JP2017035203A - Radiographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic apparatus capable of performing appropriate angiographic imaging while more reducing an exposure dose of a subject.SOLUTION: A moving speed detection unit 29 detects a moving speed of an X-ray irradiation field in an X direction as needed based on a moving speed of a top plate 3 in an X direction. An irradiation range calculation unit 31 calculates the length of the X-ray irradiation field in an X direction as needed based on the moving speed of the X-ray irradiation field. A collimator control unit 15 adjusts the width of the X-ray irradiation field as needed according to the calculated length so that the X-ray irradiation field is adjusted to a wide level automatically. As a result, even when a contrast medium moves fast, a region of interest can be reliably captured in the X-ray irradiation field. When the contrast medium moves slowly, an operator adjusts the moving speed S of the top plate 3 to a slow level so that the X-ray irradiation field is adjusted to a narrow level automatically. As a result, unnecessary exposure can be avoided. Thus, the region of interest can be captured in the X-ray irradiation field more reliably while an exposure dose of the subject is reduced more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an X-ray imaging apparatus used for contrast imaging such as angiography, and more particularly to a technique for performing tracking imaging of a contrast agent administered to a subject.

  In a medical field, for example, a long region that is long in the body axis direction of a subject, such as a blood vessel in a lower limb of the subject, may be a subject to be imaged. In this case, according to the standard of the X-ray detector, it is difficult to capture an X-ray image of the entire long region by one X-ray irradiation. Therefore, a plurality of X-ray images are taken along the body axis direction of the subject, and a plurality of X-ray images are connected in the body axis direction and reconstructed as necessary. Acquire an image (long image).

  In the case where an X-ray image of a blood vessel in the lower limb is acquired by the conventional X-ray imaging apparatus 101, a contrast agent is injected into the blood vessel of the subject M as shown in FIG. The plate 103 is sequentially moved in the body axis direction (x direction) of the subject. Due to the movement of the top plate 103, the imaging position P of the imaging system composed of the X-ray tube 105 and the FPD 107 is relatively displaced in the body axis direction (x direction) of the subject.

  Then, by irradiating the X-ray tube 105 from the X-ray tube 105 to the FPD 107 at each of a plurality of imaging positions, the image generation unit 109 performs X-enhancement of blood vessels by a contrast agent based on the X-ray detection signal output from the FPD 107. Generate a line image. When a single X-ray image in the long region is required, the reconstructing unit 111 reconstructs the X-ray image photographed at each photographing position, so that a long image suitable for diagnosis of the long region is obtained. Can be obtained.

  As a method of sequentially capturing X-ray images by moving the top plate 103 so as to track the contrast medium moving along the blood vessel, stepping imaging and bolus chase imaging are mainly used (for example, see Patent Document 1). ). In stepping imaging, as shown in FIG. 10A, X-ray imaging is performed at a plurality of predetermined imaging positions while repeatedly moving and stopping the top plate 103. That is, after taking an X-ray image at the photographing position P1 (left figure in FIG. 10 (a)), the top plate 103 is displaced faster than the moving speed of the contrast agent A, and is stopped at the next photographing position P2 (FIG. 10 (a). ) Central view). Then, an X-ray image is taken after the contrast medium A arrives at the photographing position P2, and the photographing position P is further displaced to the next photographing position P3 (FIG. 10 (a) right figure).

  On the other hand, in bolus chase imaging, as shown in FIG. 10B, the top plate 103 is continuously moved in the x direction to track the contrast medium in the blood vessel as needed, and X-ray imaging is performed at a preset timing. X-ray images are acquired. That is, after an X-ray image is captured at the imaging position P1a (the left diagram in FIG. 10B), the operator confirms the position of the contrast agent A reflected in the X-ray image, while the contrast agent A injected into the blood vessel is X The moving speed of the top plate 103 is adjusted as needed so that it always fits in the line image. Then, an X-ray image is taken at any time at a predetermined timing while moving the top plate 103 according to the moving speed of the contrast agent A (FIG. 10 (b) central view, right view).

  In the bolus chase imaging, the positions of the imaging positions P1a to P3a for imaging each X-ray image vary depending on the moving speed of the top plate 103, that is, the moving speed of the contrast medium A. In bolus chase imaging, X-ray images are continuously captured while tracking the contrast medium A as needed, so that real-time information of the contrasted blood vessels can be acquired.

JP 2005-296332 A

However, the conventional example having such a configuration has the following problems.
That is, the moving speed of the contrast medium in the x direction constantly changes depending on the thickness and shape of the blood vessel. Therefore, in general bolus chase imaging, the X-ray irradiation field for imaging an X-ray image is adjusted so that the X-ray 105a is always irradiated to the entire FPD 107. By widening the X-ray irradiation field in the x direction, the region of interest, that is, the portion of the blood vessel imaged by the contrast agent A can be more reliably accommodated inside the X-ray irradiation field.

  However, in bolus chase imaging performed by a conventional apparatus, the X-ray irradiation field is always extended to the entire FPD 107 and X-ray images are continuously captured for a long time. As a result, the exposure dose of the subject M becomes very large. Is concerned. On the other hand, when bolus chase imaging is performed in a state where the width of the X-ray irradiation field in the x direction is narrowed in advance in order to reduce the exposure dose, the moving speed of the contrast agent A is unexpectedly fast (or slow). As a result, the angiographic region, which is the region of interest, easily deviates from the X-ray irradiation field. As a result, it becomes difficult to obtain an X-ray image that favorably reflects a contrasted blood vessel that is a region of interest.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an X-ray imaging apparatus capable of performing suitable angiography while reducing the exposure dose of a subject.

In order to achieve such an object, the present invention has the following configuration.
That is, an X-ray imaging apparatus according to the present invention includes an X-ray tube that irradiates a subject with X-rays, an X-ray detector that detects X-rays transmitted through the subject, and a shielding unit that shields X-rays. A collimator for controlling an X-ray irradiation field, which is an X-ray irradiation field irradiated from the X-ray source, and the X-ray irradiation field to track the contrast agent administered to the subject. And an X-ray irradiation control unit for irradiating X-rays from the X-ray tube at a predetermined timing while the irradiation field moving means moves the X-ray irradiation field. An image generating unit that generates an X-ray image using a detection signal output from the X-ray detection unit while the irradiation field moving unit moves the X-ray irradiation field; and a body axis direction of the subject. A moving speed detector for detecting a moving speed of the X-ray irradiation field; and the moving speed An irradiation range calculation unit that calculates the length of the X-ray irradiation field in the body axis direction of the subject based on the moving speed of the X-ray irradiation field detected by the detection unit, and a body axis direction of the subject And a collimator control unit that controls opening and closing movement of the shielding unit so that the length of the X-ray irradiation field becomes the length calculated by the irradiation range calculation unit.

  [Operation / Effect] According to the X-ray imaging apparatus of the present invention, the irradiation field moving means moves the X-ray irradiation field in the body axis direction of the subject so as to track the contrast agent administered to the subject. The moving speed detecting unit detects the moving speed of the X-ray irradiation field in the body axis direction of the subject, and the irradiation range calculating unit is based on the moving speed of the X-ray irradiation field detected by the moving speed detecting unit. The length of the X-ray irradiation field in the axial direction is calculated. The collimator control unit controls the opening / closing movement of the shielding unit so that the length of the X-ray irradiation field in the body axis direction of the subject becomes the length calculated by the irradiation range calculation unit.

  Since the moving speed of the X-ray irradiation field changes in accordance with the moving speed of the contrast agent, the width of the X-ray irradiation field when taking an X-ray image is adjusted as needed according to the moving speed of the contrast agent. When the moving speed of the contrast agent is fast, the length of the X-ray irradiation field calculated by the irradiation range calculation unit becomes long. That is, when the moving speed of the contrast agent increases, the range of the X-ray irradiation field is adjusted so that the range of the X-ray irradiation field is quickly widened, so that the contrast agent of interest can be surely contained within the range of the X-ray irradiation field. .

  When the moving speed of the contrast agent is slow, the length of the X-ray irradiation field calculated by the irradiation range calculation unit is shortened. That is, when the moving speed of the contrast agent becomes slow, the range of the X-ray irradiation field is adjusted so as to be narrowed quickly, so that the exposure dose of the subject can be suitably reduced. When the moving speed of the contrast agent is low, the contrast agent of interest can be easily within the range of the X-ray irradiation field easily even if the X-ray irradiation field is narrow. Therefore, in bolus chase imaging for tracking a contrast agent, even if the moving speed of the contrast agent frequently changes, it is possible to ensure that the contrast agent of interest is always within the range of the X-ray irradiation field. In addition, the exposure amount of the subject can be reduced.

  In the above-described invention, the irradiation field moving means moves the top plate on which the subject is placed in the body axis direction of the subject, thereby moving the X-ray irradiation field in the body axis direction of the subject. It is preferable to move to.

  [Operation / Effect] According to the X-ray imaging apparatus of the present invention, the irradiation field moving means moves the top plate on which the subject is placed in the direction of the body axis of the subject, thereby covering the X-ray irradiation field. Move in the body axis direction of the specimen. In this case, since the moving speed of the X-ray irradiation field can be detected based on the moving speed of the top plate in the body axis direction of the subject, the width of the X-ray irradiation field is quickly adjusted based on the moving speed of the top board. The

  A mechanism for moving the top plate and a mechanism for detecting the moving speed of the top plate are often mounted on an X-ray imaging apparatus for the purpose of realizing a specific application. Therefore, by realizing the movement of the X-ray irradiation field by the movement of the top plate, it is possible to achieve the effect of the present invention without providing a new configuration in the X-ray imaging apparatus having the conventional configuration. That is, it is possible to realize an X-ray imaging apparatus that can surely contain the contrast agent of interest within the range of the X-ray irradiation field and can reduce the exposure dose of the subject at a lower cost.

  In the above-described invention, the irradiation field moving unit moves the imaging field including the X-ray source and the X-ray detection unit in the body axis direction of the subject, thereby moving the irradiation field of the subject. It is preferable to move in the body axis direction.

  [Operation / Effect] According to the X-ray imaging apparatus of the present invention, the irradiation field moving means moves the imaging system including the X-ray tube and the X-ray detector in the direction of the body axis of the subject. The irradiation field is moved in the body axis direction of the subject. In this case, since the moving speed of the X-ray irradiation field can be detected based on the moving speed of the imaging system in the body axis direction of the subject, the width of the X-ray irradiation field is quickly adjusted based on the moving speed of the imaging system. The

  A mechanism for moving the imaging system and a mechanism for detecting the moving speed of the imaging system are often mounted on an X-ray imaging apparatus for the purpose of realizing a specific application. Therefore, by realizing the movement of the X-ray irradiation field by the movement of the imaging system, the effect of the present invention can be achieved without providing a new configuration in the X-ray imaging apparatus having the conventional configuration. That is, it is possible to realize an X-ray imaging apparatus that can surely contain the contrast agent of interest within the range of the X-ray irradiation field and can reduce the exposure dose of the subject at a lower cost.

  In the above-described invention, it is preferable that the value of the length of the X-ray irradiation field calculated by the irradiation range calculation unit is proportional to the movement speed of the X-ray irradiation field detected by the movement speed detection unit.

  [Operation / Effect] According to the X-ray imaging apparatus of the present invention, the value of the length of the X-ray field calculated by the irradiation range calculation unit is equal to the movement speed of the X-ray field detected by the movement speed detection unit. Proportional. That is, based on the moving speed of the X-ray irradiation field, the calculation required to calculate the appropriate X-ray irradiation field width can be further simplified. Therefore, even when the moving speed of the X-ray irradiation field frequently changes in accordance with the change in the moving speed of the contrast agent, the width of the X-ray irradiation field can be adjusted more quickly to an appropriate range. It becomes possible. As a result, it is possible to more reliably store the contrast agent that is an object of interest within the range of the X-ray irradiation field and to further reduce the exposure dose of the subject.

  Further, in the above-described invention, a reconstructing unit that reconstructs a single long image by connecting a plurality of the X-ray images generated by the image generating unit in the body axis direction of the subject is provided. Is preferred.

  [Operation / Effect] According to the X-ray imaging apparatus of the present invention, the reconstruction unit connects a plurality of X-ray images generated by the image generation unit in the body axis direction of the subject to form a single long length. Reconstruct the image. In this case, by referring to a single long image, the entire long region in which the contrast medium is tracked and photographed can be diagnosed quickly and in a bird's-eye view. Therefore, the subject can be diagnosed more accurately in bolus chase imaging.

  According to the X-ray imaging apparatus of the present invention, the irradiation field moving means moves the X-ray irradiation field in the body axis direction of the subject so as to track the contrast agent administered to the subject. The moving speed detecting unit detects the moving speed of the X-ray irradiation field in the body axis direction of the subject, and the irradiation range calculating unit is based on the moving speed of the X-ray irradiation field detected by the moving speed detecting unit. The length of the X-ray irradiation field in the axial direction is calculated. The collimator control unit controls the opening / closing movement of the shielding unit so that the length of the X-ray irradiation field in the body axis direction of the subject becomes the length calculated by the irradiation range calculation unit.

  Since the moving speed of the X-ray irradiation field changes in accordance with the moving speed of the contrast agent, the width of the X-ray irradiation field when taking an X-ray image is adjusted as needed according to the moving speed of the contrast agent. When the moving speed of the contrast agent is fast, the length of the X-ray irradiation field calculated by the irradiation range calculation unit becomes long. That is, when the moving speed of the contrast agent increases, the range of the X-ray irradiation field is adjusted so that the range of the X-ray irradiation field is quickly widened, so that the contrast agent of interest can be surely contained within the range of the X-ray irradiation field. .

  When the moving speed of the contrast agent is slow, the length of the X-ray irradiation field calculated by the irradiation range calculation unit is shortened. That is, when the moving speed of the contrast agent becomes slow, the range of the X-ray irradiation field is adjusted so as to be narrowed quickly, so that the exposure dose of the subject can be suitably reduced. When the moving speed of the contrast agent is low, the contrast agent of interest can be easily within the range of the X-ray irradiation field easily even if the X-ray irradiation field is narrow. Therefore, in bolus chase imaging for tracking a contrast agent, even if the moving speed of the contrast agent frequently changes, it is possible to ensure that the contrast agent of interest is always within the range of the X-ray irradiation field. In addition, the exposure amount of the subject can be reduced.

1 is a schematic diagram illustrating a configuration of an X-ray imaging apparatus according to Embodiment 1. FIG. (A) is a functional block diagram for explaining the configuration of the X-ray imaging apparatus according to the first embodiment, and (b) is a longitudinal sectional view for explaining the configuration of the collimator according to the first embodiment. In the X-ray imaging apparatus which concerns on Example 1, it is a graph which shows an example of correlation with the moving speed S of the top plate in x direction, and the length T of the X-ray irradiation field in x direction. (A) is a graph showing an example having a proportional relationship, (b) is a graph showing an example in which the moving speed S is in a proportional relationship within a predetermined range, and (c) is a graph having a predetermined threshold as a boundary. It is a graph which shows the example which changes the length T. FIG. 3 is a flowchart for explaining an operation process of the X-ray imaging apparatus according to Embodiment 1; (A) is a flowchart according to the first embodiment, and (b) is a flowchart according to the second embodiment. It is the flowchart which divided the case about the process from step S3 which concerns on Example 1 to step S6 according to the moving speed of a contrast agent. It is a figure explaining the process from step S3 which concerns on Example 1 to step S7 in case the moving speed of a contrast agent is quick. (A) is a top view which shows the state which the contrast agent which is a region of interest displaces, (b) is a front view of the X-ray imaging apparatus which shows the state which tracks and moves a top plate, (c) is a top view. It is a longitudinal cross-sectional view which shows the state which controls a collimator according to the moving speed of a board, (d) is a top view which shows the state which expanded the X-ray irradiation field according to the moving speed of a top plate. It is a figure explaining the process from step S3 which concerns on Example 1 to step S7 in case the moving speed of a contrast agent is slow. (A) is a top view which shows the state which the contrast agent which is a region of interest displaces, (b) is a front view of the X-ray imaging apparatus which shows the state which tracks and moves a top plate, (c) is a top view. It is a longitudinal cross-sectional view which shows the state which controls a collimator according to the moving speed of a board, (d) is a top view which shows the state which narrowed the X-ray irradiation field according to the moving speed of a top plate. In the X-ray imaging apparatus which concerns on Example 1, it is a schematic diagram which shows the change of an imaging position and X-ray irradiation field by repeating step S3 to step S7. FIG. 3 is a schematic diagram illustrating an overall configuration of an X-ray imaging apparatus according to a second embodiment. It is the schematic explaining the structure of the X-ray imaging apparatus which concerns on a prior art example. It is a figure explaining operation | movement in the angiography imaging | photography of the X-ray imaging apparatus which concerns on a prior art example. (A) is a figure explaining the operation | movement in stepping imaging | photography, (b) is a figure explaining the operation | movement in bolus chase imaging | photography.

  Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating the overall configuration of the X-ray imaging apparatus according to the first embodiment.

<Description of overall configuration>
As shown in FIG. 1A, the X-ray imaging apparatus 1 according to the first embodiment has a top plate 3 on which a subject M in a horizontal posture is placed, and X that irradiates the subject M with X-rays 5a. An X-ray detector 7 that detects the X-ray 5a irradiated to and transmitted through the subject M is provided. The X-ray tube 5 and the X-ray detector 7 are disposed to face each other with the top 3 interposed therebetween.

  The X-ray detector 7 detects X-rays that are transmitted through the subject M from the X-ray tube 5, converts them into electrical signals, and outputs them as X-ray detection signals. Examples of the X-ray detector 7 include a flat panel detector (FPD). A collimator 9 is provided below the X-ray tube 5 to limit the X-ray 5a to a pyramid shape.

  As shown in FIG. 1B, the collimator 9 includes two plate-shaped shielding plates 9a arranged in the x direction. Each of the shielding plates 9a is made of a material that shields X-rays, and an example thereof is lead. In the first embodiment, each of the pair of shielding plates 9a is configured to move mirror-symmetrically in the x direction with respect to the central axis 5c of the X-ray 5a irradiated from the focal point 5b of the X-ray tube 5. And

  The spread of the X-ray 5a irradiated from the X-ray focal point 5b is limited to a pyramid shape by each of the shielding plates 9a. Then, the subject M is irradiated with the X-rays 5a that have passed through the openings formed by the shielding plates 9a. That is, the position and range of the region (X-ray irradiation field) irradiated with the X-rays 5a are adjusted by adjusting the opening by opening and closing each of the shielding plates 9a. The shielding plate 9a corresponds to the shielding part in the present invention.

  The X-ray imaging apparatus 1 includes an X-ray irradiation control unit 11, a top plate moving mechanism 13, a collimator control unit 15, an image generation unit 17, a reconstruction unit 19, an input unit 21, a monitor 23, A storage unit 25 and a main control unit 27 are provided. The X-ray irradiation control unit 11 is connected to the X-ray tube 5, and controls the tube voltage and tube current of the X-ray tube 5 to control the dose of the X-ray 5 a irradiated from the X-ray tube 5 and the X-ray. The timing for irradiating 5a is controlled.

  The top plate moving mechanism 13 is connected to the top plate 3 and moves the top plate 3 in the x direction (the longitudinal direction of the top plate 3 and the body axis direction of the subject M). When the top 3 moves in the x direction, the positional relationship between the imaging system including the X-ray tube 5 and the X-ray detector 7 and the subject M is relatively changed in the x direction. Therefore, when the top 3 moves in the x direction, the irradiation field of the X-ray 5a irradiated from the X-ray tube 5 to the subject M is displaced in the x direction. In the first embodiment, the top board moving mechanism 13 corresponds to the irradiation field moving means in the present invention.

  The collimator control unit 15 controls the opening / closing movement of each shielding plate 9 a provided in the collimator 9. In other words, the collimator control unit 15 controls the position and range of the X-ray irradiation field. The image generation unit 17 is provided at the subsequent stage of the X-ray detector 7 and generates an X-ray image based on the X-ray detection signal output from the X-ray detector 7. The relative position of the imaging system with respect to the top 3 (or the subject M) when X-ray images are taken by irradiating X-rays is hereinafter referred to as “imaging position”. The reconstruction unit 19 is provided in the subsequent stage of the image generation unit 17 and connects X-ray images generated by the image generation unit 17 in the x direction to reconstruct a long image.

  The input unit 21 inputs an operator's instruction, and examples thereof include a keyboard input type panel and a touch input type panel. The input unit 21 is provided with a speed control switch (not shown) for controlling the moving speed of the top board 3 in the x direction. The operator appropriately adjusts the moving speed of the top board 3 by appropriately operating the speed control switch. To do. The monitor 23 displays various images such as an X-ray image generated by the image generation unit 17 and a long image reconstructed by the reconstruction unit 19.

  The storage unit 25 stores various parameters referred to for control of the X-ray imaging apparatus 1 and various images generated by the image processing unit 17. Examples of parameters referred to for control of the X-ray imaging apparatus 1 include tube voltage / tube current parameters of the X-ray tube 5. The main control unit 27 is configured by a central processing unit (CPU) or the like, and in accordance with the contents input to the input unit 21 or the like, the X-ray irradiation control unit 11, the top plate moving mechanism 13, the collimator control unit 15, and image generation The respective components such as the unit 17 and the reconstruction unit 19 are collectively controlled.

  As a characteristic configuration of the present invention, the X-ray imaging apparatus 1 according to the first embodiment further includes a moving speed detection unit 29 and an irradiation range calculation unit 31. The moving speed detection unit 29 detects the moving speed of the top board 3 in the x direction as needed, and includes a potentiometer, an encoder, and the like as an example. In this case, the moving speed of the top 3 can be detected based on the distance at which the coordinate position of the top 3 in the x direction changes per unit time.

  The irradiation range calculation part 31 is provided in the upper stage of the collimator control part 15, and based on the moving speed S of the top plate 3 detected by the moving speed detection part 29, the length T in the x direction of the X-ray irradiation field is determined as needed. calculate. When the moving speed S of the top 3 is increased, the length T calculated by the irradiation range calculating unit 31 is configured to increase. The collimator control unit 15 adjusts the length of the X-ray irradiation field in the x direction by appropriately moving the shielding plate 9a in the x direction according to the value of the length T calculated by the irradiation range calculation unit 31.

  By providing such a configuration, the X-ray imaging apparatus 1 performs X-ray irradiation in the x direction in accordance with a change in the moving speed of the top 3 in the x direction, that is, a change in the moving speed of the X-ray irradiation field in the x direction. The field range changes rapidly. Therefore, the exposure dose of the subject M can be reduced while the region of interest is reliably within the range of the X-ray irradiation field in bolus chase imaging.

<Correlation between top plate moving speed S and X-ray irradiation field length T>
The X-ray imaging apparatus 1 according to the first embodiment is configured such that the length T in the x direction of the X-ray irradiation field changes according to the moving speed S of the top 3 in the x direction. That is, when the value of the movement speed S detected by the movement speed detection unit 29 increases, the value is calculated as the length T calculated by the irradiation range calculation unit 31. On the other hand, when the value of the moving speed S decreases, the irradiation range calculation unit 31 calculates the length T to a short value.

  Regarding the specific correlation between the moving speed S of the top 3 and the length T of the X-ray irradiation field in the x direction, the length T increases as the moving speed S increases, and the moving speed S decreases. As long as the length T is shortened according to the above, it may be set as appropriate. As the simplest example of the correlation, as shown in FIG. 2A, there is a relationship in which the moving speed S and the length T are proportional. In this case, the range of the X-ray irradiation field becomes wider in the x direction in proportion to the increase in the moving speed S. Other examples of the correlation between the moving speed S and the length T include the relationships shown in FIGS. 2B and 2C, details of which will be described later. In the first embodiment, as shown in FIG. 2A, the moving speed S and the length T are in a proportional relationship.

  As the moving speed of the contrast agent becomes faster, the region of interest is easily displaced outside the imaging range of the X-ray image. Therefore, generally, the faster the contrast agent moves, the faster the moving speed S of the top 3 is to track the contrast agent quickly. In proportion to the moving speed S, the length T of the X-ray irradiation field increases. That is, as the moving speed of the contrast agent increases, the irradiation range calculation unit 31 calculates the value of the length T as a larger value.

  As a result, as the moving speed of the contrast agent increases, the X-ray irradiation field becomes wider in the x direction, so that the tip region R of the contrast agent is always reliably within the X-ray irradiation field during bolus chase imaging. (See FIGS. 5 (d) and 6 (d)). Further, since the moving speed S and the length T are in a proportional relationship, the calculation required for the irradiation range calculation unit 31 to calculate the length T can be further simplified. Therefore, the responsiveness regarding the control of the length T with respect to the moving speed S becomes higher.

<Description of operation>
Next, the operation of the X-ray imaging apparatus 1 according to the first embodiment will be described. FIG. 3A is a flowchart for explaining the operation of the X-ray imaging apparatus according to the first embodiment. Here, an outline of the operation will be described by taking as an example a case where bolus chase imaging is performed by contrasting blood vessels in a lower limb of a subject.

Step S1 (Administration of contrast medium)
In performing bolus chase imaging, the operator first operates the input unit 21 to move each imaging system to the imaging start point. In the first embodiment, the imaging start point, that is, the imaging position at which an X-ray image is first captured is P1 (see FIGS. 5A and 7). Then, the operator administers a contrast medium into the blood vessel of the subject M from the base of the thigh of the subject M or the like.

Step S2 (Start of X-ray imaging)
After administration of the contrast agent, X-ray image capturing is started. That is, the surgeon operates the input unit 21 to irradiate the subject M with the X-ray 5 a from the X-ray tube 5. The X-ray detector 7 detects the X-ray 5a that passes through the subject M and outputs an X-ray detection signal. The image generation unit 17 generates an X-ray image showing the contrasted blood vessel based on the X-ray detection signal. The generated X-ray image is displayed on the monitor 23.

Step S3 (moving the top plate)
The contrast agent administered in step S1 moves in the x direction by flowing from the thigh to the toes along the bloodstream, and sequentially images the blood vessels of the lower limbs. The surgeon refers to the X-ray image displayed on the monitor 23 and moves the top 3 in the x direction so as to track the contrast agent moving in the x direction. The top 3 is moved by operating the input unit 21 or the like. As the top 3 moves in the x direction, the positional relationship between the imaging system and the subject M is relatively displaced in the x direction, so that the X-ray irradiation field is displaced in the x direction.

Step S4 (Detection of moving speed of top plate)
As the top 3 moves, the moving speed detector 29 detects the moving speed of the top as needed. That is, the moving speed detector 29 intermittently detects the moving distance G of the top 3 in the x direction based on the change in the coordinate position of the top 3 in the x direction. Then, based on the time required for moving the moving distance G, the moving speed detector 29 detects the moving speed S of the top 3 in the x direction as needed. Information on the detected moving speed S of the top 3 is transmitted from the moving speed detecting unit 29 to the irradiation range calculating unit 31 via the main control unit 27.

Step S5 (calculation of irradiation field range)
The irradiation range calculation unit 31 calculates the range of the X-ray irradiation field as needed based on the transmitted information on the moving speed S of the top 3. The irradiation range calculation unit 31 calculates the range of the X-ray irradiation field so that the length T of the X-ray irradiation field in the x direction becomes longer when the moving speed S of the top 3 is fast. On the other hand, when the moving speed S of the top 3 is slow, the irradiation range calculation unit 31 calculates the range of the X-ray irradiation field so that the length T of the X-ray irradiation field in the x direction is shortened. Information on the length T of the X-ray irradiation field in the x direction is transmitted from the irradiation range calculation unit 31 to the collimator control unit 15.

Step S6 (adjustment of X-ray irradiation field)
The collimator control unit 15 adjusts the X-ray irradiation field based on information on the length T of the X-ray irradiation field calculated by the irradiation range calculation unit 31 as needed. That is, the collimator control unit 15 controls each of the shielding plates 9a provided in the collimator 9 as needed according to the value of the length T. Each of the shielding plates 9a moves mirror-symmetrically in the x direction according to a signal transmitted from the collimator control unit 15. As a result, the X-ray 5a irradiated from the X-ray focal point 5b is adjusted in a pyramid shape that spreads in the y direction and has a length T in the x direction.

Step S7 (X-ray image capturing)
After the range of the X-ray irradiation field is adjusted according to the moving speed S of the top 3, an X-ray image is taken. That is, the surgeon operates the input unit 21 to irradiate the subject M with the X-ray 5 a from the X-ray tube 5. The X-ray detector 7 detects the X-ray 5a that passes through the subject M and outputs an X-ray detection signal. The image generation unit 17 generates an X-ray image showing the contrasted blood vessel based on the X-ray detection signal.

  Thereafter, when the contrast medium traveling along the blood vessel is further tracked and the bolus chase imaging is continued, the process returns to step S3 and the operations of steps S3 to S7 are repeated. On the other hand, when there is no need to follow the contrast agent for further imaging, the imaging of the X-ray image is terminated and the process proceeds to step S8.

  When performing bolus chase imaging, the X-ray 5a is irradiated every time a predetermined time elapses. That is, X-ray images are taken continuously, and the frame rate is preferably about 5 to 30 fps. As an example, when the frame rate is 15 fps, after the first X-ray image is captured in step S2, the processes from step S3 to step S7 are repeated at a cycle of 15 times per second, and the imaging is performed according to the contrast agent moving speed. A range X-ray image is generated as needed. The X-ray image generated in step S7 is displayed on the monitor 23 and stored in the storage unit 25 as needed.

Step S8 (Reconstruction of long image)
After the tracking of the contrast agent is completed, a long image is reconstructed as necessary. When a long image that is a single X-ray image projected for a long region including the imaging region of each X-ray image is required, each of the X-ray images obtained up to step S7 is sent to the reconstruction unit 19. Sent. The reconstruction unit 19 reconstructs a single long image by connecting the X-ray images generated by the image generation unit 17 in the x direction.

  The reconstructed long image is displayed on the monitor 23 and stored in the storage unit 25. With the acquisition of the long image, all steps related to bolus chase shooting are completed. In this way, a single long image that allows the entire long region to be looked down is acquired. If there is no need to reconstruct a long image, the process of step S8 may be omitted when the tracking imaging of the contrast agent is completed, and the entire bolus chase imaging process may be completed.

<Explanation of operation according to moving speed of contrast agent>
Here, the process from step S3 to step S7 will be described in more detail by dividing the case according to the moving speed of the contrast agent. FIG. 4 is a flowchart from step S3 to step S7 in each of the cases where the moving speed of the contrast agent in the x direction is fast and slow.

  In bolus chase imaging, the speed at which the contrast agent administered to the subject moves in the x direction constantly changes. That is, the moving speed of the contrast agent A in the x direction is high at a part where the blood flow is fast or a part where the blood vessel is straight in the x direction. On the other hand, the moving speed of the contrast agent A in the x direction is slow at a site where the blood flow is slow or a blood vessel is bent in the y direction (short direction of the top 3). For example, the surgeon appropriately adjusts the moving speed S of the top 3 in the x direction by operating a speed control switch (not shown) provided in the input unit 21 as an example.

  First, the operation when the moving speed of the contrast medium A in the x direction is high will be described with reference to each drawing in FIG. The outline of the operation is as shown in the flowchart on the left side of FIG. In this case, the contrast agent A quickly moves in the x direction along the blood vessel C of the subject M. Therefore, when the range of the X-ray irradiation field H is narrowed in the x direction, the position of the tip region R of the contrast agent A, which is a region of interest, can be easily within the range of the X-ray irradiation field H (see the left figure in FIG. 5A). ) And move out of the range of the X-ray irradiation field H (see the right figure in FIG. 5A). Therefore, if the X-ray irradiation field H is narrowed when the moving speed of the contrast agent A is fast, it is difficult to confirm the tip region R that is a region of interest in the X-ray image generated by the image generation unit 17.

  For this reason, when the moving speed of the contrast medium A is fast, it is necessary to move the top 3 quickly in the x direction in order to ensure that the tip region R of the contrast medium A is within the range of the X-ray irradiation field H. Therefore, in step S3, the operator operates a speed control switch provided in the input unit 21 to increase the moving speed S of the top 3 in the x direction. As the top 3 moves, the relative position of the imaging system with respect to the subject M shifts from P1 to P2a, which is relatively far from P1 (see the right figure in FIG. 5B). The moving speed S of the top 3 adjusted so as to have a high speed is detected by the moving speed detector 29 in step S4.

  When the moving speed S of the top 3 is high, the value of the length T calculated by the irradiation range calculation unit 31 in step S5 is a relatively long value. In this case, the value of T calculated as T1 is taken as an example. The collimator control unit 15 controls each of the shielding plates 9a so that the length in the x direction of the X-ray irradiation field H becomes the length T1 calculated by the irradiation range calculation unit 31.

  Therefore, in step S6, each of the shielding plates 9a moves mirror-symmetrically in the x direction according to the signal transmitted by the collimator control unit 15. Since the X-ray irradiation angle becomes wider in the body axis direction of the subject M, the X-ray 5a irradiated from the X-ray focal point 5b is adjusted in a cone beam shape having a thickness T1 extending in the y direction and having a thickness T1 in the x direction. (FIG. 5C). In order to more surely place the region of interest in the X-ray irradiation field H, the position of each shielding plate 9a can be controlled so that the entire surface of the X-ray detector 7 is irradiated with cone-beam X-rays 5a. preferable. That is, T1 is more preferably equal to the length L of the X-ray detector 7 in the x direction.

  In this way, the length of the X-ray irradiation field H in the x direction is increased in accordance with the increase in the moving speed S of the top 3 (FIG. 5D). Therefore, even when the moving speed of the contrast medium A is faster than expected, the X-ray irradiation field is adjusted widely in the x direction based on the increased moving speed S while increasing the moving speed S of the top 3. The tip region R, which is the region of interest, can be quickly contained within the range of the X-ray irradiation field H. As a result, since the region of interest is reliably reflected in the X-ray image acquired in step S7, it is possible to more reliably avoid the deterioration of the diagnostic ability of the X-ray image.

  Next, the operation when the moving speed of the contrast medium A in the x direction is slow will be described with reference to each drawing of FIG. The outline of the operation is as shown in the flowchart on the right side of FIG.

  When the moving speed of the contrast medium A is slow, the contrast medium A moves slowly in the x direction along the blood vessel C of the subject M. Therefore, it is not necessary to widen the X-ray irradiation field H in the x direction in order to avoid the movement of the tip region R of the contrast agent A, which is the region of interest, outside the range of the X-ray irradiation field H. On the other hand, when the range of the X-ray irradiation field H is widened, it is useless even to a region where the tip region R having a low moving speed is unlikely to be displaced, as indicated by reference symbols J1 and J2 in the right diagram of FIG. Will be irradiated with X-rays. As a result, the exposure amount of the subject M increases.

  Therefore, first, in step S3, the operator operates the speed control switch according to the moving speed of the contrast medium A, and slows down the moving speed S of the top 3 in the x direction. As the top 3 moves, the relative position of the imaging system with respect to the subject M shifts from P1 to P2b, which is relatively close to P1 (see the right figure in FIG. 6B). The moving speed S of the top 3 adjusted so as to be a slow speed is detected by the moving speed detector 29 in step S4.

  When the moving speed S of the top 3 is slow, the value of the length T calculated by the irradiation range calculation unit 31 in step S5 is a relatively short value. In this case, T2 calculated as an example is T2. The collimator control unit 15 controls each of the shielding plates 9a so that the length in the x direction of the X-ray irradiation field H becomes the length T2 calculated by the irradiation range calculation unit 31.

  Therefore, in step S6, each of the shielding plates 9a moves mirror-symmetrically in the x direction according to the signal transmitted by the collimator control unit 15. Since the X-ray irradiation angle becomes narrower in the body axis direction of the subject M, the X-ray 5a irradiated from the X-ray focal point 5b spreads in the y direction and is adjusted in a fan beam shape having a thickness T2 in the x direction. (FIG. 6C).

  As a result, the length of the X-ray irradiation field H in the x direction decreases as the moving speed S of the top plate 3 decreases (FIG. 6D). When the moving speed of the contrast medium A in the x direction is slow, the tip region R, which is a region of interest, can be easily and reliably within the range of the X-ray irradiation field H even if the X-ray irradiation field H is narrow in the x direction. . As a result, in step S7, it is possible to acquire an X-ray image in which the region of interest is reliably reflected and to further reduce the exposure dose of the subject M.

  In this way, the X-ray image capturing operation is repeated each time a predetermined time elapses while appropriately controlling the length T of the X-ray irradiation field in the x direction according to the moving speed S of the top 3. In the bolus chase imaging, the operator appropriately adjusts the moving speed S of the top 3 according to the moving speed of the contrast medium A in the x direction. Therefore, in bolus chase imaging, the imaging system irradiates X-rays 5a at each of the imaging positions P1 to P4 while displacing the relative position with respect to the subject M as an example from P1 to P4 as shown in FIG. Acquire each image.

  In this case, when the photographing position is displaced from P1 to P2, the moving speed Sa of the top 3 is adjusted so as to increase. Therefore, the range T1 of the X-ray irradiation field at the imaging position P2 becomes wide. On the other hand, when the photographing position is displaced from P2 to P3, the moving speed S2 of the top 3 is adjusted to be slow. Therefore, the range T2 of the X-ray irradiation field at the imaging position P3 is narrowed.

  The moving speed S3 of the top 3 when the photographing position is displaced from P3 to P4 is adjusted to be faster than the moving speed S1 and slower than the moving speed S2. As shown in FIG. 2A, since the moving speed S and the length T are in a proportional relationship, the length T3 of the X-ray irradiation field at the imaging position P4 is longer than the length T1 and shorter than the length T2. It is controlled to become. As described above, the X-ray imaging apparatus 1 adjusts the moving speed S of the top 3 according to the moving speed of the contrast agent, and further appropriately calculates the length T of the X-ray irradiation field in the x direction according to the moving speed S. Configured to do. Therefore, unnecessary exposure of the subject M can be preferably avoided while reliably ensuring that the distal end region of the contrast medium is within the range of the X-ray irradiation field.

<Effects of Configuration of Example 1>
The X-ray imaging apparatus 1 according to the first embodiment displaces the position of the X-ray irradiation field with respect to the subject M in the x direction by moving the top 3 in the x direction. The length T of the X-ray irradiation field in the x direction is changed at any time according to the moving speed S of the top 3 in the x direction, that is, the speed at which the X-ray irradiation field moves in the x direction. For this reason, during the execution of bolus chase imaging in which the X-ray field is moved so as to track the contrast agent, the range of the X-ray field is adjusted to an appropriate area as needed according to the change in the moving speed of the X-ray field. The

  When the moving speed of the contrast medium is high, the operator operates the input unit 21 as appropriate to increase the moving speed S of the top 3. As shown in FIG. 2A, the length T of the X-ray irradiation field in the x direction and the moving speed S are in a proportional relationship. Therefore, as the moving speed S increases, the value of the length T calculated by the shooting range calculation unit 31 increases. As a result, the range of the X-ray irradiation field becomes wider as the moving speed of the contrast agent becomes faster. Therefore, even if the contrast agent moves faster, the distal end region R that is the region of interest is reliably within the range of the X-ray irradiation field. Can fit in.

  On the other hand, when the moving speed of the contrast medium is slow, the operator adjusts the moving speed S of the top 3 to be slow according to the moving speed of the contrast medium. Therefore, as the moving speed S decreases, the value of the length T calculated by the shooting range calculation unit 31 decreases. As a result, the range of the X-ray irradiation field becomes narrow as the moving speed of the contrast agent becomes slow, so that the exposure dose of the subject M can be reduced. When the contrast agent moves slowly, the region of interest can be easily within the range of the X-ray irradiation field even if the X-ray irradiation field is narrow. Therefore, in the X-ray imaging apparatus according to the first embodiment, the region of interest can be more reliably contained within the range of the X-ray irradiation field regardless of the speed at which the contrast agent moves, and the exposure dose of the subject is further reduced. It becomes possible to do.

  Further, the moving speed of the X-ray irradiation field, that is, the moving speed S of the top 3 is automatically detected by the moving speed detecting unit 29, and the imaging range calculating unit 31 automatically sets the value of the length T based on the moving speed S. Then, the collimator control unit 15 automatically adjusts the range of the X-ray irradiation field based on the value of the length T. That is, when the operator adjusts the moving speed S of the top 3 according to the moving speed of the contrast agent, the width of the X-ray irradiation field is automatically adjusted according to the moving speed S.

  Therefore, even if the moving speed of the contrast agent changes during execution of bolus chase imaging, the X-ray irradiation field is automatically adjusted to have an appropriate width. In bolus chase imaging, the contrast medium moving speed frequently changes depending on the shape and thickness of the blood vessel in the subject. Since the apparatus according to the first embodiment includes the movement speed detection unit 29, the imaging range calculation unit 31, and the collimator control unit 15, X-ray irradiation can be promptly performed even when the movement speed of the contrast agent frequently changes. The field can be adjusted to an appropriate size.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings. In the first embodiment, by moving the top 3 in the x direction, the imaging system composed of the X-ray tube 5 and the X-ray detector 7 and the subject M are relatively moved, and the imaging position of the imaging system with respect to the subject M is set. Displace in the x direction. When the imaging position of the imaging system with respect to the subject M is displaced, the position of the X-ray irradiation field with respect to the subject M is displaced in the x direction.

  On the other hand, the X-ray imaging apparatus 1A according to the second embodiment is different from the first embodiment in that the imaging position with respect to the subject M is displaced in the x direction by directly moving each imaging system in the x direction. That is, in the overall configuration of the second embodiment, the X-ray imaging apparatus 1A includes an X-ray tube moving mechanism 33 and a detector moving mechanism 35 instead of the top plate moving mechanism 13, as shown in FIG. In the second embodiment, the X-ray tube moving mechanism 33 and the detector moving mechanism 35 correspond to the irradiation field moving means in the present invention.

  The X-ray tube moving mechanism 33 is connected to the X-ray tube 5 and moves the X-ray tube 5 in the x direction. The detector moving mechanism 35 is connected to the X-ray detector 7 and moves the X-ray detector 7 in the x direction. That is, the imaging system including the X-ray tube 5 and the X-ray detector 7 is moved synchronously in the x direction by the X-ray tube moving mechanism 33 and the detector moving mechanism 35. The moving speed detector 29 is configured to detect the moving speed in the x direction for each of the imaging systems. Examples of the configuration of the moving speed detector 29 in the second embodiment include an encoder and a potentiometer provided in each of the X-ray tube 5 and the X-ray detector 7.

  A flowchart of the operation of the X-ray imaging apparatus 1A is as shown in FIG. The flowchart according to the second embodiment is common to the first embodiment except for step S3 and step S4. That is, a contrast medium is injected (step S1), and an initial X-ray image is taken (step S2). In step S3, the surgeon refers to the X-ray image, operates the speed control switch provided in the input unit 21 according to the moving speed of the contrast agent, and moves each of the imaging systems in the x direction.

  In step S <b> 4, the moving speed detection unit 29 detects the moving speed S in the x direction for each of the imaging systems, and transmits information on the detected moving speed S to the imaging range calculation unit 31. The imaging range calculation unit 31 has a length T of the X-ray irradiation field in the x direction corresponding to the value of the moving speed S of the imaging system in the x direction, for example, based on the correlation shown in the graph of FIG. Is calculated (step S5).

  The collimator control unit 15 moves each of the shielding plates 9a in the x direction and controls the length of the x-ray irradiation field in the x direction to be T (step S6). The X-ray irradiation control unit 11 irradiates the X-ray 5a with the X-ray 5a every time a predetermined time elapses to capture an X-ray image (step S7). The operator tracks the contrast agent by adjusting the moving speed S of the imaging system as needed according to the moving speed of the contrast agent, and repeats steps S3 to S7 as appropriate. After the tracking of the contrast agent is completed, the long images are reconstructed by connecting the X-ray images in the x direction as necessary (step S8).

  The X-ray imaging apparatus 1A according to the second embodiment has a configuration in which the position of the X-ray irradiation field with respect to the subject M is displaced in the x direction by moving the imaging system. The length T of the X-ray field in the x direction is changed at any time according to the moving speed S of the imaging system in the x direction, that is, the speed at which the X-ray field moves in the x direction. Therefore, in Example 2, the same effect as Example 1 can be acquired.

  In other words, during the execution of bolus chase imaging in which the X-ray field is moved so as to track the contrast agent, the X-ray field is automatically adjusted to an appropriate area as needed with respect to changes in the moving speed of the X-ray field. . Therefore, even if the moving speed of the contrast agent frequently changes in bolus chase imaging, the region of interest can be more reliably within the range of the X-ray irradiation field, and the exposure dose of the subject can be further reduced. It becomes possible to do.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In each of the above-described embodiments, each of the shielding plates 9a is configured to move in mirror image symmetry, but each of the shielding plates 9a may be configured to move independently. In this case, since the position of the X-ray irradiation field is not limited to the central region of the X-ray detector 7, the position of the X-ray irradiation field can be set more flexibly. Moreover, you may change suitably the number of the shielding plates 9a with which the collimator 9 is provided. As an example, there may be mentioned a configuration including a pair of shielding plates 9a that move vertically in the x direction and a pair of shielding plates 9a that move horizontally in the y direction (left and right direction of the subject M) orthogonal to the x direction.

  (2) In each of the above-described embodiments, the X-ray imaging in Step S2 may be omitted, and the X-ray imaging may be performed after the top 3 (or imaging system) starts moving. That is, the configuration may be such that, after the contrast medium is injected in step S1, the process proceeds to step S3, and a plurality of X-ray images are taken while repeating the steps from step S3 to step S7.

  (3) In each of the embodiments described above, the moving speed S of the top 3 (or imaging system) in the x direction and the length T of the X-ray field H in the x direction are as shown in FIG. Although the case where the relationship is proportional has been described as an example, the correlation between the moving speed S and the length T is not limited thereto. Other examples of the correlation between the moving speed S and the length T include those shown in FIGS. 2B and 2C.

  In the example of the correlation shown in FIG. 2B, when the moving speed S is within a predetermined range from Sg to Sh, the moving speed S and the length T are in a proportional relationship. When the moving speed S is equal to or less than Sg, the length T is always a predetermined minimum value Tg. Further, when the moving speed is equal to or higher than Sh, the length T is always a predetermined maximum value Th.

  In the correlation shown in FIG. 2 (b), the length T is never longer than Th. Therefore, when the moving speed S is very high, the width of the X-ray irradiation field becomes wider than the X-ray detection surface of the X-ray detector 7, and it is possible to avoid an unnecessary increase in the exposure dose of the subject M. Therefore, the value of Th is preferably the length L of the X-ray detector 7 in the x direction.

  Further, the length T is never shorter than Tg. Therefore, even when the moving speed S is zero or very slow, a certain narrow range is secured for the X-ray irradiation field. Therefore, it is possible to avoid a situation where the X-ray irradiation field becomes unnecessarily narrow when an X-ray image is taken in a state where the X-ray irradiation field is not displaced, such as step S2. The values of Sh and Sg may be set arbitrarily. That is, in FIG. 2B, Sh is higher than S1, but Sh may be set lower than S1. Sg may be set to a value higher than S2.

  In the example of the correlation shown in FIG. 2C, the moving speed S and the length T have a correlation that draws a staircase graph. That is, when the moving speed S is equal to or greater than the predetermined threshold value Sx, the length T is a predetermined long value T1, and when the moving speed S is lower than the predetermined threshold value Sx, the length T is a predetermined low value T2. In this case, since the value that the length T can take is limited, the calculation required for the calculation of the irradiation range calculation unit 31 can be further simplified. In FIG. 2C, there is one threshold value and two possible T values. However, the threshold value of the moving speed S to be set and the number of possible T values can be changed as appropriate. Good. In this case, by setting n threshold values for the moving speed S, possible T values are (n + 1).

DESCRIPTION OF SYMBOLS 1 ... X-ray imaging apparatus 3 ... Top plate 5 ... X-ray tube 7 ... X-ray detector 9 ... Collimator 9a ... Shielding plate (shielding part)
11 ... X-ray irradiation control unit 13 ... Top plate moving mechanism (irradiation field moving means)
DESCRIPTION OF SYMBOLS 15 ... Collimator control part 17 ... Image generation part 19 ... Reconstruction part 21 ... Input part 27 ... Main control part 29 ... Movement speed detection part 31 ... Irradiation range calculation part

Claims (5)

An X-ray tube that irradiates the subject with X-rays;
An X-ray detector for detecting X-rays transmitted through the subject;
A collimator that includes a shielding unit that shields X-rays, and controls an X-ray irradiation field that is an X-ray irradiation field irradiated from the X-ray source;
Irradiation field moving means for moving the X-ray irradiation field in the body axis direction of the subject so as to track the contrast agent administered to the subject;
An X-ray irradiation control unit for irradiating X-rays from the X-ray tube at a predetermined timing while the irradiation field moving means moves the X-ray irradiation field;
An image generation unit that generates an X-ray image using a detection signal output by the X-ray detection unit while the irradiation field moving unit moves the X-ray irradiation field;
A moving speed detector that detects a moving speed of the X-ray irradiation field in the body axis direction of the subject;
An irradiation range calculation unit that calculates the length of the X-ray irradiation field in the body axis direction of the subject based on the movement speed of the X-ray irradiation field detected by the movement speed detection unit;
A collimator control unit configured to control the opening / closing movement of the shielding unit such that the length of the X-ray irradiation field in the body axis direction of the subject becomes the length calculated by the irradiation range calculation unit. X-ray imaging apparatus. The X-ray imaging apparatus according to claim 1,
The irradiation field moving means moves the X-ray irradiation field in the body axis direction of the subject by moving the top plate on which the subject is placed in the body axis direction of the subject. . The X-ray imaging apparatus according to claim 1,
The irradiation field moving means moves the X-ray irradiation field in the body axis direction of the subject by moving an imaging system including the X-ray tube and the X-ray detector in the body axis direction of the subject. X-ray imaging device. The X-ray imaging apparatus according to any one of claims 1 to 3,
The X-ray imaging apparatus in which the value of the length of the X-ray irradiation field calculated by the irradiation range calculation unit is proportional to the moving speed of the X-ray irradiation field detected by the moving speed detection unit. The X-ray imaging apparatus according to any one of claims 1 to 4,
An X-ray imaging apparatus comprising: a reconstruction unit that reconstructs a single long image by connecting a plurality of the X-ray images generated by the image generation unit in the body axis direction of the subject.

Images