JP2011130847A - X-ray ct apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus capable of preventing blurring of image data. <P>SOLUTION: The X-ray CT apparatus includes: a cradle 10 for irradiating a subject P mounted on a top board 21 with X rays and detecting the X rays transmitting the subject P for radiography; an image data generating part 30 for generating image data based on the radiography by the cradle 10; a cradle moving part 40 for moving the cradle 10 in the longitudinal direction of the top board 21; and a position detecting part 50 for detecting the position of the cradle 10 moved by the cradle moving part 40. Blurring of the image data generated by the image data generating part 30 is corrected based on the information on a second position in the vertical direction of the cradle 10 located at the radiographic position detected by the position detecting part 50. <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 capable of moving a gantry for imaging.

  An X-ray CT apparatus provides image data generated by imaging a subject, and plays an important role in medical practices such as diagnosis and treatment. This X-ray CT apparatus includes an X-ray irradiator that irradiates an object placed on a top plate supported by a bed and an X-ray detector that detects X-rays transmitted through the object. A gantry is provided. The gantry has a cylindrical opening, and the X-ray irradiation unit and the X-ray detection unit rotate around the subject accommodated in the gantry, and the subject is irradiated with X-rays and transmitted through the subject. The detected X-ray is detected and imaging is performed. As an X-ray CT apparatus, a gantry moving X-ray CT apparatus including a gantry moving unit that moves the gantry on a traveling surface such as a rail is known (for example, see Patent Document 1).

  The gantry moving X-ray CT apparatus may be used in combination with a radiotherapy apparatus that performs treatment by irradiating a lesion on a subject with radiation. In this case, the bed and the radiotherapy apparatus are arranged at predetermined positions, and the subject placed on the top is moved by moving the gantry. Then, based on the image data obtained by imaging, the subject is positioned by moving the top plate after the imaging is performed in the direction of the radiotherapy apparatus, and then the irradiated portion is irradiated with radiation.

JP 2009-142332 A

  However, since the traveling surface on which the gantry moves has unevenness of about 1 mm to 2 mm, for example, although the flatness is physically required, in recent X-ray CT apparatuses with improved spatial resolution, The image data is blurred due to the vertical displacement of the gantry. As a result, there is a possibility that the exposure of the subject to the unnecessary part in the radiotherapy may increase, and therefore, careful attention is required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an X-ray CT apparatus capable of preventing blurring of image data.

  In order to solve the above problem, an X-ray CT apparatus according to a first aspect of the present invention irradiates a subject placed on a top plate with X-rays and detects X-rays transmitted through the subject. A gantry that performs photographing, image data generating means for generating image data based on photographing on the gantry, gantry moving means for moving the gantry in the longitudinal direction of the top plate, and the gantry moving means. Position detecting means for detecting the position of the gantry, and correction means for correcting the image data generated by the image data generating means based on the position information of the gantry in the vertical direction detected by the position detecting means. It is characterized by comprising.

  According to a third aspect of the present invention, there is provided an X-ray CT apparatus according to the present invention, comprising: a gantry that irradiates a subject placed on a top plate with X-rays, detects X-rays transmitted through the subject, and performs imaging. Image data generating means for generating image data based on photographing on the gantry, gantry moving means for moving the gantry in the longitudinal direction of the top plate, and positions of the gantry moved by the gantry moving means. A position detecting means for detecting; and a vertical moving means for moving the gantry to a reference position in the vertical direction on the basis of position information in the vertical direction of the gantry detected by the position detecting means. To do.

  According to the present invention, it is possible to prevent blurring of image data by detecting the vertical position of the gantry at the photographing position and correcting based on the detected position.

The block diagram which shows the structure of the X-ray CT apparatus which concerns on the Example of this invention. The figure which shows the arrangement | positioning of the bed part and stand based on the Example of this invention, and the structure of a bed part. The figure for demonstrating an example of the detection method which detects the 2nd position which concerns on the Example of this invention. The flowchart which shows operation | movement of the X-ray CT apparatus which concerns on the Example of this invention. The figure which shows an example of the image data produced | generated by the image data production | generation part which concerns on the Example of this invention. The figure which shows an example of the track | orbit in the moving direction of the imaging | photography center of the mount frame concerning the Example of this invention. FIG. 6 is a diagram illustrating an example of image data corrected by a correction unit according to an embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an X-ray CT apparatus according to an embodiment of the present invention. The X-ray CT apparatus 100 irradiates the bed 20 on which the subject P is placed and the subject P placed on the bed 20 to detect X-rays transmitted through the subject P. The gantry 10 is movably arranged to perform photographing, and the image data generation unit 30 that generates image data by photographing on the gantry 10.

  In addition, the X-ray CT apparatus 100 includes a gantry moving unit 40 that moves the gantry 10 in the longitudinal direction of the bed unit 20, a position in the moving direction of the gantry 10 (first position), and a position in the vertical direction of this position (first 2) and a correction unit 60 that corrects the image data generated by the image data generation unit 30 based on the position information detected by the position detection unit 50.

  Furthermore, the X-ray CT apparatus 100 includes a display unit 70 that displays the image data corrected by the correction unit 60, an operation unit 80 that performs input for operating the bed unit 20 and the gantry 10, and input from the operation unit 80. Based on the input information, the bed unit 20, the gantry 10, the image data generating unit 30, the gantry moving unit 40, the position detecting unit 50, and the system control unit 90 for controlling the correcting unit 60 are provided.

  FIG. 2 is a diagram illustrating the arrangement of the bed unit 20 and the gantry 10 and the configuration of the bed unit 20. The couch unit 20 includes a couchtop 21 that is disposed apart from the gantry 10 at the home position and that supports the couchtop 21 and that can move the couchtop 21. The bed 22 includes a longitudinal movement mechanism that moves the top plate 21 in the longitudinal direction, a vertical movement mechanism that moves in the vertical direction, and a rotation mechanism that rotates in the direction of a radiation therapy apparatus (not shown).

  The gantry 10 shown in FIG. 1 irradiates X-rays to a cylindrical opening 11 that accommodates an imaging region for imaging the subject P and an imaging region of the subject P that is accommodated in the opening 11. X-ray irradiation unit 12, high voltage generation unit 13 that supplies a high voltage to X-ray irradiation unit 12, X-ray detection unit 14 that detects X-rays emitted from X-ray irradiation unit 12, and X-ray detection unit And a data collection unit 15 that collects the detection signals detected at 14 and generates projection data.

  Further, the gantry 10 includes a data transmission unit 16 including a transmission unit and a reception unit that transmit and receive the projection data generated by the data collection unit 15 to the image data generation unit 30 using, for example, light, and an X-ray. A rotating frame 17 that supports the transmitting unit of the irradiation unit 12, the high voltage generation unit 13, the X-ray detection unit 14, the data collection unit 15, and the data transmission unit 16, and an imaging in which the rotating frame 17 is positioned at the center of the opening 11 And a rotation mechanism 19 that rotates about the center 18.

  The X-ray irradiation unit 12 includes an X-ray tube, generates X-rays by the high voltage supplied from the high voltage generation unit 13, and rotates the generated X-rays by the rotation of the rotating frame 17, while in the opening 11. The subject P is irradiated. Further, the X-ray detection unit 14 has an X-ray detection element, detects X-rays transmitted through the subject P by X-ray irradiation from the X-ray irradiation unit 12 and converts them into electrical signals, and converts the converted detection signals Amplified and output to the data collection unit 15.

  The data collection unit 15 converts an analog signal, which is a detection signal from the X-ray detection unit 14, into a digital signal, and collects data for each predetermined rotation angle of the rotation frame 17 to generate projection data for one view. The projected data is output to the data transmission unit 16. Further, the data transmission unit 16 outputs the projection data from the data collection unit 15 to the image data generation unit 30.

  The image data generation unit 30 reconstructs the storage unit that stores the projection data output from the data transmission unit 16 of the gantry 10 and the image data by reconstructing the projection data of multiple views stored in the storage unit. Department. Then, the generated image data is output to the correction unit 60.

  The gantry moving unit 40 includes a guide rail disposed between the bed unit 20 and the gantry 10 at the home position, a screw shaft disposed in parallel to the guide rail, a ball screw nut that engages with the screw shaft disposed on the gantry 10, and A moving mechanism 41 configured by units such as a motor that rotates the ball screw nut and a mechanism control unit 42 that drives and controls the moving mechanism 41 are provided. Then, by rotating the ball screw nut with a motor, the gantry 10 is moved from the home position in the longitudinal direction of the top plate 21 along the guide rail, and the imaging part of the subject P placed on the top plate 21 is moved. Stops at the photographing position accommodated in the opening 11.

  The position detection unit 50 includes a position sensor that detects the first position. For example, the first position moved in the moving direction of the gantry 10 from the reference position using a position sensor such as an encoder disposed in the moving mechanism 41 of the gantry moving unit 40 with the gantry 10 at the home position as a reference position. Is detected. Further, the second position moved in the vertical direction from the reference position of the gantry 10 at the first position is detected.

(Figure 3)
FIG. 3 is a diagram for explaining an example of a detection method for detecting the second position. First, a wire passing through the imaging center 18 of the gantry 10 is stretched horizontally between the gantry 10 and the bed 20 at the home position using theo dry or the like. When the operation of collecting the second position information is performed from the operation unit 80, the gantry 10 captures an image of the wire in the range R that can be moved by the gantry moving unit 40 while moving from the home position. With this shooting, the image data generation unit 30 generates image data in the range R and outputs the generated image data to the position detection unit 50.

  The position detection unit 50 uses the two-dimensional image data generated with the region including the imaging center 18 of the gantry 10 at the home position as an imaging region as a reference, and the region including the imaging center 18 at the first position in the range R. A second position is detected from the two-dimensional image data generated as the imaging region. Here, the first position is based on the position where the wire data corresponding to the wire is located at the center of the reference image data and moved vertically from the center of the image data of the wire data generated at the first position. The second position of the gantry 10 is detected.

  Then, the information on the first position of the gantry 10 that has moved in the range R and the second position at this position is output to the correction unit 60. In addition, when an operation for moving the gantry 10 for performing photographing to the photographing position is performed from the operation unit 80, information on the first position at the photographing position is output to the correction unit 60.

  The correction unit 60 includes a storage circuit 60a that stores information on the first and second positions output from the position detection unit 50 in response to the collection operation of the second position information. Based on the first and second position information stored in the storage circuit 60a and the information on the first position of the gantry 10 at the photographing position output from the position detection unit 50, the reference position of the gantry 10 is determined. The distance shifted in the vertical direction is calculated, and the vertical blurring of the image data output from the image data generation unit 30 due to the vertical shift relative to the reference position of the gantry 10 is corrected based on the calculated distance.

  The display unit 70 includes a monitor such as a liquid crystal panel or a CRT, and displays the image data corrected by the correction unit 60.

  The operation unit 80 is an interactive interface including an input device such as a keyboard, a trackball, a joystick, and a mouse, a display panel, and various switches. The operation unit 80 can be used to move the top plate 21 and the gantry 10 of the bed unit 20. Various input operations relating to imaging of the subject P are performed.

  The system control unit 90 includes a CPU and a storage circuit, temporarily stores input information input by an operation from the operation unit 80, and then, based on the input information, rotates the rotation frame 17 on the gantry 10 and projection data. , Generation and display of image data, and control of the entire system such as control relating to movement of the top plate 21 and the gantry 10. Then, the subject P is imaged while moving the gantry 10. Further, the gantry 10 is stopped, and the subject P is imaged.

  Hereinafter, an example of the operation of the X-ray CT apparatus 100 will be described with reference to FIGS. 1 to 7. FIG. 4 is a flowchart showing the operation of the X-ray CT apparatus 100. FIG. 5 is a diagram illustrating an example of the trajectory of the imaging center 18 of the gantry 10. FIG. 6 is a diagram illustrating an example of image data generated by the image data generation unit 30. FIG. 7 is a diagram illustrating an example of image data corrected by the correction unit 60.

  In FIG. 4, the storage circuit 60 a of the correction unit 60 stores first and second position information in the movable range R of the gantry 10. The top plate 21 of the bed unit 20 is stopped at the boarding / alighting position at which the subject P can easily get on and off, and the gantry 10 is stopped at the home position. Then, after the subject P is placed on the top plate 21, when an operation for moving the top plate 21 is performed from the operation unit 80 in order to image the subject P, the X-ray CT apparatus 100 operates. Start (step S1).

  The system control unit 90 instructs the couch unit 20, the gantry 10, the image data generation unit 30, the gantry moving unit 40, the position detection unit 50, and the correction unit 60 to perform shooting. The bed 22 of the bed unit 20 moves up the table 21 from the getting on / off position until the center of the imaging region of the subject P reaches the height of the imaging center 18 of the platform 10 at the home position, and then moves in the direction of the platform 10. And it stops at the imaging position where the subject P can be imaged (step S2).

  When an operation for moving the gantry 10 in the direction of the top plate 21 for photographing is performed from the operation unit 80, the moving mechanism 41 of the gantry moving unit 40 moves the gantry 10 from the home position toward the top plate 21, The imaging part of the subject P placed on the top 21 is stopped at the imaging position where it is accommodated in the opening 11 (step S3).

  When an operation for performing imaging is performed from the operation unit 80, the X-ray irradiation unit 12 of the gantry 10 generates X-rays by the high voltage supplied from the high voltage generation unit 13, and the generated X-rays are transmitted to the rotating frame 17. While rotating by rotation, the imaging region of the subject P is irradiated. The X-ray detection unit 14 detects X-rays transmitted through the imaging region of the subject P and the top plate 21 by X-ray irradiation from the X-ray irradiation unit 12, and outputs a detection signal to the data collection unit 15. The data collection unit 15 generates projection data from the detection signal from the X-ray detection unit 14 and outputs the generated projection data to the data transmission unit 16. The data transmission unit 16 outputs the projection data from the data collection unit 15 to the image data generation unit 30. The image data generation unit 30 reconstructs the projection data output from the data transmission unit 16 of the gantry 10 to generate image data, and outputs the generated image data to the correction unit 60 (step S4).

  FIG. 5 is a diagram illustrating an example of the image data generated by the image data generation unit 30. The image data 31 includes subject data 32 corresponding to the imaging region of the subject P, top plate data 33 corresponding to the top plate 21 positioned below the subject data 32, and subject data 32 and top plate data. 33 is constituted by air data 34 corresponding to the air in the opening 11 surrounding the 33. The image center 311 of the image data 31 corresponds to the photographing center 18 of the gantry 10.

  Based on the first and second position information stored in the storage circuit 60 a and the information on the first position of the gantry 10 that has moved to the shooting position output from the position detection unit 50, the correction unit 60 A distance shifted in the vertical direction with respect to the reference position of the gantry 10 is calculated, and the image data 31 that is shifted in the vertical direction with respect to the reference position of the gantry 10 is corrected based on the calculated distance (step S5 in FIG. 4). .

Next, correction of the image data 31 corrected by the correction unit 60 will be described.
FIG. 6 is a diagram showing an example of the trajectory of the imaging center 18 in the moving direction of the gantry 10. The gantry 10 moves in a range R between the home position and the couch 22 of the couch portion 20 in the direction of the arrow L1 that is the longitudinal direction of the top plate 21 and the direction of the arrow L2 that is opposite to the L1 direction. In addition, the imaging center 18 of the gantry 10 that moves in the range R passes on a trajectory 181 represented by a curve.

  The trajectory 181 is a horizontal X-axis extending from the first and second position information stored in the storage circuit 60a of the correction unit 60 in the longitudinal direction of the top plate 21 passing through the imaging center 18 of the gantry 10 at the reference position. And plotted on a Y-axis two-dimensional coordinate axis extending in the vertical direction perpendicular to the X-axis, and corresponds to the flatness of a guide rail disposed on the floor (not shown) of the moving mechanism 41, for example. . Alternatively, the guide rail may be arranged on the ceiling and the gantry 10 may be suspended from the ceiling and moved.

  Here, if the imaging region of the subject P is, for example, a head section indicated by a broken line in FIG. 6, the imaging center 18 at the imaging region is shifted downward from the X axis by a distance D, and thus the image data generation unit 30. Therefore, the image data 31 generated in step S is shifted upward by a distance corresponding to the distance D. Therefore, in the correction unit 60, for example, the subject data 32 and the top plate data 33 of the image data 31 blurred upward are moved downward and corrected.

  In this way, the first and second position information of the gantry 10 in the range R is stored in the memory circuit 60a in the memory circuit 60a, and based on the information on the first position of the gantry 10 at the photographing position from the position detection unit 50. Thus, the distance D shifted downward with respect to the reference position of the gantry 10 at the photographing position can be calculated.

  FIG. 7 is a diagram showing the image data corrected by the correction unit 60. The image data 31a includes the subject data 32a and the top plate data 33a in which the subject data 32 and the top plate data 33 included in the image data 31 shown in FIG. 5 are moved downward by a distance D1 corresponding to the distance D. Contains.

  Thus, by moving the distance D1 according to the calculated distance D, it is possible to correct the image data 31 blurred upward. This correction can prevent image data from being blurred.

  After the photographing is finished, the gantry moving unit 40 moves the gantry 10 from the photographing position and stops at the home position (step S6). The system control unit 90 stops the bed unit 20, the platform 10, the image data generation unit 30, the platform moving unit 40, the position detection unit 50, and the correction unit 60, so that the X-ray CT apparatus 100 performs an imaging operation. Is finished (step S7).

  After the imaging is completed, the subject P is positioned by moving the top plate 21 after imaging in the direction of the radiotherapy apparatus based on the corrected image data 31a, and then the radiotherapy of the subject P is performed. Is done.

  According to the embodiment of the present invention described above, it is possible to detect the first and second positions in the moving direction and the vertical direction in the movable range R of the gantry 10. Then, based on the first and second position information in the detected range R and the first position information of the gantry 10 at the photographing position, a distance shifted vertically from the reference position of the gantry 10 at the photographing position is calculated. Then, the blurred image data 31 can be corrected based on the calculated distance. Thereby, blurring of the image data can be prevented, and unnecessary exposure of the subject P other than the lesioned part can be reduced.

  In addition, this invention is not limited to the said Example, The 1st and 2nd position which detected the 1st and 2nd position of the moving direction and the up-down direction in the movable range R of the mount frame 10 is detected. Based on the position information, when the gantry 10 is displaced in the vertical direction with respect to the reference position at the photographing position, a vertical movement mechanism that moves the gantry 10 to the reference position may be provided. Thereby, blurring of the image data can be prevented, and unnecessary exposure of the subject P other than the lesioned part can be reduced.

P subject 10 gantry 11 opening 12 X-ray irradiation unit 13 high voltage generation unit 14 X-ray detection unit 15 data collection unit 16 data transmission unit 17 rotating frame 18 imaging center 19 rotating mechanism 20 bed unit 21 top plate 22 bed 30 image 30 Data generation unit 40 Base movement unit 41 Movement mechanism 42 Mechanism control unit 50 Position detection unit 60 Correction unit 60a Storage circuit 70 Display unit 80 Operation unit 90 System control 100 X-ray CT apparatus

Claims (3)

A gantry that irradiates a subject placed on a top plate with X-rays, detects X-rays transmitted through the subject, and performs imaging;
Image data generating means for generating image data on the basis of photographing on the mount;
A platform moving means for moving the platform in the longitudinal direction of the top plate;
Position detecting means for detecting the position of the gantry moved by the gantry moving means;
An X-ray CT apparatus comprising: correction means for correcting image data generated by the image data generation means based on position information in the vertical direction of the gantry detected by the position detection means .   The correction means moves the image data generated by the image data generation means in a direction shifted vertically from the reference position of the gantry at the shooting position where the shooting was performed to obtain the image data. The X-ray CT apparatus according to claim 1, wherein the X-ray CT apparatus corrects the error. A gantry that irradiates a subject placed on a top plate with X-rays, detects X-rays transmitted through the subject, and performs imaging;
Image data generating means for generating image data on the basis of photographing on the mount;
A platform moving means for moving the platform in the longitudinal direction of the top plate;
Position detecting means for detecting the position of the gantry moved by the gantry moving means;
An X-ray CT apparatus comprising: vertical movement means for moving the gantry to a vertical reference position based on position information in the vertical direction of the gantry detected by the position detection means.

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