JP2011139778A - X-ray ct apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the exposure of a subject to X rays in diagnosing the subject by using an X-ray CT apparatus. <P>SOLUTION: The X-ray CT apparatus includes: an X-ray tube 8 for emitting X rays; an X-ray detector 9 for detecting the X rays emitted from the X-ray tube 8 and penetrating the subject P; a cradle 1 in which the X-ray tube 8 and the X-ray detector 9 are disposed opposite to each other and which has an opening 27 into which the subject P irradiated with X rays is delivered; a reconstruction processing part for reconstructing a tomographic image based on transmitted X ray data detected by the X-ray detector 9; a position detection sensor 11 disposed in the peripheral edge of an opening 9 for detecting position information of the subject P delivered into the opening 9; and a camera 12 for capturing camera images of the subject P in the range of positions detected by the position detection sensor 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray CT apparatus, and more particularly to an X-ray CT apparatus that can reduce the amount of X-ray exposure to a subject at the time of diagnosis.

  In recent years, X-ray CT apparatuses that take tomographic images of a diseased or injured part of a subject have become widespread as an apparatus for diagnosing a sick or injured subject. The X-ray CT apparatus is provided with an X-ray tube that radiates X-rays and an X-ray detector that detects X-rays, and is disposed between the X-ray tube and the X-ray detector. The specimen is positioned, X-rays are emitted from the X-ray tube, X-rays transmitted through the specimen are detected by an X-ray detector, and a tomographic image of the specimen is reconstructed based on the detected transmitted X-ray data. Yes.

  In the case of taking a tomographic image with an X-ray CT apparatus, a scanogram of the subject is taken as a previous stage. Scanogram imaging is performed in order to position the tomographic image imaging position. As described in Patent Document 1 below, X-rays emitted from an X-ray tube and transmitted through a subject are detected by an X-ray detector. It is done by detecting with.

JP 2008-2221016 A

  Therefore, in the X-ray CT apparatus described in Patent Document 1, X-rays are irradiated to the subject when the scanogram is taken and when the tomographic image is taken. The radiation exposure is increasing.

  In particular, since the tomographic imaging range is specified from within the scanning image imaging range, the scanning image imaging range is wider than the tomographic imaging range, and this also increases the X-ray exposure dose of the subject. It is a factor.

  The present invention has been made to solve such problems, and an object thereof is to reduce the X-ray exposure dose to the subject when diagnosing the subject with the X-ray CT apparatus.

  According to a first aspect of the present invention, in the X-ray CT apparatus, an X-ray tube for irradiating X-rays, an X-ray detector for detecting X-rays irradiated from the X-ray tube and transmitted through the subject, The X-ray tube and the X-ray detector are arranged to face each other, a gantry having an opening into which a subject irradiated with X-rays is sent, and transmission X-ray data detected by the X-ray detector A reconstruction processing unit that reconstructs a tomographic image based on the position, a position detection sensor that is disposed at a peripheral portion of the opening and detects position information of the subject sent to the opening, and the position in the subject And a camera that captures a camera image in a range whose position is detected by the detection sensor.

  According to the present invention, the imaging of the subject performed for positioning the tomographic image capturing position is performed using the position detection sensor and the camera. The X-ray exposure dose to the subject at the time of diagnosis by the X-ray CT apparatus can be reduced without irradiation.

It is a block diagram which shows schematic structure of a X-ray CT apparatus. It is a side view which shows the installation position of a position detection sensor and a video camera. It is explanatory drawing explaining the detection of the positional information on a subject by a position detection sensor. It is explanatory drawing explaining the range of the camera image displayed on an image display part. It is explanatory drawing explaining designation | designated of the imaging | photography range of a tomographic image.

  FIG. 1 is a block diagram illustrating a schematic configuration of an X-ray CT apparatus installed in a hospital. The X-ray CT apparatus includes a gantry 1, a bed 2, and an operation console 3.

  The gantry 1 is a part that irradiates the subject P with X-rays, detects X-rays transmitted through the subject P, and captures a tomographic image of the subject P. The gantry 1 includes a gantry controller 4, a high voltage generator 5, a rotation driver 6, a tilt driver 7, an X-ray tube 8, an X-ray detector 9, a data collector 10, a position A detection sensor 11 and a video camera 12 as a camera are provided.

  The bed 2 is a part where the subject P is placed and the placed subject P is sent to an imaging position where X-rays are irradiated. The couch 2 includes a couch top 13 on which the subject P is placed, a couch base 14 that supports the couch top 13, and a couch drive unit 15 that moves the couch top 13 up and down and horizontally. I have.

  The operation console 3 is a part that controls input / output of the X-ray CT apparatus. The operation console 3 includes a console control unit 16, an input operation unit 17, a preprocessing unit 18, an X-ray projection data storage unit 19, a reconstruction processing unit 20, an image data storage unit 21, and an image processing unit. 22, a camera image data storage unit 23, and an image display unit 24.

  The gantry control unit 4 controls each unit in the gantry 1 in accordance with an input from the input operation unit 17 of the operation console 3.

  The high voltage generator 5 supplies a high voltage necessary for irradiating the X-ray from the X-ray tube 8 to the X-ray tube 8 according to a control signal transmitted from the gantry controller 4.

  The X-ray tube 8 emits X-rays with a high voltage supplied from the high voltage generator 5. X-rays radiated from the X-ray tube 8 are formed into a fan shape or a cone shape.

  The X-ray detector 9 detects X-rays irradiated from the X-ray tube 8 and transmitted through the subject P placed on the bed top plate 13. In the case of a single slice CT apparatus, the X-ray detector 9 is configured by arranging, for example, 1000 channels of X-ray detection elements in a line in a fan shape or a linear shape. In the case of a multi-slice CT apparatus, the X-ray detector 9 includes a plurality of X-ray detector elements arranged in an array in two directions (slice direction and channel direction) orthogonal to each other, thereby two-dimensional X-rays. A detector is configured.

  The data collection unit 10 has a plurality of data collection elements arranged in an array like each X-ray detection element of the X-ray detector 9, and X-rays (actually detected by the X-ray detector 9). X-ray detection signals) are collected according to the data collection control signals output from the gantry control unit 4. This collected data becomes X-ray projection data.

  The rotation drive unit 6 drives a motor (not shown) by a control signal output from the gantry control unit 4 to rotate and drive an annular rotator 26 having a hollow portion 25 around its center line as shown in FIG. . The rotating body 26 holds the X-ray tube 8 and the X-ray detector 9 facing each other at a position sandwiching the hollow portion 25, and the rotating body 26 is mounted on the center line “a” of the hollow portion 25 and a frame. 1 is arranged in a state in which the center line of the opening 27 formed in 1 coincides. The subject P placed on the couch top 13 is sent into the opening 27 and the hollow portion 25, and a tomographic image is taken.

  The tilt drive unit 7 expands and contracts a tilt cylinder (not shown) in accordance with a control signal output from the gantry control unit 4, and tilts the gantry 1 to an arbitrary angle in the direction of arrow b shown in FIG.

  The position detection sensor 11 is installed above the periphery of the opening 27 and detects position information of the subject P sent into the opening 27.

  The video camera 12 is installed adjacent to the position detection sensor 11 on the upper side of the peripheral edge of the opening 27, and always images the subject P, and the position detection sensor 11 detects the position of the subject P. In this case, a camera image in a range where the position of the subject P is detected by the position detection sensor 11 is taken.

  The couch driving unit 15 moves the couch top 13 in the vertical direction and the longitudinal direction (arrow X direction) in response to an input from the input operation unit 17 of the operation console 3. A subject P to be imaged by tomography by irradiation with X-rays is placed on the couch top 13 in a direction in which the body axis direction of the subject P coincides with the movement direction (arrow X direction) of the couch top 13. Is placed.

  The input operation unit 17 includes a keyboard, a touch panel, a mouse, and the like, and performs various input operations for driving the X-ray CT apparatus.

  The console control unit 16 generates a control signal corresponding to the input from the input operation unit 17, and transmits this control signal to the gantry control unit 4, the bed driving unit 15, and each unit in the operation console 3.

  The preprocessing unit 18 performs preprocessing such as sensitivity correction and X-ray intensity correction on the X-ray projection data output from the data collection unit 10.

  The X-ray projection data storage unit 19 stores the X-ray projection data subjected to preprocessing such as sensitivity correction by the preprocessing unit 18.

  The reconstruction processing unit 20 forms tomographic image data by back-projecting the X-ray projection data stored in the X-ray projection data storage unit 19.

  The image data storage unit 21 stores the tomographic image data formed by the reconstruction processing unit 20 and transmits the stored tomographic image data to the image processing unit 22 in response to an input from the input operation unit 17.

  The image processing unit 22 performs various processes on the tomographic image data transmitted from the image data storage unit 21 according to the input from the input operation unit 17, such as a tomographic image at an arbitrary cross-sectional position, projection from an arbitrary direction. The image data is converted to image data such as an image or a three-dimensional image by rendering processing, and the converted image data is transmitted to the image display unit 24.

  The camera image data storage unit 23 stores the camera image data captured by the video camera 12 and transmits the stored camera image data to the image processing unit 22 in response to an input from the input operation unit 17.

  The image display unit 24 displays an image corresponding to the image data transmitted from the image processing unit 22 or an image corresponding to the camera image data transmitted from the camera image data storage unit 23.

  The installation positions of the position detection sensor 11 and the video camera 12 will be described with reference to FIG. The position detection sensor 11 and the video camera 12 are installed adjacent to each other at a position above the peripheral edge of the opening 27 in the gantry 1 in a direction perpendicular to the direction in which the subject P is fed into the opening 27 (arrow X direction). Has been.

  The detection of the position information of the subject P by the position detection sensor 11 will be described with reference to FIG. The position detection sensor 11 emits light in a fan shape at a predetermined angle “2θ” in a direction along the direction in which the subject P is fed into the opening 27, and is irradiated directly below to generate a point “Y on the surface of the subject P. The reflected light of the light reflected by (for example, the tip of the nose) is received, and the time from when the light is irradiated until when the reflected light is received is detected. Then, the distance “h” from the position detection sensor 11 to the point “Y” is detected based on the time from when the light is irradiated until when the reflected light is received. Further, from this distance “h” and angle “θ”, a dimension “2b (2b = h × tan θ × 2)” passing through the point “Y” along the body axis direction of the subject P is detected. 2b ″ is position information of the subject P in the body axis direction.

  The imaging range of the video camera 12 is switched in synchronization with the detection result of the position detection sensor 11, and the video camera 12 is in the direction of the body axis in the subject P and the direction orthogonal to the body axis according to the detection result of the position detection sensor 11. The camera image in the range of “2b × 2b” is taken.

  Camera images in the range of “2b × 2b” captured by the video camera 12 are stored in the camera image data storage unit 23 and displayed on the image display unit 24. A range indicated by “2b × 2b” in FIG. 4 is a range that is captured by the television camera 12 based on the detection result of the position detection sensor 11 and displayed on the image display unit 24 as a camera image.

  After the camera image photographed by the video camera 12 is displayed on the image display unit 24, the operator of the X-ray CT apparatus operates the input operation unit 17 while viewing the camera image on the image display unit 24, as shown in FIG. In this manner, the shooting start position “A” and the shooting end position “B” are indicated on the camera image displayed on the image display unit 24. Thereby, the imaging range “A to B” of the tomographic image performed by irradiating X-rays can be specified, and means for specifying the imaging range of the tomographic image is executed.

  When the imaging range of the tomographic image is specified, the X-ray tube 8 emits X-rays at the timing when the imaging start position “A” of the subject P sent into the opening 27 reaches the X-ray irradiable position. X-rays transmitted through the subject P are detected by the X-ray detector 9, and X-ray projection data is collected. X-ray irradiation from the X-ray tube 8 ends at the timing when the imaging end position “B” of the subject P reaches the X-ray irradiable position. Then, a tomographic image is reconstructed based on the collected X-ray projection data, and the reconstructed tomographic image is displayed on the image display unit 24.

  In such a configuration, according to the X-ray CT apparatus, the position detection sensor 11 and the video camera 12 are used to capture an image of the subject P that is used for positioning the tomographic image capturing position. Therefore, when the tomographic image capturing position is positioned, the subject P is not irradiated with X-rays, and the amount of X-ray exposure to the subject P during diagnosis by the X-ray CT apparatus can be reduced.

  Further, since the subject P can be observed in real time by the video camera 12, even when the subject P moves after the position detection by the position detection sensor 11, the subject P is not exposed to X-rays. Position detection can be performed again, and diagnostic performance can be improved.

  Furthermore, the state of the subject P in the opening 27 can be constantly observed with the video camera 12, and the diagnostic performance can be improved.

  In this embodiment, the case where the position detection sensor 11 and the video camera 12 are installed above the peripheral edge of the opening 27 in the gantry 1 is described as an example. However, the position detection sensor 11 and the video are described. The camera 12 may be additionally installed at a lateral position of the periphery of the opening 27 in the gantry 1. This is effective when the position detection sensor 11 and the video camera 12 are installed at the lateral positions of the peripheral edge to position the tomographic image capturing position from the side of the subject P.

DESCRIPTION OF SYMBOLS 1 Stand 8 X-ray tube 9 X-ray detector 11 Position detection sensor 12 Camera (video camera)
20 Reconstruction processing unit 24 Image display unit 27 Opening P Subject

Claims (2)

An X-ray tube that emits X-rays;
An X-ray detector for detecting X-rays irradiated from the X-ray tube and transmitted through the subject;
A frame on which the X-ray tube and the X-ray detector are arranged to face each other, and an opening into which a subject irradiated with X-rays is sent;
A reconstruction processing unit for reconstructing a tomographic image based on transmission X-ray data detected by the X-ray detector;
A position detection sensor that is arranged at a peripheral edge of the opening and detects position information of the subject sent into the opening;
A camera that captures a camera image of a range detected by the position detection sensor in the subject;
An X-ray CT apparatus comprising: An image display unit for displaying a camera image of the subject imaged by the camera;
Means for designating an imaging range of a tomographic image with respect to the camera image of the subject displayed on the image display unit;
The X-ray CT apparatus according to claim 1, further comprising:

Images