JP6424760B2 - Radiation phase contrast imaging device - Google Patents

Description

  The present invention relates to a radiation phase contrast imaging apparatus for imaging the internal structure of an object using phase differences of radiation transmitted through the object, and more particularly to a radiation phase contrast imaging apparatus of a type for performing scan imaging.

  Conventionally, various devices have been conceived as radiation imaging apparatuses that transmit radiation to an object to image the internal structure of the object. As a general thing of such a radiography apparatus, radiation is irradiated to an object and a projection image of radiation is taken by passing an object. In such a projected image, shading appears depending on the ease of passing radiation, which represents the internal structure of the object.

  With such a radiation imaging apparatus, only an object having the property of absorbing radiation to some extent can be imaged. For example, living soft tissues absorb little radiation. Even if such a tissue is photographed by a common device, almost nothing is reflected in the projected image. When it is going to image the internal structure of the object which does not absorb radiation in this way, in a general radiography apparatus, there are limits in principle.

  Then, the radiation phase contrast imaging device which images the internal structure of an object using the phase difference of penetrating radiation has been devised. Such devices use Talbot interference to image the internal structure of an object.

  FIG. 17 illustrates a radiation phase contrast imaging apparatus. The radiation phase contrast imaging apparatus includes a radiation source for emitting radiation, a multi-slit for aligning the phases of the radiation, a phase grating having a streak-like pattern, and a detector for detecting the radiation. In the apparatus shown in FIG. 17, the subject is arranged at a position sandwiched between the phase grating and the detector. In the multi-slit, longitudinally elongated slits are arranged in the lateral direction. The phase grating is configured by arranging in the lateral direction shield lines extending in the longitudinal direction, which are hard to transmit radiation.

  The principle of the radiation phase contrast imaging apparatus will be briefly described. When the phase grating is irradiated with the in-phase radiation, a self-image of the phase grating appears at a position separated from the phase grating by a specific distance (Talbo distance). The detector is adjusted in position with the phase grating so that the self-image is reflected. This self-image looks like the shadow of the phase grating is reflected. However, it should be noted that the self-image is an interference pattern generated by the interference of radiation and is not a simple projection.

  When an object is placed between the phase grating and the detector, radiation emitted from the phase grating will be transmitted through the object before being detected by the detector. At this time, the self image appearing on the detector is slightly disturbed by transmitting the object. This disturbance is caused by the phase shift while the radiation passes through the subject.

  By detecting the disturbed self-image with the detector and subjecting the self-image to predetermined image processing, it is possible to generate an image showing the distribution of the phase difference of the radiation transmitted through the subject. Such an image is called a fluoroscopic image. According to the radiation phase contrast imaging apparatus, even if the subject does not absorb radiation, a fluoroscopic image representing the internal structure of the subject can be generated.

  Detectors used in radiation phase contrast imaging devices are expensive. This is because it is necessary to miniaturize the detection element in order to capture the self-image in a very fine pattern. The self-image is a striped pattern, and dark lines are arranged, but the arrangement pitch of the dark lines can not be freely changed. A self-image is an image produced by the interference of light. Therefore, the arrangement pitch of the shielding lines arranged in the phase grating is determined by the wavelength of the radiation. Considering the necessity of transmitting the subject, the wavelength of the radiation needs to be set quite short, and accordingly, the arrangement pitch of the shielding lines in the phase grating becomes small. Therefore, the arrangement pitch of the dark lines of the self image also becomes narrow. In order to detect such a fine image, a detector with high spatial resolution is required. Such detectors are very expensive.

  Therefore, devices have been devised to perform scan imaging so that the detector can be small. That is, as shown in FIG. 18, a self image is to be taken by performing a plurality of photographings while moving the detector with respect to the subject. According to FIG. 18, the detector is too small to fit all of the subjects in the field of view in one shooting. However, the size of the detector can be reduced if, for example, three shots are taken while moving the detector, and the fragments of the three self images obtained at this time are joined together to obtain one self image. Even in this case, it is possible to obtain a self-image of the absorption grating over the entire subject. The smaller the size of the detector, the lower the cost of manufacturing the device.

  However, in the configuration as shown in FIG. 18, unnecessary exposure to the subject occurs. The spread of radiation output from the radiation source is so broad that the radiation can reach the entire area of the subject. However, as shown in FIG. 18, in the case of scan shooting, since the entire region of the subject can not be shot at one time, shooting is performed in three divided steps. For example, in the case of the first imaging, as shown in FIG. 19, the radiation necessary for imaging the self-image is only the radiation which spreads downward from the radiation source and is incident on the detector. The radiation emanating from the indicated radiation source upward in the figure is not detected by the detector. Therefore, the radiation indicated by oblique lines is a so-called useless radiation that is emitted to the subject without contributing to imaging. Such useless radiation should be avoided when the subject has physical properties that deteriorate due to radiation or when the subject is a living body.

  In order to avoid irradiating the subject with unnecessary radiation at the time of scan imaging, it is sufficient to provide a collimator that absorbs the radiation (see, for example, Patent Document 1).

  In addition, even if it is not scan imaging | photography, it may be better to provide a collimator. There are cases where it is desirable to provide a mode in which only a part of the subject is photographed. In such a case, it is better to provide a collimator so that radiation does not impinge on parts not relevant to imaging.

JP 2012-24339 A

However, the device according to the conventional configuration has the following problems.
That is, the apparatus configuration to provide the collimator becomes complicated.

  FIG. 20 explains the problems that arise when trying to provide a collimator in the conventional device. In the case of scan shooting, continuous shooting is performed while moving the detector with respect to the subject, but the path of the radiation beam required at the time of shooting differs for each shooting. That is, in the first imaging, the radiation must be irradiated to pass under the subject, and in the second imaging, the radiation must be irradiated to pass through the center of the subject. Then, in the third imaging, radiation must be emitted to pass through the upper side of the subject.

  That is, when it is going to provide a collimator in the apparatus which concerns on scan imaging | photography, the mechanism which moves a collimator interlockingly with a detector is needed. In FIGS. 17 to 20, there is a large space between the phase grating and the detector, and it seems easy to newly provide a movable collimator. However, in practice, it is quite difficult to provide a moving collimator. Each figure is drawn so that there is a considerable margin between the phase grating and the detector, but this is for the purpose of making the explanation easy to understand, and in the actual device, the phase grating and the detection It is not always so far from the vessel. Also, the positional relationship between the radiation source, the multi-slit, the phase grating, and the detector is strictly defined. Unless these configurations are in a fixed positional relationship, a self-image of the phase grating does not occur on the detector. It is quite difficult to newly provide a movable collimator despite such positional limitations.

  The same problem occurs even when it is desired to shoot only a part of the subject instead of scan shooting. That is, when radiation is applied to a part of the subject for imaging, it may be desirable to limit the spread of the radiation. To achieve this limitation, it is again necessary to provide the device with a collimator. The collimator needs to be mobile. If the collimator is fixed, the imaging range of the subject can not be changed. However, as described above, it is quite difficult to newly provide a movable collimator in the device.

  The present invention has been made in view of such circumstances, and an object thereof is to realize a movable collimator with a simple mechanism in a radiation phase contrast imaging apparatus.

The present invention has the following configuration in order to solve the above-mentioned problems.
That is, the radiation phase contrast imaging apparatus according to the present invention comprises: (A) a radiation source for irradiating radiation; And a unit that is integrated as one unit with a collimator that restricts A grating and a detector for detecting the self-image of the (D) phase grating are provided in this order, and the unit in a direction orthogonal to the radiation direction of the object located between the (E) unit and the detector. It also has a unit moving mechanism for changing the position where the radiation collimated by the unit is incident on the subject by moving the It is.

[Operation and Effect] According to the present invention, a movable collimator can be provided in the radiation phase contrast imaging apparatus simply by providing a simple mechanism. That is, according to the present invention, the collimator and the multi-slit are integrated. Therefore, when moving the collimator of the present invention, the multi slit also moves following.
According to conventional technical common sense, the multi-slit of the conventional configuration is configured to be fixed in the apparatus. It is because the necessity of moving the multi slit has not been found. The inventor of the present invention has conceived of a configuration in which a collimator and a multi-slit are integrated. According to the configuration of the present invention, the device configuration is much simpler than providing the collimator in the device independently of the multi-slit. On the other hand, even when the multi-slit is moved, no problem occurs in photographing.

  Further, in the above-described radiation phase contrast imaging apparatus, the radiation source is integrated into the unit, and it is more desirable that the unit moving mechanism moves the multi slit, the collimator and the radiation source integrally.

  [Operation and Effect] According to the above configuration, the positional relationship between the radiation source and the collimator is maintained. Therefore, when the collimator is moved relative to the subject, the radiation source also moves following the collimator. Then, regardless of the movement of the collimator, radiation will always be emitted from the direction orthogonal to the collimator. In this way, it is possible to always shoot an object with a strong dose.

  The radiation phase contrast imaging apparatus according to the present invention transmits radiation while (A) a radiation source for emitting radiation and (C1) a longitudinally extending absorber for absorbing radiation are arranged in the lateral direction. A unit formed by integrating a phase grating that causes light and Talbot interference and a collimator that limits the spread of radiation is integrated, and (D) a detector that detects a self image of the phase grating is provided in this order. , (E) A unit movement for changing the position where radiation collimated by the unit is incident on the subject by moving the unit in a direction perpendicular to the irradiation direction of the radiation with respect to the subject positioned between the unit and the detector It is characterized by having a mechanism.

[Operation and Effect] The present invention can also be realized by integrating the phase grating and the collimator. That is, according to the present invention, the collimator and the phase grating are integrated. Therefore, when moving the collimator of the present invention, the phase grating also moves following.
According to conventional technical common sense, the phase grating of the conventional configuration is configured to be fixed in the apparatus. This is because the necessity of moving the phase grating has not been found. The inventor of the present invention has conceived of a configuration in which a collimator and a phase grating are integrated. The arrangement according to the invention is much simpler than the arrangement provided in the device independently of the phase grating. On the other hand, even when the phase grating is moved, no problem occurs in imaging.

  Further, in the above-described radiation phase contrast imaging apparatus, it is more preferable if a multi-slit is provided between the radiation source and the unit to align the phases of the radiation by transmitting the radiation generated from the radiation source.

  [Operation and Effect] The above-described configuration shows a more specific configuration of the present invention. Even when the collimator and the phase grating are integrated, an apparatus configuration provided with a multi-slit can be employed.

  In the above-described radiation phase difference imaging apparatus, a detector moving mechanism for moving the detector in a direction orthogonal to the irradiation direction of the radiation in synchronization with the movement of the unit, and continuous shooting while moving the unit and the detector It would be more desirable to have an image combining unit that stitch together the multiple images to produce a single image.

  [Operation and Effect] The above-described configuration shows a more specific configuration of the present invention. By moving the detector, the detector can be made smaller. This is because it is possible to capture a self-image of the phase grating over a wide range by performing scan imaging.

  In the above-described radiation phase contrast imaging apparatus, it is more desirable if an absorption grating, in which longitudinally extending absorbers that absorb radiation are arranged in the horizontal direction, is provided to cover the radiation incident surface of the detector. .

  [Operation and Effect] The above-described configuration shows a more specific configuration of the present invention. If the absorption grating is provided to cover the radiation incident surface of the detector, it is possible to image the self-image of the phase grating even if the spatial resolution of the detector is low.

  According to the present invention, a movable collimator can be provided in a radiation phase contrast imaging apparatus simply by providing a simple mechanism. According to conventional technical common sense, the multi-slit of the conventional configuration is configured to be fixed in the apparatus. It is because the necessity of moving the multi slit has not been found. The inventor of the present invention has conceived of a configuration in which a collimator and a multi-slit are integrated. According to the configuration of the present invention, the device configuration is much simpler than providing the collimator in the device independently of the multi-slit. On the other hand, even when the multi-slit is moved, no problem occurs in photographing.

FIG. 1 is a functional block diagram illustrating an entire configuration of an X-ray phase contrast imaging apparatus according to a first embodiment. FIG. 6 is a schematic view illustrating scan imaging according to the first embodiment. FIG. 5 is a schematic view for explaining the positional relationship of each part constituting the device of the first embodiment. FIG. 7 is a schematic view illustrating movement of each unit at the time of scan photographing according to the first embodiment; It is a schematic diagram explaining the positional relationship of each part which comprises the apparatus which concerns on one modification of this invention. It is a schematic diagram explaining movement of each part at the time of scan photography concerning one modification of the present invention. It is a schematic diagram explaining the advantage which one modification of this invention has. It is a schematic diagram explaining the advantage which one modification of this invention has. It is a schematic diagram explaining the positional relationship of each part which comprises the apparatus which concerns on one modification of this invention. It is a schematic diagram explaining the positional relationship of each part which comprises the apparatus which concerns on one modification of this invention. It is a schematic diagram explaining the positional relationship of each part which comprises the apparatus which concerns on one modification of this invention. It is a schematic diagram explaining movement of each part at the time of scan photography concerning one modification of the present invention. It is a schematic diagram explaining the advantage which one modification of this invention has. It is a schematic diagram explaining the positional relationship of each part which comprises the apparatus which concerns on one modification of this invention. It is a schematic diagram explaining the positional relationship of each part which comprises the apparatus which concerns on one modification of this invention. It is a schematic diagram explaining the positional relationship of each part which comprises the apparatus which concerns on one modification of this invention. It is a schematic diagram explaining the structure of the radiation phase contrast imaging device of a conventional structure. It is a schematic diagram explaining the structure of the radiation phase contrast imaging device of a conventional structure. It is a schematic diagram explaining the structure of the radiation phase contrast imaging device of a conventional structure. It is a schematic diagram explaining the problem of the radiation phase contrast imaging device of conventional composition.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. X-rays correspond to radiation according to the invention and FPD stands for flat panel detector.

  FIG. 1 shows the overall configuration of an X-ray phase contrast imaging apparatus 1 according to the present invention. The configuration of the X-ray phase contrast imaging apparatus according to the present invention is, as shown in FIG. 1, a mounting table 2 on which an object M is to be mounted, an X-ray source 3 for irradiating X-rays toward the mounting table 2, and mounting And an FPD 4 for detecting X-rays transmitted through the table 2. The X-ray source 3 emits X-rays toward the lower side of the drawing of FIG. At this time, the irradiated X-ray is a beam having a certain extent of spread. The FPD 4 is provided with a detection surface that detects X-rays. The FPD 4 has an elongated shape. The paper surface penetrating direction in FIG. 1 corresponds to the longitudinal direction of the FPD 4, and the paper surface left-right direction corresponds to the lateral direction of the FPD 4. The FPD 4 detects a self-image of the phase grating 5 described later. FPD 4 corresponds to the detector of the present invention.

  Various components relating to Talbot interference are attached between the X-ray source 3 and the mounting table 2. In the vicinity of the X-ray source 3, a multi-slit S for aligning the phase of the X-ray is provided. The multi-slit S is made of a material that does not transmit X-rays, and elongated through holes are arranged in the lateral direction in the longitudinal direction. Therefore, a part of X-rays incident on the multi-slit S can pass through the multi-slit S through the through holes. When X-rays are transmitted through the multi-slit S, the phases of the X-rays whose phases are broken are aligned, and the coherence of the X-rays is enhanced. The multi slit S is configured to align the phases of the X-rays by transmitting the X-rays generated from the X-ray source 3.

  A phase grating 5 is provided between the X-ray source 3 and the mounting table 2 separately from the multi-slit S. The phase grating 5 is configured by arranging linear absorbers extending in the lateral direction in the longitudinal direction. This absorber has the property of absorbing X-rays. Therefore, when X-rays are transmitted to the phase grating 5, the X-rays incident on the absorber are absorbed there, and the X-rays incident between the two absorbers are transmitted as they are. A self-image representing the pattern of the phase grating 5 is projected onto the FPD 4. It should be noted that this self-image is not merely a projection image of the phase grating 5. The self-image is an interference pattern generated on the FPD 4 by X-rays interfered by the phase grating 5. The self image is detected by the FPD 4. The extending direction of the absorber corresponds to the left and right direction in the drawing of FIG. The phase grating 5 has a configuration in which longitudinally extending absorbers that absorb X-rays are arranged in the horizontal direction and Talbot interference occurs when transmitting X-rays.

  The self-image image generation unit 11 generates a self-image image obtained by imaging the self-image of the phase grating 5 based on the X-ray detection data output from the FPD 4. The self-image image is a reflection of the stripe pattern of the phase grating 5. This self-image is sent to the fluoroscopic image generator 12. The fluoroscopic image generation unit 12 interprets the disturbance of the stripe pattern on the self-image image to generate a fluoroscopic image in which the phase shift of the X-ray is imaged. In the fluoroscopic image, the phase shift of the X-ray different depending on the location of the subject M is visualized, and the internal structure of the subject M is shown. The self-image image generation unit 11 connects a plurality of images obtained by continuous shooting while moving the multi slit S (moving units C and S described later) and the FPD 4 to generate a single image. The self-image image generation unit 11 corresponds to the image combination unit of the present invention.

  The X-ray source 3, the multi-slit S (moving units C and S described later), the phase grating 5, the mounting table 2 and the FPD 4 are arranged in this order. In the case of FIG. 1, the mounting table 2 is provided between the phase grating 5 and the FPD 4, but the mounting table 2 may be provided between the multi-slit S and the phase grating 5. In any case, the positional relationship between the X-ray source 3, the multi-slit S, the phase grating 5 and the FPD 4 is determined relatively strictly. This is because, in order to generate a self-image of the phase grating 5 on the detection surface of the FPD 4, these components must have a predetermined positional relationship.

  The collimator C is made of a material that does not transmit X-rays, and has an elongated window. X-rays can pass through the collimator C through this window. The collimator C may seem to be configured similar to the multi-slit S, but there are the following differences. The multi-slit S has a plurality of through holes arranged therein, whereas the collimator C has only a single window. Further, while the through holes of the multi slit S have a width of several μm, the width of the window of the collimator C (the width in the direction orthogonal to the longitudinal direction) is large, 0.1 mm to several tens mm It is an extent. The window of the collimator C conforms to the shape of the FPD 4. The paper surface penetration direction in FIG. 1 corresponds to the longitudinal direction of the window, and the paper surface left-right direction corresponds to the lateral direction of the window. The collimator C is configured to limit X-rays not to be directed to the object M among unnecessary X-rays of the X-ray source 3 which are not required to irradiate the entire detection surface of the FPD 4. There is.

<Characteristic Configuration of the Present Invention>
The characteristic configuration of the present invention is that the collimator C and the multi-slit S are superimposed on each other (integrated) and integrated to constitute the moving units C, S. When the collimator C is moved, the multi-slit S moves following this, and the positional relationship between them does not change. The movement of the collimator C is realized by the moving unit drive mechanism 13. By this mechanism, the collimator C can be moved in the left and right direction on the paper surface of FIG. The moving unit drive control unit 14 is configured to control the moving unit drive mechanism 13. The moving unit drive mechanism 13 moves the moving units C and S in a direction perpendicular to the X-ray irradiation direction with respect to the subject M located between the moving units C and S and the FPD 4. As a result, the positions at which the X-rays collimated by the moving units C and S are incident on the subject M are changed. The moving unit drive mechanism 13 corresponds to the unit moving mechanism of the present invention.

  The FPD 4 according to the present invention can also be moved. The movement of the FPD 4 is realized by the FPD moving mechanism 15. By this mechanism, the FPD 4 can move in the left and right direction on the paper surface of FIG. The FPD movement control unit 16 is configured to control the FPD movement mechanism 15. The FPD moving mechanism 15 is configured to move the FPD 4 in a direction orthogonal to the X-ray irradiation direction in synchronization with the movement of the moving units C and S. The FPD moving mechanism 15 corresponds to the detector moving mechanism of the present invention.

  The main control unit 21 is constituted by a CPU, and executes a program for realizing the respective units 11, 12, 14, 16. Each unit 11, 12, 14, 16 may be realized by an arithmetic unit in charge of each unit. The console 25 is configured to input an instruction of the operator, and the display unit 26 is configured to display a fluoroscopic image. The storage unit 27 stores all of the parameters related to control of the apparatus.

<About scan shooting>
The FPD 4 according to the present invention has an elongated shape because of the need to reduce the cost. Therefore, only a narrow range of the subject M can be shot at one time. Therefore, the apparatus according to the present invention is configured to perform imaging of the entire subject by repeating imaging a plurality of times while moving the FPD 4. Such an imaging method is called scan imaging.

  FIG. 2 illustrates scan imaging according to the present invention. In the example of FIG. 2, the subject M is photographed in three divided steps. In the first shooting, the FPD 4 is located on the right side of the subject M. At this time, the right side of the subject M is photographed. In the second shooting, the FPD 4 is located at the center of the subject M. At this time, the center of the subject M is photographed. In the third shooting, the FPD 4 is located on the left side of the subject M. At this time, the left side of the subject M is photographed. If the three image fragments obtained in the first, second and third shootings are aligned and connected, a self-image can be obtained for the entire area of the subject M. The self-image image generation unit 11 executes such connection.

  Although the self-image of the phase grating 5 is reflected in the self-image image generated by the stitching process, it is distorted under the influence of the subject M in some places. While the X-rays pass through the subject M, there is a difference in the phase of the X-rays, and this difference appears as a disturbance of the self-image. Since the self-image represents the disturbance of the self-image corresponding to the entire subject, the fluoroscopic image for the whole subject can be generated from the self-image. Incidentally, the extending direction of the dark line appearing in the self-image corresponds to the moving direction of the FPD 4. This is because the extension direction of the absorber of the phase grating 5 matches the movement direction of the FPD 4.

  Since the device according to the present invention is provided with the collimator C, unnecessary exposure to the subject M can be suppressed. FIG. 3 explains that point. The collimator C is provided on the front side of the multi slit S viewed from the X-ray source 3 and transmits X-rays incident on the detection surface of the FPD 4 from the window and absorbs other X-rays. There is. However, since the FPD 4 moves with respect to the subject M during execution of scan imaging, the FPD 4 also moves along with the detection surface of the FPD 4.

  Therefore, the apparatus according to the present invention is configured to move the moving units C and S during execution of scan imaging. FIG. 4 shows the positional relationship of each part at the time of scan imaging, and moving units C, S and FPD 4 composed of the collimator C and multi-slit S emphasized by oblique lines move during scan imaging . On the other hand, the X-ray source 3, the phase grating 5 and the subject M which are not emphasized by oblique lines do not move during scan imaging.

  The upper part of FIG. 4 shows the first imaging in a series of scan imaging. Since the moving units C and S are located below the X-ray source 3 in the drawing of FIG. 4, the X-ray beams emitted from the moving units C and S are biased downward. This x-ray beam passes under the object M and all of the x-ray beam is incident on the FPD 4 which is also located below the x-ray source 3 and is detected there.

  The middle part of FIG. 4 shows the second imaging in a series of scan imaging. Since the moving units C and S are located at the same height as the X-ray source 3, the X-ray beams emitted from the moving units C and S have no bias. This x-ray beam passes through the center of the object M, and all of the x-ray beam is incident on the FPD 4 which is also located at the same height as the x-ray source 3 and is detected there.

  The lower part of FIG. 4 shows the third imaging in a series of scan imaging. Since the moving units C and S are located on the upper side of the drawing of FIG. 4 with respect to the X-ray source 3, the X-ray beams emitted from the moving units C and S are biased upward. This x-ray beam passes above the object M and all of the x-ray beam is incident on the FPD 4 which is also located above the x-ray source 3 and is detected there.

  In this way, the mobile units C and S move to flee from the FDP 4 to be overtaken and move to follow the FPD 4 after being overtaken by the FPD 4 and detect the FPD 4 in any case of each photographing It transmits X-rays incident on the surface and absorbs other X-rays. Although the moving units C and S and FPD 4 during scan imaging move in the same direction, the movement distances are different from each other. In scan imaging, the FPD 4 farther from the X-ray source 3 moves more than the moving units C and S closer to the X-ray source 3. This is due to the radial spread of the x-ray beam.

  As described above, according to the present invention, the movable collimator C can be provided in the X-ray phase contrast imaging apparatus simply by providing a simple mechanism. That is, according to the present invention, the collimator C and the multi-slit S are integrated. Therefore, when moving the collimator C of the present invention, the multi-slit S also follows and moves.

  According to conventional technical common sense, the multi-slit S of the conventional configuration is configured to be fixed in the apparatus. It is because the necessity of moving the multi slit S has not been found. The inventor of the present invention has conceived of a configuration in which the collimator C and the multi-slit S are integrated. According to the configuration of the present invention, the device configuration is much simpler than providing the collimator C in the device independently of the multi-slit S. On the other hand, even when the multi-slit S is moved, no problem occurs in photographing. Since the multi-slit S is configured by repeatedly arranging the same pattern, it is possible to use the same part of the multi-slit S and perform scan imaging without any problem.

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

  (1) According to the above configuration, the collimator C and the multi-slit S are integrated, but the present invention is not limited to this configuration. As shown in FIG. 5, the collimator C and the phase grating 5 may be superimposed (bonded) and integrated to form the moving units C, 5. In this case, the multi slit S need not be provided with a collimator.

  FIG. 6 shows the positional relationship of each part at the time of scan photographing according to the present modification, and the moving units C, 5 and FPD 4 composed of the collimator C and the phase grating 5 highlighted by oblique lines scan Move during shooting. On the other hand, the X-ray source 3, the multi-slit S and the subject M which are not emphasized by oblique lines do not move during scan imaging.

  As shown in the upper, middle, and lower parts of FIG. 6, the situation in which imaging is performed while moving the moving units C and 5 while giving a bias to the direction of the X-ray beam is the same as in the first embodiment described in FIG. It is.

  As shown in FIG. 6, the mobile units C and 5 move to flee from the FDP 4 to be overtaken and move to follow the FPD 4 after being overtaken by the FPD 4 and in any case of each shooting It transmits X-rays incident on the detection surface of the FPD 4 and absorbs other X-rays. The moving units C and 5 and the FPD 4 during scan imaging move in the same direction, but the movement distances are different from each other, similar to the first embodiment described in FIG. 4.

  Providing the collimator C on the phase grating 5 as described above has the following advantages. In fact, if the collimator C is placed as close to the FPD 4 as possible, a clear fluoroscopic image can be obtained. 7 and 8 explain the reason. FIG. 7 shows that X-rays emitted from the X-ray source 3 are limited by a collimator and then projected onto a projection plane.

  The X-ray source 3 generates X-rays from a certain focal point, but even if it is a focal “point”, it actually has a certain extent of spread. That is, as shown in FIG. 7, the X-ray source 3 generates X-rays from the entire X-ray generation range having a certain extent. When a fluoroscopic image is to be obtained, it is ideal that x-rays emanate from one point. However, in reality, as shown in FIG.

  FIG. 7 shows the case where the collimator C is placed near the X-ray source 3. Let's compare how X-rays generated at one end of the X-ray generation range and X-rays generated at the other end pass through the collimator and are projected onto the projection plane. Then, the path when the X-ray generated at one end of the X-ray generation range goes to the projection plane and the path when the X-ray generated at the other end of the X-ray generation range goes to the projection plane are largely inconsistent I understand.

  In the case of FIG. 7, when observing the shadow of the collimator on which the projection plane is projected, the portion that hits the window frame is not clear. In the region represented by symbol d on the projection plane, X-rays generated at one end of the X-ray generation range are incident without being blocked by the collimator, but X-rays generated at the other end are blocked by the collimator and are not incident The phenomenon is happening. Therefore, the area indicated by reference sign d is a gray zone which may or may not be a shadow of the collimator. An arrangement in which such gray zones are projected is undesirable for obtaining clear fluoroscopic images.

  FIG. 8 shows the case where the collimator C is placed away from the X-ray source 3. Let's compare how X-rays generated at one end of the X-ray generation range and X-rays generated at the other end pass through the collimator and are projected onto the projection plane. Then, it can be seen that the path when the X-ray generated at one end of the X-ray generation range is directed to the projection plane and the path when the X-ray generated at the other end of the X-ray generation range is directed to the projection plane are not so different .

  In the case of FIG. 8, it can be seen that the gray zone indicated by symbol d in FIG. 7 is considerably smaller. Such a small gray zone is desirable for obtaining clear fluoroscopic images. In the case of the present invention, the phase grating 5 is farther from the X-ray source 3 than the multi-slit S. Therefore, if the collimator C is provided in the phase grating 5 as in this modification, a clear fluoroscopic image can be obtained.

  The present invention can also be realized by integrating the phase grating 5 and the collimator C. That is, according to the present invention, the collimator C and the phase grating 5 are integrated. Therefore, when moving the collimator C of the present invention, the phase grating 5 also moves following.

  According to conventional technical common sense, the phase grating 5 of the conventional configuration is configured to be fixed in the apparatus. This is because the necessity for moving the phase grating 5 has not been found. The inventor of the present invention has conceived of a configuration in which the collimator C and the phase grating 5 are integrated. According to the configuration of the present invention, the device configuration is much simpler than providing the collimator C in the device independently of the phase grating 5. On the other hand, even when the phase grating 5 is moved, no problem occurs in imaging. Since the phase grating 5 is configured by repeatedly arranging the same pattern, it is possible to use the same portion of the phase grating 5 and perform scan imaging without any problem.

  (2) A variation of the modification in which the collimator C is provided on the phase grating 5 is a configuration in which the multi slit S is omitted as shown in FIG. Some of the X-ray sources 3 can output X-rays with high coherence alone even without the multi-slit S. Such an X-ray source 3 has a configuration in which diamond films are arranged at equal intervals in the X-ray generation range described in FIGS. 7 and 8, and is configured to generate a stripe-shaped X-ray beam. . The stripe-shaped X-ray beams interfere while expanding to form an in-phase X-ray beam. Therefore, in the configuration of FIG. 9, even if the multi-slit S is omitted, X-ray phase difference due to Talbot interference can be imaged.

  (3) According to the configuration of the first embodiment, nothing is provided on the detection surface of the FPD 4, but the present invention is not limited to this configuration. As shown in FIG. 10, an absorption grating may be provided to cover the detection surface of the FPD 4. The absorption grating is a grating in which elongated absorbers absorbing X-rays are arranged in a stripe, and generates a moiré with the self-image of the phase grating 5. The FPD 4 detects this moiré. The self-image generation unit 11 according to the present modification can reconstruct a self-image by analysis of moire. In the absorption grating, an absorption grating in which longitudinally extending absorbers that absorb X-rays are arranged in the horizontal direction is provided so as to cover the X-ray incident surface in the FPD 4.

  In this case, a moiré image covering the entire subject is taken many times by alternately repeating the scan shooting and the movement of the absorption grating. It is assumed that a fragment of a moiré image in which moiré is reflected is shot, for example, three times in one-time scan shooting. The imaging of these three fragments is performed with the positional relationship between the FPD 4 and the absorption grating fixed. The three fragments obtained are connected together by the self-image generation unit 11 to generate a moire image over the entire subject. Thus, the first scan photographing is completed, and a single moiré image is generated. In the configuration of the modified example, while changing the positional relationship of the absorption grating with respect to the FPD 4, the second, third, and fourth scan imaging is performed, and a moiré image across the entire subject is generated each time. The self-image image generation unit 11 generates a self-image image of the phase grating 5 based on the series of moiré images.

  According to this modification, even if the spatial resolution of FPD 4 is low, it is possible to image the self-image of phase grating 5.

  (4) According to the configuration of the first embodiment, the moving unit is composed of the collimator C and the multi-slit S, but the present invention is not limited to this configuration. As shown in FIG. 11, the X-ray source 3 may be moved integrally with the collimator C and the multi slit S. The moving units 3, C, and S in this modification can also be considered to include the X-ray source 3.

  FIG. 12 shows the positional relationship of each part at the time of scan imaging according to the present modification, and the moving units 3 and C composed of the X-ray source 3, the collimator C and the multi-slit S highlighted by oblique lines , S and FPD 4 move during scan imaging. At this time, the units constituting the moving units 3, C, and S move while maintaining the relative positional relationship. On the other hand, the phase grating 5 and the subject M which are not emphasized by oblique lines do not move during scan imaging.

  Further, in the configuration of the first embodiment, the moving speeds of the moving units C, S and FPD 4 during scan imaging are not constant, but in the case of scan imaging according to this modification, the moving units 3, C, S and The FPD 4 moves at the same speed in the same direction. Therefore, the moving units 3, C, S and FPD 4 during scan imaging move while maintaining their relative positions.

  In the case of this modification, as shown in the upper, middle, and lower parts of FIG. 12, there is no change in the emission direction of the X-ray beam even if the moving units 3, C, S are moved. The line is incident on FPD 4 at the shortest distance. This configuration is different from the configuration of the first embodiment in which imaging is performed while giving a bias to the direction of the X-ray beam.

  The advantages of such a configuration will be described. In the case of the first embodiment, the X-rays may be obliquely applied to the multi-slit S when capturing a fragment of an image. The multi-slit S is formed of a member having a thickness so as to be able to reliably absorb X-rays. When such a multi-slit S is viewed from the front, as shown on the left side of FIG. 13, it looks as if the through holes are lined up without any thickness. However, if the multi-slit S is viewed from an oblique direction, the side surface of the multi-slit S can be seen as shown on the right side of FIG. Since this situation is the same in the interior of the through hole, it appears that a part of the through hole is blocked. That is, when X-rays are obliquely applied to the multi-slit S, a part of the X-rays passing through the through hole is absorbed by the side surface of the multi-slit S. Such a phenomenon can not occur when X-rays are applied from the front of the multi-slit S.

  Under such circumstances, X-rays passing through the multi-slit S are more frequent when the X-rays are directed in the direction orthogonal to the multi-slit S than in the oblique direction. In the case of this modification, since the X-rays always enter the multi-slit S from orthogonal directions, imaging of fragments can always be performed with a strong X-ray dose, and underexposure does not occur when imaging each fragment.

  (5) In the above-mentioned modification (4), although a mobile unit was constituted by collimator C, multi slit S, and X-ray source 3, FPD 4 may be added to this. By doing so, the FPD moving mechanism 15 and the FPD movement control unit 16 shown in FIG. 1 can be omitted.

  (6) In the configuration of the first embodiment, the collimator C is provided on the surface of the multi-slit S on the X-ray source 3 side, but the present invention is not limited to this configuration. As shown in FIG. 14, a collimator C may be provided on the surface of the multi-slit S on the FPD 4 side.

  (7) In the configurations of the above-mentioned modifications (1) and (2), the collimator C is provided on the surface of the phase grating 5 on the X-ray source 3 side, but the present invention is not limited to this configuration. As shown in FIG. 15, a collimator C may be provided on the surface of the phase grating 5 on the FPD 4 side.

  (8) In the configuration of the first embodiment, the FPD 4 is compact, but the present invention is not limited to this configuration. As shown in FIG. 16, the FPD 4 may be made large and X-rays may be detected by a part of the FPD 4. Such an apparatus configuration is effective when only a part of the subject M is to be photographed. In the configuration of the present modified example, the FPD 4 does not necessarily have to be moved, and the FPD moving mechanism 15 and the FPD movement control unit 16 need not necessarily be provided.

  (9) In addition, the first embodiment and the modification according to the present invention may be combined and implemented.

C Collimator S Multi slit 3 X-ray source (radiation source)
4 FPD (detector)
5 phase grating 11 self-image generating unit (image combining unit)
13 Moving unit drive mechanism (unit moving mechanism)
15 FPD moving mechanism (detector moving mechanism)

Claims (6)

(A) a radiation source for emitting radiation;
(B) A unit configured by overlapping and integrating a multi-slit for aligning the phase of radiation by passing radiation generated from the radiation source, and a collimator for limiting the spread of radiation;
(C) A phase grating in which longitudinally extending absorbers absorbing radiation are arranged in the lateral direction and Talbot interference occurs when the radiation is transmitted;
(D) A detector for detecting a self-image of the phase grating is provided in this order,
(E) Changing the position where the collimated radiation is incident on the subject by moving the unit in a direction perpendicular to the radiation direction of the subject with respect to the subject located between the unit and the detector What is claimed is: 1. A radiation phase-contrast imaging apparatus comprising a unit moving mechanism. In the radiation phase contrast imaging device according to claim 1,
The radiation phase contrast imaging apparatus, wherein the radiation source is integrated in the unit, and the unit moving mechanism moves the multi slit, the collimator, and the radiation source integrally. (A) a radiation source for emitting radiation;
(C1) A longitudinally extending absorber for absorbing radiation is arranged in the lateral direction and a phase grating that causes Talbot interference when transmitting the radiation, and a collimator for limiting the spread of the radiation are overlapped and integrated. Units to be configured,
(D) A detector for detecting a self-image of the phase grating is provided in this order,
(E) Changing the position where the collimated radiation is incident on the subject by moving the unit in a direction perpendicular to the radiation direction of the subject with respect to the subject located between the unit and the detector What is claimed is: 1. A radiation phase-contrast imaging apparatus comprising a unit moving mechanism. In the radiation phase contrast imaging device according to claim 3,
A radiation phase difference imaging apparatus characterized in that a multi slit is provided between the radiation source and the unit to align the phases of the radiation by passing radiation generated from the radiation source. In the radiation phase contrast imaging device according to any one of claims 1 to 4,
A detector moving mechanism for moving the detector in a direction orthogonal to the radiation direction in synchronization with the movement of the unit;
A radiation phase-contrast imaging apparatus, comprising: an image combining unit that combines a plurality of images obtained by continuous shooting while moving the unit and the detector and generates a single image. The radiation phase contrast imaging device according to any one of claims 1 to 5,
2. A radiation phase contrast imaging apparatus, comprising: an absorption grating in which longitudinally extending absorbers absorbing radiation are arranged in a lateral direction so as to cover the radiation incident surface of the detector.

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