JP2003116826A - Method and apparatus for photographing radiation image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently generate a phase contrast image by efficiently detecting radiation images obtained at a plurality of photographing positions. SOLUTION: The method for photographing the radiation image comprises the steps of arranging a plurality of detection panels 31, 32, and 33 at the plurality of the photographing positions, irradiating the panels 31, 32, and 33 with an X-ray 12 transmitted through an object 21, and obtaining image data Sn which represent the X-ray images of the subject at the plurality of the photographing positions. The panels 31, 32, and 33 have higher resolutions as the panels 31, 32, and 33 separate farther from the object 21. An arithmetic unit 40 generates image data Sp which represents the phase contrast image from the image data Sn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects radiation applied to a subject at a plurality of photographing positions having different distances from the subject to obtain a plurality of radiation images, and uses these plurality of radiation images to perform phase contrast. The present invention relates to a radiation image capturing method and apparatus suitable for generating an image.

[0002]

2. Description of the Related Art Conventionally, radiation (X-ray, α
Rays, β rays, γ rays, electron rays, ultraviolet rays, etc.) to radiate the radiation that has passed through the subject, such as a stimulable phosphor sheet or a radiation detection panel in which a plurality of detection elements are arranged two-dimensionally. Image data representing a radiation image of a subject is detected by a detector, various image processing is performed on the image data, and the image data is then reproduced.

Here, in the method using the stimulable phosphor sheet, a part of the radiation energy transmitted through the subject is accumulated, and when excitation light is irradiated thereafter, stimulated emission light of a light amount corresponding to the accumulated energy is emitted. Using the stimulable phosphor (stimulable phosphor), the radiation image information of the subject is recorded on the sheet-shaped stimulable phosphor (that is, the stimulable phosphor sheet), and the stimulable phosphor sheet is used as a laser beam. Is a method of generating stimulated emission light by scanning with excitation light such as, and photoelectrically reading the generated stimulated emission light to obtain image data representing a radiation image of a subject. The method using a radiation detection panel uses a radiation detection panel in which a plurality of detection elements are arranged two-dimensionally, and an electric signal according to the amount of radiation applied to the radiation detection panel is generated in each detection element. This is a method of obtaining image data representing a radiation image of a subject based on an electric signal.

By the way, the radiation image thus obtained represents the difference in the intensity of the transmitted radiation in the subject as an image. For example, when a subject including a bone part and a soft part is photographed, the radiation that has passed through the bone part is greatly attenuated, so that the amount of radiation that reaches the detector is small, but the radiation that has passed through the soft part is not significantly attenuated, so that the detection is performed. The radiation dose reaching the vessel is relatively high. Therefore, in the case of such a subject, a radiographic image in which the bone portion is white and the soft portion is black and the contrast difference is large, that is, a large amount of information is obtained.

However, for example in breast cancer diagnosis,
When the subject is mainly composed of only the soft part, the difference in radiation attenuation amount due to the tissue is not so large, so that only a radiation image with a small contrast difference, that is, a small amount of information can be obtained.

Therefore, there has been proposed a phase contrast imaging method for visualizing a phase difference of radiation caused by passing through a subject. In this phase contrast imaging method, since radiation is an electromagnetic wave similar to light and a wave propagates and propagates, when two different substances are irradiated with radiation, the difference in how the radiation propagates in the substance causes The subject is photographed based on the fact that the phases of the radiation waves are different before and after the transmission of the substance, resulting in a phase difference. Here, when the subject is a soft part, the phase difference of the radiation becomes larger than the difference of the attenuation amount of the radiation, so the phase contrast imaging method is used to capture the phase difference of the radiation as a phase contrast image. This makes it possible to visualize a subtle difference in tissues contained in the soft part. For the phase contrast imaging method, see `` Pe
ter Cloetens, et al., "Quantitative aspects of coh
erent hard X-ray imaging: Talbot image and hologra
phic reconstruction ", Proc, SPIE, Vol.3154 (1977),
72-82 (Reference 1) "and" Peter Cloetens, et al., "
Hard x-ray phase imaging using simple propagation
of a coherent synchrotron radiation beam ", J. Phys.
D: Appl. Phys. 32 (1999), A145-A151 (reference 2) "for details. According to these documents, image data representing a plurality of radiographic images is obtained by performing imaging using a two-dimensional detector such as a radiation detection panel at a plurality of imaging positions having different distances from the subject, and a plurality of image data is obtained. A phase contrast image can be generated by performing a calculation based on a predetermined algorithm using.

On the other hand, when obtaining a radiation image, the radiation dose applied to the two-dimensional detector changes in inverse proportion to the square of the distance between the radiation source and the two-dimensional detector. Further, since the radiation spreads from the radiation source and propagates, the larger the distance between the subject and the two-dimensional detector, the larger the size of the radiation image detected by the two-dimensional detector. Therefore, there has been proposed a radiographic image capturing apparatus in which a gain when reading a radiographic image is adjusted and an enlargement ratio of the radiographic image is obtained according to the distance between the subject and the two-dimensional detector (Japanese Patent Laid-Open No. 2004-242242). 2000-245721).

[0008] Further, there has been proposed a method for obtaining a phase contrast image with high accuracy by performing enlarging / reducing processing and density converting processing on radiation images obtained at a plurality of photographing positions (Japanese Patent Application No. 2001-146138).
issue).

[0009]

By the way, when a plurality of radiation images are photographed as described above, the diffraction amount of X-rays radiated to the detection panel increases as the photographing position is farther from the subject, and the high frequency due to the diffraction image is increased. More information of X is included in the X-ray. Here, the higher the resolution of the two-dimensional detector, the more the high-frequency information can be detected. Therefore, by using the high-resolution two-dimensional detector, the radiographic image is acquired without missing the high-frequency information. be able to. However, since the high-frequency information is not included so much at the shooting position close to the subject, using a high-resolution two-dimensional detector makes it possible to read out a signal even though the high-frequency information is not included. It takes a long time and the radiographic image cannot be acquired efficiently.

The present invention has been made in view of the above circumstances, and an object thereof is to efficiently acquire a plurality of radiation images for generating a phase contrast image.

[0011]

A radiographic image capturing method according to the present invention irradiates a subject with radiation and detects the radiation transmitted through the subject at a plurality of photographing positions having different distances from the subject. In a radiographic image capturing method for acquiring a plurality of radiographic images, the radiographic images are acquired such that the resolution of the radiographic image becomes higher at an imaging position farther from the subject.

In the radiographic image capturing method according to the present invention, the radiation image may be acquired by detecting the radiation with a two-dimensional detector having a higher resolution at a capturing position farther from the subject. Good.

The resolution of the two-dimensional detector can be increased by reducing the light receiving area of the detecting elements and arranging the detecting elements more densely.

Further, in the radiographic image capturing method according to the present invention, the radiographic image is acquired by reducing the thinning-out amount of the signal read from the two-dimensional detector at a capturing position farther from the subject. May be.

"The thinning amount of the signal read from the two-dimensional detector is reduced as the photographing position is farther from the subject."
Means that when a signal read from one detection element of a plurality of adjacent detection elements is used as a pixel value of a radiation image corresponding to the plurality of detection elements, the read signal is increased at an imaging position close to the subject. Decreasing the number of detection elements that do not read out the signal as the distance from the subject decreases, and decrease the number of detection elements that thin out.

In the radiation image capturing method according to the present invention, a phase contrast image may be generated based on the plurality of radiation images.

The first radiographic image capturing apparatus according to the present invention is arranged at a plurality of image capturing positions at different distances from the subject, and detects radiation transmitted through the subject at the plurality of image capturing positions. A plurality of two-dimensional detectors having higher resolutions at distant photographing positions are provided, and a plurality of radiation images are acquired by detecting radiation transmitted through the subject by the two-dimensional detectors at the plurality of photographing positions. It is characterized by that.

The first radiographic image capturing apparatus according to the present invention may further include image generating means for generating a phase contrast image based on the plurality of radiographic images.

A second radiation image capturing apparatus according to the present invention is a two-dimensional detector for detecting radiation transmitted through an object,
Moving means for moving the two-dimensional detector in the optical axis direction of the radiation, and a position sensor for detecting that the two-dimensional detector has reached a plurality of predetermined imaging positions on a moving path by the moving means. The two-dimensional detection when the two-dimensional detector reaches each of the photographing positions, based on a plurality of photographing units sequentially arranged in the optical axis direction and a detection result of the position sensor. Read-out means for reading a plurality of radiographic images by reading signals from the imaging device, and the two-dimensional detector of the imaging unit arranged farther from the subject has a higher resolution. It is a thing.

In the second radiographic image capturing apparatus according to the present invention, the reading means may be provided for each of the plurality of image capturing units. Thereby, the radiation images can be acquired at the same time in each imaging unit, and as a result, the radiation images can be efficiently acquired at all the imaging positions.

The second radiographic image capturing apparatus according to the present invention may further include image generating means for generating a phase contrast image based on the plurality of radiographic images.

A third radiation image capturing apparatus according to the present invention comprises a two-dimensional detector for detecting the radiation that has passed through an object, a moving means for moving the two-dimensional detector in the direction of the optical axis of the radiation, and the movement. A position sensor that detects that the two-dimensional detector has reached a plurality of predetermined imaging positions on the movement path by the means, and the two-dimensional detector uses the position sensor to detect each of the images based on the detection result of the position sensor. When the position is reached, the signal is read from the two-dimensional detector,
The reading means is a means for acquiring a plurality of radiographic images, the reading means performing reading of signals from the two-dimensional detector by reducing the thinning amount at an imaging position farther from the subject. It is a thing.

The third radiographic image capturing apparatus according to the present invention may further include image generating means for generating a phase contrast image based on the plurality of radiographic images.

[0024]

According to the present invention, since a radiographic image having a higher resolution is acquired at a photographing position farther from the subject, the high frequency information due to the diffraction image, which appears more frequently at the photographing position farther from the subject, is lost. A radiographic image can be acquired without using it. On the other hand, at a shooting position close to the subject, a radiographic image having a lower resolution than that at a shooting position far from the subject can be obtained, so that the signal can be efficiently read out from the two-dimensional detector.
It is possible to efficiently acquire a plurality of radiation images.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the first embodiment of the present invention is applied. As shown in FIG. 1, this phase contrast imaging apparatus detects an X-ray source 10 that irradiates an object with X-rays, an object support unit 20 that supports an object 21, and an X-ray transmitted through the object 21 to detect an object. Image data Sn representing a plurality of 21 X-ray images
The recording unit 30 that obtains (n = 1 to N) and the calculation unit 40 that generates the image data Sp representing the phase contrast image based on the plurality of image data Sn are provided.

The X-ray source 10 includes a radiation source 11 that emits synchrotron radiation, and a crystal 13 such as silicon that monochromates the synchrotron radiation into monochromatic X-rays (hereinafter simply referred to as X-rays) 12. The synchrotron radiation emitted from the radiation source 11 is reflected by the crystal 13 to obtain a monochromatic X-ray 12.

The subject support unit 20 includes a support base 24 that supports the subject 21.

The recording section 30 is composed of a fluorescent substance and a plurality of detection elements arranged two-dimensionally, and is arranged in a plurality of preset photographing positions (in the present embodiment, 3).
Detection panel 31, 32, 33 and each detection panel 3
Read-out means 3 for obtaining a plurality of image data Sn by reading electrical signals from a plurality of detection elements constituting 1, 32, and 33.
4, 35, 36. It should be noted that only one read-out means is provided, and this read-out means allows each of the detection panels 31, 32, 3 to be read.
The electric signals may be sequentially read out from 3.

Here, when photographing is performed using a plurality of detection panels 31, 32, 33 as in the first embodiment, the diffraction amount of the X-ray 12 increases as the distance from the subject 21 increases. As a result, more high frequency information based on the diffraction image is included. On the other hand, the higher the resolution of the detection panel, the higher the frequency of information that can be detected. Therefore, by using the high-resolution detection panel, the image data Sn representing the radiation image is obtained without missing the high frequency information. be able to. However, since the high-frequency information is not included so much at the shooting position close to the subject 21, if a detection panel with high resolution is used, it will take a long time to read out the signal although the high-frequency information is not included. It will take time.

Therefore, in the present embodiment, the detection panel arranged at the photographing position farther from the subject 21,
It has a high resolution. More specifically, as shown in FIG. 2, the detection panel arranged at a photographing position farther from the subject 21 has detection elements with a smaller light receiving area arranged more densely to increase the resolution of the detection panel. There is. As a result, even at a position away from the subject 21, high frequency information based on the diffraction image can be accurately detected.

The calculation unit 40 includes detection panels 31, 32, 3
The difference in the resolution of the X-ray image represented by the image data Sn obtained in 3 is corrected, and the size of the X-ray image is represented by the image data S3 obtained at the photographing position farthest from the subject 21. The X-ray image represented by the image data Sn is reduced so as to have the same size as the line image, and the image data Sp representing the phase contrast image is obtained from the reduced image data Sn. .

Here, when the resolutions of the detection panels 31, 32 and 33 are different as in the first embodiment, when the image data Sp representing a phase contrast image, which will be described later, is generated, it is represented by each image data Sn. It is necessary to match the resolution of the X-ray image obtained. In the present embodiment, the image data S1, S obtained on the detection panels 31, 32
The correction is performed so that the resolution of the X-ray image represented by 2 matches the resolution of the X-ray image represented by the image data S3 obtained by the detection panel 33 having the highest resolution. This is to prevent the information of the X-ray image having the highest resolution from being lost.

Further, in the case where the plurality of detection panels 31, 32 and 33 are used for photographing as in the first embodiment, the size of the X-ray image becomes larger at the photographing position where the distance from the subject 21 is larger. Therefore, the size of the X-ray image represented by the image data Sn (resolution-corrected) is corrected according to the distance from the subject 21. Specifically, when the enlargement ratio at another photographing position with respect to the photographing position farthest from the subject 21 is M (<1), the enlargement processing is performed to make the size of the X-ray image 1 / M times. As described above, the size is adjusted to the X-ray image obtained at the imaging position farthest from the subject 21, as in the case of the resolution.
This is to prevent the information of the X-ray image having the highest resolution from being lost.

Since the size of the X-ray image at the time of photographing becomes large, the dose of the X-ray 12 irradiated per unit area of the detection panel becomes small. To correct this, when the magnification ratio at the imaging position with respect to the position of the subject 21 is L, each pixel of the X-ray image is multiplied by 1 / L ² to reduce the dose of the X-ray 12 due to the enlargement of the image. May be compensated.

Then, the image data S subjected to the reduction processing
Based on n, the image data Sp representing the phase contrast image is obtained by the method described in Document 1 above. The method described in Document 1 will be described below. It is assumed that the transmittance of the subject 21 is represented by the following formula (1).

[Equation 1] However, T (x, y): transmittance function A (x, y): transmittance intensity function ψ (x, y): phase shift amount function (x, y): coordinate value representing the position on the detection panel

Here, in the case of a thin object whose transmittance intensity is negligible (that is, A (x, y) is close to 1), the subject 21 and the detection panel 31 are expressed by the following equation (2). , 32, 33 and the spatial frequency component I _dn (fx, fy) obtained by Fourier transforming the image I _dn (x, y) captured at a distance dn (n = 1 to N).
The spatial frequency component of the amount of phase shift is calculated using this.

Here, the relationship between the X-ray dose applied to the detection panels 31, 32 and 33 and each pixel value of the image represented by the image data Sn can be detected in advance. Therefore, from this relationship, a conversion table for converting the pixel value of the image represented by the image data Sn into the X-ray dose is created, and the distance d is calculated by referring to this conversion table.
position of an image represented by the acquired image data Sn in n (x, y) image from the pixel value in the I _dn (x,
y) can be obtained.

[Equation 2] However, N: number of image data Sn f: spatial frequency ψ (fx, fy ≠ 0): spatial frequency component I _dn (fx, fy) of phase shift amount when frequency is not 0: I _dn (x, y) Spatial frequency component of

Then, the phase shift amount, that is, the phase difference ψ (x, y) can be calculated by inverse Fourier transforming the spatial frequency component of the phase shift amount. here,
Since the phase difference ψ (x, y) takes a value in the range of 0 to 2π,
By assigning the calculated phase difference ψ (x, y) to an 8-bit value, for example, image data Sp representing a phase contrast image can be obtained.

Here, the transmittance intensity is negligible A
Although it is assumed that (x, y) is close to 1, the phase shift amount can be calculated using a similar algorithm for a thick object.

Further, in the first embodiment, the other X-ray images are enlarged so as to have the size of the X-ray image obtained at the photographing position farthest from the subject 21, so that if necessary. It is preferable to perform reduction processing on the phase contrast image so as to obtain a desired size.

Next, the operation of the first embodiment will be described. FIG. 3 is a flowchart showing the operation of the first embodiment. First, the radiation source 11 is driven so that the synchrotron radiation light is reflected by the crystal 13, whereby monochromatic X-rays 12 are emitted from the X-ray source 10 and X-rays the subject 21.
The line 12 is irradiated (step S1). Then, at the plurality of photographing positions, the reading means 34, 35, 36 read the electric signals of the plurality of detection elements constituting the detection panels 31, 32, 33, and the image data Sn at each photographing position.
Is acquired (step S2).

The acquired image data Sn is input to the arithmetic unit 40, where the resolution is corrected and the enlargement process is performed, and the image data Sp representing the phase contrast image is generated as described above (step S3). ), The processing ends. The image data Sp is used for reproduction by a monitor or print output by a printer.

As described above, in the first embodiment,
Since the X-ray image is acquired by using the detection panel having the higher resolution at the photographing position farther from the subject 21, the X-ray image can be acquired without missing the high frequency information from the diffraction image. On the other hand, at the photographing position close to the subject 21, an X-ray image having a lower resolution than that at the photographing position far from the subject 21 can be obtained, so that the signal can be efficiently read from the detection panel. It is possible to efficiently acquire a plurality of X-ray images and efficiently generate a phase contrast image.

Next, a second embodiment of the present invention will be described. FIG. 4 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the second embodiment of the present invention is applied. Since the second embodiment is different from the first embodiment only in the structure of the recording unit, the same structures as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. Omit it.

The recording unit 130 in the second embodiment is
It is provided with first and second photographing units 130A and 130B.

The first and second photographing units 130A,
Reference numeral 130B denotes a detection panel 131A, 131B composed of a fluorescent substance and a plurality of detection elements arranged two-dimensionally, and a detection panel 131A, 131B in a direction parallel to the traveling direction of the X-ray 12 transmitted through the subject 21. Moving means 132A, 132B for moving and detection panels 131A, 13
Read-out means 133A, 1 for obtaining image data Sna, Snb at each photographing position by reading electric signals from a plurality of detection elements constituting detection panels 131A, 131B at a plurality of photographing positions set in advance on the movement path of 1B.
33B.

The moving means 132A and 132B extend in the direction parallel to the traveling direction of the X-rays 12 and the supporting portions 135A and 135B formed with the female screw portion for supporting the detection panels 131A and 131B. Support part 135A,
Male screw portions 136A, 13 that are screwed into female screw portions of 135B
6B and a motor 13 for rotating the male screw portions 136A, 136B around a rotation shaft extending in the traveling direction of the X-ray 12.
7A, 137B, and control units 138A, 138B for controlling driving and stopping of the motors 137A, 137B. Then, the motor 1 is controlled by the control units 138A and 138B.
By driving 37A and 137B, the male screw portion 136
A and 136B are rotated, and the support portions 135A and 135B, that is, the detection panels 131A and 13B, are rotated according to the rotation direction.
1B moves toward the subject 21 and away from the subject 21.

Further, the first and second photographing units 13
The moving means 13 is provided at each photographing position in 0A and 130B.
Detection panel 131A moved by 2A and 132B,
Position sensors 51A, 52A, 51B, and 52B that detect that 131B has reached each of the photographing positions are provided. Position sensors 51A, 52A, 51B, 52B
Outputs a detection signal when the detection panels 131A and 131B reach the photographing position, which is read out by the reading means 133A and 1A.
33B is input. The reading means 133A and 133B are
When the detection signal is input, the detection panels 131A and 131
The electric signals are read from the plurality of detection elements constituting B to obtain the image data Sna and Snb at the photographing position.

In the second embodiment, in the first and second photographing units 130A and 130B,
Position sensors 51A, 52A and 51 are provided at two locations, respectively.
Since B and 52B are provided, four image data Sn (S1 to S4) are obtained at four image capturing positions.

Here, in the second embodiment, the resolution of the detection panel 131B constituting the photographing unit 130B on the side far from the subject 21 is the resolution of the detection panel 131A constituting the photographing unit 130A on the side closer to the subject 21. It is higher than the resolution. Specifically, the light receiving area of the detection panel of the detection panel 131B is set to the detection panel 131A.
The light receiving area is smaller than the light receiving area and the former is arranged more densely than the latter. As a result, even at a position distant from the subject 21, high frequency information based on the diffraction image included in the X-ray 12 can be accurately detected.

The arithmetic unit 40, as in the first embodiment,
The difference in resolution of the X-ray image represented by the image data Sn is corrected, and the size of the X-ray image represented by the image data Sn is represented by the image data S1 obtained at the photographing position farthest from the subject 21. The X-ray image represented by the image data Sn is enlarged so as to have the same size as the X-ray image, and the image data Sp representing the phase contrast image is obtained.

Next, the operation of the second embodiment will be described. FIG. 5 is a flowchart showing the operation of the second embodiment. First, the radiation source 11 is driven so that the synchrotron radiation light is reflected by the crystal 13, whereby monochromatic X-rays 12 are emitted from the X-ray source 10 and X-rays the subject 21.
The line 12 is irradiated (step S11). At the same time,
First, shooting is performed in the first shooting unit 130A. That is, the control unit 138A drives the motor 137A to move the detection panel 131A in a direction away from the initial position closest to the subject 21 (step S1).
2). The position sensors 51A and 52A are moved according to the movement.
At the timing when the detection signal from the
The electric signals of the plurality of detection elements constituting the detection panel 131A are read by the 33A to obtain the image data Sna at each photographing position (step S13).

In the first photographing unit 130A, the photographing is performed in the second photographing unit 130B after the photographing at the photographing position farthest from the subject 21.
That is, the control unit 138B drives the motor 137B to move the detection panel 131B in a direction away from the initial position closest to the subject 21 (step S14).
Then, at the timing when the detection signals from the position sensors 51B and 52B are input according to the movement, the reading means 133B.
Thus, the electric signals of the plurality of detection elements constituting the detection panel 131B are read to obtain the image data Snb at each photographing position (step S15).

The acquired image data Sna, Snb are input to the arithmetic unit 40, where the image data Sp representing the phase contrast image is generated as in the first embodiment (step S16), and the process ends. The image data Sp is used for reproduction by a monitor or print output by a printer.

In the second embodiment, after the first photographing unit 130A has photographed,
Although the second photographing unit 130B is photographing, the first and second photographing units 130A and 130B
At the same time, the images may be taken simultaneously.

Further, in the second embodiment, two image pickup units are used, but three or more image pickup units may be used. In this case, a detection panel having a higher resolution is used for the detection panel used in the subsequent photographing unit.

Next, a third embodiment of the present invention will be described. FIG. 6 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the third embodiment of the present invention is applied. Note that, in the third embodiment, only the configuration of the recording unit is different from that of the first embodiment, and thus the same configurations as those of the first embodiment are designated by the same reference numerals, and detailed description will be omitted. Omit it.

The recording section 230 in the third embodiment is
A detection panel 231 including a phosphor and a plurality of detection elements arranged two-dimensionally, and an X-ray 1 transmitted through a subject 21.
The moving means 232 that moves the detection panel 231 in a direction parallel to the traveling direction of the two, and the plurality of detection elements that configure the detection panel 231 at a plurality of imaging positions preset on the movement path of the detection panel 231. And a read-out unit 233 for obtaining an image data Sn at each photographing position by reading an electric signal from the.

The moving means 232 is used for the detection panel 23.
A support portion 235 formed with a female screw portion, which supports 1;
A male screw portion 236 that extends in a direction parallel to the traveling direction of the X-rays 12 and that is screwed into a female screw portion of the support portion 235, and a male screw portion 236 around a rotation axis that extends in the traveling direction of the X-rays 12 A rotation motor 237 and a control unit 238 that controls driving and stopping of the motor 237 are provided. Then, the male screw portion 236 is rotated by driving the motor 237 by the control portion 238, and the support portion 235, that is, the detection panel 231 moves in a direction toward the subject 21 and a direction away from the subject 21 depending on the rotation direction.

Position sensors 251A, 251B, 25 for detecting that the detection panel 231 moved by the moving means 232 has reached each shooting position.
1C is arranged respectively. Position sensor 251A,
251B and 251C output a detection signal when the detection panel 231 reaches the photographing position, which is the reading means 233.
Entered in. When the detection signal is input, the reading unit 233 reads the electric signals from the plurality of detection elements that form the detection panel 231, and obtains the image data Sn at the photographing position.

Here, the reading means 233 is the detection panel 2
The resolution of the X-ray image is changed by changing the thinning-out amount at the time of reading the signal from 31 according to the distance from the subject 21. Specifically, as shown in FIG. 7, 3 × 3 is set at the shooting position closest to the subject 21.
= The signal read from one of the nine detection elements is set as the pixel value of the pixel corresponding to the nine detection elements in the X-ray image. That is, where signals should be originally read from nine detection elements, signals are read from only one detection element, and signals to be read from the nine detection elements are signals read from the one detection element. , And obtain an X-ray image. Further, at the next imaging position, the signal read from one of the 2 × 2 = 4 detection elements is used as the pixel value of the pixel corresponding to the four detection elements in the X-ray image. That is, where the signals should originally be read out from the four detection elements, the signals are read out from only one detection element,
Considering that the signal to be read from each of the detection elements is the same as the signal read from the one detection element,
Obtain an X-ray image. Then, at the imaging position farthest from the subject 21, an X-ray image is obtained from the signals read from all the detection elements.

As described above, by reducing the thinning-out amount of the signal read from the detection panel 231 as the distance from the subject 21 increases, it is possible to obtain an X-ray image having a higher resolution as the distance from the subject 21 increases. Further, at the shooting position close to the subject 21, the signals are read with a larger thinning amount than at the shooting positions far from the subject 21, so that the signals can be efficiently read from the detection panel. , It is possible to efficiently acquire a plurality of X-ray images and efficiently generate a phase contrast image.

Further, in the first embodiment, the X-ray images are acquired by the detection panels 31, 32, 33, but instead of the detection panels 31, 32, 33, the fourth panel shown in FIG. As in the embodiment, the stimulable phosphor sheet 61 and the X-ray film 62 may be used. Where X
The line film 62 is more granular than the stimulable phosphor sheet 61, and as a result, an X-ray image with high resolution can be obtained.

When an X-ray image is stored and recorded on the stimulable phosphor sheet 61, the sheet 61 is irradiated with excitation light to generate stimulated emission light, and the stimulated emission light is photoelectrically read. In the reading unit 70, image data S1 representing an X-ray image is obtained. On the other hand, when an X-ray image is recorded on the X-ray film 62, development processing is performed, and the reading unit 80 that reads the image from the film reads the X-ray image from the developed X-ray film 62 '. Thus, the image data S2 representing the X-ray image is obtained.

The obtained plurality of image data S1 and S2 are
As in the first embodiment, the image data Sp is input to the calculation unit 40 and the image data Sp representing the phase contrast image is generated.

In each of the above embodiments, the radiation source 1
Although the one that emits the synchrotron radiation is used as No. 1, it is not limited to this. Also, subject 2
Although a monochromatic X-ray is used as the X-ray 12 for irradiating 1
It is not limited to monochromatic X-rays.

Further, in each of the above-described embodiments, the subject 21 is irradiated with the X-rays 12, but radiation other than X-rays (α rays, β rays, γ rays, electron rays, ultraviolet rays, etc.) is used. May be.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which a radiation image capturing apparatus according to a first embodiment of the present invention is applied.

FIG. 2 is a diagram for explaining the thickness of a detection panel.

FIG. 3 is a flowchart showing the operation of the first embodiment.

FIG. 4 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the second embodiment of the present invention is applied.

FIG. 5 is a flowchart showing the operation of the second embodiment.

FIG. 6 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the third embodiment of the present invention is applied.

FIG. 7 is a diagram for explaining a state in which signals are thinned out and read out.

FIG. 8 is a schematic block diagram showing the configuration of a phase contrast imaging apparatus to which the radiation image capturing apparatus according to the fourth embodiment of the present invention is applied.

[Explanation of symbols]

10 X-ray source 11 X-ray source 12 X-ray 13 Crystal 20 Object support 21 Object 30,130 Recording parts 31, 32, 33, 131A, 131B, 231 Detection panels 33, 133A, 133B, 233 Read-out means 40 Operation part 51A, 51B, 52A, 52B, 251A, 251
B, 251C Position sensor 61 Accumulative phosphor sheet 62 X-ray film 70, 80 Reading unit 130A, 130B Imaging unit 132A, 132B, 232 Moving means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) G06T 1/00 400 G06T 1/00 400B 5C024 420 420B 5C076 H04N 1/387 101 H04N 1/387 101 5/321 5/321 5/335 5/335 PF term (reference) 2G088 EE01 EE27 FF02 GG19 GG20 GG21 GG25 JJ05 JJ22 JJ23 JJ24 KK32 KK35 2H013 AC03 4C093 AA01 CA02 DA06 EA01 BA02 AB17 AB02 AB17 AB02 AB02 FA17 EB21 EB17 AB02 BF17 EB21 AB32 FA02 EB17 EB17 AB02 BF17 EB17 FA02 BC23 CA06 CB10 DC20 5B057 AA08 BA03 CA02 CA08 CA12 CA16 CD07 CE11 CG09 CH07 5C024 AX12 AX17 CX37 CX41 HX00 5C076 AA21 AA22 BB40 CB05

Claims (11)

[Claims] 1. A radiographic image capturing method for acquiring a plurality of radiographic images by irradiating a subject with radiation and detecting the radiation that has passed through the subject at a plurality of capturing positions having different distances from the subject, A radiographic image capturing method, characterized in that the radiographic image is acquired such that the resolution of the radiographic image becomes higher at a capturing position farther from the subject. 2. The shooting position farther from the subject,
The radiographic image capturing method according to claim 1, wherein the radiographic image is acquired by detecting the radiation with a two-dimensional detector having a high resolution. 3. The photographing position farther from the subject,
The radiographic image capturing method according to claim 1, wherein the radiographic image is acquired by reducing a thinning-out amount of a signal read from the two-dimensional detector. 4. The radiographic image capturing method according to claim 1, wherein a phase contrast image is generated based on the plurality of radiographic images. 5. The resolution is higher at a photographing position farther from the subject, which is arranged at each of a plurality of photographing positions having different distances from the subject and detects radiation transmitted through the subject at the plurality of photographing positions. A radiation image capturing apparatus comprising: a plurality of two-dimensional detectors, wherein a plurality of radiation images are acquired by detecting the radiation transmitted through the subject by the two-dimensional detectors at the plurality of capturing positions. 6. The radiographic image capturing apparatus according to claim 5, further comprising image generating means for generating a phase contrast image based on the plurality of radiographic images. 7. A method for detecting radiation that has passed through an object 2
A two-dimensional detector, moving means for moving the two-dimensional detector in the optical axis direction of the radiation, and arrival of the two-dimensional detector at a plurality of predetermined imaging positions on the moving path by the moving means. When the two-dimensional detector reaches each of the photographing positions based on a detection result of the plurality of photographing units, which are provided with a position sensor for detecting and are sequentially arranged in the optical axis direction, and the position sensor. A reading means for reading a signal from the two-dimensional detector to obtain a plurality of radiation images, and the two-dimensional detector of the imaging unit arranged farther from the subject has a higher resolution. A radiographic image capturing device. 8. The radiographic image capturing apparatus according to claim 7, wherein the reading unit is provided for each of the plurality of image capturing units. 9. The radiographic image capturing apparatus according to claim 7, further comprising image generating means for generating a phase contrast image based on the plurality of radiographic images. 10. A two-dimensional detector that detects radiation that has passed through an object, a moving unit that moves the two-dimensional detector in the optical axis direction of the radiation, and a predetermined movement path by the moving unit. A position sensor that detects that the two-dimensional detector has reached a plurality of shooting positions, and the two-dimensional detection when the two-dimensional detector has reached each of the shooting positions based on a detection result of the position sensor. And a reading means for reading a signal from the two-dimensional detector by obtaining a plurality of radiographic images by reading a signal from the detector, and reducing a thinning amount at an imaging position farther from the subject. A radiographic image capturing apparatus characterized by being provided. 11. Based on the plurality of radiographic images,
The radiographic image capturing apparatus according to claim 10, further comprising image generating means for generating a phase contrast image.