JP2011050691A - X-ray diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve usability of a Last-Image-Hold function. <P>SOLUTION: An X-ray diagnostic apparatus comprises an X-ray tube 1, an X-ray detector 2, a C-shaped arm 51 on which the X-ray tube and the X-ray detector are mounted, a holding mechanism 52-54 to rotatably hold the C-shaped arm as for a plurality of rotation axes, a bed 18 having a movable top plate 17 on which a subject is put, and a pasting processing part 24 to paste a plurality of images including a last image, which is generated immediately before an X-ray radiation stops, together into one sheet based on an angle of the C-shaped arm and a position of the top plate so as to generate a pasted image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray diagnostic apparatus having a rotatable C-arm together with a movable bed.

  The last image hold function (Last Image Hold function) is a variety of X-ray diagnostics that freezes the fluoroscopic image and the captured image (collectively referred to as the final image) acquired immediately before the X-ray irradiation stop to the monitor after the X-ray irradiation stop. This is a very convenient function installed in the device.

  For example, the final image is displayed on a monitor installed in an examination room where an operator performs treatments and various operations in the vicinity of the subject, or an imaging room where a radiographer mainly performs image-related processing, so that the region of interest can be identified and a radiographed image. It can be used for positioning operations such as angle adjustment.

  However, the Last Image Hold function for displaying the final image has a narrow field of view, and its effect is limited to support operations such as shooting positioning.

JP 2009-11480 A

  An object of the present invention is to improve the usefulness of the Last Image Hold function.

  An aspect of the present invention includes an X-ray tube, an X-ray detector, a C-arm on which the X-ray tube and the X-ray detector are mounted, and the C-arm can be freely rotated with respect to a plurality of rotation axes. Based on the holding mechanism for holding, a bed having a movable top plate on which the subject is placed, the angle of the C-arm and the position of the top plate, the final generated just before the X-ray irradiation stop Provided is an X-ray diagnostic apparatus comprising a bonding processing unit that generates a combined image by combining a plurality of images including images.

  According to the present invention, the usefulness of the Last Image Hold function can be improved.

1 is a configuration diagram of an X-ray diagnostic apparatus according to an embodiment of the present invention. It is a figure which shows the mount part of the X-ray diagnostic apparatus of FIG. It is a flowchart which shows operation | movement of this embodiment. It is a figure which shows an example of the planar bonding process by the bonding process part of FIG. It is explanatory drawing of the expansion rate used by the planar bonding process of FIG. It is a figure which shows the planar bonding process by the bonding process part of FIG. It is a figure which shows the other example of the planar bonding process by the bonding process part of FIG. It is a figure which shows an example of the three-dimensional bonding process by the bonding process part of FIG. It is a supplementary figure of FIG. It is a figure which shows an example of the three-dimensional radiation projection bonding process by the bonding process part of FIG. It is a supplementary figure of FIG.

Hereinafter, an X-ray diagnostic apparatus according to the present invention will be described with reference to the drawings according to preferred embodiments.
FIG. 1 is a diagram showing the configuration of the X-ray diagnostic apparatus according to this embodiment. FIG. 2 is a view showing the appearance of the gantry of the X-ray diagnostic apparatus according to this embodiment. The X-ray tube 1 is attached to one end of the C-arm 51. An X-ray diaphragm 12 for limiting the X-ray irradiation field is attached to the X-ray irradiation window of the X-ray tube 1. The X-ray detector 2 is attached to the other end of the C-arm 51 in a direction facing the X-ray tube 1. A line connecting the focal point of the X-ray tube 1 and the center of the X-ray detector 2 is referred to as an imaging axis (fifth rotation axis Z5). The X-ray tube 1 and the X-ray detector 2 are respectively provided on the C-arm 51 so as to be rotatable about the fifth rotation axis Z5. The X-ray detector 2 employs a combination of an image intensifier and a TV camera, or a flat detector that directly converts X-rays into electrical signals.

  The floor turning arm 54 is provided on the floor surface 59 so as to be rotatable (d) around a substantially vertical first rotation axis Z1 at one end thereof. At the other end of the floor turning arm 54, a stand 53 is supported so as to be rotatable (c) around a substantially vertical second rotation axis Z2. An arm holder 52 is supported on the stand 53 so as to be rotatable (b) around a substantially horizontal third rotation axis (C-arm horizontal rotation axis) Z3. The arm holder 52 supports a substantially C-shaped arm 51 slidably rotatable (a) around a substantially horizontal fourth rotational axis (slide rotational axis) Z4 orthogonal to the C-shaped arm horizontal rotational axis Z3. When the rotation around the second rotation axis Z2 is stopped, the first rotation axis Z1, the third rotation axis Z3, the fourth rotation axis Z4, and the fifth rotation axis Z5 intersect at a fixed point IS called an isocenter.

  Between the X-ray detector 2 and the X-ray tube 1, the subject 150 placed on the top plate 17 of the bed 18 is arranged. The top plate 17 has a substantially rectangular shape. The top plate 17 is provided on the bed 18 so as to be movable along its longitudinal direction. The top plate 17 is provided on the bed 18 so as to be movable up and down along a vertical direction parallel to the first rotation axis Z1. The photographing magnification can be changed by changing the height of the top plate 17.

  Five C-arm angle sensors 32 are provided for detecting the angles of the rotating portions corresponding to the five rotation axes Z1, Z2, Z3, Z4, and Z5, respectively. The top plate position sensor 33 is provided to detect the position of the top plate 17 in the longitudinal direction and the height of the top plate 17. The shooting position and shooting angle can be specified by the outputs of the five C-arm angle sensors 32 and the top panel position sensor 33.

  The apparatus main body 20 includes, as main components related to the present embodiment, a system control unit 21, a display control unit 22, an image storage unit 23, a bonding processing unit 24, and a density conversion unit that control the entire X-ray diagnostic apparatus. Section 25 and image processing section 26. The display control unit 22 configures and displays the display screens of the examination room monitor 34 installed in the examination room and the operation room monitor 35 installed in the operation room. The image storage unit 23 outputs a plurality of images output from the X-ray detector 2 and converted into digital image data by an analog-digital converter (not shown) at least during the current image inspection period, that is, a period from the start of X-ray irradiation to the stop of X-rays. The image data of each of the five rotation axes Z1 to Z5 of the C arm 51 detected by the C arm angle sensor 32 when each image is generated under the control of the system control unit 21 and The position and height data of the top plate 17 detected by the top plate position sensor 33 is stored in association with each other.

  As an image inspection, a so-called fluoroscopic examination in which a subject is repeatedly photographed as a moving image at a constant cycle of 1/30 seconds, for example, will be described as an example. An imaging examination is also included in which a high-intensity image is generated with one or several shots at a high X-ray dose when the imaging button operation on the console 31 is pressed.

  When the conventional “Last Image Hold mode” is selected by the operator via the console 31, an image generated immediately before the X-ray stop is displayed among the plurality of images stored in the image storage unit 23. Used selectively for the Hold function. In addition, when the new “pasting mode” according to the present embodiment is selected, among the plurality of images stored in the image storage unit 23, the final image generated immediately before the X-ray stop and the final image A plurality of images generated before the final image during the same fluoroscopic period as the images are used for the pasting function. In the pasting mode, a plurality of images generated during the fluoroscopic period are pasted into a common image space according to the respective photographing positions and photographing angles specified from the outputs of the sensors 32 and 33, so that one wide-field image is obtained. (Hereinafter referred to as a pasted image) is generated. The generation of the combined image is an important matter in the present embodiment.

  The bonding processing unit 24 includes five angles related to the five rotation axes Z1 to Z5 of the C arm 51 detected by the C arm angle sensor 32, and the position and height of the top plate 17 detected by the top plate position sensor 33. Based on the above, the shooting position and shooting angle of each of the plurality of images to be combined are specified, and the plurality of images are bonded to the common image space based on the specified shooting position and shooting angle. In other words, the coordinates on the detector coordinate system (x, y) in which a plurality of images are expressed based on the specified imaging position and imaging angle are represented in the coordinate system (X, Y) that defines a common image space. Convert to coordinates. The common image space can be arbitrarily set, but typically, the longitudinal center axis BL of the top plate 17 is defined as the X axis, and the Y axis is defined horizontally and orthogonal to the X axis.

  In the pasting process, the density conversion unit 25 substantially unifies the average density of each of the plurality of images to be pasted to the average density of the final image. Further, in the pasting process, a plurality of images to be pasted may partially overlap, but the density conversion unit 25 weights and adds two or more overlapping images with respect to the overlapping portion. . Typically, among two or more overlapping images, the weight of the image with the newest shooting time is 1.0, and the weight of the other images is zero. That is, the pixel value of the image with the latest shooting time is selected as the pixel value of the overlap portion.

  In accordance with an operator instruction input from the console 31, the image processing unit 26 cuts out (clipping) a part of the combined image generated by the combining processing unit 24 and the density conversion unit 25, and enlarges / compresses the combined image. A display image to be displayed on the monitors 34 and 35 is generated by reducing the size.

  FIG. 3 shows a bonding process procedure in the bonding mode in the present embodiment. The bonding process may be performed in parallel with the generation of an image during a fluoroscopic period from the start of X-ray irradiation to the stop of X-ray irradiation, or may be performed after the fluoroscopic period ends with the stop of X-ray irradiation. As a preliminary preparation, the system control unit 21 identifies a model having five movable axes as a model with the gantry having the C-shaped arm 51, identifies an examination technique / technique, and restricts a movable range. The installation setting conditions to be identified are identified (S0), and the outputs of the sensors 32 and 33 are matched with the reference positions of the five movable axes (S1).

  When the operator presses the fluoroscopic trigger button via the console 3, generation of X-rays from the X-ray tube 1 is started under the control of the system control unit 21, and the subject is detected via the X-ray diaphragm 12. Continuous or intermittent X-ray irradiation is started. In synchronization with the X-ray irradiation, the X-ray detector 2 repeats the detection of the transmitted X-ray of the subject at a constant period, and the image data is stored in the image storage unit 23. The image data includes the angle data of each of the five rotation axes Z1 to Z5 of the C arm 51 detected by the C arm angle sensor 32 when each image is generated, and the top position detected by the top position sensor 33. The position and height data of the plate 17 are stored in association with each other.

  When the operator presses the fluoroscopic end button via the console 3, the bonding process is automatically started under the control of the system control unit 21. A plurality of images to be combined are generated in a continuous fluoroscopic period from when the fluoroscopic trigger button is pressed and X-ray irradiation is started until when the fluoroscopic end button is pressed and X-ray irradiation is stopped. It is an image. It should be noted that all images generated during the fluoroscopy period may be the target of pasting, or some of the images extracted at regular intervals from images generated during the fluoroscopy period may be the target of pasting. A plurality of images generated in synchronization with the timing at which the shooting position or shooting angle has changed by a predetermined distance or more from the images generated during the period may be used as the objects to be combined. The selection of the range to be bonded is selected in advance by the operator via the console 3 before the start of fluoroscopy. Here, a case will be described as an example where a plurality of images generated in synchronization with the timing at which the photographing position or the photographing angle is changed are to be combined.

  The system control unit 21 detects from the image generated during the fluoroscopic period, the five angles related to the five rotation axes Z1 to Z5 of the C arm 51 detected by the C arm angle sensor 32, and the top position sensor 33. Based on the position and height of the top plate 17, an image to be pasted is selected. The data of the selected plurality of images is read from the image storage unit 23 to the pasting processing unit 24 together with the data of the five angles about the five rotation axes Z1 to Z5 of the C arm 51 and the position and height of the top plate 17. (S2).

  There are three methods for the bonding processing by the bonding processing unit 24. The bonding processing unit 24 is equipped with processing programs of two methods. Either method is selected in advance by the operator via the console 3.

  4 and 5 show a planar bonding method. The resolution of the combined image is determined by the resolution (enlargement ratio) of the final image. Initially provided as a horizontal plane passing through the isocenter and parallel to the top plate 17 based on the five angles about the five rotation axes Z1 to Z5 of the C-arm 51 associated with each image and the position and height of the top plate 17 The pixel coordinates of each image are converted into the bonding surface coordinates so that the pixels of each image are projected perpendicularly to the bonded surface (S3). Even when the imaging axis is inclined, as shown in FIG. 6, the pixels of each image are projected vertically on the bonding surface. The projection is not limited to the parallel projection shown in FIGS. 5 and 6, and may be a focused projection with respect to the X-ray focal point.

  When two or more images partially overlap each other after the coordinate conversion, two or more images overlapping each other with respect to the overlapping portion are weighted and added. Actually, among two or three or more overlapping images, the weight of the image with the newest shooting time is set to 1.0, and the weight of the other images is set to zero. That is, the pixel value of the image with the latest photographing time is selected as the pixel value of the overlap portion (S4). In addition, the average density of each of the plurality of images to be bonded is substantially unified to the average density of the final image.

  The composite image generated in this manner is initially reduced by the image processing unit 26 so that the entire image can be accommodated in the image display area of the monitors 34 and 35 and displayed on the monitors 34 and 35 (S5). . After the initial display, a part of the combined image may be cut out and displayed large in accordance with an arbitrary instruction input from the console 31 by the operator, or the entire combined image may be enlarged and displayed in a large size.

  8 to 11 show a three-dimensional bonding method. In the three-dimensional bonding method, a human body model corresponding to a standard body shape is used. On the surface of the human body model on the X-ray tube 1 side or the detector 2 side, based on the five angles about the five rotation axes Z1 to Z5 of the C arm 51 and the position and height of the top plate 17, Project pixel values. The projection method may be parallel projection as shown in FIGS. 8 and 9, or may be focused projection as shown in FIGS.

  As described above, after the fluoroscopy is stopped, a plurality of images including the final image are displayed on one sheet. In this embodiment, it is possible to store a fluoroscopic image that is continuously performed, and to obtain a fluoroscopic image of the whole body of the patient (the fluoroscopic part) by reconstructing it after taking into account the positional information of the holding device / bed device. To do. According to the present embodiment, it is possible to effectively use a fluoroscopic image that has been discarded without being collected for diagnosis, and to construct an image history effective for reducing the X-ray exposure and positioning the holding device / bed device. Is possible.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  The present invention can be used in the field of X-ray diagnostic apparatuses having a Last Image Hold function.

  DESCRIPTION OF SYMBOLS 1 ... X-ray tube, 2 ... X-ray detector, 12 ... X-ray diaphragm, 20 ... Apparatus main body, 21 ... System control part, 22 ... Display control part, 23 ... Image memory | storage part, 24 ... Bonding process part, 25 A density conversion unit, 26 an image processing unit, 32 a C-arm angle sensor, 33 a top plate position sensor, 34 an examination room monitor, and 35 an operation room monitor.

Claims (5)

An X-ray tube;
An X-ray detector;
A C-arm on which the X-ray tube and the X-ray detector are mounted;
A holding mechanism for rotatably holding the C-arm with respect to a plurality of rotation axes;
A bed having a movable top plate on which the subject is placed;
Based on the angle of the C-arm and the position of the top plate, a pasting process is performed in which a plurality of images including a final image generated immediately before the X-ray irradiation stop is pasted together to generate a pasted image. X-ray diagnostic apparatus comprising a unit.   The X-ray diagnosis apparatus according to claim 1, further comprising an image processing unit that matches an average density of each of the plurality of images with an average density of the final image.   The X-ray diagnostic apparatus according to claim 1, wherein a pixel of an image having an occurrence time closest to the final image or the final image is selected as a portion where the image is partially overlapped.   The X-ray diagnosis apparatus according to claim 1, wherein the bonding processing unit generates the bonded image when the X-ray irradiation is stopped.   The X-ray diagnostic apparatus according to claim 1, wherein the combining processing unit combines the plurality of images planarly or three-dimensionally.

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