JP2006149426A - Radiographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent interference fringes due to the movement of a grid and to improve photographing quality by adjusting the movement of the grid corresponding to a body thickness. <P>SOLUTION: The body thickness of a subject M is measured by an ultrasonic distance meter 39, and a control part 40 adjusts the moving speed of the grid 21 for each photographing corresponding to the body thickness. Thus, the movement of the grid 21 is linked with the operation of a phototimer 7. Thus, the interference fringes due to the movement of the grid 21 are prevented and the photographing quality is improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an X-ray imaging apparatus including an X-ray imaging unit that visualizes transmitted X-rays transmitted through a subject.

  Conventionally, as this type of apparatus, an imaging unit that visualizes transmitted X-rays irradiated from an X-ray tube and transmitted through a subject, a phototimer that controls the irradiation time of the X-rays, and a front surface of the imaging unit are swung. An X-ray imaging apparatus provided with a grid (see, for example, Patent Document 1).

In such an apparatus, the grid is operated and X-rays are irradiated, and the phototimer is activated to cut off the X-ray irradiation and complete the imaging. The moving speed of the grid is automatically determined according to the X-ray irradiation time set by the photographer, and is set to be slow when the irradiation time is long and fast when the irradiation time is short.
JP 2003-32546 A

However, the conventional example having such a configuration has the following problems.
That is, in the conventional apparatus, although the exposure in the imaging unit can be made constant by the action of the phototimer, the phototimer operates faster when the body thickness is thin, so the grid movement stop is earlier than the X-ray irradiation stop. Become. Further, when the body thickness is thick, the phototimer operates late, so that the grid movement stop is slower than the X-ray irradiation stop. As a result, there is a problem in that interference fringes between the grid and the imaging unit are generated and imaging quality is deteriorated.

  The present invention has been made in view of such circumstances, and by adjusting the movement of the grid in accordance with the body thickness, it is possible to prevent interference fringes caused by the movement of the grid and improve the photographing quality. An object of the present invention is to provide an X-ray imaging apparatus capable of performing the above.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention according to claim 1 is an X-ray imaging unit that detects transmitted X-rays irradiated from the X-ray irradiation unit and transmitted through the subject, an irradiation time control unit that controls an X-ray irradiation time, In an X-ray imaging apparatus comprising a grid that is swung in front of the X-ray imaging means, the body thickness measuring means for measuring the body thickness of the subject, and for each imaging according to the measured body thickness, Grid speed control means for adjusting the moving speed of the grid.

  [Operation / Effect] According to the invention described in claim 1, the body thickness of the subject is measured by the body thickness measuring means, and the grid speed control means determines the moving speed of the grid for each imaging according to the body thickness. adjust. Therefore, the movement of the grid can be linked to the operation of the irradiation time control means. Therefore, it is possible to prevent the interference fringes resulting from the movement of the grid and improve the photographing quality.

  In the present invention, the grid speed control means slows the moving speed when the body thickness is thick, and increases the moving speed when the body thickness is thin, based on the moving speed determined according to the photographing conditions. (Claim 2). When the body thickness is thick, the time until the operation of the irradiation time control means becomes long, so that it is slower than the moving speed determined according to the imaging conditions. On the other hand, when the body thickness is thin, the time until the irradiation time control means operates is shortened, so that it is faster than the moving speed determined according to the imaging conditions. Thereby, the movement of the grid can be linked to the operation of the irradiation time control means.

  In the present invention, the body thickness measuring means preferably includes an ultrasonic distance meter. The body thickness of the subject can be measured without contact, and the measurement can be performed efficiently.

  According to the X-ray imaging apparatus according to the present invention, the body thickness of the subject is measured by the body thickness measuring means, and the grid speed control means adjusts the moving speed of the grid for each imaging according to the body thickness. The movement of the grid can be linked to the operation of the irradiation time control means. Therefore, it is possible to prevent the interference fringes resulting from the movement of the grid and improve the photographing quality.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram illustrating a schematic configuration of an X-ray imaging apparatus according to the embodiment, FIG. 2 is a longitudinal sectional view illustrating a schematic configuration of an imaging unit, and FIG. 3 is a diagram illustrating a schematic configuration of a grid. It is.

In this embodiment, an explanation will be given by taking a standing stand as an example in which the subject M is imaged in a standing position.
An imaging stand 1 for performing X-ray imaging of the subject M is erected on the floor surface. The imaging stand 1 includes an imaging unit 3 for detecting X-rays. The imaging unit 3 is provided in a posture protruding from the imaging stand 1 by the base member 5, and includes a phototimer 7, an X-ray flat panel detector 9, and a grid mechanism 11 from the imaging stand 1 side. is doing.

  A base 13 is attached to the base member 5, and this base 13 includes a photo timer 7, an X-ray flat panel detector 9, and a grid mechanism 11. These are covered with an inner cover 15 and further covered with the base 13 with an outer cover 17 indicated by a two-dot chain line. The inner cover 15 and the outer cover 17 are made of a material that transmits X-rays.

  The phototimer 7 is for detecting the amount of X-ray exposure, and outputs the detected X-ray dose. The X-ray flat panel detector 9 is an X-ray detector configured using semiconductor technology. A grid mechanism 11 is provided on the front surface (right side in FIG. 1) of the X-ray flat panel detector 9.

  The X-ray flat panel detector 9 corresponds to the X-ray imaging means in the present invention, and the phototimer 7 corresponds to the irradiation time control means in the present invention.

  The grid mechanism 11 includes four bearings 19 provided to be rotatable around a horizontal axis within the inner cover 15, and these bearings 19 hold the grid 21 by gripping the upper side and the lower side of the grid 21. Maintaining a standing posture. The upper portion of the swing plate 23 is connected to the lower portion of the grid 21, and the belt 25 is connected to the lower portion of the swing plate 23. The belt 25 is disposed below the bearing 19 disposed in the lower part, is stretched around driven pulleys 27 and 29 that are rotatably provided around the vertical axis, and is a photographing stand for the base 13. It is stretched over a main pulley 31 that is arranged on one side and is rotated around a vertical axis. The main pulley 31 is rotationally driven by a motor 33.

  The grid mechanism 11 is configured as described above, and the grid 21 can be swung in the horizontal direction by driving the motor 33 to rotate forward and backward. The movement start and stop and the speed of the swing follow the control from the control unit (40) as will be described later.

  Note that the imaging unit 3 described above is configured to be movable up and down with respect to the photographing stand 1.

  An X-ray irradiation unit 35 is provided on the opposite side of the imaging stand 1 with the subject M interposed therebetween. The X-ray irradiation unit 35 includes an X-ray tube 37 that irradiates X-rays, and includes an operation switch and an operation panel (not shown). This operation switch is used to release braking described later and move the X-ray irradiation unit 35 to a desired position. The operation panel is used to instruct photographing conditions and the like.

  The X-ray irradiation unit 35 is provided with an ultrasonic distance meter 39 according to the X-ray irradiation direction. The ultrasonic distance meter 39 performs distance measurement based on the time from when an ultrasonic wave is emitted until it returns, and according to an instruction from the control unit 40, emits an ultrasonic wave for a predetermined time and its direction. Is output to the control unit 40 as a measurement distance signal SL. The control unit 40, for example, the positional information (X direction) of the X-ray irradiation unit 35, the known distance from the imaging stand 1 to the surface of the imaging unit 3, and the known position of the imaging stand 1 (X Direction) and the measurement distance signal SL, the body thickness of the subject M is obtained.

  The X-ray irradiation unit 35 corresponds to the X-ray irradiation unit in the present invention, the ultrasonic distance meter 39 corresponds to the body thickness measurement unit, and the control unit 40 corresponds to the grid speed control unit.

A horizontal movement mechanism 41 is disposed on the ceiling surface.
The horizontal movement mechanism 41 is attached with an upper end of a suspension holding mechanism 43 that holds the X-ray irradiation unit 35 so as to be movable up and down in the vertical direction. An X-ray irradiation unit 35 is attached to the lower end of the suspension holding mechanism 43. The suspension holding mechanism 43 holds the X-ray irradiation unit 35 so as to be movable up and down, and can be moved in the horizontal direction X and the paper surface direction Y of FIG. Moreover, the X-ray irradiation part 35 is moved to a Z direction by raising / lowering.

  Please refer to FIG. 4 and FIG. 4 is a cross-sectional view taken along arrow AA in FIG. 1, and FIG. 5 is a cross-sectional view in a direction orthogonal to FIG.

  The horizontal movement mechanism 41 includes a fixed rail 45 fixed to the ceiling, and a section 47 that indicates an imaging center CX in the X direction of X-ray imaging is fixed to this with a screw. A micro switch 51 indicating an imaging center CX in the X direction of X-ray imaging is attached to the moving rail 49 via an L-shaped support member 53. The microswitch 51 is adjusted to a position where the detection piece comes into contact with the slice 47. In addition, a section 55 indicating the imaging center CY in the Y direction of X-ray imaging is attached to the moving rail 49 with a screw. A micro switch 59 indicating an imaging center CY in the Y direction of X-ray imaging is attached to the suspension portion 57 via an L-shaped support member 61. The microswitch 59 is adjusted to a position where the detection piece comes into contact with the slice 55.

  A roller 64 supported by the moving rail support member 63 is attached to the U-shaped guide surface of the fixed rail 45. Therefore, the moving rail 49 is supported so as to be movable in the X direction together with the suspension portion 57. In addition, a roller 67 disposed on a suspension portion support member 65 erected on the suspension portion 57 is provided on the U-shaped guide surface of the moving rail 49 disposed so as to be orthogonal to the fixed rail 45. Has been placed. Therefore, the suspension part 57 is supported so as to be movable in the Y direction together with the X-ray irradiation part 35.

  The X-direction imaging center CX and the Y-direction imaging center CY are set for a bed (not shown).

  Reference is now made to FIG. FIG. 6 is a diagram showing the configuration of the braking mechanism. Note that the X-direction and Y-direction braking mechanisms have the same configuration, and therefore the X-direction braking mechanism will be described as an example.

  The X-direction braking mechanism 67 is provided in the moving rail support member 63. Specifically, one end side of a lever 73 that swings around a swing fulcrum 71 is connected to the tip of a rod 69 that expands and contracts according to the on / off state of the solenoid SOL1, and the other end side of the lever 73 is connected. A brake shaft 77 having a brake member 75 having a large friction coefficient such as rubber attached to the tip is attached. Further, the tip end portion of the rod 69 is biased in the extending direction by the tension coil spring 79.

  When the solenoid SOL1 is turned on, the rod 69 contracts, the lever 73 is swung, and the braking shaft 77 is moved to the opposite side of the fixed rail 45, whereby the braking member 75 pressed against the fixed rail 45 is Move away from the fixed rail 45. That is, the braking by the braking member 75 is released. When the solenoid SOL1 is turned off, the rod 69 is pulled by the tension coil spring 79, and the lever 73 is swung to push the braking shaft 77 toward the fixed rail 45, whereby the braking member 75 is pressed against the fixed rail 45. Braking.

  Please refer to FIG. FIG. 7 shows the internal structure of the suspension part.

  One end side is supported by the rope support member 81, wound around the pulley 86 via the pulleys 82 to 85, hung on the hook 87 at the tip of the suspension portion 57, wound around the pulley 88, and connected to the pulleys 89 to 92. The suspension 57 is suspended and supported by a rope 94 whose other end is supported by the rope support member 93. When the suspension part 57 is expanded and contracted, that is, when the X-ray irradiation part 35 is moved up and down in the Z direction, the pulleys 84, 86, 88, 90 rotate, and the pulleys 83, 85, 89, 91 move back and forth (a, b in the figure) Move in the direction). At this time, the pulleys 83, 85, 89, 91 are urged in the direction a by a spring member (not shown). This spring member is designed so as to urge the pulleys 83, 85, 89, 91 in the a direction in proportion to the gravity regardless of the height of the X-ray irradiation unit 35 supported by the suspension 57 at the lower end. Has been. Further, a drum 95 that rotates in conjunction with the pulleys 84, 86, 88, 90 is provided.

  In the above configuration, when the solenoid SOL3 is turned on, the contact between the brake member 97 and the drum 95 is released, the pulleys 56, 58, 60, 62 can be rotated, and the telescopic brake of the suspension part 27 is released. It will be. When the solenoid SOL3 is turned off, the brake member 68 is pressed against the drum 67, so that the rotation of the pulleys 84, 86, 88, 90 is suppressed and the brake is applied.

  The operation switches (not shown) attached to the X-ray irradiation unit 35 operate / inactivate the solenoids SOL1 and the like described above. The photographer operates the operation switch to release the braking in each direction, and manually moves the X-ray irradiation unit 35 to a desired position. In addition, when the microswitches 51 and 59 are operated, braking is automatically applied, and the X-ray irradiation unit 35 is temporarily stopped at the center in the XY direction.

  A position signal is output from the above-described horizontal movement mechanism 41 and the like, and is supplied to the position detection unit 99. The position detection unit 99 obtains the position of the X-ray irradiation unit 35 based on the position signal and outputs it to the control unit 40. The control unit 40 controls the high voltage device 101 based on the photographing condition by the photographer input from the operation unit (not shown). The control objects are tube voltage, tube current, exposure time, and the like. The control unit 40 controls the phototimer 7 and the grid mechanism 11 based on the imaging conditions, and takes in a signal from the X-ray flat panel detector 9 and outputs it to the monitor 103. The instruction to start the X-ray exposure is performed by operating a foot switch 105 disposed on the floor surface, for example.

  Further, prior to the X-ray exposure, the control unit 40 operates the ultrasonic distance meter 39 and obtains the body thickness of the subject M based on the measurement distance signal SL and the like. Then, the moving speed of the grid 21 of the grid mechanism 11 is controlled for each shooting in consideration of the shooting conditions including the exposure time.

  Specifically, when the body thickness is thick, the time until reaching the prescribed X-ray dose detected by the phototimer 7 is longer than the prescribed time, so that the prescribed speed determined according to the exposure time. However, when the driving speed of the motor 33 is slowed and the body thickness is thin, the time until the X-ray dose detected by the phototimer 7 is shorter than the specified time, so that it is determined according to the exposure time. Control is performed such that the drive speed of the motor 33 is slower than the speed. The degree of adjustment based on the specified speed is determined by conducting experiments with the subject M having various body thicknesses in advance, collecting adjustment data, and obtaining the optimum driving speed of the motor 33 based on the adjustment data. Is preferred.

  Next, with reference to FIG. 8, the operation of the apparatus configured as described above will be described. FIG. 8 is a flowchart for explaining the operation.

Step S1
The photographer stands the subject M along the photographing stand 1 and moves the X-ray irradiation unit 35 to a position facing the imaging unit 3. In that case, each operation switch (not shown) attached to the X-ray irradiation unit 35 is operated to release the braking in each direction of XYZ and manually move in each direction. Further, an operation panel (not shown) attached to the X-ray irradiation unit 35 is operated to input imaging conditions. Examples of imaging conditions include tube voltage, tube current, and imaging time, which are instructions to the high voltage apparatus 101.

Step S2
Prior to imaging, ultrasonic waves are generated from the ultrasonic distance meter 39, and the control unit 40 obtains the body thickness of the subject M based on the measurement distance signal SL. In this embodiment, since the body thickness of the subject M is measured in a non-contact manner using the ultrasonic distance meter 39, the measurement can be performed efficiently.

Step S3
The control unit 40 corrects the moving speed (driving speed of the motor 33) of the grid mechanism 11 based on the imaging time input in step S1 based on the obtained body thickness of the subject M, and drives the grid mechanism 11. The moving speed (drive signal SD) to be obtained is obtained.

  At this time, the control unit 40 does not operate the grid mechanism 11 at a specified speed defined by the imaging conditions, but considers the body thickness obtained in step S2. That is, when the body thickness is thick, the time required to reach the prescribed X-ray dose detected by the phototimer 7 is longer than the prescribed time, so the driving speed is higher than the prescribed speed determined according to the exposure time. When the body thickness is small, the time until the X-ray dose detected by the phototimer 7 is shorter than the specified time, so the drive speed is set to be higher than the specified speed determined according to the exposure time. Control to speed up.

Step S4
When the photographer operates the foot switch 105, the control unit 40 starts driving the motor 33 with the drive signal SD to start swinging the grid 21, and operates the high-voltage device 101 under conditions according to the shooting conditions. As a result, X-rays are exposed while the grid 21 is swung.

Step S5
The control unit 40 stops the X-ray exposure from the X-ray irradiation unit 35 based on the signal from the phototimer 7 and outputs a signal to stop driving the grid mechanism 11. Thereby, the X-ray exposure to the subject M is stopped and the operation of the grid mechanism 11 is also stopped.

Step S6
The control unit 40 displays a transmitted X-ray image on the monitor 103 based on the signal from the X-ray flat panel detector 9.

  As described above, the X-ray imaging apparatus in this embodiment measures the body thickness of the subject M, and the control unit 40 adjusts the moving speed of the grid 21 for each imaging according to the body thickness. Therefore, the movement of the grid 21 can be linked to the operation of the phototimer 7. Therefore, it is possible to prevent the interference fringes resulting from the movement of the grid 21 and improve the photographing quality.

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

  (1) In the above-described embodiment, the stand is described as a standing stand, but the present invention can be applied even to an apparatus having a bed.

  (2) In the embodiment described above, an X-ray flat panel detector is employed as the X-ray imaging means. However, if the apparatus is an X-ray film or the like and is provided with a phototimer, the present invention is used. Applicable.

  (3) In the above-described embodiment apparatus, the ultrasonic distance meter 39 is attached to the X-ray irradiation unit 35, but this may be configured separately from the X-ray irradiation unit 35. Further, instead of the ultrasonic method, an optical method or an electromagnetic method may be adopted.

  (4) In the above-described embodiment, the phototimer 7 and the X-ray flat panel detector 9 are configured as separate units. However, the X-ray irradiation amount is controlled by X-ray imaging means such as the X-ray flat panel detector 9. A configuration of a photo timer integrated type to be detected may be employed.

It is a block diagram which shows schematic structure of the X-ray imaging apparatus which concerns on an Example. It is a longitudinal cross-sectional view which shows schematic structure of an imaging part. It is a figure which shows schematic structure of a grid. It is AA arrow sectional drawing of FIG. It is arrow sectional drawing of the direction orthogonal to FIG. It is a figure which shows the structure of a braking mechanism. It is a figure which shows the internal mechanism of a suspension part. It is a flowchart with which operation | movement description is provided.

Explanation of symbols

M ... subject 1 ... imaging stand 3 ... imaging unit 7 ... photo timer 9 ... X-ray flat panel detector (X-ray imaging means)
DESCRIPTION OF SYMBOLS 11 ... Grid mechanism 21 ... Grid 35 ... X-ray irradiation part (X-ray irradiation means)
39 ... Ultrasonic distance meter (body thickness measuring means)
40: Control unit (control means)
99 ... Position detector 101 ... High-voltage device 103 ... Monitor

Claims (3)

  X-ray imaging means for detecting transmitted X-rays irradiated from the X-ray irradiation means and transmitted through the subject, irradiation time control means for controlling the irradiation time of the X-rays, and swung on the front surface of the X-ray imaging means In an X-ray imaging apparatus including a grid, body thickness measuring means for measuring the body thickness of a subject, and grid speed control means for adjusting the moving speed of the grid for each imaging according to the measured body thickness And an X-ray imaging apparatus.   2. The X-ray imaging apparatus according to claim 1, wherein the grid speed control means slows down the moving speed when the body thickness is thick, based on the moving speed determined according to the imaging conditions, and thins the body thickness. An X-ray imaging apparatus characterized by increasing the moving speed in some cases. The X-ray imaging apparatus according to claim 1, wherein the body thickness measuring means includes an ultrasonic distance meter.

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