JP2008295714A - Table system, and x-ray ct apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the degree of a warpage of a top board at a high detection resolving power by a simple structure while keeping a high supporting rigidity of the top board in a table system which is suitable for, e.g., an X-ray CT photographing, in which the top board for mounting an object is let out in the horizontal direction. <P>SOLUTION: A light receiving position specifying section 125 specifies the light receiving position of a laser beam 600 which changes in response to the warpage of a base 104 by a laser light source 122 being installed on the base 104 which supports the top board 102, and a light detector 124. From the light receiving position, the degree of the warpage of the top board 102 is indirectly detected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a table system and an X-ray CT apparatus, and more particularly to a table system having a top plate that is fed out from a base in a horizontal direction and an X-ray CT apparatus having such a table system.

  In the X-ray CT apparatus, a table system for supporting a subject to be imaged, that is, a patient, is used. In the table system, the top plate is extended from the base in the horizontal direction, and the patient is carried into the imaging space (see, for example, page 3-4 of Patent Document 1 and FIG. 1).

  In such a table system, since the overhang load of the top plate increases as the feeding amount of the top plate increases, the transport resistance increases. If the transport force is increased in advance to overcome the transport resistance under the expected maximum load and smooth transport is possible, there is too much room for the transport force for patients with light weight. Problems arise.

In order to solve this problem, for example, the degree of bending of the top plate is detected by converting it into a rotational moment using a predetermined member that can contact the lower surface of the top plate, and based on the detection signal. A table system that controls the rotational force of the driving roller of the top plate has been proposed (see, for example, Patent Document 2). Also, for example, the home position (home) of the cradle
position) and the pressure acting on the driving roller of the cradle are detected, and the degree of bending of the top plate is indirectly detected based on the detected distance and pressure, and the driving motor (motor) is detected. There has been proposed a cradle device that controls the current supplied to the slab (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 10-108861 JP 2005-245560 A Japanese Utility Model Publication No. 7-9310

  However, in the above table system that detects the degree of bending of the top plate by converting it into a rotational moment, the support rigidity of the top plate cannot be increased when trying to increase the detection resolution, and a table with little deflection is desired. There is a problem that conflicts with the demands of doctors and engineers. In order to guarantee the maximum expected load, a cradle device that detects the distance from the home position of the cradle and the pressure acting on the driving roller and indirectly detects the degree of cradle deflection based on these distances. There is a problem that the detectable range of pressure acting on the drive roller needs to be relatively wide, and the structure becomes large and the cost increases.

  In view of the above circumstances, the present invention provides a table system capable of detecting the degree of bending of the top plate with a high detection resolution with a simple structure while keeping the support rigidity of the top plate high, and such a table system. An object of the present invention is to provide an X-ray CT apparatus having the same.

  In a first aspect, the present invention provides a base, a top plate supported so as to be able to be fed out in the horizontal direction from the base, and transporting the top plate in the top plate feeding direction by applying a transport force to the top plate. Conveying means, light generating means for generating a light beam provided on the base, and light detecting means for detecting the light beam on a light receiving surface, the light receiving position of which changes according to the bending of the base. There is provided a table system comprising: a light detecting means; and a bending detecting means for detecting the bending of the base by detecting the light receiving position.

  In a second aspect, the present invention further includes a control unit that controls the transport unit based on the detected light receiving position so that the transport force increases as the degree of bending of the base increases. A table system according to the first aspect is provided.

  In a third aspect, the present invention provides that the base is adjustable in tilt in the vertical direction, and the tilt of the portion located in the imaging space of the top plate is based on the detected light receiving position. The table system according to the first aspect is further provided with a control means for controlling the inclination of the base so as to be compensated for the deflection angle of the base.

  In a fourth aspect, the present invention provides that the height of the base is adjustable, and the height of a portion of the top plate located in the imaging space is bent based on the detected light receiving position. The table system according to the first aspect is further provided with control means for controlling the height of the base so as to be compensated by the amount.

  In a fifth aspect, the present invention relates to the magnitude of the difference between the light receiving position of the light beam detected before the top plate is extended and the light receiving position of the light beam detected after the top plate is extended. A table system according to any one of the second to fourth aspects, which is controlled based on the above, is provided.

  In a sixth aspect, the present invention provides the light-receiving position of the light beam detected before the object is placed on the top plate and the light detection position detected after the subject is placed on the top plate. Provided is a table system according to any one of the second to fourth aspects, which is controlled based on the magnitude of the difference between the light receiving position of the luminous flux.

  In a seventh aspect, the present invention provides the light generating means that generates a light beam in a predetermined direction including a component in the same direction as the top plate feeding direction, and the light detecting means is configured such that the light receiving position is bent by the base. A light receiving position specifying means for outputting a detection signal reflecting the light receiving position, wherein the deflection detecting means specifies the light receiving position based on the detection signal. A table system according to any one of the first to sixth aspects is provided.

  In an eighth aspect, the present invention provides the table system according to any one of the first to seventh aspects, wherein an optical path of the light beam is a single line.

  In a ninth aspect, the present invention further includes an optical system that reflects the light beam at least once, and an optical path of the light beam is a polygonal line, and any one of the first to eighth aspects is provided. Provide a table system of perspective.

  In a tenth aspect, the present invention provides the table system according to the ninth aspect, wherein the light reflecting surface of the optical system is a curved surface.

  In an eleventh aspect, in the present invention, the light generation means is disposed on one end side in the top plate feeding direction of the base, and the light detection means is disposed on the other end side of the base. A table system according to any one of the eighth to tenth aspects is provided.

  In a twelfth aspect, the present invention relates to the ninth aspect or the tenth aspect, in which the light generating means and the light detecting means are both arranged on one end side in the top plate feeding direction of the base. Provide a table system.

  In a thirteenth aspect, the present invention provides the first aspect, wherein the base includes a pipe frame extending in a top plate feeding direction, and the light generation means and the light detection means are provided in the pipe frame. To a table system according to any one of the twelfth aspects.

  In a fourteenth aspect, the present invention provides the table according to any one of the first to thirteenth aspects, wherein the light receiving surface of the light detection means is configured by a large number of charge coupled devices (CCDs). Provide a system.

  In a fifteenth aspect, the present invention provides the table system according to any one of the first to fourteenth aspects, wherein the light generating means is a laser light source.

  In a sixteenth aspect, the present invention is an X-ray CT apparatus for reconstructing an image based on projection data of a plurality of views obtained by scanning an object carried in a radiographing space with an X-ray mounted on a table system. The table system is supported by a base, a top plate supported so as to be able to be fed out from the base in a horizontal direction, and transporting the top plate in the top plate feeding direction by applying a transport force to the top plate. Means, light generating means for generating a light beam provided on the base, and light detecting means for detecting the light beam on a light receiving surface, the light detection position of which varies depending on the deflection of the base And an X-ray CT apparatus comprising: a deflection detecting unit that detects the deflection of the base by detecting the light receiving position.

  In a seventeenth aspect, the present invention further includes a control unit that controls the transport unit based on the detected light receiving position so that the transport force increases as the degree of deflection of the base increases. An X-ray CT apparatus according to the sixteenth aspect is provided.

  In an eighteenth aspect, according to the present invention, the base is capable of adjusting a tilt in a vertical direction, and based on the detected light receiving position, a tilt of a portion of the top plate located in the photographing space is The X-ray CT apparatus according to the sixteenth aspect is further provided with control means for controlling the inclination of the base so as to compensate for the deflection angle of the top plate.

  In a nineteenth aspect, according to the present invention, the height of the base is adjustable, and the height of the portion of the top plate located in the imaging space is based on the detected light receiving position. The X-ray CT apparatus according to the sixteenth aspect is further provided with control means for controlling the height of the base so that the amount of deflection is compensated.

  In a twentieth aspect, the present invention compensates, based on the detected light receiving position, a portion where the image is located in the imaging space of the top board by a deflection amount and / or a deflection angle of the portion. An X-ray CT apparatus according to a sixteenth aspect is further provided, further comprising data processing means for performing data processing so as to obtain an image obtained when scanned.

  According to the present invention, using the light generating means and the light detecting means provided on the base that supports the top board, the light receiving that changes according to the degree of bending of the base accompanying the extension of the top board. Since the position is detected and the degree of bending of the top plate is detected, a slight bending of the base can be detected as a change in the light receiving position of the light beam without significantly changing the table structural design. A table system capable of detecting the degree of bending of the top plate with a high detection resolution and a X-ray CT apparatus having such a table system can be realized with a simple structure while maintaining a high support rigidity. .

  The best mode for carrying out the invention will be described below with reference to the drawings. Note that the present invention is not limited to the best mode for carrying out the invention.

(First embodiment)
FIG. 1 is a block diagram of an X-ray CT apparatus. This apparatus is an example of the best mode for carrying out the present invention. An example of the best mode for carrying out the present invention relating to an X-ray CT apparatus is shown by the configuration of the apparatus. An example of the best mode for carrying out the present invention relating to a table system is shown by a part of the configuration of the present apparatus.

As shown in FIG. 1, the apparatus includes a scanning gantry 2, a table system 100, and an operation console 6. The scanning gantry 2 has an X-ray tube 20. X-rays (not shown) emitted from the X-ray tube 20 are collimated by a collimator 22 to form a fan-shaped X-ray beam, ie, a fan beam (fan).
beam) The X-ray detector 24 is irradiated with the X-ray detector 24 after being shaped (collimation). The X-ray detector 24 has a large number of X-ray detection elements arranged in an array in accordance with the spread of the X-ray beam. The configuration of the X-ray detector 24 will be described later.

  In the space between the X-ray tube 20 and the X-ray detector 24, an object to be imaged is mounted on the table system 100 and is carried in. The table system 100 is an example of a table system in the present invention. The table system 100 will be described later. The X-ray tube 20, the collimator 22, and the X-ray detector 24 constitute an X-ray irradiation / detection device. The X-ray irradiation / detection apparatus will be described later.

A data collection unit 26 is connected to the X-ray detector 24. The data collection unit 26 converts the detection signals of the individual X-ray detection elements of the X-ray detector 24 into digital data (digital).
data). The detection signal of the X-ray detection element is a signal representing the projection of the object by X-rays. Hereinafter, this is also referred to as projection data or simply data.

  X-ray irradiation from the X-ray tube 20 is controlled by an X-ray controller 28. The connection relationship between the X-ray tube 20 and the X-ray controller 28 is not shown. The collimator 22 is controlled by a collimator controller 30. The connection relationship between the collimator 22 and the collimator controller 30 is not shown.

  The components from the X-ray tube 20 to the collimator controller 30 described above are mounted on the rotating unit 34 of the scanning gantry 2. The rotation of the rotating unit 34 is controlled by the rotation controller 36. The connection relationship between the rotating unit 34 and the rotation controller 36 is not shown.

  The operation console 6 has a data processing device 60. The data processing device 60 is configured by, for example, a computer. A control interface (interface) 62 is connected to the data processing device 60. The scanning gantry 2 and the table system 100 are connected to the control interface 62. The data processing device 60 controls the scanning gantry 2 and the table system 100 through the control interface 62.

  The data acquisition unit 26, the X-ray controller 28, the collimator controller 30 and the rotation controller 36 in the scanning gantry 2 are controlled through the control interface 62. Note that illustration of individual connections between these units and the control interface 62 is omitted.

  A data collection buffer 64 is connected to the data processing device 60. A data collection unit 26 of the scanning gantry 2 is connected to the data collection buffer 64. Data collected by the data collection unit 26 is input to the data processing device 60 through the data collection buffer 64.

  A storage device 66 is connected to the data processing device 60. The storage device 66 stores projection data input to the data processing device 60 through the data collection buffer 64 and the control interface 62, respectively. The storage device 66 also stores a program for the data processing device 60. When the data processing device 60 executes the program, the operation of this device is performed.

The data processing device 60 performs image reconstruction using the projection data collected in the storage device 66 through the data collection buffer 64. For image reconstruction, for example, filtered back projection (filtered back projection)
back projection) method or the like is used.

A display device 68 and an operation device 70 are connected to the data processing device 60. The display device 68 is configured by a graphic display or the like. The operation device 70 is a pointing device.
a keyboard having a device, and the like.

  The display device 68 displays the reconstructed image and other information output from the data processing device 60. The operation device 70 is operated by a user and inputs various instructions and information to the data processing device 60. The user operates the present apparatus interactively using the display device 68 and the operation device 70.

  FIG. 2 is a diagram showing a schematic configuration of the X-ray detector 24. As shown in the figure, the X-ray detector 24 is a multi-channel X-ray detector in which a large number of X-ray detection elements 24 (ik) are arranged in a two-dimensional array. The plurality of X-ray detection elements 24 (ik) form an X-ray detection surface curved in a cylindrical concave shape as a whole.

  i is a channel number, for example, i = 1, 2,. k is a column number, for example, k = 1, 2,. The X-ray detection elements 24 (ik) each have the same column number k and constitute a detection element array. Note that the number of detection element rows of the X-ray detector 24 is not limited to 32, and may be an appropriate plural number or a single number.

The X-ray detection element 24 (ik) is configured by a combination of, for example, a scintillator and a photodiode. However, the present invention is not limited to this. For example, a semiconductor X-ray detection element using cadmium tellurium (CdTe) or the like, or xenon gas (Xe
An ionization chamber type X-ray detection element using gas) may be used.

  FIG. 3 is a diagram showing the interrelationship among the X-ray tube 20, the collimator 22, and the X-ray detector 24 in the X-ray irradiation / detection apparatus. 3A is a diagram showing a state seen from the front of the scanning gantry 2, and FIG. 3B is a diagram showing a state seen from the side. As shown in the figure, the X-rays radiated from the X-ray tube 20 are shaped by the collimator 22 into a fan-shaped X-ray beam 500 and irradiated to the X-ray detector 24.

  FIG. 3A shows the spread of the fan-shaped X-ray beam 500 in one direction. Hereinafter, this direction is also referred to as a width direction. The width direction of the X-ray beam 500 coincides with the channel arrangement direction in the X-ray detector 24. (B) shows the expansion of the X-ray beam 500 in the other direction. Hereinafter, this direction is also referred to as a thickness direction of the X-ray beam 500. The thickness direction of the X-ray beam 500 coincides with the parallel arrangement direction of a plurality of detection element rows in the X-ray detector 24. The two spreading directions of the X-ray beam 500 are perpendicular to each other.

  FIG. 4 is a diagram showing the relationship between the X-ray irradiation / detection apparatus and the object 8. The object 8 placed on the top plate 102 of the table system 100 is carried into the X-ray irradiation space with the body axis intersecting the X-ray beam 500 as described above, for example, as shown in FIG. The scanning gantry 2 has a cylindrical structure including an X-ray irradiation / detection device inside.

  The X-ray irradiation space is formed in the inner space of the cylindrical structure of the scanning gantry 2. An image of the object 8 sliced by the X-ray beam 500 is projected onto the X-ray detector 24. The X-ray detector 24 detects X-rays transmitted through the object 8 for each detector row. The thickness th of the X-ray beam 500 applied to the object 8 is adjusted by the opening degree of the aperture of the collimator 22.

In parallel with the rotation of the X-ray irradiation / detection device, the X-ray irradiation / detection device is moved relative to the target 8 by continuously moving the top plate 102 in the body axis direction of the target 8 as indicated by an arrow 42. Thus, the object 8 turns along a spiral trajectory surrounding the object 8. As a result, the so-called helical scan (helical scan)
scan) is performed. If the X-ray irradiation / detection device is rotated while the top plate 102 is stopped, an axial scan is performed.

  Projection data of a plurality of views (for example, about 1000) per scan rotation is collected. The projection data is collected by a series of X-ray detector 24 -data collection unit 26 -data collection buffer 64. Image reconstruction is performed by the data processing device 60 based on the projection data collected in this way.

Here, the table system 100 will be described.
FIG. 5 is a diagram schematically showing the mechanical structure of the table system 100. As shown in the figure, the table system 100 has a top plate 102. The top plate 102 is supported horizontally by the base 104. The top plate 102 is mounted with the object 8 and can be extended (rightward) and retracted (leftward) in the horizontal direction from the base 104. A scanning gantry 2 (not shown) exists in the feeding direction. The base 104 has a horizontal rail 142 on which the top plate 102 can move. The top plate 102 has a plurality of wheels 144 at the end opposite to the feeding side, and is mounted on the rails 142 so that the rails 142 are vertically sandwiched by these wheels 144. In addition, the base 104 has a transport unit 112. The transport unit 112 is provided in the vicinity of the top end of the rail 142 on the top plate feeding side so as to be in contact with the lower surface of the top plate 102 and applies a transport force to the top plate 102 to transport the top plate 102 in the top plate feeding direction. The conveyance unit 112 includes a feed roller that rotates in contact with the lower surface of the top plate 102. The configuration of the transport unit 112 will be described later.

  FIG. 6 is a block diagram showing a main part of the table system 100. As shown in the figure, the table system 100 includes a laser (LASER) light source 122 that is provided on a base 104 and generates a laser beam 600 in a predetermined direction including a component in the same direction as the top plate feeding direction. The table system 100 is a photodetector that receives and detects the laser beam 600 on the light receiving surface 124a and outputs a detection signal reflecting the light receiving position of the laser beam 600 on the light receiving surface 124a. Has a photodetector 124 provided at a position that changes according to the degree of bending of the base 104 as the top plate 102 is fed. The light receiving surface 124a is composed of a charge coupled device (CCD) which is a large number of light detecting elements, and the light detector 124 outputs a detection signal of each light detecting element in which the light receiving position of the laser beam 600 is reflected. The table system 100 also includes a light receiving position specifying unit 125 that specifies the light receiving position of the laser beam 600 based on the detection signal of the photodetector 124, and the degree of bending of the base 104 based on the specified light receiving position. A control unit 116 that controls the transport unit 112 is provided so that the transport force of the top plate 102 increases as the size increases.

  The detection signal of the photodetector 124 is subjected to high-frequency component suppression processing by a low pass filter (LPF) 120 and input to the control unit 116, and a control signal based on this input signal is sent from the control unit 116 to the drive unit 118. The feed roller is driven by the drive unit 118 based on this control signal. This low-pass filter 120 detects the detection signal of the photodetector 124 when the top plate 102 and the base 104 are shaken by the body movement of the object 8 placed on the top plate 102 or the vibration when the top plate 102 is fed out. This is to prevent fluctuations in intensity and to identify the substantial light receiving position of the laser beam 600. In addition, as a frequency range of the detection signal suppressed by the low-pass filter 120, for example, several hertz (Hz) or more can be considered.

FIG. 7 is a diagram showing the positional relationship between the base 104, the laser light source 122, and the photodetector 124. FIG. 7A is a diagram showing a state seen from the side surface of the base 104, and FIG. 7B is a diagram showing a state seen from the upper surface of the base 104. As shown in the figure, the base 104 has two pipe frames (pipe) extending in parallel to the top plate feeding direction on both side portions.
frame) 104a. In one pipe frame 104a, a laser light source 122 is arranged on one end side in the top plate feeding direction, and a photodetector 124 is arranged on the other end side. The laser beam 600 emitted from the laser light source 122 is detected by the photodetector 124. The photodetector 124 detects the laser beam 600 and outputs a detection signal reflecting the light receiving position. The laser light source 122 and the light detector 124 may be provided on the outer surface of the base 104, but are unnecessary in the light detector 124 so as not to block the laser beam 600 generated from the laser light source 122. In order to prevent light from being detected, it is desirable to provide them inside the base 104.

  FIG. 8 is a diagram showing a schematic configuration of the photodetector 124. As shown in the figure, the photodetector 124 is a multi-pixel photodetector in which a large number of photodetectors 124 (pq) are arranged in a two-dimensional array. The plurality of light detecting elements 124 (pq) form a planar light receiving surface as a whole. Each photodetecting element 124 (pq) outputs a detection signal corresponding to the intensity of light to be detected. Note that the present invention is not limited to this, and a predetermined detection signal may be output only when a binarized signal, that is, light whose intensity exceeds a predetermined threshold value is detected.

  p is a column number, for example, p = 1, 2,. q is a row number, for example, q = 1, 2,. Note that the number of rows and the number of columns of the photodetector elements of the photodetector 124 are not limited to these, and may be an appropriate plural number, or one of the number of rows and the number of columns may be singular. .

  The photodetecting element 124 (pq) is constituted by, for example, a charge coupled device (CCD). Note that the present invention is not limited to this, and may be, for example, a photodiode.

  Here, a method for specifying the light receiving position of the laser beam 600 by the light receiving position specifying unit 125 will be described.

  FIG. 9 is a diagram illustrating a state in which the light receiving region of the laser beam 600 is changed by extending the top plate 102 from the home position to a predetermined position. As shown in the figure, the light receiving surface 124a of the photodetector 124 is composed of, for example, 12 × 16 pixels. The light receiving region of the laser beam 600 is, for example, a circular region having a diameter of about 5 pixels on the light receiving surface 124a. For example, the light receiving region R0 of the laser beam 600 before the top plate is extended is located below the light receiving surface 124a. When the top plate 102 is gradually fed out, the top plate 102 is gradually bent, and the base 104 is also bent accordingly. As a result, the light receiving surface 124a falls downward with respect to the laser beam 600, and the light receiving region of the laser beam 600 moves above the light receiving surface 124a. The light receiving region R1 is a light receiving region of the laser beam 600 when the top plate 102 is extended to a predetermined position. Here, for ease of explanation, the number of pixels on the light receiving surface is reduced. However, in actuality, the number of pixels may be larger, for example, about 120 × 160 pixels.

  The light receiving position of the laser beam 600 can be specified, for example, by obtaining the center of gravity for the detection signal intensities of all the light detecting elements constituting the light receiving surface 124a. That is, if the coordinates of the photodetecting elements of row number p and column number q are Xpq and the detection signal intensity of this photodetecting element is I (Xpq), the coordinate Z1 representing the light receiving position can be calculated according to the following equation. .

      Z1 = Σ {Xpq × I (Xpq)} / ΣI (Xpq) (1)

  For example, the light receiving position of the laser beam 600 can be obtained as an intersection of a line segment corresponding to the maximum width in the p direction of the light receiving region and a line segment corresponding to the maximum width in the q direction of the light receiving region. That is, the coordinate range in which the photodetection elements whose detection signal intensity exceeds a predetermined threshold continues for the longest is [Xpa1, qa, Xpa2, qa] in the p direction and [Xpb, qb1, Xpb, qb2], the coordinate Z1 representing the light receiving position is as follows.

      Z1 = Xpb, qa (2)

  The light receiving position of the laser beam 600 may be represented only by coordinates in a predetermined direction in which the light receiving position mainly changes among the row direction and the column direction.

  As described above, various methods for specifying the light receiving position of the laser beam 600 are conceivable, but any method may be adopted.

  FIG. 10 is a diagram illustrating a configuration of the transport unit 112. As shown in the figure, the transport unit 112 includes a feed roller 202, a receiving roller 204, and a motor 206. These are mounted on the base 104 so that the rotation axes thereof are parallel to each other.

  The feed roller 202 contacts the lower surface of the top plate 102 and feeds the top plate 102 in the horizontal direction by using friction. The receiving roller 204 is attached to the top feeding side with respect to the feeding roller 202. The motor 206 is attached to the top plate retracting side with respect to the feed roller 202.

  The feed roller 202 and the motor 206 are configured such that the pulleys 222 and 262 are coupled to each other by a belt 264 so that the motor 206 applies a rotational force to the feed roller 202. The connection between the feed roller 202 and the motor 206 may be performed by an appropriate rotation transmission means such as a gear instead of the pulley and the belt.

  The motor 206 is reversibly rotatable. Therefore, the top plate 102 is fed reversibly in the horizontal direction by the feed roller 202, and is fed out (right direction) and pulled back (left direction). By having such a motor, the feed roller 202 can be appropriately driven.

  The rotation shaft of the feed roller 202 is supported by a bearing fixed to the base 104. This is represented by a black triangle. A column 224 erected on the base 104 is loosely fitted on the rotation shaft of the feed roller 202. Since the position of the rotation shaft of the feed roller 202 is fixed, the support rigidity of the top plate 102 by the feed roller 202 can be increased.

  The receiving roller 204 is attached to a column 244 on the base 104 and is opposed to the lower surface of the top plate 102.

  When the top plate 102 is fed out by such a transport unit 112, the bending amount acting on the top plate 102, that is, the overhang, is increased by the load that combines the weight of the top plate 102 and the weight of the subject 8 with the increase in the feed amount, ie, the overhang amount. The load increases and the top plate 102 bends downward. Along with this, the bending moment acting on the base 104 also increases and the base 104 bends downward. When the base 104 bends downward, the relative position of the laser beam 600 emitted from the laser light source 122 with respect to the photodetector 124 changes. Thereby, slight bending of the base 104 can be detected as a change in the light receiving position of the laser beam 600.

  The light receiving position specifying unit 125 specifies the light receiving position of the laser beam 600 by using the detection signals of the individual light detecting elements 124 (pq) constituting the light detecting unit 124, and the control unit 116 Based on the specified light receiving position, the force with which the feed roller 202 conveys the top plate 102 is controlled.

  The control of the transport force is a control for changing the transport force based on the magnitude of the difference between a predetermined reference position and the light receiving position of the laser beam 600, for example. More specifically, for example, the light receiving position specified by using the detection signal of the photodetector 124 in the state before the top plate 102 is fed out is used as the reference position, and the reference position and the top plate 102 are specified after feeding out. A predetermined parameter (parameter) such as a distance to the light receiving position or a length indicating a horizontal component or a vertical component of the distance is calculated, and the conveyance force is set to 200 while the parameter does not exceed the predetermined threshold M. The control is such that [N] (newton) is set and when the threshold value M is exceeded, the value is increased to 300 [N].

  In addition, the control of the conveyance force is not limited to this, and the threshold value may be set in multiple stages, and the conveyance force may be controlled in multiple stages according to the magnitude of the parameter value with respect to the threshold value, or depending on the parameter value The conveyance force may be continuously controlled. Further, a correspondence relationship between the light receiving position of the laser beam 600 and an appropriate conveyance force may be obtained in advance by experiments or the like, and the conveyance force may be controlled with reference to this correspondence relationship.

Further, for example, in the state before the top plate 102 is extended, the light receiving position specified by using the detection signal of the light detector 124 in the state before the object 8 is placed on the top plate 102 is used as the reference position. And a predetermined parameter such as a distance between the light receiving position specified after placing the object 8 on the top plate 102 or a length indicating a horizontal component or a vertical component of the distance, and the like. Look-up table (look-up) that defines the correspondence between feed amount and transport force for each parameter range
(table), the conveyance force may be controlled to be changed based on the feeding amount of the top plate 102 in accordance with the correspondence relationship according to the calculated parameter value.

  According to the present embodiment, the light receiving position specifying unit 125 is mounted on the base board accompanying the extension of the top board 102 by the laser light source 122 and the photodetector 124 provided on the base board 104 that supports the top board 102. The light receiving position of the laser beam 600 that changes in accordance with the degree of bending of the 104 is specified, and the control unit 116 controls the conveying force applied to the top plate 102 based on the light receiving position, so the structural design of the table is significantly changed. Without detecting the bending of the base plate 104 as a change in the light receiving position of the laser beam 600, the bending moment of the top plate 102, that is, the overhang load can be indirectly detected with high sensitivity. A table system having a simple structure and an appropriate margin of the conveying force of the top plate 102 while maintaining a high support rigidity of the 102, and an X-ray having such a table system It is possible to realize a T device.

  Hereinafter, as a second embodiment to a fourth embodiment of the present invention, a mechanism for detecting the deflection of the base 104 using the laser light source 112 and the photodetector 124 is applied to correct the deflection of the top plate 102. A table system and an X-ray CT apparatus will be described.

(Second Embodiment)
A table system and an X-ray CT apparatus according to a second embodiment of the present invention will be described. As shown in FIG. 5, the mechanical structure of the table system 200 according to the present embodiment is substantially the same as that of the table system 100 according to the first embodiment. However, the base 104 is configured by an actuator or the like. And the tilt of the base 104 in the vertical direction can be adjusted.

  FIG. 11 is a block diagram showing a main part of the table system 200 according to the present embodiment. The table system 200 includes a laser light source 122 and a photodetector 124 provided on the base 104, a light receiving position specifying unit 125, a deflection angle calculating unit 126, and a control unit 116. The light receiving position specifying unit 125 specifies the light receiving position of the laser beam 600 based on the detection signal of the photodetector 124. Further, the deflection angle calculation unit 126 determines the magnitude of the difference between the light receiving position of the laser beam 600 specified before feeding the top plate and the light receiving position of the laser beam 600 specified after feeding the top plate, Based on the correspondence between the degree of bending and the degree of bending of the base 104, the bending angle of the top plate 102 in the imaging space S is calculated. That is, the bend angle calculation unit 126 calculates the bend amount and bend angle of the tip of the top plate 102 based on the degree of bend of the base 104, and shoots the top plate 102 based on the extension amount of the top plate 102 and the like. The deflection angle of the part located in the space S is calculated. For example, as shown in FIG. 4, when the imaging space S is scanned by irradiating an X-ray beam 500 having a thickness th on the body axis of the object 8, a tomographic image is obtained from the projection data obtained by this scan. It means a reconstructed space of thickness th. The control unit 116 controls the inclination of the base 104 by controlling the inclination adjusting mechanism 113 so that the inclination of the portion of the top plate 102 located in the imaging space S is compensated for the calculated deflection angle. The above-described correspondence relationship between the degree of bending of the top plate 102 and the degree of bending of the base 104 may be obtained in advance through experiments or the like, for example.

  For the control of the tilt of the base 104, a correspondence relationship between the light receiving position of the laser beam 600 and the deflection angle to be compensated is obtained in advance by experiments or the like, and the laser beam 600 is received by referring to the correspondence relationship. You may make it control the inclination of the base 104 directly from a position.

  Further, for example, in the state before the top plate 102 is extended, the light receiving position specified by using the detection signal of the light detector 124 in the state before the object 8 is placed on the top plate 102 is used as the reference position. And a predetermined parameter such as a distance between the light receiving position specified after placing the object 8 on the top plate 102 or a length indicating a horizontal component or a vertical component of the distance, and the like. With reference to a look-up table that defines the correspondence between the feed amount and the deflection angle to be compensated for the top plate 102 for each parameter range, the top plate 102 is in accordance with the correspondence relationship according to the calculated parameter value. Control may be performed so as to compensate for the deflection angle of the top plate 102 based on the amount of feed.

  According to the present embodiment, a tomographic image in which the slice plane is perpendicular to the body axis of the target 8 can be obtained even if the top plate 102 is bent.

  An X-ray CT apparatus having such a table system 200 is also an example of an embodiment of the present invention.

(Third embodiment)
A table system and an X-ray CT apparatus according to a third embodiment of the present invention will be described. As shown in FIG. 5, the mechanical structure of the table system 300 according to the present embodiment is substantially the same as that of the table system 100 according to the first embodiment, but the base 104 has an elevating mechanism 114. The height of the table 104 can be adjusted.

  FIG. 12 is a block diagram showing a main part of the table system 300 according to the present embodiment. The table system 300 includes a laser light source 122 and a photodetector 124 provided on the base 104, a light receiving position specifying unit 125, a deflection amount calculating unit 127, and a control unit 116. The light receiving position specifying unit 125 specifies the light receiving position of the laser beam 600 based on the detection signal of the photodetector 124. Further, the bending amount calculation unit 127 determines the difference between the light receiving position of the laser beam 600 specified before the top plate is extended and the light receiving position of the laser beam 600 specified after the top plate is extended, Based on the correspondence between the degree of bending and the degree of bending of the base 104, the amount of bending of the portion of the top plate 102 located in the imaging space S is calculated. That is, the bending amount calculation unit 126 calculates the bending amount and the bending angle of the tip of the top plate 102 based on the degree of bending of the base 104, and shoots the top plate 102 based on the feeding amount of the top plate 102 and the like. The amount of deflection of the portion located in the space is calculated. The control unit 116 controls the height of the base 104 by controlling the lifting mechanism 114 so that the height of the portion of the top plate 102 located in the imaging space S is compensated by the calculated amount of deflection. The above-described correspondence relationship between the degree of bending of the top plate 102 and the degree of bending of the base 104 may be obtained in advance through experiments or the like, for example.

  As for the control of the height of the base 104, a correspondence relationship between the light receiving position of the laser beam 600 and the amount of deflection to be compensated is obtained in advance by experiments or the like, and the correspondence relationship is referred to by referring to the correspondence relationship. The height of the base 104 may be controlled directly from the light receiving position.

  Further, for example, in the state before the top plate 102 is extended, the light receiving position specified by using the detection signal of the light detector 124 in the state before the object 8 is placed on the top plate 102 is used as the reference position. And a predetermined parameter such as a distance between the light receiving position specified after placing the object 8 on the top plate 102 or a length indicating a horizontal component or a vertical component of the distance, and the like. With reference to a look-up table that defines the correspondence relationship between the feed amount and the deflection amount to be compensated for the top plate 102 for each parameter range, the top plate 102 is in accordance with the correspondence relationship according to the calculated parameter value. Control may be made so as to compensate for the amount of deflection of the top plate 102 based on the amount of the feed.

  According to the present embodiment as described above, a tomographic image in which the body axis of the object 8 does not shake with respect to the imaging space S can be obtained even if the top plate 102 is bent.

  An X-ray CT apparatus having such a table system 300 is also an example of an embodiment of the present invention.

(Fourth embodiment)
An X-ray CT apparatus having a table system according to a fourth embodiment of the present invention will be described. The configuration of the X-ray CT apparatus according to the present embodiment is basically the same as the configuration according to the first embodiment, as shown in FIG. Further, as shown in FIG. 5, the mechanical structure of the table system 400 included in the present apparatus is substantially the same as that of the table system 100 according to the first embodiment.

  FIG. 13 is a block diagram showing a main part of the table system 400 according to the present embodiment. The table system 400 includes a laser light source 122 and a photodetector 124 provided on the base 104, a light receiving position specifying unit 125, and a deflection calculating unit 128. The light receiving position specifying unit 125 specifies the light receiving position of the laser beam 600 based on the detection signal of the photodetector 124. In addition, the bending calculation unit 128 determines the magnitude of the difference between the light receiving position of the laser beam 600 specified before feeding the top plate and the light receiving position of the laser beam 600 specified after feeding the top plate, and the bending of the top plate 102. Based on the correspondence relationship between the degree of the above and the degree of bending of the base 104, the bending amount and the bending angle of the portion of the top plate 102 located in the imaging space S are calculated. That is, the bending calculation unit 128 calculates the bending amount and the bending angle of the tip of the top plate 102 based on the degree of bending of the base 104, and the imaging space of the top plate 102 based on the feeding amount of the top plate 102 and the like. The amount of bending and the bending angle of the portion located at S are calculated. The calculated deflection amount and deflection angle are sent to the data processing device 60 via the control interface 62. When the data processing device 60 reconstructs the projection data, it uses the input deflection amount and deflection angle of the top plate 102 to select a portion where the reconstructed image is located in the imaging space S of the top plate 102. Data processing is performed so as to obtain an image obtained when scanning is performed by compensating the calculated deflection amount and deflection angle. The above-described correspondence relationship between the degree of bending of the top plate 102 and the degree of bending of the base 104 may be obtained in advance through experiments or the like, for example.

  In the data processing, the correspondence relationship between the light receiving position of the laser beam 600 and the deflection amount and the deflection angle to be compensated is obtained in advance by experiments or the like, and the light receiving position of the laser beam 600 is determined by referring to the correspondence relationship. May be used to perform data processing.

Further, for example, in the state before the top plate 102 is extended, the light receiving position specified by using the detection signal of the light detector 124 in the state before the object 8 is placed on the top plate 102 is used as the reference position. And a predetermined parameter such as a distance between the light receiving position specified after placing the object 8 on the top plate 102 or a length indicating a horizontal component or a vertical component of the distance, and the like. A look-up table (look-up) that defines the correspondence between the feed amount and the deflection amount and deflection angle of the top plate 102 for each parameter range.
data) so that an image is obtained when scanning is performed by compensating for the deflection amount and the deflection angle based on the feed amount of the top plate 102 in accordance with the correspondence relationship according to the calculated parameter value. Processing may be performed.

  According to the present embodiment, a tomographic image is obtained in which the slice plane is perpendicular to the body axis of the target 8 even when the top plate 102 is bent, and the body axis of the target 8 is not blurred with respect to the imaging space S. be able to.

  Here, both the amount of deflection and the angle of deflection of the top plate 102 are calculated, and data processing is performed so that the reconstructed image becomes an image obtained by scanning both with compensation of these. Either one of the deflection amount or the deflection angle of the plate 102 may be calculated, and data processing may be performed so that the reconstructed image becomes an image obtained when scanning is performed by compensating either one of these.

  According to the second to fourth embodiments, the deflection of the top plate 102 can be corrected particularly in the CT apparatus, the PET CT apparatus, and the NUC CT apparatus used for the treatment plan. As a result, the influence of the deflection of the top plate 102 and the base 104 itself on the positional accuracy of the tomographic image without using the more rigid top plate 102 and base 104, which requires a significant increase in cost and size. Can be avoided.

(Other embodiments)
FIG. 14 is a diagram showing another example of the main part in the base 104, in which a laser light source 122 and a photodetector 124 are provided on one end side of the pipe frame 104 a of the base 104, and the light reflecting plate 123. Is shown on the other end side.

  In the first to fourth embodiments, the optical path of the laser beam 600 is a single straight line. However, as shown in the figure, a light reflector or the like that reflects the laser beam 600 generated by the laser light source 122 at least once. This optical system may be further provided, and the optical path of the laser beam 600 may be a polygonal line. In this way, the optical path length of the laser beam 600 can be made longer, and the amount of change in the light receiving position of the laser beam 600 with respect to the degree of deflection of the base 104 can be increased, and the detection sensitivity of the deflection of the top plate 102 can be increased. Can be higher.

  In the first to fourth embodiments, the laser light source 122 is arranged on one end side in the top plate feeding direction of the base 104, and the photodetector 124 is arranged on the other end side of the base 104. However, as shown in the figure, the above optical system may be further provided so that the laser light source 122 and the photodetector 124 are both arranged on one end side in the top plate feeding direction of the base 104. In this way, the laser light source 122 and the photodetector 124 can be arranged close to each other, and the control signal for controlling the laser light source 122 and the wiring for transmitting the detection signal of the photodetector 124 are shortened. It is possible to simplify the structure of the table system.

  In addition, when reflecting a laser beam using optical systems, such as a light reflection board, you may make a light reflection surface into a curved surface. In this way, the amount of change in the light receiving position of the laser beam 600 with respect to the degree of bending of the base 104 can be adjusted by the curvature of the curved surface, and the detection sensitivity of the bending of the top plate 102 can be easily set to a desired sensitivity. Can be adjusted.

  In the first to fourth embodiments, the laser beam is used. However, any electromagnetic wave having directivity can be used regardless of visible or invisible.

1 is a block diagram of an X-ray CT apparatus which is an example of the best mode for carrying out the invention. Diagram showing the configuration of the X-ray detector Diagram showing the configuration of the X-ray irradiation / detection device Diagram showing the relationship between X-ray irradiation / detection device and target Diagram showing the mechanical structure of the table system The block diagram which shows the principal part of a table system. The figure which shows the principal part in the base The figure which shows the typical structure of a photodetector The figure which shows a mode that the acceptance area of the laser beam changed Diagram showing the configuration of the transport unit The block diagram which shows the principal part of the table system by other embodiment. The block diagram which shows the principal part of the table system by other embodiment. The block diagram which shows the principal part of the table system by other embodiment. The figure which shows the other example of the principal part in a base

Explanation of symbols

2 Scanning gantry 6 Operation console 20 X-ray tube 22 Collimator 24 X-ray detector 26 Data acquisition unit 28 X-ray controller 30 Collimator controller 34 Rotation unit 36 Rotation controller 60 Data processing device 62 Control interface 64 Data acquisition buffer 66 Storage device 68 Display Apparatus 100, 200, 300, 400 Table system 102 Top plate 104 Base 104a Pipe frame 112 Conveying section (conveying means)
113 Inclination adjusting mechanism 114 Elevating mechanism 116 Control unit (control means)
118 Drive unit 120 Low-pass filter 122 Laser light source (light generating means)
123 Light reflector (optical system)
124 photodetector (light detection means)
124a Light receiving surface 125 Light receiving position specifying unit (light receiving position specifying means)
126 Deflection angle calculation unit 127 Deflection amount calculation unit 128 Deflection calculation unit 144 Wheel 202 Feed roller 204 Receiving roller 206 Motor 222 Pulley 224 Column 262 Pulley 264 Belt 500 X-ray beam 600 Laser beam (light beam)

Claims (20)

The base,
A top plate supported so as to be able to be fed out from the base in the horizontal direction;
Conveying means for applying a conveying force to the top plate to convey the top plate in the top plate feeding direction;
Light generating means for generating a light beam provided on the base, and light detecting means for detecting the light beam on a light receiving surface, the light detecting means for changing the light receiving position according to the deflection of the base. A table system comprising: a deflection detection unit configured to detect deflection of the base by detecting the light receiving position.   2. The table system according to claim 1, further comprising a control unit configured to control the transport unit based on the detected light receiving position so that the transport force increases as the degree of bending of the base increases. The base is adjustable in vertical inclination,
The apparatus further comprises control means for controlling the inclination of the base so that the inclination of the portion of the top panel located in the imaging space is compensated by the deflection angle of the part based on the detected light receiving position. The table system according to 1. The base is adjustable in height,
Control means for controlling the height of the base so that the height of the portion located in the imaging space of the top plate is compensated by the amount of deflection of the portion based on the detected light receiving position, The table system according to claim 1.   The control unit performs control based on a magnitude of a difference between a light receiving position of the light beam detected before the top plate is extended and a light receiving position of the light beam detected after the top plate is extended. Item 5. The table system according to any one of Items4.   The control means determines the difference between the light receiving position of the light beam detected before placing the target on the top plate and the light receiving position of the light beam detected after placing the target on the top plate. The table system according to any one of claims 2 to 4, wherein the table system is controlled based on a size. The light generating means generates a light beam in a predetermined direction including a component in the same direction as the top plate feeding direction,
The light detection means is provided at a position where the light receiving position changes according to the degree of bending of the base, and outputs a detection signal reflecting the light receiving position,
The table system according to any one of claims 1 to 6, wherein the deflection detection unit includes a light reception position specifying unit that specifies the light reception position based on the detection signal.   The table system according to any one of claims 1 to 7, wherein an optical path of the light beam is a single straight line. An optical system that reflects the light beam at least once;
The table system according to any one of claims 1 to 8, wherein an optical path of the light beam is a polygonal line.   The table system according to claim 9, wherein the light reflecting surface of the optical system is a curved surface.   The said light generation means is distribute | arranged to the one end part side in the top-plate delivery direction of the said base, The said light detection means is distribute | arranged to the other end part side of the said base, The any one of Claims 8-10. The table system described in the section.   The table system according to claim 9 or 10, wherein both the light generation means and the light detection means are arranged on one end side in the top plate feeding direction of the base. The base has a pipe frame extending in the top plate feeding direction,
The table system according to any one of claims 1 to 12, wherein the light generation means and the light detection means are provided in the pipe frame.   The table system according to any one of claims 1 to 13, wherein a light receiving surface of the light detection means is configured by a large number of charge coupled devices (CCDs).   The table system according to any one of claims 1 to 14, wherein the light generation means is a laser light source. An X-ray CT apparatus for reconstructing an image based on projection data of a plurality of views obtained by scanning with X-rays an object mounted on a table system and carried into an imaging space,
The table system
The base,
A top plate supported so as to be able to be fed out from the base in the horizontal direction;
Conveying means for applying a conveying force to the top plate to convey the top plate in the top plate feeding direction;
Light generating means for generating a light beam provided on the base, and light detecting means for detecting the light beam on a light receiving surface, the light detecting means for changing the light receiving position according to the deflection of the base. An X-ray CT apparatus comprising: a deflection detecting unit that detects deflection of the base by detecting the light receiving position.   The X-ray CT apparatus according to claim 16, further comprising a control unit that controls the transport unit so that the transport force is increased when the degree of bending of the base is increased based on the detected light receiving position. . The base is adjustable in vertical inclination,
Control means for controlling the tilt of the base so that the tilt of the portion of the top plate located in the imaging space is compensated for the deflection angle of the top plate based on the detected light receiving position, The X-ray CT apparatus according to claim 16. The base is adjustable in height,
Control means for controlling the height of the base so that the height of the portion of the top plate located in the imaging space is compensated by the amount of deflection of the portion based on the detected light receiving position. The X-ray CT apparatus according to claim 16.   Based on the detected light receiving position, the image is an image obtained when a portion of the top plate located in the photographing space is scanned while compensating for the amount of deflection and / or the angle of deflection of the portion. The X-ray CT apparatus according to claim 16, further comprising data processing means for performing data processing.

Images