JP2008245999A - Radiographic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide radiographic equipment capable of obtaining a high-quality sectional image. <P>SOLUTION: The radiographic equipment comprises: an X-ray source 122 for irradiation a subject 1 with X rays from a plurality of irradiation locations disposed in a line or circular arc; an image generating part 130 for generating electric signals corresponding to the dose of X rays penetrating the subject 1 and generating photography images for the respective irradiation locations by amplifying the electric signals; a control part 108 for setting the amplification rate of the electric signals for each photography image based on the irradiation location of the X-ray source; and an image reconstruction part for generating a sectional image of the subject 1 by reconstructing the plurality of photography images. The radiographic equipment may hold an amplification rate table, in which the amplification rate for each of the plurality of irradiation locations is set, for each of a plurality of kinds of reference body sizes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radiation imaging apparatus capable of obtaining a high-quality cross-sectional image.

  In recent years, in an X-ray imaging apparatus (CR: computed radiography), in order to observe an affected area in more detail, a plurality of images obtained by moving an X-ray tube and irradiating an object with X-rays from different angles are obtained. Tomosynthesis imaging that can obtain an image in which a desired tomographic plane is emphasized has been proposed. In tomosynthesis imaging, the X-ray tube is moved in parallel with the flat panel in accordance with the characteristics of the imaging device and the required tomographic images, and multiple captured images are captured at different irradiation angles, and these captured images are acquired. Is reconstructed to create a tomographic image.

  In tomosynthesis imaging, the subject is imaged at different irradiation angles (irradiation positions), but when the irradiation angle is different, the distance between the X-ray tube and the subject and the apparent body thickness of the subject are different. For this reason, the irradiation dose and the transmittance of the subject change for each irradiation angle, and the X-ray dose that can be detected by the flat panel changes for each irradiation angle. Specifically, when the subject is photographed from an oblique direction, the X-ray dose that can be detected by the flat panel is lower than when the subject is photographed from the front (vertical direction) of the subject. End up. Therefore, the quality of the cross-sectional image obtained by reconstruction is also lowered.

  With respect to such problems, Patent Document 1 below discloses a technique for controlling the output of the X-ray source in accordance with the irradiation position of the X-ray tube. However, in the technique described in Patent Document 1, when the subject is photographed from an oblique direction, it is necessary to increase the X-ray dose irradiated to the subject as compared with the case of photographing from the front of the subject.

JP 2000-501552 A

As described above, in tomosynthesis imaging, when an object is imaged from an oblique direction, the X-ray dose that can be detected by the X-ray detection unit is lower than when the object is imaged from the front (vertical direction) of the object. The quality of the will also deteriorate. Therefore, the quality of the cross-sectional image obtained by reconstruction is also lowered.
The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a radiation imaging apparatus capable of obtaining a high-quality cross-sectional image.

In order to solve the above-described problem, a radiographic apparatus according to the present invention includes an X-ray source that emits X-rays toward a subject from each of a plurality of irradiation positions arranged along a straight line or an arc,
An image generation unit that generates an electrical signal corresponding to the X-ray dose transmitted through the subject and amplifies the electrical signal to generate a captured image for each of a plurality of irradiation positions;
An amplification factor setting unit for setting the amplification factor of the electrical signal for each of the captured images based on the irradiation position of the X-ray source;
An image reconstructing unit configured to reconstruct the plurality of captured images to generate a cross-sectional image of the subject.

  For each of a plurality of types of reference body types, an amplification factor holding unit that holds an amplification factor table that defines the amplification factor for each of the plurality of irradiation positions, and reference body type identification information that identifies the reference body type to which the subject belongs are input. An input unit may be further provided. The amplification factor setting unit may read the amplification factor table corresponding to the reference body type identification information input to the input unit from the amplification factor holding unit, and set the amplification factor according to the read amplification factor table. Good.

Another radiation imaging apparatus according to the present invention includes an X-ray source that emits X-rays toward a subject at different angles from each of a plurality of irradiation positions arranged along a straight line or an arc,
An image generation unit that generates an electrical signal corresponding to the X-ray dose transmitted through the subject and amplifies the electrical signal to generate a captured image for each of a plurality of irradiation positions;
An amplification factor setting unit for setting the amplification factor of the electrical signal for each of the captured images based on the X-ray irradiation angle with respect to the subject;
An image reconstructing unit configured to reconstruct the plurality of captured images to generate a cross-sectional image of the subject.

  An amplification factor holding unit that holds an amplification factor table that defines the amplification factor for each of the plurality of irradiation angles for each of a plurality of types of reference body shapes, and reference body type identification information that identifies the reference body type to which the subject belongs. An input unit may be further provided. The amplification factor setting unit may read the amplification factor table corresponding to the reference body type identification information input to the input unit from the amplification factor holding unit, and set the amplification factor according to the read amplification factor table. Good.

Another radiation imaging apparatus according to the present invention includes an X-ray source that emits X-rays toward a subject at different angles from each of a plurality of irradiation positions arranged along a straight line or an arc,
An image generation unit that generates an electrical signal corresponding to the X-ray dose transmitted through the subject and amplifies the electrical signal to generate a captured image for each of a plurality of irradiation positions;
A body thickness measuring unit for measuring the body thickness of the subject when viewed from each of the plurality of irradiation positions or irradiation angles;
Based on the measurement result of the body thickness measurement unit, an amplification factor setting unit that sets the amplification factor of the electrical signal for each of the captured images;
An image reconstructing unit configured to reconstruct the plurality of captured images to generate a cross-sectional image of the subject.

  In each of the radiographic apparatuses described above, the image generation units are arranged in a matrix, and each of the plurality of pixels generates a charge corresponding to the X-ray dose irradiated to each of the plurality of pixels. You may have the read-out means which produces | generates the said electrical signal by reading, and the amplification part which amplifies the said electrical signal according to the amplification factor which the said amplification factor setting part set.

  The image generation unit is arranged in a matrix, and reads the charge from a plurality of pixels that generate charges corresponding to the irradiated X-ray dose and a predetermined number of pixels adjacent to each other, and the predetermined number Reading means for generating the electric signal by adding the electric charge, an amplifying unit for amplifying the electric signal according to the amplification factor set by the amplification factor setting unit, and setting the predetermined number based on the amplification factor The adjacent addition number setting unit may be included.

  An image processing unit that averages a predetermined number of pixel data adjacent to each other to generate one averaged pixel data, and an average number that sets the predetermined number for each of the plurality of captured images based on the amplification factor And a setting unit. Each of the plurality of captured images may include an image processing unit that changes a contrast ratio according to the amplification factor at the time of generating the captured image. The image reconstruction unit may set a contribution rate of each of the plurality of captured images when generating the cross-sectional image based on an amplification factor when generating the captured image.

Another radiation imaging apparatus according to the present invention includes an X-ray source that emits X-rays toward a subject at different irradiation angles from each of a plurality of irradiation positions arranged along a straight line or an arc,
An image generation unit that generates an electrical signal corresponding to an X-ray amount transmitted through the subject and amplifies the electrical signal to generate a captured image for each of a plurality of irradiation positions or irradiation angles;
An image reconstruction unit that generates a cross-sectional image of the subject by reconstructing the plurality of captured images;
The image reconstruction unit sets a contribution rate of each of the plurality of captured images when generating the cross-sectional image based on an irradiation position or an irradiation angle when generating the captured image.

  A plurality of imaging units including the X-ray source, the image generation unit, and the amplification factor setting unit may be provided. In this case, the image reconstruction unit reconstructs the plurality of captured images and generates the cross-sectional image for each of the plurality of imaging units.

  According to the present invention, the amplification factor of the electrical signal when generating the captured image is changed according to the irradiation position of the X-ray, the irradiation angle, or the body thickness of the subject. For this reason, it can suppress that the quality of a picked-up image falls. Therefore, the high-quality cross-sectional image can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram for explaining the configuration of an X-ray imaging system according to the first embodiment of the present invention. The X-ray imaging system shown in this figure is a system in which a plurality of X-ray imaging apparatuses 10 are connected to an image processing apparatus 20 via communication lines. The X-ray imaging apparatus 10 is an apparatus that performs tomosynthesis imaging, and generates a plurality of captured images by irradiating an object with X-rays from different angles by moving an X-ray tube along a straight line or an arc. The image processing apparatus 20 processes a plurality of captured images generated by the X-ray imaging apparatus 10 to generate a cross-sectional image indicating a desired cross-section of the subject. The image processing apparatus 20 generates a cross-sectional image by processing a plurality of captured images for each X-ray imaging apparatus 10.

  FIG. 2 is a diagram for explaining the principle of tomosynthesis imaging. For example, images I1, I2,..., In are generated by X-rays emitted from the positions R1, R2,. Each of the images I1, I2,..., In has an image of a point Q1 in the subject at a position corresponding to the points P11, P21,. An image of Q2 is provided at points P12, P22,..., Pn2 on the X-ray detector 132.

  When it is desired to emphasize the cross section where the point Q1 exists in the subject, “an image obtained by moving the image I2 by (P21-P11)”,..., “An image obtained by moving the image In by (Pn1-P11)” Is added. Thereby, a tomographic image including the point Q1 in the subject is generated. Similarly, when it is desired to emphasize the cross section where the point Q2 exists in the subject, “the image obtained by moving the image I2 by (P22-P12)”,..., “The image In is moved by (Pn2-P12). Add the selected image. Thereby, the captured image is reconstructed and a tomographic image including the point Q2 in the subject is generated.

  FIG. 3 is a block diagram illustrating an example of the configuration of the X-ray imaging apparatus 10. The X-ray imaging apparatus 10 is provided with an operation unit 106 (input unit), and each unit of the X-ray imaging apparatus 10 operates in accordance with information input by the operator via the operation unit 106.

  When the subject is imaged by the X-ray imaging apparatus 10, the subject 1 is irradiated with X-rays from the X-ray tube 122. The amount of X-ray irradiation to the subject 1 is controlled by the control unit 108 controlling the tube voltage / tube current control unit 121 of the high voltage generation unit 120.

  X-rays that have passed through the subject 1 are converted into electric signals in units of pixels by the X-ray detection unit 132 of the flat image generation unit 130. The signal processing unit 134 of the image generation unit 130 generates a captured image by amplifying the pixel unit electrical signal generated by the X-ray detection unit 132 and transmits the captured image to the image processing unit 110. The signal processing unit 134 and the X-ray detection unit 132 are controlled by the control unit 108 via the control unit 136 of the image generation unit 130.

  The image processing unit 110 corrects a defect (for example, pixel omission) of a captured image caused by the image generation unit 130. The photographed image after the correction processing is stored in the image storage unit 104 in accordance with the amplification factor of the electric signal and the photographing angle or position at the time of image generation according to an instruction from the control unit 108. The captured image, the amplification factor, and the imaging angle or position stored in the image storage unit 104 are transmitted to the image processing apparatus 20 via the communication unit 114. The captured image stored in the image storage unit 104 is displayed on the display unit 107.

  The X-ray irradiation angle of the X-ray tube 122 to the subject 1 can be changed by driving the moving mechanism 124 to move the X-ray tube 122 in a direction parallel to the image generation unit 130. The image generation unit 130 can move in a direction parallel to the image generation unit 130 when the movement mechanism 138 is driven. For this reason, the image generation unit 130 can face the X-ray tube 122 via the subject 1 regardless of the position of the X-ray tube 122. The moving mechanisms 124 and 138 are driven by the moving mechanism driving unit 140, but the moving mechanism driving unit 140 is controlled by the control unit 108.

  The X-ray tube 122 is provided with an angle sensor that detects the irradiation angle of the X-ray tube 122 and a distance sensor that measures the distance from the X-ray tube 122 to the subject 1. A position sensor for measuring the position of the tube 122 is attached. The measurement results of the position sensor, angle sensor, and distance sensor are output to the angle body thickness measurement unit 102. The angle body thickness measurement unit 102 receives the measurement values of the angle sensor and the position sensor for each captured image, and outputs the received measurement values to the control unit 108. In addition, the angle body thickness measurement unit 102 performs a process of calculating the body thickness of the subject from the measurement result of the distance sensor for each angle or position of the X-ray tube 122 that performs imaging, and the calculated body thickness of the subject is captured. Is stored in the body thickness storage unit 103 in association with the angle or position of the X-ray tube 122. Note that the angle and position stored in the image storage unit 104 are transmitted to the image processing apparatus 20 via the communication unit 114 in a state associated with the captured image.

  As described above, the image generation unit 130 generates an electric signal corresponding to the detected X-ray dose, and generates a captured image by amplifying the electric signal. As is clear from FIG. 2, when the X-ray irradiation angle is different, the distance between the X-ray tube and the subject and the apparent body thickness of the subject are different. For this reason, the irradiation dose and the transmittance of the subject change for each irradiation angle or irradiation position, and the X-ray dose that can be detected by the X-ray detection unit 132 changes for each irradiation angle. In order to deal with this, in the present embodiment, the amplification factor when generating a captured image is set based on the angle or position of the X-ray tube 122 at the time of imaging or the body thickness of the subject at the time of imaging. The control parameter storage unit 112 stores an amplification factor for each angle or position of the X-ray tube 122 or the body thickness of the subject at the time of imaging. Further, when the amplification factor increases, the noise of the photographed image increases. To cope with this, the control parameter storage unit 112 stores a parameter value for changing the intensity of the noise suppression processing in association with the amplification factor. Yes.

  4 is a schematic plan view for explaining an example of a specific configuration of the image generation unit 130. FIG. 5 is a diagram for explaining an example of a specific configuration of the X-ray detection unit 132 of the image generation unit 130. FIG. In the example shown in FIG. 5, the X-ray detector 132 has a configuration in which an X-ray sensitive semiconductor film 131, a carrier collection electrode 133a, and an active matrix substrate 132a are stacked in this order from the X-ray incident side. .

  The semiconductor film 131 is, for example, amorphous selenium that converts X-rays directly into electric charges. A plurality of carrier collection electrodes 133a are arranged in a two-dimensional matrix. Further, the active matrix substrate 132a is made of glass having electrical insulation, for example.

  On the active matrix substrate 132a, capacitors for collecting and storing electric charges and thin film transistors are formed for each carrier collection electrode 133a. In the thin film transistor, a carrier collection electrode 133a and a capacitor are connected to a source. One pixel 133 is configured by one set of carrier collection electrode 133a, a capacitor, and a thin film transistor. In plan view, as shown in FIG. 4, pixels 133 are arranged in a matrix. The carrier collecting electrode 133a and the capacitor are not shown in FIG.

  On the active matrix substrate 132a, a first gate bus line is formed for each row, and a second data bus line is formed for each column. Each first gate bus line is connected to the gate of each thin film transistor constituting the same row. The first gate bus line transmits the gate pulse generated by the gate driver 134c to each thin film transistor. The second data bus line is connected to the drains of the thin film transistors constituting the same column. The electric charge accumulated in each capacitor is read out as an electric signal via the second data bus line in units of rows.

An amplifier 134a is connected to each second data bus line. The amplifier 134a amplifies the read electrical signal. The amplified electrical signal is sampled and held by the S / H circuit 134d, converted to pixel data by the A / D converter 134b, and transmitted to the image processing unit 110 shown in FIG. One captured image is constituted by a plurality of pixel data. The amplification factor of the amplifier 134a is controlled by the control unit 136.
In the example illustrated in FIGS. 4 and 5, the amplifier 134a, the A / D converter 134b, the S / H circuit 134d, and the gate driver 134c constitute the signal processing unit 134 illustrated in FIG.

  Note that the configuration of the X-ray detection unit 132 is not limited to the configuration illustrated in FIGS. 4 and 5, and may include a sheet coated with a stimulable phosphor material, for example. In this case, the stimulable phosphor material accumulates a part of the energy of the irradiated radiation (X-rays). When the stimulable phosphor material is irradiated with excitation light such as laser light, light emission (stimulated light emission) is generated according to the accumulated energy. When this light is converted into an electric signal by a photoelectric conversion element in units of pixels and this electric signal is amplified, a photographed image is generated. The amplification factor at this time is controlled by the control unit 136.

  FIG. 6A is a diagram illustrating an example of the amplification factor table 112 a stored in the control parameter storage unit 112. In the example shown in the figure, the amplification factor table 112a is defined for each reference body type identification information for identifying a plurality of types of reference body types (for example, lean type, standard type, and obesity type). Each amplification factor table 112a defines an amplification factor for each of a plurality of irradiation angles or irradiation positions. The amplification factor table 112a determines the amplification factor so that the X-ray irradiation position increases from the front of the subject (or as the X-ray irradiation angle θ shown in FIG. 3 increases from 90 °).

  FIG. 6B is a diagram illustrating an example of the noise suppression parameter table 112b stored in the control parameter storage unit 112. When the example shown in this figure is applied, the noise suppression process adds the charges read from adjacent pixels when reading the charges from each pixel of the X-ray detection unit 132 to generate an electrical signal. This is a process of making one electrical signal. The noise suppression parameter table 112b holds the number of pixels to which charges are added in order to generate one electric signal in association with the amplification factor. Specifically, the noise suppression parameter table 112b increases the number of pixels as the amplification factor increases.

  FIG. 7 is a block diagram illustrating a configuration of the image processing apparatus 20. The communication unit 210 stores a plurality of captured images transmitted from the X-ray imaging apparatus 10 in the image storage unit 202, and imaging conditions (for example, irradiation angle or irradiation position, and amplification factor) transmitted from the X-ray imaging apparatus 10. ) Is stored in the photographing condition storage unit 204 in association with the photographed image. The captured image stored in the image storage unit 202 is subjected to noise suppression processing by the noise suppression processing unit 212a of the image processing unit 212 as necessary. The noise suppression processing conditions at this time are determined based on the amplification factor at the time of shooting. The image processing parameter storage unit 208 stores data indicating correspondence between noise suppression processing conditions and amplification factors. Then, the image reconstruction unit 212b of the image processing unit 212 reconstructs the plurality of captured images stored in the image storage unit 202 by the method described with reference to FIG. 2, for example, and generates a tomographic image of the subject. The generated tomographic image is displayed on the display unit 207, for example.

  Note that the image processing apparatus 20 includes an operation unit 206. The image processing unit 212 and the like operate according to information input by the operator via the operation unit 206.

  FIG. 8 is a diagram illustrating data stored in the image processing parameter storage unit 208 in a table format. In the case where the example shown in this figure is applied, the noise suppression process is a process of averaging a plurality of adjacent pixel data into one averaged pixel data, or a process of changing the contrast ratio. The image processing parameter storage unit 208 holds the number of pixel data necessary for generating one piece of averaged pixel data and the change ratio of the contrast ratio in association with the amplification factor. In the example shown in this figure, as the amplification factor increases, the number of pixel data is increased and the contrast ratio is increased.

  FIG. 9 is a flowchart showing the operation of the X-ray imaging apparatus 10. When the identification information of the subject and the reference body shape identification information indicating which reference body shape the subject body shape corresponds to are input to the operation unit 106 (S2), the control unit 108 inputs the noise suppression parameter table 112b and the input The amplification factor table 112a corresponding to the reference body type identification information is read from the control parameter storage unit 112 (S4).

  Then, the control unit 108 drives the moving mechanism driving unit 140 to move the X-ray tube 122 until reaching a predetermined irradiation position (or until reaching a predetermined irradiation angle). At this time, the image generation unit 130 is also moved as necessary. In addition, the control unit 108 supplies the control unit 136 with the amplification factor of the electric signal generated by the X-ray detection unit 132 (for example, the amplification factor of the amplifier 134a illustrated in FIG. 4) and the charge for generating one electric signal. The number of pixels to be added (the number of pixels to be adjacently added) is set (S6). The amplification factor and the number of pixels at this time are set according to the X-ray irradiation position (the position of the X-ray tube 122) or the X-ray irradiation angle according to the amplification factor table 112a and the noise suppression parameter table 112b.

  Next, the control unit 108 controls the high voltage generation unit 120 via the tube voltage / tube current control unit 121 to irradiate the subject 1 with X-rays from the X-ray tube 122 (S8). The X-rays that have passed through the subject 1 are converted into charges by the X-ray detection unit 132 of the flat image generation unit 130, and the charges are collected in units of pixels. Then, the signal processing unit 134 reads out the electric charges while adding them in units of the set number of pixels, generates an electric signal, and amplifies the electric signal with the set amplification factor, thereby obtaining a captured image. A plurality of pieces of pixel data to be configured are generated, and the plurality of pieces of pixel data (that is, captured images) are transmitted to the image processor 110 (S10).

  The image processing unit 110 performs defect correction processing on the received captured image (S12). Then, the control unit 108 causes the image storage unit 104 to store the captured image after the correction processing in association with the subject identification information and the amplification factor applied when the captured image is generated.

  The X-ray imaging apparatus 10 performs the processing shown in S6 to S12 until generation, correction, and storage of a captured image are performed at all X-ray irradiation positions (or X-ray irradiation angles) (S14). Thereafter, the communication unit 114 of the X-ray imaging apparatus 10 transmits all the captured images and the amplification factors corresponding thereto to the image processing apparatus 20 in association with the identification information of the subject (S16). The image processing apparatus 20 stores the received captured image in the image storage unit 202 in association with the identification information of the transmission source X-ray imaging apparatus 10 and the identification information of the subject, and sets the amplification factor for each captured image. The photographing condition storage unit 204 stores the photographed image in association with the information for identifying the photographed image.

  As described above, in the example shown in the figure, the amplification factor of the electric signal when the captured image is generated is changed depending on the X-ray irradiation position (or X-ray irradiation angle). Specifically, the amplification factor is increased as the X-ray irradiation position moves away from the front of the subject (or as the X-ray irradiation angle θ shown in FIG. 3 moves away from 90 °). Therefore, it is possible to suppress degradation of the quality of the captured image without increasing the amount of X-ray irradiation when the subject is imaged from an oblique direction.

  Further, although noise may increase due to a decrease in the X-ray dose to be dropped, in the processing example shown in FIG. 9, the X-ray irradiation position is away from the front of the subject (or shown in FIG. 3). As the amplification factor increases (with the X-ray irradiation angle θ away from 90 °), the number of pixels required to generate one pixel data is increased. Therefore, it is possible to further suppress the deterioration of the quality of the generated cross-sectional image.

  FIG. 10 is a flowchart illustrating a cross-sectional image generation process performed by the image processing apparatus 20. First, the noise suppression processing unit 212a of the image processing unit 212 reads out one of the captured images associated with the identification information of the subject for which a cross-sectional image is to be generated from the image storage unit 202, and corresponds to the captured image. The amplification factor to be read is read from the imaging condition storage unit 204 (S20). Next, the noise suppression processing unit 212a reads the contrast ratio change rate corresponding to the read amplification factor from the image processing parameter storage unit 208 (S22). Then, the noise suppression processing unit 212a changes the contrast ratio of the captured image read in S20 according to the change rate read in S22 (S24), and stores the changed captured image in the image storage unit 202 (S26). The noise suppression processing unit 212a performs the processing shown in S20 to S24 on all the captured images associated with the identification information of the subject for which the cross-sectional image is to be generated (S28).

  Thereafter, the image reconstruction unit 212b of the image processing unit 212 performs a reconstruction process of the captured image after the contrast ratio change stored in the image storage unit 202, and generates a cross-sectional image (S30). The processing performed at this time is the same as the processing described with reference to FIG. Note that the image reconstruction unit 212b may set the contribution of each captured image when generating the cross-sectional image according to the amplification factor when generating each captured image. For example, the image reconstruction unit 212b reduces the contribution of the captured image as the amplification factor increases. Next, the display unit 207 displays the generated cross-sectional image (S32).

  As described above, in the present embodiment, as described above, it is possible to suppress deterioration in the quality of a captured image without increasing the X-ray irradiation amount when an object is imaged from an oblique direction. Therefore, a high-quality cross-sectional image can be obtained without increasing the exposure amount of the subject.

  Further, in the captured image obtained by photographing the subject from an oblique direction, the contrast ratio may decrease due to a decrease in the X-ray dose to be dropped. However, in the processing example illustrated in FIG. The contrast ratio is increased as the amplification factor is increased away from the front of the subject (or the X-ray irradiation angle θ shown in FIG. 3 is away from 90 °). Therefore, the quality of the generated cross-sectional image can be further improved.

  Next, an X-ray imaging system according to the second embodiment of the present invention will be described with reference to FIGS. 11 and 12. Since the configuration of the X-ray imaging system according to the present embodiment is the same as that of the first embodiment, description thereof is omitted.

  FIG. 11 is a flowchart showing the operation of the X-ray imaging apparatus 10 according to the present embodiment. The operation of the X-ray imaging apparatus 10 shown in this figure is to charge an electric signal to generate one electrical signal when the X-ray tube 122 is moved to a predetermined irradiation position (or to a predetermined irradiation angle). The number of pixels to be added (the number of adjacent pixels to be added) is set to a fixed number (for example, one or two) without changing according to the X-ray irradiation position (position of the X-ray tube 122) (S5) The operation is the same as that shown in FIG. Hereinafter, the same process is denoted by the same step number, and the description thereof is omitted.

FIG. 12 is a flowchart showing a section image generation process performed by the image processing apparatus 20 according to the present embodiment. The operation of the image processing apparatus 20 shown in this figure is that the noise suppression processing unit 212a reads the number of pixels corresponding to the amplification rate read in S20 from the image processing parameter storage unit 208 together with the change ratio of the contrast ratio. After (S21) and S21, before the process shown in S26, a noise suppression process is performed by averaging a plurality of adjacent pixel data to generate one averaged pixel data (S23), and the noise The operation is the same as that shown in FIG. 10 except that the captured image after the suppression processing and the contrast ratio change is stored in the image storage unit 202 (S23). In the present embodiment, the image reconstruction unit 212b performs a noise suppression process and a reconstruction process of a captured image after changing the contrast ratio, and generates a cross-sectional image (S30). Hereinafter, the same process is denoted by the same step number, and the description thereof is omitted.
As described above, also in the second embodiment, the same effect as that of the first embodiment can be obtained.

  Next, an X-ray imaging system according to a third embodiment of the present invention will be described with reference to FIGS. In the X-ray imaging system according to the present embodiment, the gain table 112a of the X-ray imaging apparatus 10 holds the gain in association with the body thickness of the subject, and the control unit 108 is connected to the image generation unit 130. The X-ray according to the first embodiment, except that the amplification factor of the electrical signal when generating the captured image is set based on the apparent body thickness of the subject at each X-ray irradiation position. It is the same as the photographing system. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 13 is a diagram showing a data configuration of the amplification factor table 112a in the present embodiment. In the example shown in the figure, the amplification factor table 112a divides the range of values that the body thickness of the subject can take into a plurality of sections, and sets the amplification factor for each section. Specifically, the gain is set to increase as the body thickness of the subject increases. In the present embodiment, the control parameter storage unit 112 may store a conversion formula for converting the body thickness into an amplification factor instead of the amplification factor table 112a.

  FIG. 14 is a flowchart for explaining the operation of the X-ray imaging apparatus 10 in the present embodiment. In the present embodiment, the angle body thickness measurement unit 102 of the X-ray imaging apparatus 10 uses a measurement result of a distance sensor attached to the X-ray tube 122 to determine a plurality of predetermined X-ray irradiation positions or X The apparent body thickness of the subject when viewed from each line irradiation angle is calculated and stored in the body thickness storage unit 103 in association with the X-ray irradiation position or X-ray irradiation angle (S40). Next, the control unit 108 converts the body thickness stored in the body thickness storage unit 103 into an amplification factor according to the data held in the amplification factor table 112a, and the amplification factor for each X-ray irradiation position or X-ray irradiation angle. Are associated with each other (S42). The subsequent processing (S6 to S16) is the same as that in the first embodiment.

The operation of the image processing apparatus 20 in the present embodiment is the same as that in the first embodiment.
As described above, the present embodiment can provide the same effects as those of the first embodiment.

Next, an X-ray imaging system according to the fourth embodiment of the present invention will be described with reference to FIG. In the X-ray imaging system according to the present embodiment, among the processes performed by the X-ray imaging apparatus 10, the processes after performing S <b> 42 are the processes described using S <b> 5 to S <b> 16 in FIG. 11 in the second embodiment. And the operation of the image processing apparatus 20 is the same as that of the X-ray imaging system according to the third embodiment except that the operation is the same as that of the second embodiment.
According to this embodiment, the same effect as that of the third embodiment can be obtained.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. In each of the embodiments described above, for example, the image processing unit 110 of the X-ray imaging apparatus 10 may have the function of the image processing unit 212 of the image processing apparatus 20.

  In each of the above-described embodiments, the image reconstruction unit 212b determines the contribution rate of each of the plurality of captured images when generating the cross-sectional image, the irradiation position, the irradiation angle, or the subject 1 when generating the captured image. You may set based on an apparent body thickness. In this case, the amplification factor may be a constant for all captured images.

1 is a block diagram illustrating a configuration of an X-ray imaging system according to a first embodiment of the present invention. The figure for demonstrating the principle of tomosynthesis imaging | photography. 1 is a block diagram showing an example of the configuration of an X-ray imaging apparatus 10. FIG. FIG. 3 is a schematic plan view for explaining an example of a specific configuration of the image generation unit 130. Schematic for demonstrating an example of the specific structure of the X-ray detection part 132. FIG. (A) is a figure which shows an example of the gain table 112a which the control parameter memory | storage part 112 has memorize | stored, (B) is a figure which shows an example of the noise suppression parameter table 112b which the control parameter memory | storage part 112 has memorize | stored. FIG. 3 is a block diagram showing the configuration of the image processing apparatus 20. The figure which shows the data which the image process parameter memory | storage part 208 memorize | stores in a table format. 3 is a flowchart showing the operation of the X-ray imaging apparatus 10. 5 is a flowchart showing a cross-sectional image generation process performed by the image processing apparatus 20. 6 is a flowchart showing the operation of the X-ray imaging apparatus 10 according to the second embodiment. 9 is a flowchart illustrating a cross-sectional image generation process performed by the image processing apparatus 20 according to the second embodiment. The figure which shows the gain table 112a which concerns on 3rd Embodiment. 10 is a flowchart for explaining the operation of the X-ray imaging apparatus 10 according to the third embodiment. 9 is a flowchart for explaining the operation of the X-ray imaging apparatus 10 according to the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Subject, 10 ... X-ray imaging apparatus, 20 ... Image processing apparatus, 102 ... Angular body thickness measurement part, 103 ... Body thickness storage part, 104 ... Image storage part, 106 ... Operation part, 107 ... Display part, 108 ... Control unit 110 ... Image processing unit 112 ... Control parameter storage unit 112a ... Amplification factor table 112b ... Noise suppression parameter table 114 ... Communication unit 120 ... High voltage generation unit 121 ... Tube voltage / tube current control unit, DESCRIPTION OF SYMBOLS 122 ... X-ray tube, 124 ... Moving mechanism, 130 ... Image generation part, 131 ... Semiconductor film, 132 ... X-ray detection part, 132a ... Active matrix substrate, 133 ... Pixel, 133a ... Carrier collection electrode, 134 ... Signal processing part 134a ... Amplifier, 134b ... A / D converter, 134c ... Gate driver, 136 ... Control unit, 138 ... Move mechanism, 140 ... Move mechanism drive unit, 20 ... Image storage unit 204 ... Shooting condition storage unit 206 ... Operation unit 207 ... Display unit 208 ... Image processing parameter storage unit 210 ... Communication unit 212 ... Image processing unit 212a ... Noise suppression processing unit 212b ... Image reconstruction unit

Claims (12)

An X-ray source that emits X-rays from a plurality of irradiation positions arranged along a straight line or an arc toward the subject;
An image generation unit that generates an electrical signal corresponding to the X-ray dose transmitted through the subject and amplifies the electrical signal to generate a captured image for each of a plurality of irradiation positions;
An amplification factor setting unit for setting the amplification factor of the electrical signal for each of the captured images based on the irradiation position of the X-ray source;
An image reconstruction unit that generates a cross-sectional image of the subject by reconstructing the plurality of captured images;
A radiation imaging apparatus comprising: For each of a plurality of types of reference body shapes, an amplification factor holding unit that holds an amplification factor table that defines the amplification factor for each of the plurality of irradiation positions,
An input unit for inputting reference body type identification information for identifying a reference body type to which the subject belongs;
The amplification factor setting unit reads an amplification factor table corresponding to the reference body type identification information input to the input unit from the amplification factor holding unit, and sets the amplification factor according to the read amplification factor table. The radiation imaging apparatus described in 1. An X-ray source that emits X-rays toward a subject at different angles from each of a plurality of irradiation positions arranged along a straight line or an arc;
An image generation unit that generates an electrical signal corresponding to the X-ray dose transmitted through the subject and amplifies the electrical signal to generate a captured image for each of a plurality of irradiation positions;
An amplification factor setting unit for setting the amplification factor of the electrical signal for each of the captured images based on the X-ray irradiation angle with respect to the subject;
An image reconstruction unit that generates a cross-sectional image of the subject by reconstructing the plurality of captured images;
A radiation imaging apparatus comprising: An amplification factor holding unit for holding an amplification factor table that defines the amplification factor for each of the plurality of irradiation angles for each of a plurality of types of reference body types;
An input unit for inputting reference body type identification information for identifying a reference body type to which the subject belongs;
The amplification factor setting unit reads an amplification factor table corresponding to the reference body type identification information input to the input unit from the amplification factor holding unit, and sets the amplification factor according to the read amplification factor table. The radiation imaging apparatus described in 1. An X-ray source that emits X-rays toward a subject at different angles from each of a plurality of irradiation positions arranged along a straight line or an arc;
An image generation unit that generates an electrical signal corresponding to the X-ray dose transmitted through the subject and amplifies the electrical signal to generate a captured image for each of a plurality of irradiation positions;
A body thickness measuring unit for measuring the body thickness of the subject when viewed from each of the plurality of irradiation positions or irradiation angles;
Based on the measurement result of the body thickness measurement unit, an amplification factor setting unit that sets the amplification factor of the electrical signal for each of the captured images;
An image reconstruction unit that generates a cross-sectional image of the subject by reconstructing the plurality of captured images;
A radiation imaging apparatus comprising: The image generation unit
A plurality of pixels arranged in a matrix, each generating a charge corresponding to the irradiated X-ray dose;
Reading means for generating the electrical signal by reading the charge from each of the plurality of pixels;
An amplification unit that amplifies the electrical signal according to the amplification factor set by the amplification factor setting unit;
The radiation imaging apparatus according to any one of claims 1 to 5. The image generation unit
A plurality of pixels arranged in a matrix, each generating a charge corresponding to the irradiated X-ray dose;
Reading means for reading out the electric charge from each of a predetermined number of pixels adjacent to each other and generating the electric signal by adding the predetermined number of electric charges;
An amplification unit that amplifies the electrical signal according to the amplification factor set by the amplification factor setting unit;
An adjacent addition number setting unit that sets the predetermined number based on the amplification factor;
The radiation imaging apparatus according to any one of claims 1 to 5. An image processing unit that averages a predetermined number of pixel data adjacent to each other to generate one averaged pixel data; and
An averaged number setting unit that sets the predetermined number for each of the plurality of captured images based on the amplification factor;
The radiation imaging apparatus according to any one of claims 1 to 7, further comprising:   The radiation imaging apparatus according to claim 1, further comprising an image processing unit that changes a contrast ratio for each of the plurality of captured images according to the amplification factor at the time of generating the captured image.   The said image reconstruction part sets the contribution rate of each of these some picked-up images when producing | generating the said cross-sectional image based on the amplification factor at the time of producing | generating the said picked-up image. The radiographic apparatus according to the item. An X-ray source that emits X-rays toward a subject at different irradiation angles from each of a plurality of irradiation positions arranged along a straight line or an arc;
An image generation unit that generates an electrical signal corresponding to an X-ray amount transmitted through the subject and amplifies the electrical signal to generate a captured image for each of a plurality of irradiation positions or irradiation angles;
An image reconstruction unit that generates a cross-sectional image of the subject by reconstructing the plurality of captured images;
Comprising
The image reconstruction unit sets the contribution ratio of each of the plurality of captured images when generating the cross-sectional image to an irradiation position, an irradiation angle, or an apparent body thickness of the subject when generating the captured image. Radiography device set based on. A plurality of imaging units having the X-ray source, the image generation unit, and the amplification factor setting unit,
The radiographic apparatus according to claim 1, wherein the image reconstruction unit reconstructs the plurality of captured images and generates the cross-sectional image for each of the plurality of imaging units.

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