

Figure 17 is an explanatory view showing a displacement of the fringes S _n due to the presence or absence of an object. As shown in FIG. 17, since the stripe _Sn is displaced depending on the presence or absence of the subject _, the signal output values of the adjacent pixels P _{n, m} and P _{n + 1, m} also change. Here, the pixel _P n in the case of no object, _m, the signal output value of the _{P n + 1, m} each _R n, _m, and _{R n + 1, m,} the pixel _P n in the case where there is an object, _{m, P n + 1, m} , S _{n, m} and S _{n + 1, m} respectively, the deformation equivalent amount H _{n, m} by the subject is expressed by equation (19).

H _{n, m} = (S _{n, m} −S _{n + 1, m} ) / (S _{n, m} + S _{n + 1, m} ) − (R _{n, m} −R _{n + 1, m} ) / (R _{n, m} + R _{n + 1, m} ) ... (19)
A differential phase image is obtained by passing an LUT representing the relationship between the deformation equivalent amount and the differential phase amount obtained in advance with respect to the deformation equivalent amount H for each pixel, and the differential phase image is obtained along the X axis. Then, a phase difference image is obtained.

Further, at the time of outputting the absorption image, the control device 251 calculates the absorption image based on a value corresponding to the output sum of the radiation dose between the two adjacent pixels 31 in the X-ray detector 203, and displays it on the display device 225. Output. Specifically, the absorption images K _{n, m} , K _{n + 1, m} are calculated based on the average output between the two pixels P _{n, m} , P _{n + 1, m} according to equations (20), (21).

K _{n, m} = (S _{n, m} + S _{n + 1, m} ) / 2 (20)
K _{n + 1, m} = (S _{n, m} + S _{n + 1, m} ) / 2 (21)
At the time of outputting an absorption image having a phase edge effect, the control device 251 outputs a value corresponding to the output sum of the radiation dose between the adjacent two pixels _{Pn, m 1} , P _{n + 1} , m in the X-ray detector 203. Then, an absorption image having a phase edge effect is calculated from a value corresponding to the ratio of the output difference between the adjacent two pixels P _{n, m} , P _{n + 1} , m and the output sum. Specifically, the signal output E _{n, m} of the pixel P _{n, m} is calculated by Expression (22) _{, and} the signal output E _{n + 1, m} of the pixel P _{n + 1, m} is calculated by Expression (23).
E _{n, m} = (S _{n, m} + S _{n + 1, m} ) / 2 × {1- (S _{n, m} −S _{n + 1, m} ) / (S _{n, m} + S _{n + 1, m} ) + (R _{n, m} − Rn _{+ 1, m} ) / (Rn _{, m} + Rn _{+ 1, m} )} (22)
E _{n + 1, m} = (S _{n, m} + S _{n + 1, m} ) / 2 × {1+ (S _{n, m} −S _{n + 1, m} ) / (S _{n, m} + S _{n + 1, m} ) − (R _{n, m} −R _{n + 1, m} ) / (Rn _{, m} + Rn _{+ 1, m} )} (23)
The calculation flow of these differential phase image, phase difference image, absorption image, and absorption image having the phase edge effect is shown in the data flow diagram of FIG.

  The X-ray imaging 621 is a process of receiving an imaging instruction signal, performing X-ray imaging, and outputting the detected image data in which the X-ray detector 14 gives a specific imaging ID to the detected image data. .

  The detector offset gain correction 622 is performed by the control device 51 of the imaging apparatus main body 5 with respect to the detected image data, in which the variation of the offset / gain characteristics for each pixel of the X-ray detector 14 is specific to the X-ray detector 14. This is a process of correcting and creating detection data after offset / gain correction.

  The operation source image data storage 623 is a process in which the control device 51 stores the offset / gain corrected detection data in the internal storage device as operation source image data.

  The deformation equivalent amount calculation 624 is a process in which the control device 51 calculates deformation equivalent amount image data from the calculation source image data. At this time, for example, as described above, the deformation equivalent image data may be calculated by using the equation (19).

  The differential phase image calculation 625 is a process in which the control device 51 calculates differential phase image data from the deformation equivalent amount image data. At this time, for example, as described above, differential phase image data may be calculated by LUT conversion.

  The differential phase image data storage 626 is a process in which the control device 51 stores the differential phase image data in the internal storage device.

  The ID addition file creation 627 is a process in which the control device 51 assigns an order ID to the differential phase image data stored in the internal storage device, creates a file, and outputs a differential phase image file. At this time, it is preferable to assign the order ID based on the photographing ID and the correspondence relationship between the photographing ID and the order ID because a common order ID is given to images obtained from the same detected image data.

  The differential phase image file storage 628 is a process in which the control device 51 stores the differential phase image file in the storage device.

  The integration process 629 is a process in which the control device 51 performs an integration process on the differential phase image data stored in the internal storage device to calculate phase difference image data. At this time, for example, as described above, the phase difference image data may be obtained by integration along the X axis.

  The storage 530 of the phase difference image data is a process in which the control device 51 stores the phase difference image data in the internal storage device.

The ID addition file creation 631 is a process in which the control device 51 assigns an order ID to the phase difference image data stored in the internal storage device, creates a file, and outputs a phase difference image file. At this time, it is preferable to assign the order ID based on the photographing ID and the correspondence relationship between the photographing ID and the order ID because a common order ID is given to images obtained from the same detected image data.
The phase difference image file saving 631 is a process in which the control device 51 saves the phase difference image file in the storage device.

  The absorption image calculation 633 is a process in which the control device 51 calculates absorption image data from calculation source image data stored in the internal storage device. At this time, for example, as described above, the absorption image data may be calculated by averaging the output signals of the two pixels across which the stripes of the X-ray dose distribution cross.

  The absorption image data storage 634 is a process in which the control device 51 stores the absorption image data in the internal storage device.

  The ID addition file creation 635 is a process in which the control device 51 assigns an order ID to the absorption image data stored in the internal storage device to form a file and outputs an absorption image file. At this time, it is preferable to assign the order ID based on the photographing ID and the correspondence relationship between the photographing ID and the order ID because a common order ID is given to images obtained from the same detected image data.

  The absorption image file storage 636 is a process in which the control device 51 stores the absorption image file in the storage device.

  The absorption image calculation 537 having the phase edge effect is a process in which the control device 51 calculates an absorption image having the phase edge effect from the calculation source image data stored in the internal storage device. At this time, for example, as described above, the absorption image data having the phase edge effect may be calculated using the equations (22) and (23).

  The storage 638 of absorption image data having a phase edge effect is a process in which the control device 51 stores absorption image data having a phase edge effect in the internal storage device.

  In the ID addition file creation 639, the control device 51 assigns an order ID to the absorption image data having the phase edge effect stored in the internal storage device, forms a file, and outputs an absorption image file having the phase edge effect. It is processing. At this time, it is preferable to assign the order ID based on the photographing ID and the correspondence relationship between the photographing ID and the order ID because a common order ID is given to images obtained from the same detected image data.

  The storage 640 of the absorption image file having the phase edge effect is a process in which the control device 51 stores the absorption image file having the phase edge effect in the storage device.

  In the above description, the control device 51 creates the calculation source image data by correcting the offset gain from the detection image data output from the X-ray detector 14, and the differential phase image and the phase difference are calculated from the calculation source image data. An image, an absorption image, and an absorption image having a phase edge effect were calculated, but a differential phase image, a phase difference image, an absorption image, and an absorption having a phase edge effect from a calculation source image data by a console separate from the control device 51. An image may be calculated, and the sharing of calculation and processing is not limited to the above example.

  As described above, according to the present embodiment, X-rays transmitted through the subject H are spread over two adjacent pixels 231 among the many pixels 231 of the X-ray detector 203 by one X-ray refractive lens array 207. Thus, the phase image can be detected with a simple configuration as compared with the Talbot interferometer method that requires at least two diffraction gratings. This makes it possible to capture the boundary between different tissues with a large density difference and between gas and tissue with high contrast, even with a structure that is simpler than the Talbot interferometer method and less X-ray absorption of the subject H. It becomes possible.

  In addition, the bandpass center wavelength is not limited like a bandpass filter using a material having a K edge on the lower wavelength side than the desired wavelength, and the X-ray refraction lens 241, the X-ray shielding member 242, and those Can be made to function as an X-ray bandpass filter 240 having the desired wavelength as the center wavelength of the bandpass. Thereby, X-rays having a desired wavelength can be extracted even with X-rays having a wavelength of 1 mm or less.

  In addition, since the control device 251 calculates the differential phase image based on a value corresponding to the ratio between the output difference between the adjacent two pixels 231 and the output sum, discrete X-rays transmitted through the subject H are discrete. A differential phase image in which the amount of fringe displacement is taken into consideration is calculated.

  Then, since the absorption image is calculated by the control device 251 based on the value corresponding to the output sum between the two adjacent pixels 231, the absorption image can be calculated together with the differential phase image by one shooting.

  Furthermore, the absorption image is calculated by the control device 251 from the value corresponding to the output sum between the two adjacent pixels and the value corresponding to the ratio between the output difference between the two adjacent pixels and the output sum. An absorption image having a phase edge effect as well as a phase image and an absorption image can be calculated by one shooting.

  In addition, since the control device 251 integrates the differential phase image to calculate the phase difference image, the phase difference image can be calculated together with the differential phase image, the absorption image, and the absorption image having the phase edge effect by one shooting. .

  In this embodiment, the display device 225 such as a CRT display or a liquid crystal display has been described as an example of a device that outputs an X-ray image. However, other than this, an X-ray image is printed on a medium such as a film or paper. It may be a print type output device.

  In the present embodiment, the X-ray refractive lens array 207 in which a plurality of X-ray refractive lenses 271 are stacked has been described as an example. For example, as shown in FIG. 21, the X-ray refractive lens 271 has one layer. It may be a line refraction lens array 207A.

  In addition, as shown in FIG. 22, for example, an X-ray refractive lens group 209a is formed by arranging a plurality of X-ray refractive lenses 271b having a curved surface 277 having a circular cross section in the X-ray optical axis direction. Also good.

Further, in the present embodiment, the FPD is exemplified as the X-ray detector 203. However, the X-ray detector 203 according to the present invention is not limited to this, and other than the FPD, for example, stimulable fluorescence. Examples include cassettes that contain body sheets.
[Third embodiment]
In the second embodiment, the X-ray refracting lens array 207 exemplifies the case where the X-rays are focused into discrete stripes. However, as in the third embodiment, the X-rays are reduced. The refractive lens array 207 may narrow X-rays into discrete dots. The third embodiment is the same as the second embodiment except that the X-ray refracting lens array 207 narrows the X-rays into discrete dots and the following changes associated therewith.

  23A and 23B are explanatory diagrams showing an example of an X-ray refractive lens array 207A that narrows X-rays into discrete dots, wherein FIG. 23A is a front view, and FIG. 23B is an RR cross-sectional view of FIG. (C) is QQ sectional drawing of (a). As shown in FIG. 23A, the X-ray refractive lens array 207A has a plurality of X-ray refractive lenses 271a arranged in a matrix. Each X-ray refracting lens 271a has a shape of a parabolic rotator with the X-ray optical axis as the center of rotation, a concave curved surface 272a concaved toward the X-ray tube 202 side, and an X-ray detector 203 side. The concave curved surface 273a is formed to face the concave curved surface 273a, and X-rays are refracted by the concave curved surfaces 272a and 273a. As a result, each X-ray refractive lens 271a collects the incident X-rays to form X-ray irradiation amount distribution dots on the X-ray image detection surface 232.

FIG. 24 is an explanatory diagram showing the displacement of the dots in the X-ray dose distribution depending on the presence or absence of the subject. Here, “the dot of the X-ray dose distribution spans between two adjacent pixels” means that a minute region having a dose that is half or more of the minute region of the maximum dose in each stripe is called a dot region. As shown in FIG. 24, in both the X direction and the Y direction of the refraction direction by the X-ray refractive lens means, the dot area D _{n, m} is 2 pixels adjacent in the X direction × total of 2 pixels adjacent in the Y direction. Four pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P _{n + 1, m + 1} straddle and 4 pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P _{n + 1, m + 1} And the pixel does not extend to pixels adjacent to the adjacent dot areas D _{n + 2, m} , D _{n, m + 2} , D _{n + 2, m + 2} .

  This is because, in both the X direction and the Y direction, an X-ray shielding plate having a hole having a width of 1/3 or less of the pixel size of the X-ray detector is set to a predetermined amount of 1/3 or less of the pixel size of the X-ray detector. The measurement can be performed by irradiating X-rays under the same conditions as the normal X-ray irradiation conditions in the absence of a subject.

As shown in FIG. 24, since the dots of the X-ray irradiation distribution are displaced depending on the presence or absence of the subject, four pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P adjacent to the dots D _{n, m} The signal output values of _{n + 1 and m + 1} will also change. Here, the signal output values of the pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P _{n + 1, m + 1} when there is no subject are respectively R _{n, m} , R _{n + 1, m} , R _{n, m + 1} , R _{n + 1, m + 1} and then, the pixel _P n in the case where there is an _{object, m, P n + 1,} m, P n, m + 1, P n + 1, m + 1 , respectively _S n signal output _{value, m, S n + 1,} m, S n, m + 1 , S _{n + 1, m + 1} , the deformation equivalent amount Hx _{n, m in} the X direction due to the subject and the deformation equivalent amount Hy _{n, m in the} X direction due to the subject are expressed by equations (24) and (25).

Hx _{n, m} = {(S _{n, m} + S _{n, m + 1} ) − ((S _{n + 1, m} + S _{n + 1, m + 1} )} / ((S _{n, m} + S _{n, m + 1} + S _{n + 1, m} + S _{n + 1, m + 1} ) − {(Rn _{, m} + Rn _{, m + 1} )-(Rn _{+ 1, m} + Rn _{+ 1, m + 1} )} / (Rn _{, m} + Rn _{, m + 1} + Rn _{+ 1, m} + Rn _{+ 1, m + 1} ) (24)
Hy _{n, m} = {(S _{n, m} + S _{n + 1, m} ) − (S _{n, m + 1} + S _{n + 1, m + 1} )} / (S _{n, m} + S _{n + 1, m} + S _{n, m + 1} + S _{n + 1, m + 1} ) − {( Rn _{, m} + Rn _{+ 1, m} )-((Rn _{, m + 1} + Rn _{+ 1, m + 1} )} / (Rn _{, m} + Rn _{+ 1, m} + Rn _{, m + 1} + Rn _{+ 1, m + 1} ) (25)
The X-direction deformation equivalent amount Hx _{n, m} and the Y-direction deformation equivalent amount Hy _{n, m with} respect to each pixel represent the relationship between the X-direction deformation equivalent amount and the differential phase amount, which are obtained in advance. By passing the LUT, the LUT representing the relationship between the deformation equivalent amount in the Y direction and the differential phase amount, the differential phase image in the X direction and the differential phase image in the Y direction are obtained. The phase difference image is obtained by integrating along the Y, and the phase difference image is obtained by integrating the differential phase image in the Y direction along the Y axis.

Further, the control device 51 sets the output sum of the radiation dose between the four pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P _{n + 1, m + 1} adjacent to the dot D _{n, m} in the X-ray detector 14. Based on the corresponding values, the absorption images _{Kn, m} , _{Kn + 1, m} , _{Kn, m + 1} , _{Kn + 1, m + 1} are calculated. Specifically, based on the average output H between the four pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P _{n + 1, m + 1} adjacent to the dot D _{n, m} obtained by the equation (25). To calculate an absorption image.

K _{n, m} = K _{n + 1, m} = K _{n, m + 1} = K _{n + 1, m + 1} = (S _{n, m} + S _{n + 1, m} + S _{n, m + 1} + S _{n + 1, m + 1} ) / 4 (26)
Then, the control device 51 sets the output sum of the radiation dose between the four pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P _{n + 1, m + 1} adjacent to the dot D _{n, m} in the X-ray detector 14. From the corresponding value and the value corresponding to the ratio of the output difference between the four pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P _{n + 1, m + 1} adjacent to the dot D _{n, m} and the output sum An absorption image having a phase edge effect is calculated. Specifically, the signal outputs E _{n, m} , E _{n + 1, m} , E _{n, m + 1} , E _{n + 1, m + 1} of the pixels P _{n, m} , P _{n + 1, m} , P _{n, m + 1} , P _{n + 1, m + 1} are _expressed by the formula ( 27) to (30).
E _{n, m} = (S _{n, m} + S _{n + 1, m} + S _{n, m + 1} + S _{n + 1, m + 1} ) / 4 × [1-{(S _{n, m} + S _{n, m + 1} ) − (S _{n + 1, m} + S _{n + 1, m + 1} )} / (S _{n, m} + S _{n, m + 1} + S _{n + 1, m} + S _{n + 1, m + 1} ) − {(R _{n, m} + R _{n, m + 1} ) − (R _{n + 1, m} + R _{n + 1, m + 1} )} / (R _{n, m} + Rn _{, m + 1} + Rn _{+ 1, m} + Rn _{+ 1, m + 1} )] * [1-{( _{Sn, m} + _{Sn + 1, m} )-( _{Sn, m + 1} + _{Sn + 1, m + 1} )} / ( _{Sn, m} + _{Sn + 1) ,} M _{+ Sn, m + 1} + _{Sn + 1, m + 1} )-{(Rn _{, m} + Rn _{+ 1, m} )-(Rn _{, m + 1} + Rn _{+ 1, m + 1} )} / (Rn _{, m} + Rn _{+ 1, m} + Rn _{, m + 1} + R _{n + 1, m + 1} )] ... (27)
E _{n + 1, m} = (S _{n, m} + S _{n + 1, m} + S _{n, m + 1} + S _{n + 1, m + 1} ) / 4 × [1 + {(S _{n, m} + S _{n, m + 1} ) − (S _{n + 1, m} + S _{n + 1, m + 1} ) } / (S _{n, m} + S _{n, m + 1} + S _{n + 1, m} + S _{n + 1, m + 1} ) − {(R _{n, m} + R _{n, m + 1} ) − (R _{n + 1, m} + R _{n + 1, m + 1} )} / (R _{n, m} + R _{n, m + 1} + R _{n + 1, m} + R _{n + 1, m + 1} )] × [1-{(S _{n, m} + S _{n + 1, m} ) − (S _{n, m + 1} + S _{n + 1, m + 1} )} / (S _{n, m} + S _{n + 1, m} + _{Sn, m + 1} + _{Sn + 1, m + 1} )-{(Rn _{, m} + Rn _{+ 1, m} )-(Rn _{, m + 1} + Rn _{+ 1, m + 1} )} / (Rn _{, m} + Rn _{+ 1, m} + Rn _{, m + 1} + Rn _{+ 1) , M + 1} )] (28)
E _{n, m + 1} = (S _{n, m} + S _{n + 1, m} + S _{n, m + 1} + S _{n + 1, m + 1} ) / 4 × [1-{(S _{n, m} + S _{n, m + 1} ) − (S _{n + 1, m} + S _{n + 1, m + 1} )} / ((S _{n, m} + S _{n, m + 1} + S _{n + 1, m} + S _{n + 1, m + 1} ) − {(R _{n, m} + R _{n, m + 1} ) − (R _{n + 1, m} + R _{n + 1, m + 1} )} / (R _{n ,} M + Rn _{, m + 1} + Rn _{+ 1, m} + Rn _{+ 1, m + 1} )] × [1 + {( _{Sn, m} + _{Sn + 1, m} )-( _{Sn, m + 1} + _{Sn + 1, m + 1} )} / ( _{Sn, m} + _{Sn + 1) ,} M _{+ Sn, m + 1} + _{Sn + 1, m + 1} )-{(Rn _{, m} + Rn _{+ 1, m} )-(Rn _{, m + 1} + Rn _{+ 1, m + 1} )} / (Rn _{, m} + Rn _{+ 1, m} + Rn _{, m + 1} + R _{n + 1, m + 1)} ] ··· (29
E _{n + 1, m + 1} = (S _{n, m} + S _{n + 1, m} + S _{n, m + 1} + S _{n + 1, m + 1} ) / 4 × [1 + {(S _{n, m} + S _{n, m + 1} ) − (S _{n + 1, m} + S _{n + 1, m + 1} ) } / (S _{n, m} + S _{n, m + 1} + S _{n + 1, m} + S _{n + 1, m + 1} ) − {(R _{n, m} + R _{n, m + 1} ) − (R _{n + 1, m} + R _{n + 1, m + 1} )} / (R _{n, m} + R _{n, m + 1} + R _{n + 1, m} + R _{n + 1, m + 1} )] × [1 + {(S _{n, m} + S _{n + 1, m} ) − (S _{n, m + 1} + S _{n + 1, m + 1} )} / (S _{n, m} + S _{n + 1, m} + S _{n, m + 1} + S _{n + 1, m + 1} ) − {(R _{n, m} + R _{n + 1, m} ) − (R _{n, m + 1} + R _{n + 1, m + 1} )} / (R _{n, m} + R _{n + 1, m} + R _{n, m + 1} + R _{n + 1, m} + 1)] ··· (3 )
[Fourth embodiment]
In addition to this, as shown in FIG. 25, for example, the X-ray bandpass filter 40B has a plurality of X-ray refractive lenses 41b, and the plurality of X-ray refractive lenses 41b are the actual focal points of the X-ray tubes. On the X-ray image detection surface side of 202, the X-ray tube is arranged so as to have a radial shape centering on the actual focal point 202. A plurality of holes 46b of the X-ray shielding member 42b are formed so as to face the X-ray image detection surface side of each X-ray refractive lens 41, respectively. The positional relationship among the X-ray refracting lens 41b, the X-ray shielding member 42b, and the hole 46b of the X-ray shielding member 42b is as described in the embodiment of the X-ray bandpass filter 40B.

  The many holes 46b of the X-ray shielding member 42b narrow the X-rays radiated toward the X-ray image detection surface into dots, so that the X-rays are formed into discrete dots on the X-ray detector 203. It will be squeezed to become. In this way, even with a structure that is simpler than the Talbot interferometer method and that absorbs less X-rays from the subject H, the contrast between different tissues with a large density difference and the boundary between gas and tissue is high. Can be captured.

[Others]
Although an example of a two-dimensional image sensor disposed on the X-ray image detection surface has been described as an X-ray detector for detecting an X-ray image irradiated on the X-ray image detection surface, the present invention is not limited to this. With an image reading device (CR: computed radiography) that reads the stimulable phosphor sheet placed on the image detection surface, an imaging device that captures the light emission of the phosphor sheet placed on the X-ray image detection surface, etc. There may be other X-ray image detectors as long as they detect an X-ray image irradiated on the X-ray image detection surface.

Claims (20)

An X-ray refractive lens that refracts X-rays;
An X-ray bandpass filter comprising: an X-ray shielding member having a slit or a hole provided at a position where X-rays having a desired wavelength refracted by the X-ray refractive lens are condensed. In the X-ray bandpass filter according to claim 1,
The X-ray shielding member is arranged such that a slit or a hole of the X-ray shielding member is positioned at a position where X-rays of the wavelength refracted by the X-ray refractive lens are condensed for each of a plurality of different desired wavelengths. An X-ray bandpass filter characterized in that it can be moved to In the X-ray bandpass filter according to claim 1 or 2,
The lens diameter D of the X-ray refracting lens and the width d of the slit or hole in a direction parallel to the direction having the refractive power of the X-ray refracting lens orthogonal to the optical axis of the X-ray refracting lens are expressed by the following formula (1). An X-ray bandpass filter characterized by satisfying
d ≦ D / 2 (1) In the X-ray bandpass filter according to any one of claims 1 to 3,
X-rays incident on the X-ray refractive lens are substantially parallel X-rays;
The X-ray bandpass filter, wherein the slit or hole of the X-ray shielding member is positioned in the vicinity of a focal position of an X-ray having a desired wavelength refracted by the X-ray refracting means. In the X-ray bandpass filter according to any one of claims 1 to 3,
X-rays incident on the X-ray refractive lens are X-rays irradiated from an X-ray source having a focal diameter α,
The distance R1 between the focal position of the X-ray source and the lens center of the X-ray refractive lens, the distance R2 between the lens center of the X-ray refractive lens and the slit or hole of the X-ray shielding member, and the slit or hole An X-ray bandpass filter, wherein the width d satisfies the following formula (2).
d ≧ R2 / R1 × α (2) X-ray bandpass filter according to any one of claims 1 to 5,
An X-ray irradiation system comprising: an X-ray source that irradiates the X-ray bandpass filter with X-rays. In the X-ray irradiation system according to claim 6,
The X-ray source has an X-ray generator for generating characteristic X-rays;
An X-ray irradiation system, wherein the X-ray bandpass filter sets a peak wavelength of the characteristic X-ray to a desired wavelength. The X-ray irradiation system according to claim 6 or 7,
An X-ray imaging system comprising: an X-ray image detector that detects X-rays irradiated from the X-ray source and passing through slits or holes of the X-ray shielding member. In the X-ray imaging system according to claim 8,
A subject table for placing the subject;
A first diffraction grating that produces a Talbot effect by diffracting X-rays irradiated from the X-ray source through the object table;
A second diffraction grating that diffracts the X-rays diffracted by the first diffraction grating,
The X-ray imaging system, wherein the X-ray image detector detects X-rays diffracted by the second diffraction grating. In the X-ray imaging system according to claim 9,
An X-ray imaging system, wherein a half-value width of a wavelength distribution of X-rays irradiated by the X-ray source is ¼ or less of a peak wavelength of the X-rays. In the X-ray imaging system according to claim 8,
X-ray optical means for narrowing X-rays generated from the X-ray source so as to have a dot-shaped or striped X-ray irradiation dose distribution discretely arranged on the X-ray image detection surface of the X-ray image detector When,
And a deformation equivalent amount detecting means for detecting a deformation equivalent amount corresponding to the discretely arranged dot-like or stripe-like deformation based on the detection result of the X-ray image detector. X-ray system. In the X-ray imaging system according to claim 11,
The X-ray optical system is an X-ray imaging system, wherein the X-ray optical means is an X-ray refractive lens group in which a plurality of second X-ray refractive lenses are arranged in the X-ray optical axis direction. The X-ray imaging system according to claim 11 or 12,
The X-ray optical means is provided in such a manner that each of a plurality of second X-ray refracting lenses forms a dot or stripe of an X-ray dose distribution on a plane perpendicular to the X-ray optical axis direction. An X-ray imaging system characterized by being an X-ray refractive lens array. The X-ray imaging system according to claim 13,
The focal diameter of the X-ray source is a, the arrangement period of the second X-ray refractive lens in the direction orthogonal to the X-ray optical axis direction is p, the center of the X-ray source and the center of the second X-ray refractive lens And the distance between the lens center of the second X-ray refractive lens and the X-ray image detection surface of the X-ray detector is R4, the following equation (3) is satisfied: X-ray imaging system.
a × R4 <p × (R3 + R4) (3) The X-ray imaging system according to any one of Claims 11 to 14,
The X-ray optical means is a discrete dot so that X-rays emitted from the X-ray source in the absence of a subject may straddle at least two adjacent pixels among the plurality of pixels of the X-ray detector. X-ray imaging system characterized by focusing on a X-ray dose distribution in the form of stripes or stripes. The X-ray imaging system according to claim 15,
An X-ray imaging system comprising differential phase image calculation means for calculating a differential phase image based on a value corresponding to a ratio between an output difference between two adjacent pixels and an output sum in the X-ray detector. . The X-ray imaging system according to claim 16,
The detection result of the X-ray detector based on X-rays emitted from the X-ray source without the subject and the X-rays based on X-rays transmitted from the X-ray source through the subject with the subject present An X-ray imaging system comprising differential phase image calculation means for calculating the differential phase image based on a comparison result with a detection result of a line detector. The X-ray imaging system according to any one of claims 15 to 17,
An X-ray imaging system comprising absorption image calculation means for calculating an absorption image based on a value corresponding to an output sum between the two adjacent pixels in the X-ray detector. The X-ray imaging system according to any one of claims 15 to 17,
An absorption image including a phase edge effect from a value corresponding to the output sum between the two adjacent pixels in the X-ray detector and a value corresponding to a ratio between the output difference between the two adjacent pixels and the output sum. An X-ray imaging system comprising edge absorption image calculation means for calculating The X-ray imaging system according to claim 16 or 17,
An X-ray imaging system comprising phase difference image calculation means for calculating a phase difference image by integrating the differential phase image calculated by the differential phase image calculation means.