JP2010099389A - X-ray ct device and scanogram image creating program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray CT device obtaining a scanogram image photographing a plurality of regions at different angular positions by one scanning. <P>SOLUTION: This X-ray CT device includes: a photographing section in which an X-ray tube and an X-ray detector are disposed opposite to each other in a rotating part in a gantry and X-rays are applied to a subject to perform X-ray photographing; a bed having a top plate for placing the subject and capable of moving the top plate into the gantry; and a control part which controls the rotating part when the plurality of regions of the subject are scanogram-photographed and sets the irradiating angle of X-ray for each of the plurality of regions to switch the photographing direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an X-ray CT apparatus for obtaining a tomographic image of a subject and a scan image creation program.

  In general, in an organization such as a hospital, an image diagnostic apparatus such as an X-ray CT apparatus (computer tomography apparatus) is used, and projection data obtained by imaging a subject is collected to observe medical image information. ing. In such an X-ray CT apparatus, an X-ray tube and an X-ray detector are arranged opposite to each other, and projection data is collected by moving a top plate on which a subject is placed between the X-ray tube and the X-ray detector. I am doing so.

  On the other hand, when data collection is started, it is necessary to make a scan plan, and X-ray tube voltage, X-ray tube current, X-ray irradiation angle, scan position, scan range, etc. are set in advance. . In this scan plan, it is common to capture a scanogram, specify the scan start position, stop position, etc. using the scanogram, and set the scan range, imaging conditions, and the like.

  In scanning scan images, the X-ray tube and the X-ray detector are stopped (fixed) and the top plate on which the subject is mounted is moved while moving in the body axis direction of the subject. A plane transmission image like an image is obtained.

  By the way, when obtaining a scanogram, it is common to perform imaging while fixing the X-ray irradiation angle on the subject, but it may be better to change the X-ray irradiation angle depending on the region to be imaged. For example, it is better to use a scanogram of the side image obtained by photographing the head of the subject from the side for positioning the head, and to use a scanogram of the top image obtained by photographing the abdomen of the subject from the upper surface for positioning the abdomen. good.

  However, when imaging over the head and abdomen is required, two scano imagings are required to obtain the side image and top image scan image, increasing the exposure opportunity of the subject and increasing the exposure dose. There is a problem.

Patent Document 1 describes an example in which a plurality of regions of a subject are specified, and the top plate is moved while repeating irradiation and stopping of X-rays, and a scano image is captured for each of the plurality of regions. According to this example, unnecessary exposure to the subject can be reduced. However, in order to obtain a scano image with different irradiation angles such as a side image and a top image, multiple scano imagings are required, and the amount of exposure of the subject increases, so there is room for further improvement.
JP 2006-122479 A

  The conventional X-ray CT apparatus has a problem in that the amount of exposure of the subject increases because multiple scano imagings such as side images and top images with different irradiation angles are required. .

  In view of the above circumstances, an object of the present invention is to provide an X-ray CT apparatus and a scan image creation program capable of obtaining scanograms obtained by imaging a plurality of sites from different angular positions in a single scan.

  The X-ray CT apparatus of the present invention according to claim 1 is an imaging in which an X-ray tube and an X-ray detector are arranged opposite to each other in a rotating part in a gantry, and X-ray imaging is performed by irradiating the subject with X-rays. And a table on which the subject is placed, a bed on which the top plate can be moved into the gantry, a data collection unit for collecting signals detected by the X-ray detector, and the subject And a control unit that controls the rotation unit when scanning a plurality of regions, and sets the X-ray irradiation angle for each of the plurality of regions to switch the imaging direction.

  According to a sixth aspect of the present invention, the rotating unit in the gantry has an imaging unit in which an X-ray tube and an X-ray detector are arranged to face each other, and the top plate on which the subject is placed is moved into the gantry. A program for generating a scanogram by irradiating the subject with X-rays, wherein the computer scans the first scanogram while moving the top plate while controlling the rotation unit at a predetermined rotation angle. A function to control the rotating unit when the top plate moves to a preset position, and a function to take a second scanogram while moving the top plate by switching the X-ray irradiation angle. This is a scanogram creation program for realizing.

  In the present invention, since a plurality of parts can be scanned with different scans in a single scan, the exposure opportunity of the subject can be reduced and a scano image suitable for observation can be obtained.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

 FIG. 1 is a block diagram showing the overall configuration of an X-ray CT apparatus (computer tomography apparatus) according to an embodiment of the present invention. In FIG. 1, an X-ray CT apparatus 100 has a gantry 11 and a rotating unit 12 is provided in the gantry 11 and is rotated by a rotating mechanism (not shown). An X-ray tube 13 and an X-ray detector 14 are disposed in the rotating unit 12 so as to face each other. The central portion of the rotating unit 12 is opened and placed on the couch top 15. A subject P is inserted.

 X-rays that have passed through the subject P are converted into electrical signals by the X-ray detector 14, amplified by the data acquisition unit 16, and converted into digital data. This digital data is transmitted to the operation console 22 (described later) as projection data via the data transmission device 17. The X-ray detector 14 includes a number of X-ray detection elements arranged in a matrix in the body axis direction (slice direction) and body width direction (channel direction) of the subject P, and the detector arranged in the slice direction. Collect projection data for each column.

 The gantry 11 is provided with a gantry controller 18 and a slip ring 19. The couchtop 15 can be moved back and forth to the opening of the gantry 11 by a couch drive device provided on the couch 20, and a drive signal is supplied to the couch drive device from the couch controller 21. The bed 20 is provided with a detector that electrically detects the position of the top plate 15 in the slice direction (the body axis direction of the subject P), and the bed 20 provides the position information of the bed to the bed control unit 21. send.

 An operation console 22 constitutes a computer system. The operation console 22 has a preprocessing unit 23, and data from the data transmission device 17 is sent to the preprocessing unit 23. The preprocessing unit 23 performs processing such as signal intensity correction and signal loss correction, and outputs projection data onto the bus line 221.

 A system control unit 24 is connected to the bus line 221, and an operation unit 25 is connected to the system control unit 24. A data storage unit 26, a reconstruction processing unit 27, an image data processing unit 28, and a display unit 29 are connected to the bus line 221.

 The system control unit 24 functions as a host controller, includes a CPU and a ROM, and controls the operation of each unit of the operation console 22 and the gantry control unit 18, the bed control unit 21, and the high voltage generation unit 30. The system control unit 24 stores a program for scanning a plurality of parts from different angular positions in one scan at the time of scanning a scanogram. Detailed operations of scano imaging will be described later. In the following description, the scano image shooting is referred to as scano shooting.

 The data storage unit 26 stores data such as tomographic images, and the reconstruction processing unit 27 extracts a region of interest or an organ of interest from the volume data, and reconstructs 3D image data and the like. The image data processing unit 28 processes the data stored in the data storage unit 26 or the image data after reconstruction.

 The display unit 29 displays an image obtained by image data processing. The operation unit 25 includes a keyboard, a mouse, and the like. The operation unit 25 is operated by a user and performs various settings for data processing. In addition, various information such as the patient's condition and examination method is input.

 The high voltage generator 30 supplies power to the X-ray tube 13 via the slip ring 19 and supplies power (tube voltage and tube current) necessary for X-ray exposure. The X-ray tube 13 generates beam X-rays that spread in two directions: a slice direction parallel to the body axis direction of the subject P and a channel direction perpendicular thereto.

  In such an X-ray CT apparatus 100, a scan range is set, volume scan (3D scan) is performed, and reconstruction by the reconstruction processing unit 27 can generate volume data within that range. In addition, the X-ray tube 13 is fixed at a certain rotation angle, the top plate 15 is moved, and a wide range is scanned to obtain a plane transmission image such as an X-ray image when the subject P is viewed from one direction. Can do. This plane transmission image is an image showing the imaging region of the subject and is generally called a scano image or a scout image (hereinafter referred to as a scano image).

  The scano image data acquired in this way is used when making a scan plan, and the scan start position, stop position, etc. are specified using the scano image, and the scan range and imaging conditions for X-ray CT imaging are set. Used for. The scano image data and the volume data are stored in the data storage unit 26. A plurality of tomographic image data (slice image data) can be generated by cutting out data on each cross section from the volume data.

  In the present invention, there is a feature in the method of scanning photography, and a method for creating a scanning image will be specifically described below.

  In general, scanning images (scanning imaging) are performed by fixing the X-ray irradiation angle from the X-ray tube 13 to the subject P and moving the top plate 15 of the bed 20 in the body axis direction. For example, when X-rays are irradiated from directly above the subject P (top position) and the top plate 15 is moved to scan the range from the head to the abdomen, a scanogram as shown in FIG. 2 is obtained. Can do.

  In FIG. 2, reference numeral 40 denotes a scanano image. Actually, it is an image like an X-ray image, but it is simply shown in the figure. In FIG. 2, the scan image of the top image (image taken from the upper surface of the subject) is illustrated for both the head 41 and the chest to the abdomen 42. On the other hand, when performing actual X-ray CT imaging, a scanogram taken from the side of the subject P is better for the head, and a scanogram taken from the top (top) of the chest and abdomen is desired. In some cases.

  Therefore, the present invention is characterized in that a scano image obtained by photographing a plurality of parts from different angular positions is obtained by a single scan. That is, assuming that the X-ray tube 13 is on the upper surface (top position) of the subject as the reference position, when scanning the head, the rotating unit 12 of the gantry 11 is rotated about 90 degrees from the reference position. X-rays from the X-ray tube 13 are irradiated from the side of the head. Then, the top plate 15 is moved by a predetermined amount (an amount corresponding to the length of the head), and a scanogram of the head (first scanogram) is taken.

  Next, after the scanography of the head is completed, the rotating unit 12 of the gantry 11 is rotated to the original reference position, the X-ray tube 13 is positioned on the top of the subject P, and the top plate 15 is moved by a predetermined amount. The second scano image is taken by moving it by an amount corresponding to the range from the chest to the abdomen.

  As a result, as shown in FIG. 3, a scan image 40 in which the head 41 is a side image and a top image from the chest to the abdomen 42 can be obtained in one scan. The actual scano image is an image like an X-ray image, but is shown in a simplified manner in FIG. In FIG. 3, the portion indicated by the alternate long and short dash line x indicates the scan line for scanning.

  Thus, a scan image obtained by photographing a plurality of parts from different angular positions can be obtained by a single scan. For example, the following first to fourth examples are used for switching the rotation angle (that is, the X-ray irradiation angle) of the rotating unit 12 for each imaging region.

  In the first example, the user (engineer, doctor, etc.) confirms that the top plate 15 of the bed 20 has reached the switching position from the head to the chest while viewing the scano image being photographed. This is a method for switching the rotation angle of the rotating unit 12. In this case, the operation of the operator becomes troublesome, but it is not necessary to add hardware or software for switching.

  The second example is a method of automatically switching by image processing. This uses images obtained by scanning the subject P by scanning the top plate 15 and uses the subject images of the current scan row and the immediately preceding scan row (lateral images orthogonal to the body axis of the subject). ) Are sequentially compared, and the rotation angle of the rotation unit 12 is switched when the amount of change in the scanogram (lateral width or area, luminance, etc.) exceeds a preset threshold value.

  That is, since the lateral width of the subject P changes abruptly at the border between the head and the chest, when the amount of change in the scanogram exceeds a predetermined threshold, it is determined that the chest is pointed to the chest. The rotation angle of 12 is switched from the side position to the top position. Thereby, the X-ray irradiation direction can be automatically switched.

  The operation of the second example will be described with reference to the flowchart of FIG. The operation of the following flowchart is performed according to the program of the system control unit 24.

  Step S1 is a scan photographing start step, in which the rotating unit 12 is rotated and fixed at an angle (side) suitable for photographing the head, and scan photographing is performed while the top 15 is moved. In step S2, the horizontal width (or area or luminance) of the latest scan line of the subject image obtained by scanography and the immediately preceding scan line is compared, and it is determined whether or not a preset threshold value is exceeded. If it is less than or equal to the threshold value, the top 15 is moved in step S5.

  When the lateral width (or area or brightness) from the head to the chest changes to a preset threshold value or more, the process proceeds to step S4 to rotate the rotating unit 12 to an angle (top) suitable for photographing the chest. Then, the process proceeds to step S5 while maintaining the angle, and scano imaging is performed while moving the top board 15. Then, when the photographing in the predetermined scan range is finished, the scan photographing is finished in step S6.

  In this way, the rotation angle of the rotation unit 12 can be switched using a portion where the amount of change in the subject image changes rapidly, such as the boundary between the head and the chest, as a criterion. Therefore, depending on the setting of the threshold value, not only the boundary from the head to the chest but also the boundary from the chest to the abdomen can be determined and the X-ray irradiation direction can be automatically switched.

  Note that the image information of the latest scan line and the immediately preceding scan line of the subject image obtained by scanography is sequentially stored in the data storage unit 26, and the amount of change (lateral width or area, etc.) is compared with the system. Performed by the control unit 24, the system control unit 24 controls the gantry control unit 18 to switch the rotation angle of the rotation unit 12.

  A third example is a method in which a marker is attached to the top board 15, and when the marker is detected by scano imaging, it is determined as a scan point for scano imaging and the rotation angle of the rotating unit 12 is switched.

  That is, as shown in FIG. 1, the marker m is attached to the top plate 15 on which the subject P is placed, and the marker m is placed at the boundary between the head and the chest, for example. In the scano imaging of the head, the rotation angle of the rotating unit 12 is fixed to the side position. When a marker image is detected by scano imaging, the rotation angle of the rotation unit 12 is switched from the side position to the top position. As a result, the X-ray irradiation direction is automatically switched, and from the chest to the abdomen, the rotation angle of the rotating unit 12 is fixed at the top position, and the scano imaging is performed.

  Further, a plurality of (for example, two) markers are placed on the top board 15, and when the first marker is detected and when the second marker is detected, the rotating unit 12 of the gantry 11 is rotated by a different angle. You may do it. For example, the first marker is placed at the boundary between the head and the chest, and the second marker is placed at the boundary between the chest and the abdomen, so that the rotation unit 12 is rotated at different angles according to the imaging region, and scanography is performed. .

  In this case, scano imaging is first performed at the side position, scano imaging is performed at the top position when the first marker is detected, and scano imaging is performed by switching to another angle when the second marker is detected. As described above, if the number of detected markers and the X-ray irradiation angle are registered in advance, the angle of the rotating unit 12 can be automatically switched according to the program of the system control unit 24.

  The marker detection result obtained by scanography is sent from the data storage unit 26 to the system control unit 24. The system control unit 24 controls the gantry control unit 18 in response to the marker detection result, and the rotation unit. Switch 12 angles.

  The fourth example is a method of automatically switching the rotation angle of the rotating unit 12 according to the moving distance of the top plate 15. That is, as shown in FIG. 5A, when the subject P is placed on the top 15 and is inserted into the gantry 11 from the head, the head of the subject P is moved before the top 15 moves (initial). The distance L1 between the boundary P1 between the chest and the chest and the X-ray irradiation position (the chain line y in FIG. 5) is measured in advance. The measured distance information is input to the system control unit 24 by the operation unit 25. And the system control part 24 rotates the rotation part 12 of the gantry 11 by controlling the gantry control part 18 in the point which the top plate 15 moved only the distance L1, as shown in FIG.5 (b).

  For example, as shown in FIG. 5A, when the position of the end of the top plate 15 before the top plate 15 is moved is L0, at the initial stage when the top plate 15 starts moving, Scanning the head with the rotation angle fixed to the side position. As shown in FIG. 5 (a), when it is detected that the end L0 has moved by the distance L1, the rotation angle of the rotation unit 12 is automatically switched from the side to the top angle, and from the chest to the abdomen, Scano imaging is performed with the rotation angle of the rotating unit 12 fixed at the top position.

  Alternatively, as shown in FIG. 5 (a), a distance L2 between the X-ray irradiation position (one-dot chain line y in FIG. 5) and another part P2 of the subject P is measured in advance, and the top 15 is the distance. The rotating unit 12 of the gantry 11 can be rotated to another angle at a point moved by L2. That is, it is possible to perform scano imaging by rotating the rotating unit 12 at different angles according to the imaging region.

  In this case, for example, first, the scan of the head is performed on the side, the scan of the chest is performed at the top position when moved by the distance L1, and the scan of the abdomen is performed at another angle when the scan is further performed by the distance L2. As described above, if the moving distance of the top plate 15 and the X-ray irradiation angle are registered in advance, the angle of the rotating unit 12 can be automatically switched according to the program of the system control unit 24.

  The position information of the top 15 is sent from the bed control unit 21 to the system control unit 24, and the system control unit 24 actually receives the information on the distance L1 (or L2) input in advance by the operation unit 25 and the table top. The distance traveled by the plate 15 is compared, and when the top plate 15 moves to the set position, the gantry control unit 18 is controlled to switch the angle of the rotating unit 12.

  As described above, in the embodiment of the present invention, since the scano imaging from a plurality of directions can be performed by one scano imaging, the exposure to the subject is reduced and the same observation as the scano image obtained by the multiple scano imaging is performed. Can be obtained.

  The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the claims.

1 is a block diagram showing an X-ray CT apparatus according to an embodiment of the present invention. Explanatory drawing which shows an example of the scano image acquired in the embodiment. Explanatory drawing which shows the other example of the scano image acquired in the embodiment. 6 is a flowchart for describing a scano image capturing operation in the embodiment. Explanatory drawing which shows the other example of imaging | photography operation | movement of the scanogram in the same embodiment.

Explanation of symbols

100 ... X-ray CT apparatus 11 ... Gantry
DESCRIPTION OF SYMBOLS 12 ... Rotating part 13 ... X-ray tube 14 ... X-ray detector 15 ... Top plate 16 ... Data collection part 17 ... Data transmission apparatus 18 ... Base control part 19 ... Slip ring 20 ... Bed 21 ... Bed control part 22 ... Operation console (Computer system)
23 ... Pre-processing unit 24 ... System control unit 25 ... Operation unit 26 ... Data storage unit 27 ... Reconstruction processing unit 28 ... Image data processing unit 29 ... Display unit 30 ... High voltage generation unit 40 ... Scano image

Claims (9)

An imaging unit that performs X-ray imaging by irradiating a subject with X-rays by disposing an X-ray tube and an X-ray detector opposite to a rotating unit in a gantry;
A couch on which the subject is placed; a couch capable of moving the couch into the gantry;
A data collection unit for collecting signals detected by the X-ray detector;
A control unit that controls the rotating unit when scanning a plurality of parts of the subject, and sets the X-ray irradiation angle for each of the plurality of parts to switch the imaging direction. X-ray CT apparatus. The control unit controls the rotation unit to a predetermined rotation angle and takes a first scanogram while moving the top plate,
The second scanning image is captured while moving the top plate by controlling the rotating unit to switch the X-ray irradiation angle when the top plate moves to a preset position. Item 2. The X-ray CT apparatus according to Item 1.   The control unit determines a change amount of the first scanogram that sequentially changes as the top plate moves, and controls the rotating unit when the change amount exceeds a preset threshold value. The X-ray CT apparatus according to claim 2, wherein the X-ray irradiation angle is switched to capture the second scanogram. Attach a marker to the top plate,
The control unit controls the rotation unit to switch the irradiation angle of the X-ray and detect the second scan image when detecting the marker image as the top plate moves. The X-ray CT apparatus according to claim 2. The control unit obtains movement information of the top board,
3. The X-ray according to claim 2, wherein when the top plate moves by a preset distance, the rotation unit is controlled to switch an irradiation angle of the X-ray and the second scanogram is captured. CT device. The rotating part in the gantry has an imaging part in which an X-ray tube and an X-ray detector are arranged to face each other, and the top plate on which the subject is placed is moved into the gantry to irradiate the subject with X-rays and scan. A program for creating an image,
On the computer,
A function of taking a first scano image while controlling the rotating unit to a predetermined rotation angle and moving the top plate;
A function of controlling the rotating unit when the top plate moves to a preset position, and taking a second scanogram while moving the top plate by switching the X-ray irradiation angle;
Scano image creation program to achieve the above.   The X-ray irradiation angle is switched by controlling the rotating unit when a change amount of a scano image that sequentially changes as the top plate moves exceeds a preset threshold value. The scano image creation program described.   The scan image creation program according to claim 6, wherein an image of a marker attached to the top plate is detected to control the rotating unit to switch the X-ray irradiation angle.   The scan image according to claim 6, wherein the moving information of the top plate is obtained and the rotation unit is controlled to switch the irradiation angle of the X-ray when the top plate moves by a preset distance. Creation program.

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