Radiation phase difference imaging device

Abstract

The invention provides a radiation phase difference imaging apparatus. The radiation phase difference imaging apparatus includes an X-ray source, a first grating for forming a self-image, a second grating for interfering with the self-image of the first grating, and a moving mechanism for moving a subject mounting table for holding a subject. The movement mechanism is capable of moving the subject mounting table in the X-ray optical axis direction so as to cross the first grating on the X-ray source side of the first grating and on the second grating side of the first grating.

Description

[0001] This application is a divisional application of application No. 201811010609.1, filed on August 31, 2018, entitled "Radiation Phase Difference Photography Device". TECHNICAL FIELD

[0002] The present application relates to a radiation phase difference photography device, and particularly relates to a radiation phase difference photography device that generates a phase contrast image based on a phase shift of X-rays. BACKGROUND

[0003] In the past, a radiation phase difference photography device that generates a phase contrast image based on a phase shift of X-rays is known. Such a radiation phase difference photography device is disclosed in International Publication No. 2009 / 104560, for example.

[0004] An X-ray imaging device (radiation phase difference photography device) is disclosed in International Publication No. 2009 / 104560, which has an X-ray source that generates X-rays, a first grating that diffracts the X-rays generated from the X-ray source, a second grating that further diffracts the X-rays that have been diffracted at the first grating to generate a Moire fringe pattern, and an X-ray image detector (image signal detector) that detects the Moire fringe pattern generated at the second grating. The X-ray imaging device of International Publication No. 2009 / 104560 is configured to perform X-ray imaging by arranging an object between the X-ray source and the first grating, and to generate a phase contrast image based on a phase shift of X-rays that occurs due to the object.

[0005] In the X-ray imaging device of International Publication No. 2009 / 104560, the magnitude of the contrast in the phase contrast image has a negative correlation with the distance of the object from the first grating. Thus, in the X-ray imaging device of International Publication No. 2009 / 104560, the position of the object for which visibility (contrast that can be visually recognized) can be ensured in the phase contrast image is generally limited to a range on the side close to the first grating between the X-ray source and the first grating.

[0006] In the radiation phase difference imaging apparatus of International Publication No. 2009 / 104560, the magnification and reduction rate of the subject in the phase contrast image depends on the distance of the subject from the X-ray source. Thus, in order to change the magnification and reduction rate, it is necessary to change the position of the subject along the optical axis direction of the X-rays between the X-ray source and the image signal detector. However, in the radiation phase difference imaging apparatus of International Publication No. 2009 / 104560, the subject is disposed between the X-ray source and the first grating, and thus the range in which the position of the subject can be changed along the optical axis direction is limited to the X-ray source side of the first grating. Thus, it is considered that there is a problem that, in a case where ensuring visibility in the phase contrast image is assumed as a premise, the range in which the magnification and reduction rate of the subject in the phase contrast image can be changed is easily limited to the range on the side close to the first grating on the X-ray source side of the first grating. SUMMARY

[0007] The present application has been achieved in order to solve the problems as described above, and an object of the present application is to provide a radiation phase difference imaging apparatus capable of ensuring visibility in a phase contrast image while expanding the range in which the magnification and reduction rate of a subject can be changed.

[0008] In order to achieve the above object, a radiation phase difference imaging apparatus of one aspect of the present application includes an image signal generation system including an X-ray source and an image signal detector that detects an image signal based on X-rays irradiated from the X-ray source; a plurality of gratings disposed between the X-ray source and the image signal detector, including a first grating for forming a self-image with the X-rays irradiated from the X-ray source and a second grating for interfering with the self-image of the first grating; an image processing section that generates a phase contrast image based on a phase shift of the X-rays due to a subject disposed between the X-ray source and the image signal detector; a subject placement table for holding the subject; and a moving mechanism that moves the subject placement table to the X-ray source side of the first grating and the second grating side of the first grating along the optical axis direction of the X-rays so as to pass over the first grating.

[0009] In the radiation phase difference imaging apparatus of one aspect of the present application, according to the above-described configuration, the subject placement table can be moved by the moving mechanism toward the X-ray source side of the first grating and the second grating side. Thereby, compared with the configuration in which the position of the subject placement table is changed only on the X-ray source side of the first grating, the range in which the subject placement table can be moved in the optical axis direction can be expanded to the second grating side in addition to the X-ray source side of the first grating. The size of the contrast in the phase contrast image depends on the distance of the subject from the first grating, and therefore, in the case where the subject placement table can be moved toward both the X-ray source side and the second grating side with respect to the first grating, the range in which the contrast is the same level can be ensured on both the X-ray source side and the second grating side of the first grating. As a result, the visibility in the phase contrast image can be ensured while expanding the variable range of the magnification of the subject.

[0010] The radiation phase difference imaging apparatus of the above-described one aspect is preferably configured such that, when the subject placement table is moved in the optical axis direction of the X-ray so as to pass over the first grating, at least one of the subject placement table and the first grating is retreated in a direction different from the optical axis direction to a non-interference position in which the subject does not interfere with the first grating in the optical axis direction. If configured like this, interference between the subject and the first grating can be suppressed when the subject placement table is moved in the optical axis direction of the X-ray so as to pass over the first grating.

[0011] In this case, it is preferable that the direction in which the object table is supported and the direction in which the first grating is supported be different from each other. Here, in a case where the object table and the first grating are supported from the same direction, if the configuration that supports the object table and the configuration that supports the first grating are not moved in a direction orthogonal to each other, the object table or the first grating cannot be retracted to the non-interference position. In contrast, in a case where the object table and the first grating are supported from different directions, by moving the configuration that supports the object table and the configuration that supports the first grating in a direction orthogonal to each other, the object table or the first grating can be retracted to the non-interference position, and in addition, by moving the configuration that supports the object table and the configuration that supports the first grating in a direction away from each other, the object table or the first grating can be retracted to the non-interference position. Thus, compared to a case where the object table and the first grating are supported from the same direction, by supporting the object table and the first grating from different directions, it is possible to be less limited in the arrangement for avoiding interference between the configuration that supports the object table and the configuration that supports the first grating. In addition, in a case where the configuration that supports the object table and the configuration that supports the first grating are moved in a direction away from each other, the object table and the first grating can be retracted in the direction in which they are supported, respectively, and thus a simple device structure can be achieved. As a result, compared to a case where the object table and the first grating are supported from the same direction, it is possible to easily suppress interference between the object and the first grating.

[0012] In the configuration in which at least one of the above-described object table and the first grating is retracted to the non-interference position, the moving mechanism is preferably configured to retract the object table in a direction different from the optical axis direction and to move the object table in the optical axis direction so as to pass over the first grating. If configured as such, the object table can be retracted to the non-interference position and moved in the optical axis direction so as to pass over the first grating by one moving mechanism. As a result, a device structure for moving the object table in the optical axis direction of the X-rays so as to pass over the first grating without interference between the object and the first grating (simplification of the moving mechanism) can be achieved with a small number of components.

[0013] It is preferable that the configuration in which at least one of the above-described object placement table and the first grating is retracted to a non-interference position further includes a retraction mechanism that retracts the first grating in a direction different from the optical axis direction, and the movement mechanism is configured to move the object placement table in the optical axis direction so as to pass over the first grating in a state in which the first grating is retracted to the non-interference position by the retraction mechanism. If configured as such, the retraction mechanism and the movement mechanism can be configured as simple structures that respectively have only a function of retracting the first grating to the non-interference position and a function of moving the first grating in the optical axis direction. As a result, it is possible to suppress the complication of the device configuration, and it is possible to realize a device configuration (simplification of the movement mechanism) for moving the object placement table in the optical axis direction of the X-rays so that the object passes over the first grating without interference with the first grating.

[0014] It is preferable that the configuration including the above-described retraction mechanism further includes a position detection section that detects the position of the object, and the movement mechanism is configured to move the object placement table to a position other than the return position of the first grating retracted by the retraction mechanism, based on the position of the object detected by the position detection section. If configured as such, it is possible to avoid the contact of the first grating with the object when the first grating retracted by the retraction mechanism is returned to the photographing position.

[0015] In the above-described one aspect of the radiographic phase difference photographing device, it is preferable that the movement mechanism is configured to be able to move the object placement table in a first range on the X-ray source side of the first grating and in a second range on the second grating side of the first grating, the distance of the second range with respect to the first grating being equal to the distance of the first range with respect to the first grating. If configured as such, it is possible to include positions in which the contrast in the phase contrast image is equal to each other due to the equal distance from the first grating, in both the first range and the second range. As a result, it is possible to reliably generate a phase contrast image in which the magnification and reduction ratio is changed while the contrast is almost not changed.

[0016] In the above-described one aspect of the radiographic phase difference photographing device, it is preferable that a third grating is further included, the third grating being disposed between the X-ray source and the first grating, for improving the coherence of the X-rays emitted from the X-ray source, and the movement mechanism is configured to be able to move the object placement table in a range from the first grating to the third grating and in a range from the first grating to the second grating in the optical axis direction. If configured as such, in a configuration including the third grating, it is possible to maximize the range in which the object placement table can be moved, between the third grating and the second grating. As a result, in a configuration including the third grating, it is possible to maximize the variable amplitude of the magnification and reduction ratio of the object in the phase contrast image. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1is a schematic view showing the overall structure of a radiographic apparatus according to a first embodiment of the present application.

[0018] Figure 2 is a view showing a case where the subject stand is retreated to a non-interference position in the radiographic apparatus according to the first embodiment.

[0019] Figure 3 is a view showing a case where the subject stand retreated to the non-interference position is moved in the optical axis direction so as to pass the first grating in the radiographic apparatus according to the first embodiment.

[0020] Figure 4 is a view showing a case where the subject stand moved in the optical axis direction so as to pass the first grating is returned to the imaging position in the radiographic apparatus according to the first embodiment.

[0021] Figure 5A is a view for explaining the relationship between the position of a subject and the magnification / contraction rate of a phase contrast image.

[0022] Figure 5B is another view for explaining the relationship between the position of a subject and the magnification / contraction rate of a phase contrast image.

[0023] Figure 6A is a view for explaining the relationship between the position of a subject and the contrast in a phase contrast image in a case where the subject is arranged on the X-ray source side of the first grating.

[0024] Figure 6B is another view for explaining the relationship between the position of a subject and the contrast in a phase contrast image in a case where the subject is arranged on the X-ray source side of the first grating.

[0025] Figure 7A is a view for explaining the relationship between the position of a subject and the contrast in a phase contrast image in a case where the subject is arranged on the second grating side of the first grating.

[0026] Figure 7B is another view for explaining the relationship between the position of a subject and the contrast in a phase contrast image in a case where the subject is arranged on the second grating side of the first grating.

[0027] Figure 8A is a view for explaining the relationship between the magnification / contraction rate of a phase contrast image and the contrast in a phase contrast image.

[0028] Figure 8B is another view for explaining the relationship between the magnification / contraction rate of a phase contrast image and the contrast in a phase contrast image.

[0029] Figure 9 It is a schematic diagram showing the overall structure of a radiation phase difference imaging apparatus according to a second embodiment of the present invention.

[0030] Figure 10 This is a diagram showing a state in which the first grating is retracted to a non-interference position in the radiation phase difference imaging apparatus according to the second embodiment.

[0031] Figure 11 This is a diagram showing a state in which the subject mounting table is moved in the optical axis direction so as to pass over the first grating while the first grating is retracted to the non-interference position in the radiation phase difference imaging apparatus according to the second embodiment.

[0032] Figure 12 This is a diagram showing a state in which the first grating is returned to the imaging position in a state in which the subject mounting table has been moved in the optical axis direction so as to pass over the first grating in the radiation phase difference imaging apparatus according to the second embodiment.

[0033] Figure 13 It is a schematic diagram showing the overall configuration of a radiation phase difference imaging apparatus according to a modified example of the first embodiment of the present invention.

[0034] Figure 14 It is a schematic diagram showing the overall configuration of a radiation phase difference imaging apparatus according to a first modified example of the second embodiment of the present invention.

[0035] Figure 15 It is a schematic diagram showing the overall configuration of a radiation phase difference imaging apparatus according to a second modified example of the second embodiment of the present invention. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0037] [First embodiment]

[0038] Reference Figure 1 The structure of the X-ray phase imaging device 100 according to the first embodiment of the present invention will be described. The X-ray phase imaging device 100 is an example of a "radiation phase difference imaging device" in the patent claims.

[0039] (Structure of X-ray Phase Imaging Device)

[0040] like Figure 1 As shown, the X-ray phase imaging device 100 includes an image signal generating system 10 including an X-ray source 11 and an image signal detector 12, a plurality of gratings including a first grating G1 and a second grating G2, a control unit 21, a subject mounting table 30, a moving mechanism 40 and a grating holding unit 50.

[0041] In the X-ray phase imaging apparatus 100, the X-ray source 11, the first grating G1, the second grating G2, and the image signal detector 12 are arranged in this order in the irradiation axis direction (optical axis direction, Z direction) of the X-rays. That is, the first grating G1 and the second grating G2 are arranged between the X-ray source 11 and the image signal detector 12. Further, in the present specification, a horizontal direction orthogonal to the optical axis direction of the X-rays and a vertical direction are set as the X direction and the Y direction, respectively.

[0042] The X-ray source 11 generates X-rays by applying a high voltage. The X-ray source 11 is configured to irradiate the generated X-rays in a microfocus.

[0043] The first grating G1 is a diffraction grating (phase grating) that changes the phase of the passing X-rays. The first grating G1 has slits G1a and X-ray absorbing portions G1b arranged in a prescribed period (grating pitch) d1 in the Y direction. Each of the slits G1a and the X-ray absorbing portions G1b is formed so as to extend in the X direction.

[0044] The first grating G1 is arranged between the X-ray source 11 and the second grating G2, and is provided in order to form a self-image by the X-rays irradiated from the X-ray source 11 (by Talbot effect). Further, the Talbot effect refers to an effect in which, when X-rays having coherence pass through a grating in which slits are formed, an image (self-image) of the grating is formed at a position at a prescribed distance (Talbot distance) from the grating.

[0045] The second grating G2 has a plurality of slits G2a and X-ray absorbing portions G2b arranged in a prescribed period (grating pitch) d2 in the Y direction. Each of the slits G2a and the X-ray absorbing portions G2b is formed so as to extend in the X direction.

[0046] The second grating G2 is arranged between the first grating G1 and the image signal detector 12, and is provided in order to interfere with the self-image formed by the first grating G1. The second grating G2 is arranged at a position at a Talbot distance from the first grating G1 so that the self-image interferes with the second grating G2.

[0047] The image signal detector 12 detects the X-rays irradiated from the X-ray source 11, and converts the detected X-rays into an electric signal. The image signal detector 12 is, for example, an FPD (Flat Panel Detector). The image signal detector 12 is configured from a plurality of conversion elements (not shown) and pixel electrodes (not shown) arranged on the plurality of conversion elements. The plurality of conversion elements and the pixel electrodes are arranged in a prescribed period (pixel pitch) in the X direction and the Y direction. The detection signal (image signal) of the image signal detector 12 is sent to an image processing section 21a included in the control section 21.

[0048] The control unit 21 has an image processing unit 21a capable of generating an X-ray image. In addition, the control unit 21 is configured to control the operation of the moving mechanism 40. The control unit 21 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.

[0049] The image processing unit 21a is configured to generate a phase contrast image based on a detection signal transmitted from the image signal detector 12. The image processing unit 21a includes, for example, a GPU (Graphics Processing Unit), a processor configured as an FPGA (Field-Programmable Gate Array) for image processing, and the like. The phase contrast image is a general term for images captured using the first grating G1 and the second grating G2, and includes, for example, at least one of an absorption image, a phase differential image, and a dark field image. The absorption image is an X-ray image obtained by imaging a difference in the degree of absorption of X-rays by the subject T. The phase differential image is an X-ray image obtained by imaging a shift in the phase of X-rays. The dark field image is a visibility image obtained from a change in visibility based on small-angle scattering of an object. In addition, the dark field image is also referred to as a small-angle scattering image. The "visibility" refers to the sharpness.

[0050] The phase contrast image is generated based on a signal intensity variation curve of X-rays in a case where at least one of the first grating G1 and the second grating G2 is translated in the direction of the pitch of the gratings (Y direction). Specifically, by using the principle that X-rays that have passed through the subject T are refracted, the size of the shift in the phase of the signal intensity variation curve of X-rays in a case where the subject T is arranged with respect to the signal intensity variation curve of X-rays in a case where the subject T is not arranged is imaged, and thus a phase differential image is generated. The difference between the detection intensity of X-rays (included in the signal intensity variation curve) in a case where the subject T is arranged and the detection intensity of X-rays (included in the signal intensity variation curve) in a case where the subject T is not arranged is imaged, and thus an absorption image is generated. The size of the reduction (loss) in the amplitude of the signal intensity variation curve of X-rays in a case where the subject T is arranged with respect to the amplitude of the signal intensity variation curve of X-rays in a case where the subject T is not arranged is imaged, and thus a dark field image is generated.

[0051] The subject placing table 30 has a placing surface 30a capable of holding the subject T. The subject placing table 30 can also have, for example, a chuck mechanism, a holding mechanism, and the like of the subject placing table 30, which are not shown. In addition, the subject placing table 30 is configured to be supported by the moving mechanism 40 from the lower side (Yl direction) in the vertical direction orthogonal to the optical axis direction.

[0052] The moving mechanism 40 is configured to be capable of moving the subject placing table 30 in the optical axis direction (Z direction). The moving mechanism 40 has a movable base portion 41, a linear motion mechanism 42, and a driving portion 43.

[0053] The movable base portion 41 is configured to be disposed below the subject placing table 30 to support the subject placing table 30. That is, the movable base portion 41 is configured to move in the optical axis direction together with the subject placing table 30. In addition, the movable base portion 41 is configured to be capable of moving in the optical axis direction between the X-ray source 11 and the second grating G2.

[0054] The linear motion mechanism 42 is a linear motion mechanism for moving the movable base portion 41 together with the subject placing table in the optical axis direction. The linear motion mechanism 42 includes a shaft portion 42a, a moving portion 42b, and a power input portion 42c.

[0055] The linear motion mechanism 42 is a ball screw mechanism. That is, the shaft portion 42a is a ball screw shaft extending in the optical axis direction for moving the moving portion 42b in the optical axis direction. The moving portion 42b is a ball nut screwed with the shaft portion 42a and is fixed to the movable base portion 41. The power input portion 42c transmits power input from the driving portion 43 to the shaft portion 42a to rotate the shaft portion 42a.

[0056] The driving portion 43 is configured to input power directly to the power input portion 42c or to input power to the power input portion 42c via a driving transmission portion, which is not shown. The driving portion 43 is, for example, a motor such as a servo motor or a step motor. The operation of the driving portion 43 is controlled by the control portion 21.

[0057] The grating holding portion 50 has a grating holding portion 51 holding the first grating G1 and a grating holding portion 52 holding the second grating G2. The first grating G1 and the second grating G2 are configured to be supported by the grating holding portion 51 and the grating holding portion 52, respectively, from the upper side (Y2 direction) in the vertical direction orthogonal to the optical axis direction. That is, in the first embodiment, the direction (Yl direction) in which the subject placing table 30 is supported and the direction (Y2 direction) in which the first grating G1 is supported are different from each other.

[0058] According to the above structure, in the X-ray phase imaging device 100, the moving mechanism 40 can be used to move the subject mounting table 30 holding the subject T in the imaging position P1 (within the irradiation range 90 of the X-ray) and along the optical axis within the range RM1 between the X-ray source 11 and the first grating G1.

[0059] (Structure for moving the subject mounting table in the optical axis direction so as to cross the first grating)

[0060] In the first embodiment, the subject stage 30 is configured to be movable along the optical axis so as to pass over the first grating G1. Furthermore, when the subject stage 30 is moved along the optical axis between the X-ray source and the first grating G1, it is necessary to prevent the subject T and the subject stage 30 from interfering with the X-ray source 11 or the first grating.

[0061] Here, refer to Figure 1 A description will be given of a configuration for moving the subject mounting table 30 in the optical axis direction (Z direction) so as to cross the first grating G1 without causing interference.

[0062] like Figure 1 As shown, the moving mechanism 40 further includes a linear motion mechanism 44 and a driving unit 45 .

[0063] The direct-acting mechanism 44 is a direct-acting mechanism (elevating mechanism) for moving the subject stage 30 in a vertical direction (Y direction) perpendicular to the optical axis direction. The direct-acting mechanism 44 includes a shaft portion 44a, a moving portion 44b, and a power input portion 44c.

[0064] Similar to the direct-acting mechanism 42, the direct-acting mechanism 44 is a ball screw mechanism. Specifically, the shaft 44a is a ball screw shaft extending in the vertical direction, which is used to move the movable portion 44b in the vertical direction. The movable portion 44b is a ball nut threadedly engaged with the shaft 44a and is fixed to the subject mounting platform 30. The power input portion 44c is fixed to the movable base portion 41 and transmits power input from the drive portion 45 to the shaft 44a, causing the shaft 44a to rotate.

[0065] The drive unit 45 is configured to input power directly to the power input unit 44c or to input power to the power input unit 44c via a drive transmission unit (not shown). The drive unit 45 is, for example, a servo motor, a stepping motor, or other motor. The operation of the drive unit 45 is controlled by the control unit 21.

[0066] According to the above structure, in the X-ray phase imaging device 100, the moving mechanism 40 can be used to move the subject stage 30 in the vertical direction (Y direction) perpendicular to the optical axis direction. In addition, the moving mechanism 40 is configured to move the subject stage 30 from the imaging position P1 in the Y1 direction to a position where the subject T and the subject stage 30 do not overlap (intersect) with the first grating G1 when viewed from the optical axis direction. That is, in the first embodiment, the X-ray phase imaging device 100 is configured so that when the subject stage 30 is moved in the optical axis direction (Z direction) of the X-ray so as to pass over the first grating G1, the subject stage 30 is retreated in a direction different from the optical axis direction (Y1 direction) to a non-interference position P2 where the subject T and the first grating G1 do not interfere with each other in the optical axis direction.

[0067] (Movement of the subject mounting stage along the optical axis so as to cross the first grating)

[0068] Next, refer to Figures 2-4 The operation of moving the subject mounting platform 30 in the optical axis direction so as to pass over the first grating G1 will be described. Figure 1 In addition, the current position of the subject T is as follows Figure 1 In this way, it is located between the X-ray source 11 and the first grating G1 in the Z direction.

[0069] First, if Figure 2 As shown, the control unit 21 controls the moving mechanism 40 to retract the subject T and the subject mounting platform 30 at the photographing position P1 to the non-interference position P2. Specifically, the control unit 21 drives the driving unit 45 to use the direct-acting mechanism 44 to move the subject mounting platform 30, which holds the subject T, in the Y1 direction by a predetermined distance (amount P1-P2) required for the subject T to retract to the non-interference position P2.

[0070] Then, if Figure 3 As shown, the control unit 21 controls the moving mechanism 40 to move the subject T and the subject mounting stage 30 along the optical axis so that the subject T passes over the first grating G1 while the subject T is at the non-interference position P2. Specifically, the control unit 21 drives the drive unit 43 to use the direct-acting mechanism 42 to move the subject mounting stage 30, which holds the subject T, in the Z2 direction by a predetermined distance (required for the subject T to pass over the first grating G1 along the optical axis).

[0071] Then, if Figure 4As shown, the control section 21 controls the moving mechanism 40 to return the subject T, which is present between the first grating G1 and the second grating G2 and is present in the non-interference position P2, to the photographing position PI. Specifically, the control section 21 causes the driving section 45 to drive to move the subject mount 30, which holds the subject T, in the Y2 direction (by the amount of (P2-PI)) by the direct driving mechanism 44 (by the amount required for the subject T to return to the photographing position PI).

[0072] As described above, in the first embodiment, the moving mechanism 40 retreats the subject mount 30 to the non-interference position P2 in the direction (Yl direction) different from the optical axis direction (Z direction) and moves the subject mount 30 in the optical axis direction (Z direction) so as to pass over the first grating G1.

[0073] Thus, in the X-ray phase imaging apparatus 100, in addition to being able to move the subject mount 30, which holds the subject T, in the optical axis direction within the range RM1 between the X-ray source 11 and the first grating G1 by the moving mechanism 40, it is also possible to move the subject mount 30, which holds the subject T, in the optical axis direction within the range RM2 (refer to Figure 4 ) between the first grating G1 and the second grating G2 by the moving mechanism 40. Further, the distance of the X-ray source 11 from the first grating G1 and the distance of the first grating G1 from the second grating G2 depend on the grating pitch dl of the first grating G1 and the grating pitch d2 of the second grating G2, and thus the sizes of the range RM1 and the range RM2 are not limited to being substantially equal distances as depicted in the figures.

[0074] (Relationship between position of subject and magnification / reduction rate of phase contrast image)

[0075] Next, the relationship between the position of the subject T between the X-ray source 11 and the image signal detector 12 and the magnification / reduction rate of the phase contrast image will be described with reference to FIG. 5 and FIG. 8.

[0076] As shown in FIG. 5, in the case where the subject T is disposed at a position at a distance LI from the X-ray source 11, the size of the subject T in the Y direction as detected by the image signal detector 12 is HI. In contrast, as shown in FIG. 8, in the case where the subject T is disposed at a position at a distance L2 (which is smaller than the distance LI) from the X-ray source 11, the size of the subject T (in the Y direction) as detected by the image signal detector 12 is H2 (which is larger than HI). Figure 5A Figure 5B

[0077] ​​That is, by bringing the subject T closer to the X-ray source 11 side (Z1 side), the subject T in the phase contrast image can be enlarged. In addition, by bringing the subject T closer to the image signal detector 12 side (Z2 side), the subject T in the phase contrast image can be reduced. In addition, in FIG5 , an example of arranging the subject T between the first grating G1 and the second grating G2 is not shown, but the properties related to the enlargement and reduction of the subject T are the same as those in the case of arranging the subject T between the X-ray source 11 and the first grating G1. Therefore, as Figure 8A As shown, in the X-ray phase imaging apparatus 100 , the magnification in the phase contrast image is negatively correlated with the distance from the X-ray source 11 to the subject T in the optical axis direction.

[0078] (Relationship between the Position of the Subject and the Contrast in the Phase Contrast Image)

[0079] Next, the relationship between the position of the subject T between the X-ray source 11 and the image signal detector 12 and the contrast in the phase contrast image will be described with reference to FIG. 6 to FIG. 8 .

[0080] exist Figure 6A and Figure 6B In FIG, the subject T is arranged between the X-ray source 11 and the first grating G1. Figure 7A and Figure 7B In FIG. 1 , the subject T is arranged between the first grating G1 and the second grating G2. Figure 6A 、 Figure 6B 、 Figure 7A as well as Figure 7B In FIG, the solid line shows the X-ray when the subject T is arranged, and the dashed line shows the X-ray when the subject T is not arranged. Figure 6A 、 Figure 6B 、 Figure 7A as well as Figure 7B , it is shown that X-rays (solid lines) irradiated to the same position of the subject T are refracted at a predetermined angle.

[0081] like Figure 6A As shown, when the subject T is arranged at a position offset by a distance GL1 from the first grating G1 toward the X-ray source 11 side (Z1 side), the position reached by the X-rays that have passed through the first grating G1 is offset by an offset amount D1 between the case where the subject T is arranged and the case where the subject T is not arranged. Figure 6BAs shown, when the subject T is configured at a position offset by a distance GL2 (larger than the distance GL1) from the first grating G1 toward the X-ray source 11 side (Z1 side), the position reached by the X-rays passing through the first grating G1 is offset by an offset D2 (smaller than the offset D1) between the case where the subject T is configured and the case where the subject T is not configured.

[0082] like Figure 7A As shown, when the subject T is arranged at a position offset by a distance GL1 from the first grating G1 to the second grating G2 side (Z2 side), the position reached by the X-rays that have passed through the first grating G1 is offset by an offset amount D1 between the case where the subject T is arranged and the case where the subject T is not arranged. Figure 7B As shown, when the subject T is configured at a position offset by a distance GL2 from the first grating G1 to the second grating G2 side (Z2 side), the position reached by the X-rays passing through the first grating G1 is offset by an offset amount D2 between the case where the subject T is configured and the case where the subject T is not configured.

[0083] That is, whether the subject T is arranged on the side of the X-ray source 11 or on the side of the second grating G2, the phase shift of the X-rays generated by the subject T becomes larger by bringing the subject T closer to the first grating G1 (reducing the distance between the subject T and the first grating G1). On the other hand, the phase shift of the X-rays generated by the subject T becomes smaller by moving the subject T away from the first grating G1 (increasing the distance between the subject T and the first grating G1). Therefore, as Figure 8B As shown, the magnitude of the X-ray phase shift (the contrast in the phase contrast image) is negatively correlated with the distance between the subject T and the first grating G1 .

[0084] (Relationship between the magnification ratio of a phase contrast image and the contrast in the phase contrast image)

[0085] In addition, if Figure 8B As shown, on both the X-ray source 11 side of the first grating G1 and the second grating G2 side, the contrast in the phase contrast image has a negative correlation with the distance from the first grating G1 at the same ratio. Specifically, the contrast when the subject T is positioned at a distance GL from the first grating G1 on the X-ray source 11 side of the first grating G1 is approximately equal to the contrast when the subject T is positioned at a distance GL from the first grating G1 on the second grating G2 side of the first grating G1.

[0086] Here, in the X-ray phase imaging apparatus 100, as described above, the subject T can be moved in the optical axis direction within the range RM1 between the photographing position PI and the range RM1 between the X-ray source 11 and the first grating Gl and the range RM2 between the first grating Gl and the second grating G2. Thus, in the first embodiment, within the range of the range RM1 and the range RM2, the subject placement table 30 can be moved within a first range R1 on the X-ray source 11 side of the first grating Gl and a second range R2 on the second grating G2 side of the first grating Gl, the distance GL of the second range R2 from the first grating Gl being equal to the distance GL of the first range R1 from the first grating Gl.

[0087] Thus, in the first embodiment, the positions on both the X-ray source 11 side and the second grating G2 side of the first grating Gl that have a phase contrast in the phase contrast image that is substantially equal to each other due to the distance GL from the first grating Gl being equal. That is, in the X-ray phase imaging apparatus 100, photographing of the subject T can be performed at two positions that are within the range RM1 and the range RM2 and have a distance GL from the first grating Gl that is equal. As a result, in the X-ray phase imaging apparatus 100, X-ray images of two magnifications can be captured with substantially equal contrast. In addition, as shown in FIG. 8, in the X-ray phase imaging apparatus 100, the magnification can be changed within a range corresponding to the variation in the contrast with respect to the distance GL and within a range corresponding to 2 x GL. Further, the widths of the first range R1 and the second range R2 are determined by the distance GL from the first grating Gl that depends on the contrast of the subject T. In addition, the widths of the first range R1 and the second range R2 are each not more than the range RM1 and the range RM2.

[0088] (EFFECTS OF THE FIRST EMBODIMENT)

[0089] In the first embodiment, the following effects can be obtained.

[0090] In the first embodiment, as described above, the X-ray phase imaging apparatus 100 is provided with the moving mechanism 40 that moves the subject placement stage 30 that holds the subject T. The moving mechanism 40 is capable of moving the subject placement stage 30 to the X-ray source 11 side (Z1 side) of the first grating G1 and the second grating G2 side (Z2 side) of the first grating G1. Thereby, compared with a structure that changes the position of the subject placement stage 30 only on the X-ray source 11 side of the first grating G1, it is possible to expand the range in which the subject placement stage 30 is capable of moving in the optical axis direction (Z axis direction) to the second grating G2 side of the first grating G1 in addition to the X-ray source 11 side of the first grating G1. Since the size of the contrast in the phase contrast image depends on the distance of the subject T from the first grating G1, in the case where the subject placement stage 30 is capable of moving to both the X-ray source 11 side and the second grating G2 side of the first grating G1, it is possible to secure a range in which the contrast is the same level on both the X-ray source 11 side and the second grating G2 side of the first grating G1. As a result, it is possible to secure visibility in the phase contrast image while expanding the variable range of the magnification of the subject T.

[0091] Further, in the first embodiment, as described above, the X-ray phase imaging apparatus 100 is configured such that, when the subject placement stage 30 is moved in the optical axis direction (Z direction) of the X-rays so as to pass over the first grating G1, the subject placement stage 30 is retracted to a non-interference position P2 in which the subject T does not interfere with the first grating G1 in the optical axis direction, in a direction different from the optical axis direction (Y1 direction). Thereby, it is possible to suppress interference between the subject T and the first grating G1 when the subject placement stage 30 is moved in the optical axis direction of the X-rays so as to pass over the first grating G1.

[0092] Further, in the first embodiment, as described above, the X-ray phase imaging apparatus 100 is configured such that the direction (Y1 direction) in which the subject placement stage 30 is supported and the direction (Y2 direction) in which the first grating G1 is supported are different from each other. Thereby, compared with a case where the subject placement stage 30 and the first grating G1 are supported from the same direction, by supporting the subject placement stage 30 and the first grating G1 from different directions, it is less likely to be limited by the arrangement for avoiding interference between the configuration that supports the subject placement stage 30 (the moving mechanism 40) and the configuration that supports the first grating G1 (the grating holding portion 51). Further, by moving the configuration that supports the subject placement stage 30 and the configuration that supports the first grating G1 in directions away from each other, it is possible to retract the subject placement stage 30 in the direction in which it is supported, and thus it is possible to realize a simple apparatus structure. As a result, compared with a case where the subject placement stage 30 and the first grating G1 are supported from the same direction, it is possible to easily suppress interference between the subject T and the first grating G1.

[0093] Furthermore, in the first embodiment, as described above, the X-ray phase imaging apparatus 100 is configured such that the moving mechanism 40 retracts the subject stage 30 in a direction (Y1 direction) different from the optical axis direction (Z direction) and moves the subject stage 30 along the optical axis so as to pass over the first grating G1. Thus, a single moving mechanism 40 can be used to retract the subject stage 30 to the non-interference position P2 and move the subject stage 30 along the optical axis so as to pass over the first grating G1. As a result, a device structure (simplification of the moving mechanism 40) can be implemented with a small number of components to move the subject stage 30 along the optical axis of X-rays so as to pass over the first grating G1 without interfering with the subject T.

[0094] Furthermore, in the first embodiment, as described above, the X-ray phase imaging apparatus 100 is configured such that the moving mechanism 40 can move the subject stage 30 within a first range R1 on the X-ray source 11 side of the first grating G1 and a second range R2 on the second grating G2 side of the first grating G1. The distance GL of the second range R2 from the first grating G1 is equal to the distance of the first range R1 from the first grating G1. This allows both the first range R1 and the second range R2 to include positions where the contrast in the phase contrast image is equal due to the equal distance GL from the first grating G1. As a result, phase contrast images can be reliably generated in which the magnification ratio is changed while the contrast remains unchanged.

[0095] [Second embodiment]

[0096] Next, refer to Figures 9-12 The second embodiment will be described. In the example described in this second embodiment, unlike the X-ray phase imaging apparatus 100 of the first embodiment, which includes a moving mechanism 40 for both moving the subject mounting table 30 along the optical axis (Z direction) and retreating to the non-interference position P2, a mechanism for retreating to the non-interference position P3 is provided separately from the moving mechanism 240 of the subject mounting table 30. In the figures, identical components to those of the first embodiment are denoted by the same reference numerals.

[0097] (Structure of X-ray Phase Imaging Apparatus)

[0098] like Figure 9 As shown, the X-ray phase imaging device 200 according to the second embodiment of the present invention includes a moving mechanism 240, a retracting mechanism 60, a control unit 221, and a position detection unit 23. The X-ray phase imaging device 200 is an example of a "radiation phase difference imaging device" in the patent claims.

[0099] Like the moving mechanism 40 of the X-ray phase imaging apparatus 100 of the first embodiment, the moving mechanism 240 is configured to be able to move the subject placement table 30 in the optical axis direction (Z direction). On the other hand, unlike the moving mechanism 40 of the X-ray phase imaging apparatus 100 of the first embodiment, the moving mechanism 240 is not provided with a structure for retreating the subject placement table 30 to the non-interference position P3. That is, the moving mechanism 240 is a structure obtained by deleting the direct drive mechanism 42 and the driving section 43 from the moving mechanism 40 of the X-ray phase imaging apparatus 100 of the first embodiment.

[0100] The retreat mechanism 60 is a structure for retreating the first grating G1 to the non-interference position P3. That is, the retreat mechanism 60 is provided in order to move the subject placement table 30 in the optical axis direction so as to pass over the first grating G1. The retreat mechanism 60 has a suspension section 61, a direct drive mechanism 62, and a driving section 63.

[0101] The suspension section 61 is configured to be fixed to the direct drive mechanism 62 and to suspend the first grating G1 and the second grating G2 from the Y2 direction side.

[0102] The direct drive mechanism 62 is a direct drive mechanism (elevation mechanism) for moving the first grating G1 and the second grating G2 in the vertical direction (Y direction) orthogonal to the optical axis direction. The direct drive mechanism 62 includes a shaft section 62a, a moving section 62b, and a power input section 62c.

[0103] Like the direct drive mechanisms 42 and 44 of the X-ray phase imaging apparatus 100 of the first embodiment, the direct drive mechanism 62 is a ball screw mechanism. That is, the shaft section 62a is a ball screw shaft extending in the vertical direction, for moving the moving section 62b in the vertical direction. The moving section 62b is a ball nut screwing with the shaft section 62a, and is fixed to the suspension section 61. The power input section 62c transmits power input from the driving section 63 to the shaft section 62a to rotate the shaft section 62a.

[0104] The driving section 63 is configured to input power directly to the power input section 62c or to input power to the power input section 62c via a not-illustrated drive transmission section. The driving section 63 is, for example, a motor such as a servo motor or a step motor. The operation of the driving section 63 is controlled by the control section 221.

[0105] The control section 221 is configured to control the operation of the moving mechanism 240 and the retreat mechanism 60. In addition, the control section 221 is configured to perform control to stop the operation of the retreat mechanism 60 on the basis of a signal transmitted from the position detection section 23.

[0106] The position detection unit 23 is configured to detect the position of the subject T along the optical axis. When the first grating G1 returns from the non-interference position P3 to the imaging position P1, if the subject T is positioned at the desired return position, the position detection unit 23 outputs a signal to the control unit 221 to stop the operation of the retraction mechanism 60. This allows the movement mechanism 240 to move the subject stage 30 to a position other than the return position of the first grating G1, which has been retracted by the retraction mechanism 60. The position detection unit 23 includes, for example, an optical sensor such as an infrared sensor, an image sensor (camera), and the like.

[0107] According to the above structure, in the X-ray phase imaging device 200, the first grating G1 can be moved in the vertical direction (Y direction) perpendicular to the optical axis direction using the retraction mechanism 60. In addition, the retraction mechanism 60 is configured to move the first grating G1 in the Y2 direction to a position where the first grating G1 does not overlap (intersect) with the subject T and the subject mounting table 30 when viewed from the optical axis direction. That is, in the second embodiment, the X-ray phase imaging device 200 is configured so that when the subject mounting table 30 is moved in the optical axis direction (Z direction) of the X-ray so as to pass over the first grating G1, the first grating G1 is retracted in a direction different from the optical axis direction (Y2 direction) to a non-interference position P3 where the subject T and the first grating G1 do not interfere with each other in the optical axis direction.

[0108] (Movement of the subject mounting stage along the optical axis so as to cross the first grating)

[0109] Next, refer to Figures 10-12 The operation of moving the subject mounting platform 30 in the optical axis direction so as to pass over the first grating G1 will be described. Figure 9 In addition, the current position of the subject T is as follows Figure 9 In this way, it is located between the X-ray source 11 and the first grating G1 in the Z direction.

[0110] First, if Figure 10 As shown, the control unit 221 controls the retraction mechanism 60 to retract the first grating G1 at the imaging position P1 to the non-interference position P3. Specifically, the control unit 221 drives the drive unit 63 to move the first grating G1 held by the grating holding unit 51 in the Y2 direction by a predetermined distance (amount P1-P3) required for the first grating G1 to retract to the non-interference position P3 using the direct-acting mechanism 62.

[0111] Then, if Figure 11As shown, the control section 221 controls the moving mechanism 240 to move the subject T and the subject placement stage 30 in a manner to pass over the first grating G1 in a state where the first grating G1 is in the non-interference position P3. Specifically, the control section 221 causes the driving section 43 to drive to move the subject placement stage 30 holding the subject T in the Z2 direction (a prescribed distance required for the subject T to pass over the first grating G1 in the optical axis direction) by the direct drive mechanism 42.

[0112] Then, as shown in FIG. 6, the control section 221 controls the moving mechanism 40 to move the subject placement stage 30 in a manner to pass over the first grating G1 in a state where the first grating G1 is in the non-interference position P3. Figure 12 As shown, the control section 221 controls the retreat mechanism 60 to return the first grating G1, which is on the X-ray source 11 side (Z1 side) of the subject placement stage 30 and in the non-interference position P3, to the photographing position P1 in the optical axis direction. Specifically, the control section 221 causes the driving section 63 to drive to move the first grating G1 held by the grating holding section 51 in the Y1 direction (a prescribed distance (an amount of P3-P1) required for the first grating G1 to return to the photographing position P1) by the direct drive mechanism 62.

[0113] As described above, in the second embodiment, the moving mechanism 40 moves the subject placement stage 30 in a manner to pass over the first grating G1 in a state where the first grating G1 is retreated to the non-interference position P3 by the retreat mechanism 60.

[0114] Further, the other structures of the second embodiment are the same as those of the above-described first embodiment.

[0115] (Effects of the second embodiment)

[0116] In the second embodiment, the following effects can be obtained.

[0117] In the second embodiment, as described above, the X-ray phase imaging apparatus 200 is provided with the moving mechanism 240 that moves the subject placement stage 30 holding the subject T. The moving mechanism 240 can move the subject placement stage 30 to the X-ray source 11 side (Z1 side) of the first grating G1 and the second grating G2 side (Z2 side) of the first grating G1. Thereby, as with the X-ray phase imaging apparatus 100 of the first embodiment, it is possible to expand the variable range of the magnification and reduction rate of the subject T while ensuring the visibility in the phase contrast image.

[0118] Further, in the second embodiment, as described above, the X-ray phase imaging apparatus 200 is configured to, when the subject placement table 30 is moved in the optical axis direction (Z direction) of the X-rays so as to pass over the first grating G1, cause the first grating G1 to retreat to the non-interference position P3 in which the subject T does not interfere with the first grating G1 in the optical axis direction, in a direction different from the optical axis direction (Y2 direction). Thus, as with the X-ray phase imaging apparatus 100 of the first embodiment, it is possible to suppress interference between the subject T and the first grating G1 when the subject placement table 30 is moved in the optical axis direction of the X-rays so as to pass over the first grating G1.

[0119] Further, in the second embodiment, as described above, the X-ray phase imaging apparatus 200 includes the retreat mechanism 60 that retreats the first grating G1 in a direction different from the optical axis direction (Z direction) (Y2 direction). The movement mechanism 240 is configured to move the subject placement table 30 in the optical axis direction so as to pass over the first grating G1, in a state in which the first grating G1 is retreated to the non-interference position by the retreat mechanism 60. Thus, it is possible to configure the retreat mechanism 60 and the movement mechanism 240 as simple structures that each have only a function of retreating the first grating G1 to the non-interference position P3 and a function of moving the first grating G1 in the optical axis direction. As a result, it is possible to suppress complication of the apparatus structure, and to realize an apparatus structure (simplification of the movement mechanism) for moving the subject placement table 30 in the optical axis direction of the X-rays so as to pass over the first grating G1 without interference between the subject T and the first grating G1.

[0120] Further, in the second embodiment, as described above, the X-ray phase imaging apparatus 200 further includes the position detection section 23 that detects the position of the subject T. The movement mechanism 240 is configured to move the subject placement table 30 to a position other than the return position of the first grating G1 that is retreated by the retreat mechanism 60, on the basis of the position of the subject T detected by the position detection section 23. Thus, it is possible to avoid contact between the first grating G1 and the subject T and the subject placement table 30 when the first grating G1 that is retreated by the retreat mechanism 60 is returned to the imaging position P1.

[0121] Further, the other effects of the second embodiment are the same as those of the first embodiment described above.

[0122] [Modifications]

[0123] The embodiments disclosed this time are thus illustrative and not restrictive in all aspects. The scope of the application is shown not by the above description of the embodiments, but by the claims, and includes all modifications (modifications) within the meaning and range equivalent to the claims.

[0124] For example, in the first embodiment described above, an example is shown in which the subject placement table 30 is configured to retreat in the Yl direction to a non-interference position P2 at which the subject T and the first grating G1 do not interfere in the optical axis direction, but the present application is not limited to this. In the present application, the subject placement table can be configured to retreat in the Y2 direction, or the subject placement table can be configured to retreat in the X direction.

[0125] In addition, in the second embodiment described above, an example is shown in which the first grating G1 is configured to retreat in the Y2 direction to a non-interference position P3 at which the subject T and the first grating G1 do not interfere in the optical axis direction, but the present application is not limited to this. In the present application, the subject placement table can be configured to retreat in the Yl direction, or the subject placement table can be configured to retreat in the X direction.

[0126] In addition, in the first embodiment described above, the direction in which the subject placement table 30 is supported and the direction in which the subject placement table 30 is retreated are set to the same direction (the Yl direction), but the present application is not limited to this. In the present application, the direction in which the subject placement table is supported and the direction in which the subject placement table is retreated can be set to different directions.

[0127] In addition, in the second embodiment described above, the direction in which the first grating G1 is supported and the direction in which the first grating G1 is retreated are set to the same direction (the Y2 direction), but the present application is not limited to this. In the present application, the direction in which the first grating is supported and the direction in which the first grating is retreated can be set to different directions.

[0128] In addition, in the first embodiment described above, the subject placement table 30 is configured to retreat using the moving mechanism 40, and in the second embodiment described above, an example is shown in which the first grating G1 is configured to retreat using the retreat mechanism 60, but the present application is not limited to this. In the present application, both a structure in which the subject placement table is configured to retreat using the moving mechanism of the first embodiment described above and a structure in which the first grating is configured to retreat using the retreat mechanism of the second embodiment described above can be provided.

[0129] In addition, in the first embodiment described above and the second embodiment described above, an example is shown in which the direct motion mechanisms 42, 44, and 62 are configured as ball screw mechanisms, but the present application is not limited to this. In the present application, as long as the direct motion mechanism is a mechanism for linear motion in a prescribed direction, it can be configured as, for example, a pulley mechanism, a rack and pinion mechanism, or the like.

[0130] Further, in the first embodiment and the second embodiment described above, an example in which the subject table 30 is configured to be movable within a first range R1 on the X-ray source 11 side (Z1 side) of the first grating G1 and a second range R2 on the second grating G2 side (Z2 side) of the first grating G1, and the distance GL of the second range R2 from the first grating G1 is substantially equal to the distance of the first range R1 from the first grating G1, is shown, but the present application is not limited to this. In the present application, the range in which the subject table 30 is movable can be different between the X-ray source 11 side (Z1 side) of the first grating G1 and the second grating G2 side (Z2 side) of the first grating G1.

[0131] Further, in the first embodiment and the second embodiment described above, an example in which the subject table 30 is configured to be movable within a first range R1 on the X-ray source 11 side (Z1 side) of the first grating G1 and a second range R2 on the second grating G2 side (Z2 side) of the first grating G1, and the distance GL of the second range R2 from the first grating G1 is substantially equal to the distance of the first range R1 from the first grating G1, is shown, but the present application is not limited to this. In the present application, the range in which the subject table 30 is movable can be different between the X-ray source 11 side (Z1 side) of the first grating G1 and the second grating G2 side (Z2 side) of the first grating G1. Figure 13 Figure 14 Further, in the first embodiment and the second embodiment described above, an example in which the subject table 30 is configured to be movable within a first range R1 on the X-ray source 11 side (Z1 side) of the first grating G1 and a second range R2 on the second grating G2 side (Z2 side) of the first grating G1, and the distance GL of the second range R2 from the first grating G1 is substantially equal to the distance of the first range R1 from the first grating G1, is shown, but the present application is not limited to this. In the present application, the range in which the subject table 30 is movable can be different between the X-ray source 11 side (Z1 side) of the first grating G1 and the second grating G2 side (Z2 side) of the first grating G1.

[0132] Further, in the first embodiment and the second embodiment described above, an example in which the subject table 30 is configured to be movable within a first range R1 on the X-ray source 11 side (Z1 side) of the first grating G1 and a second range R2 on the second grating G2 side (Z2 side) of the first grating G1, and the distance GL of the second range R2 from the first grating G1 is substantially equal to the distance of the first range R1 from the first grating G1, is shown, but the present application is not limited to this. In the present application, the range in which the subject table 30 is movable can be different between the X-ray source 11 side (Z1 side) of the first grating G1 and the second grating G2 side (Z2 side) of the first grating G1.

[0133] ​The X-ray phase imaging apparatus 400 has the third grating G3 and the grating holding section 350 including the grating holding section 53 in addition to the structure of the X-ray phase imaging apparatus 200. In addition, the X-ray phase imaging apparatus 400 differs from the X-ray phase imaging apparatus 200 in that the retreat mechanism 460 including the suspension section 461 capable of suspending the third grating G3 in addition to the first grating G1 and the second grating G2 is provided. Further, in the X-ray phase imaging apparatus 400 of the first modification of the second embodiment, as with the X-ray phase imaging apparatus 300 of the modification of the first embodiment, the subject placement table 30 is capable of moving in the optical axis direction within the range RM3 between the X-ray source 11 and the first grating G1 and between the first grating G1 and the third grating G3.

[0134] In addition, in the above-described second embodiment, an example in which the first grating G1 and the second grating G2 are caused to move in the Y2 direction by the retreat mechanism 60 is shown, but the present application is not limited thereto. In the present application, as with the X-ray phase imaging apparatus 500 of the second modification of the second embodiment shown in Figure 15 Further, the X-ray phase imaging apparatus 500 is an example of the "radiation phase difference photographing apparatus" of the patent claim.

[0135] The X-ray phase imaging apparatus 500 differs from the X-ray phase imaging apparatus 200 provided with the retreat mechanism 60 including the suspension section 61 for suspending the grating holding section 51 and the grating holding section 52 in that the retreat mechanism 560 including the suspension section 561 is provided. The suspension section 561 is configured to suspend only the grating holding section 51 of the grating holding sections 51 and 52 for holding the first grating G1 and the grating holding section 52 for holding the second grating G2.

[0136] In addition, in the above-described second embodiment, an example in which the first grating G1 is caused to retreat to the non-interference position P3 when the subject placement table 30 is caused to move in the optical axis direction (Z direction) of the X-ray so as to pass over the first grating G1 is shown, but the present application is not limited thereto. In the present application, it is also possible to simultaneously use as a structure of an apparatus configured to generate an absorption image based on the intensity of the X-ray in a state in which the grating is caused to retreat by the retreat mechanism.

[0137] Further, in the first embodiment and the second embodiment described above, an example in which the first grating G1 is provided as a phase grating to form a self-image using Talbot effect is shown, but the present application is not limited to this. In the present application, the self-image can be a fringe pattern, and an absorption grating can be used instead of the phase grating. When the absorption grating is used, a region that simply generates a fringe pattern according to an optical condition such as a distance (non-interferometer) and a region that generates a self-image using Talbot effect (interferometer) are generated.

[0138] Further, in the first embodiment and the second embodiment described above, an example in which the first grating G1 has slits G1a and X-ray absorbing portions G1b arranged in a prescribed period (grating pitch) d1 in the Y direction, and each of the slits G1a and the X-ray absorbing portions G1b is formed to extend in the X direction is shown, but the present application is not limited to this. In the present application, the first grating G1 can have slits and X-ray absorbing portions arranged in a prescribed period (grating pitch) in the X direction, and each of the slits and the X-ray absorbing portions can be formed to extend in the Y direction.

[0139] Further, in the first embodiment and the second embodiment described above, an example in which the second grating G2 has slits G2a and X-ray absorbing portions G2b arranged in a prescribed period (grating pitch) d2 in the Y direction, and each of the slits G2a and the X-ray absorbing portions G2b is formed to extend in the X direction is shown, but the present application is not limited to this. In the present application, the second grating G2 can have slits and X-ray absorbing portions arranged in a prescribed period (grating pitch) in the X direction, and each of the slits and the X-ray absorbing portions can be formed to extend in the Y direction.

Claims

1. A radiographic phase-contrast imaging device comprising: an image signal generating system including an X-ray source and an image signal detector for detecting an image signal based on X-rays irradiated from the X-ray source; a plurality of gratings, the plurality of gratings being arranged between the X-ray source and the image signal detector, and including a first grating for forming a self-image using X-rays emitted from the X-ray source, and a second grating for interfering with the self-image of the first grating; an image processing unit that generates a phase contrast image based on a phase shift of X-rays caused by a subject disposed between the X-ray source and the image signal detector; a subject placement table for holding the subject; and A moving mechanism moves the object mounting table to the X-ray source side of the first grating and the second grating side of the first grating along the optical axis direction of X-rays so as to cross the first grating.

2. The radiation phase contrast imaging device according to claim 1, wherein: The radiation phase difference photography device is configured such that, when the subject mounting table is moved along the optical axis direction in a manner that passes over the first grating, at least one of the subject mounting table and the first grating is retreated along a direction different from the optical axis direction to a non-interference position where the subject and the first grating do not interfere with each other in the optical axis direction.

3. The radiation phase contrast imaging device according to claim 2, wherein: The radiation phase difference imaging device is configured such that a direction in which the subject mounting table is supported and a direction in which the first grating is supported are different from each other.

4. The radiation phase contrast imaging device according to claim 2 or 3, wherein: The moving mechanism is configured to retract the subject mounting table in a direction different from the optical axis direction and move the subject mounting table in the optical axis direction so as to pass over the first grating.

5. The radiation phase contrast imaging device according to claim 2, wherein: further comprising a retraction mechanism for retracting the first grating in a direction different from the optical axis direction, The moving mechanism is configured to move the subject mounting table in the optical axis direction so as to pass over the first grating in a state where the first grating is retracted to the non-interference position by the retraction mechanism.

6. The radiation phase contrast imaging device according to claim 5, wherein: further comprising a position detection unit for detecting the position of the subject, The moving mechanism is configured to move the subject mounting table to a position other than a return position of the first grating retracted by the retraction mechanism, based on the position of the subject detected by the position detection unit.

7. The radiation phase contrast imaging device according to claim 1, wherein: The moving mechanism is configured to move the object mounting table within a first range on the X-ray source side of the first grating and a second range on the second grating side of the first grating, wherein the distance of the second range relative to the first grating is equal to the distance of the first range relative to the first grating.

8. The radiation phase contrast imaging device according to claim 1, wherein: further comprising a third grating disposed between the X-ray source and the first grating for improving the coherence of the X-rays emitted from the X-ray source, The moving mechanism is configured to be able to move the subject mounting table along the optical axis direction within a range from the first grating to the third grating and within a range from the first grating to the second grating.

Images