JP2004209239A - X-ray diagnostic apparatus and radiography method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray diagnostic apparatus capable of performing a radiography under the best condition by tracking a flow of a contrast medium and improving the operability by reducing a burden on an operator. <P>SOLUTION: A top board 15 to place a subject P thereon is held by a C arm 13 between an X-ray tube 20 and an X-ray detector 30 opposing each other. The X-ray diagnostic apparatus radiographs along the body axis direction of the subject by moving the top board or the C arm relatively. The X-ray diagnostic apparatus is equipped with an X-ray diaphragm control part 55 for controlling an X-ray irradiation range to the direction of the flow of the contrast medium injected into the subject. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an X-ray diagnostic apparatus and an X-ray imaging method, and particularly to an X-ray diagnostic apparatus and an X-ray imaging method suitable for performing a lower limb contrast examination.

    An X-ray diagnostic apparatus is a modality that can be used for inspection and diagnosis of various parts of a subject. One of the examinations by the X-ray diagnostic apparatus is a lower limb contrast examination.

  In the lower limb contrast examination using this X-ray diagnostic apparatus, a contrast agent is injected into the artery from the groin of the subject, and X-ray imaging is performed while following the flow of the contrast agent. For this reason, the shooting range covers a wide range from the vicinity of the pelvis to the toes, and it is not possible to obtain the whole image by one shot, so partial shooting is performed several times and then the images are pasted together To get the whole picture. However, since this imaging range includes parts having different sizes (thickness, length, etc.) such as thighs, knees, shins, and ankles, the X-ray irradiation range is set to a size that can cover the vicinity of the pelvis, for example. For example, if the shin portion is photographed in the state where the shin is kept, halation occurs and the image quality is impaired.

  Therefore, in order to eliminate such inconvenience, conventionally, the opening degree in the width direction of the X-ray aperture device has been adjusted so that the X-ray is not irradiated to the region outside the contour of the subject.

Also, as disclosed in Japanese Patent Application Laid-Open No. Hei 6-217973 (particularly, pages 21-22, FIG. 50), when moving and photographing the lower limb, the contour data of the subject corresponding to the position data of the couch is pressed by the press key. There is also known a method in which a control table is created by extracting the control table and the control table is referred to at the time of X-ray imaging. That is, by referring to this control table, the opening degree in the width direction of the X-ray diaphragm device is controlled for each position of the bed, and as a result, X-rays are not irradiated to the region outside the contour of the subject. there were. In this case, the opening in the length direction of the X-ray diaphragm device (that is, the body axis direction of the subject) was always constant.
JP-A-6-219773

  However, in a wide range from near the pelvis to the toes, the blood flow velocity is not constant, and there are parts where the flow is slow and parts where the flow is fast, and even simple parts and complicated parts where blood vessels run is there. For this reason, if the moving imaging of the lower limb is performed with a constant opening in the length direction of the X-ray diaphragm device (that is, the direction of the lower limb of the subject), a part of the image obtained by the imaging that is not diagnostically satisfactory There was a problem that there was.

  For such a problem, it is also possible to adopt a method of increasing the number of times of imaging by narrowing the imaging interval in the direction of the lower limb of the subject. In such a case, the opening in the longitudinal direction of the X-ray aperture device is inevitably narrowed, which leads to the solution of the above-described problem. Since the photographing must be performed while following the flow of the contrast agent in the narrowed state, the operation is complicated and enlarged.

  Therefore, the present invention provides an X-ray diagnostic apparatus and an X-ray imaging method that can perform X-ray imaging under optimal conditions by following the flow of a contrast agent, reduce the burden on the operator, and improve operability. The purpose is to provide.

  In order to achieve the above object, according to one aspect of an X-ray diagnostic apparatus according to the present invention, an X-ray source that generates X-rays, an X-ray detector that detects the X-rays, The X-ray detector and the X-ray detector are opposed to each other, and the X-ray source and the X-ray detector are arranged such that a top plate on which a subject is placed is located in a spatial space between the X-ray source and the X-ray detector. Holding means for holding a vessel, and setting one of the top plate and the holding means relative to the other while moving the contrast medium with respect to the subject into which the contrast agent has been injected. Perspective imaging means for performing perspective imaging along a direction in which the contrast agent substantially flows to obtain a perspective image, and imaging parameters required for main imaging based on the perspective image obtained by the perspective imaging means, at least the The shooting parameters set for each part Meter setting means, based on the shooting parameters set by the shooting parameter setting means, while moving one of the top plate and the holding means relative to the other, the contrast agent was injected Main imaging means for performing the main imaging on the subject.

  In addition, the X-ray imaging method according to the present invention, an X-ray source that generates X-rays, an X-ray detector that detects the X-rays, and the X-ray source and the X-ray detector facing each other, Holding means for holding the X-ray source and the X-ray detector so that a top plate on which the subject is placed is located in a spatial space between the X-ray source and the X-ray detector. It is an imaging method performed by the line diagnostic apparatus. In this imaging method, the contrast agent set to the subject with respect to the subject into which the contrast agent has been injected while moving one of the top plate and the holding unit relative to the other. Obtaining a perspective image by performing fluoroscopic imaging along a direction in which substantially flows, and, at least for each part continuous in the direction, the photographing parameters necessary for main imaging based on the fluoroscopic image obtained by the fluoroscopic imaging. And, based on the set imaging parameters, while moving one of the top plate and the holding means relative to the other, while the contrast agent is injected into the subject Performing the actual photographing.

  The X-ray irradiation range can be controlled so as to be optimal following the flow of the contrast agent, and a good X-ray diagnostic image can be obtained. In addition, an X-ray diagnostic apparatus with good operability can be provided by greatly reducing the burden on the operator.

    Hereinafter, preferred embodiments of the X-ray diagnostic apparatus according to the present invention will be described in detail with reference to the drawings.

  A first embodiment of the X-ray diagnostic apparatus according to the present invention will be described in detail with reference to FIGS.

  The X-ray diagnostic apparatus according to the first embodiment includes a holding device 10, an X-ray tube 20, an X-ray detector 30, and a control device 50.

  FIG. 1 is a perspective view showing a partial schematic configuration of a holding device 10 of the X-ray diagnostic apparatus. The holding device 10 includes a holding device main body 11, a C-arm holding mechanism 12, a C-arm 13, and a top plate holding mechanism 14. , And a top plate 15.

  The holding device main body 11 is fixed to the floor, and holds the C-arm holding mechanism 12 slidably in a direction substantially parallel to the floor (indicated by an arrow A in the figure). In the C-arm holding mechanism 12, the C-arm 13 can be rotated (indicated by an arrow B in the figure) on a plane substantially perpendicular to the floor around the position of attachment to the C-arm holding mechanism 12. At the same time, it is slidably mounted in an arc direction (indicated by an arrow C in the figure) so that it can be inclined with respect to a top plate 15 described later. An X-ray tube 20 and an X-ray detector 30, which will be described later, are attached to the C-arm 13 so as to face each other with the top plate 15 therebetween.

  On the other hand, the top plate holding mechanism 14 is vertically movable (indicated by an arrow D in the drawing) and rotatable (indicated by an arrow E in the drawing) with respect to the holding device main body 11.

The top plate holding mechanism 14 can slide the top plate 15 in the width direction (indicated by an arrow F in the drawing) and can move in the thickness direction (indicated by an arrow G in the drawing). Installed in state. Further, the top board 15 can also be rotated (indicated by an arrow H in the drawing) about the central axis in the longitudinal direction with respect to the top board holding mechanism 14. The top 15 is for placing the subject P as shown in FIG.

  Now, an X-ray tube 20 is attached to one end of the C-arm 13 held by the C-arm holding mechanism 12 so as to face the top plate 15 side. , An X-ray diaphragm 21 and a compensation filter 22 (see FIG. 2). The X-ray diaphragm 21 is for narrowing the irradiation range of the X-rays radiated from the X-ray tube 20 to a desired range so as not to irradiate an unnecessary part of the subject with the X-rays. As shown in the figure, the diaphragm blades 21a to 21d made of a lead plate are combined in a grid pattern. The aperture blades 21a to 21d are individually driven by a servo motor via a rack and pinion mechanism (not shown), and therefore, by bringing the opposed aperture blades 21a, 21b and 21c, 21d into and out of contact with each other, desired irradiation is performed. A range (shown by hatching in the figure, also referred to as an irradiation field or a diaphragm opening) is formed. The compensation filter 22 is used to partially attenuate the X-ray dose in the X-ray irradiation range. The X-ray tube 20, the X-ray aperture 21, and the compensation filter 22 can be advanced (represented by an arrow I in the drawing) from the side where the X-ray tube is attached to the C-arm 13 to the top plate 15 side.

  Further, an X-ray detector 30 is attached to the other end of the C-arm 13 so as to face the X-ray tube 20 with the top plate 15 therebetween. As shown in FIG. 2, for example, the X-ray detector 30 includes an image intensifier (hereinafter, abbreviated as II) 31 and an image pickup tube or a solid-state image pickup device (for example, Charge). A television camera 32 having a coupled device (CCD) is coupled via an optical system 33. I. An X-ray grid 34 is provided on the front surface of the base 31, that is, on the top plate 15 side. Here, I. I. Numeral 31 denotes an X-ray radiated from the X-ray tube 20 and transmitted through the subject P and converted into an optical image. The optical image is incident on a television camera 32 via an optical system 33 and transmitted to a TV video signal. Is converted to Note that the X-ray grid 34 indicates that scattered X-rays generated by the subject P I. This is for preventing the light from entering the light source 31. Such an X-ray detector 30 can move forward and backward (indicated by an arrow J in FIG. 1) from the side of attachment to the C-arm 13 to the top plate 15 side.

  Next, a control device 50 which is one of the main components of the X-ray diagnostic apparatus along with the holding device 10 will be described with reference to FIG. FIG. 2 is a system diagram showing the X-ray tube 20 and the X-ray detector 30 provided in the holding device 10 as well as each device constituting the control device 50.

  That is, the control device 50 includes a system controller 51 that plays a central role of controlling the overall operation of the entire X-ray diagnostic apparatus, and a keyboard for the operator to give predetermined instructions to the system controller 51. Alternatively, an operation panel 52 including a touch panel, a pointing device such as a mouse or a trackball, a high voltage generator 53 for generating a high voltage applied to the X-ray tube 20, an X-ray controller 54 for controlling the same, An X-ray aperture controller 55 for controlling the amount of movement of the aperture blades 21a to 21d to obtain an irradiation range, that is, a desired opening of the X-ray aperture 21, a compensation filter controller 56 for controlling the position of the compensation filter 22, and the like, C The operation of the arm holding mechanism 12 and the C arm 13 held by the arm holding mechanism 12 and the top plate holding mechanism 14 and the Like holding device controller 57 that controls the operation of the top plate 15 is provided that.

  In addition, the control device 50 includes: I. I.31 controlling I.31 I. The controller 58, a television camera controller 59 for controlling the television camera 32, an image obtained from the television camera 32 or an image processed by an image processor 60 described later is converted into an X-ray controller 54 and an X-ray aperture controller 55. The image storage unit 61 stores the X-ray control condition by the compensation filter controller 56, or the imaging position by the holding device controller 57 and the image processing condition in the image processor 60, and the image stored in the image storage unit 61. An image processor 60 that performs gradation processing, spatial filter processing, or addition processing or subtraction processing on an image obtained in real time from the TV camera 32, and displays an image obtained from the TV camera 32 in real time. A display device 62 and the like for displaying images processed by the image processor 60 are also provided.

  Further, based on the position signal from the X-ray diaphragm controller 55 at the time of obtaining the image, the control device 50 determines an appropriate aperture position and size for the image stored in the image storage 61. A diaphragm position / size / angle calculator 63 that calculates the height / angle and generates the graphic, calculates an appropriate moving speed of the C-arm 13 for a plurality of parts from the moving point of the contrast agent of interest and the photographing position information, A photographing parameter storage 64 which stores the information together with the aperture position, its size, and the photographing interval, and in a predetermined photographing sequence, an appropriate moving speed of the C-arm 13 stored in the photographing parameter memory 64 based on positional information at each time. An imaging parameter controller 65 for controlling the X-ray aperture controller 55, the holding device controller 57, and the like are also provided so that

  The operation when the lower limb contrast examination is performed by the X-ray diagnostic apparatus configured as described above will be described below. Although the directions are indicated by arrows in FIG. 2, the width direction of the subject P placed on the top 15 is represented by X, the body axis direction is represented by Y, and the thickness direction is represented by Z.

  First, for the subject P, fluoroscopic imaging is performed over a wide range from the vicinity of the pelvis to the toes, and the opening degree of the X-ray aperture 21 is set for each region. The fluoroscopic imaging as a pre-scan using a contrast agent is performed, for example, by bolus-administering a small amount of a contrast agent to the lower limb of a subject and performing positioning for main imaging using weak X-rays. In this case, since the entire image of the desired diagnostic range cannot be obtained by one imaging, the C arm 13 (that is, the X-ray tube 20 and the X-ray detector 30) is The top plate 15 is moved in the longitudinal direction (that is, the Y direction) to perform partial shooting several times, and then the whole image is obtained by laminating the images. This moving operation is performed by moving the C-arm holding mechanism 12 in the direction of arrow A shown in FIG. 1 via the holding device controller 57. Further, the rotation angle (see the direction of arrow B in FIG. 1) and the inclination angle (see the direction of arrow C in FIG. 1) of the C-arm 13 with respect to the top plate 15 are set so that the desired part can be best depicted. .

  FIG. 4A schematically shows the range of X-ray imaging of the subject P in the lower limb contrast examination, and FIG. 4B shows a long image obtained by laminating images obtained in advance by fluoroscopic collection. FIG. 6 shows a state in which the opening degree of the X-ray aperture 21 is set for each part for the main photographing in the image displayed in the length scale.

  That is, first, a contrast medium is injected into the subject P shown in FIG. 4A, and the range indicated by the arrow is divided into several times to perform fluoroscopic collection, and each fluoroscopic image is stored in the image storage 61. To memorize. Next, under the control of the system controller 51, each of the fluoroscopic images stored in the image storage 61 is read out, and these are combined in an image processor 60. As shown in FIG. Is displayed as a long image as a whole image of the lower limb.

  For the perspective image displayed long on the display device 62 or the perspective image of each imaging region of interest, the operator uses the pointing device provided on the operation panel 52 to perform the main imaging for each desired part. An optimal size of the X-ray diaphragm 21 is set. That is, over a wide range from the vicinity of the pelvis to the toes, depending on the region to be observed with particular interest, the size of each region, the flow of the contrast agent, and the like, the imaging position and the aperture opening corresponding to the position (ie, The shooting range is set as shown by the dotted line in FIG.

  That is, in FIG. 4B, the opening of the X-ray aperture 21 is set to 1 at the imaging position 1, the opening of the X-ray aperture 21 is set to 2 at the imaging position 2, and further imaging is performed. At the position 3, the opening degree of the X-ray aperture 21 is set to the state of 3, and at the imaging position n, the opening degree of the X-ray aperture 21 is set to the state of n. Here, the openings 1, 2, 3,... N of the X-ray aperture 21 are not necessarily all different, and may be the same depending on the imaging position. Further, it is preferable that the imaging ranges do not overlap as much as possible in the body axis direction (Y direction) of the subject P at the adjacent imaging positions, but it is preferable to reduce the exposure, but the flowing contrast agent is contained in the screen. For this purpose, the photographing rate f (maximum is 30 frames per second, but can be changed to 15 frames or 7.5 frames by setting) according to the speed λ of the contrast agent is adjusted. It is inevitable that some overlap will occur.

  When the aperture opening is set for each imaging position by the pointing device in this manner, the amount of movement of the blades 21a to 21d constituting the X-ray aperture 21 in the x and y directions is calculated by the aperture position / size / angle calculator 63. Is calculated, and the calculated result is stored in the imaging parameter storage 64.

  It is also possible to read out a plurality of X-ray fluoroscopic images obtained in advance through fluoroscopic collection from the image storage 61 and display them in a trace form, and to perform imaging according to the velocity λ of the contrast agent by a feedback flow as shown in FIG. The rate f, the moving speed of the C-arm 13, and the like can be set.

  That is, as shown in FIG. 5 (a), an image that has been perspectively collected in a state where a contrast agent has been injected into the subject in advance and stored in the image storage unit 61 is converted into a display device 62 as shown in FIG. 5 (b). And a trace image is displayed for each cine reproduced or set frame. FIG. 5A schematically shows images from m frames to n frames stored in the image storage unit 61. The m frame image has a shooting time of Tm and a collection position of lm. The acquisition time of the image of n frames is Tn, and the acquisition position is ln. Here, m <n, and the collection rate f is, for example, 30 fps.

  Next, as shown in FIG. 5B, the operator sequentially displays images on the display device 62, confirms the diffusion state of the contrast agent while watching the images, and stops the desired image. Then, as shown by a dotted frame in FIG. 5C, the opening degree of the X-ray diaphragm 21 (the positions of the blades 21a to 21d in the x and y directions) which is optimal for the main photographing of the image. Set. This setting is performed by operating the pointing device on the operation panel 52 to operate the X-ray aperture controller 55.

  Therefore, since the frame interval of the peak traced image is m to n, the moving speed λ of the contrast agent can be obtained from the position information of the two designated points and the time information based on the collection rate f by the equation (1).

λ = (ln−lm) / (Tn−Tm) (1)
If the moving speed λ of the contrast agent is faster than the moving speed of the C-arm 13 at the time of imaging, the flow of the contrast agent may not be captured in the screen. By increasing the setting or increasing the imaging rate f and resetting the setting, the region that the doctor is trying to observe with particular interest is set as the imaging region, and the flow of the contrast agent enters the entire region. And shoot.

  At this time, based on the size of the X-ray diaphragm 21 set for each image, an error (Δ) for pasting the preceding and following images when displaying the entire image in a long format is automatically added. Further, the photographing elapsed times Tm, Tn and the photographing positions lm, ln are support information for determining the photographing interval K and the photographing rate f.

  By repeating this operation sequentially for each imaging region, various setting values such as a rotation angle, an inclination angle, a speed, and the like, and contrast of the imaging position over the entire imaging range, that is, according to the position of the C-arm 13 with respect to the top plate 15, are obtained. Imaging parameters (set values) such as the speed of the agent are stored in the imaging parameter storage 64 as, for example, a storage table shown in FIG.

  After the preparation work, the aperture, the imaging interval, and the moving speed for each imaging region are determined, the main imaging is performed. The main imaging includes a mask sequence performed before injecting a contrast agent into a subject and a contrast sequence performed by injecting a contrast agent. That is, for the subject before the contrast agent is injected by the mask sequence, for example, the pelvis is controlled under the control of the imaging parameter controller 65 in accordance with the aperture, the imaging rate, the moving speed, and the like determined by the above-described fluoroscopic acquisition. A predetermined portion is photographed from the direction toward the toe, and the obtained mask image is stored in the image storage 61 together with the position information.

  Thereafter, a contrast agent is injected into the subject, and imaging by a contrast sequence is performed under the control of the imaging parameter controller 65 according to the flow direction of the contrast agent to obtain a contrast image. Note that information such as the moving speed of the C-arm 13 and the like during imaging and the elapsed time after the injection of the contrast agent are sequentially supplied to the imaging parameter controller 65. The control is performed so that the photographing is performed under the conditions stored in H.64.

  When the contrast image is obtained, the image is stored in the image storage 61 together with the positional information. Further, in the image processor 60, the previously captured mask image is read out from the image storage 61, and the contrast image is stored in the image processor 60. To obtain a subtraction image. The subtraction image is stored in the image storage 61 including the position information and is displayed on the display device 62 in real time. It is needless to say that the contrast image and the mask image to be subjected to the subtraction process are images of the same part of the subject. The subtraction image is an image in which the same background portion of the contrast image and the mask image is removed and only the portion where the contrast agent flows is displayed.

  As described above, at the time of actual photographing, various setting values (photographing parameters) stored in the photographing parameter storage 64 are read, and a mask image and a contrast image can be obtained under the control of the system controller 51 according to the set values. If this is the case, it is possible to obtain an appropriate diagnostic image for each imaging region while extremely reducing the burden on the operator.

  Such an operation procedure of the present embodiment is shown by a flowchart in FIG. 7, and will be described again along this flowchart.

  That is, in step S10, first, the position and angle of the C arm 13 are set to the initial position. Specifically, the position and angle of the C-arm 13 with respect to the top plate 15 are detected, and whether or not there is a deviation from the initial position is detected. If there is a deviation, it is corrected by the operation of the holding device controller 57. This instruction is given by the system controller 51. When the position and the angle of the C-arm 13 are set, in step S20, the opening degree of the X-ray aperture 21 (the blade 21a) at that position is determined from the set value (see FIG. 6) stored in the imaging parameter storage 64. ２１21d, x, y positions) are retrieved, and the X-ray aperture controller 55 is operated to set the aperture to a predetermined opening. This is also performed by the system controller 51. Subsequently, as step S30, the moving speed β of the C-arm 13 at that position is searched from the set values stored in the photographing parameter storage 64 similarly. The data of the opening degree of the X-ray aperture 21 and the moving speed β of the C-arm 13 are transmitted to the imaging parameter controller 65 as step S40. Therefore, in step S50, based on the set values stored in the imaging parameter storage 64, actual imaging is performed under the control of the imaging parameter controller 65 to obtain a mask image and a contrast image.

  When a contrast image is obtained in the main photographing, the operator keeps pressing a photographing button (not shown) provided on the operation panel 52 while watching the contrast image displayed on the display device 62 in real time. For example, the C-arm 13 is automatically moved following the flow of the contrast agent, and a contrast image is captured. However, when the follow-up of the contrast agent by the automatic control is deviated for some reason, the subsequent movement operation of the C-arm 13 is manually performed by operating a joystick (not shown) provided on the operation panel. Switching is made to follow the contrast agent. In this case, only the control of the X-ray aperture 21 is automatic.

  As described above, according to the embodiment of the present invention, the burden on the operator is greatly reduced, and an X-ray diagnostic apparatus with good operability is provided.

  As another embodiment of the present invention, as shown in FIG. 8, the Y direction of the top 15 is based on the information of the set value storage table (see FIG. 6) stored in the shooting parameter storage 64. , The relationship between the position of the C-arm 13 and the moving speed of the contrast agent or the moving speed of the C-arm 13 can be displayed as a profile and provided as diagnostic information.

  In addition, an image useful for diagnosis is read out of the captured images stored in the image storage 61 and displayed as a cine on the display device 62 as shown in FIG. If the measurement start point and the measurement end point are displayed, and the measured moving speed of the contrast agent and the like are also displayed in characters, it is possible to provide information to be referred to at the time of diagnosis by a doctor with good timing.

  Further, as shown in FIG. 10A, by setting a region of interest (ROI) arbitrarily using a pointing device provided on the operation panel 52 on the image displayed in a long format, the subtraction of the region is performed. The image can be read from the image storage 61 and displayed on the display device 62. Then, even if the portion is composed of a plurality of images such as m1 and m2, those images may be displayed on the display device 62 in a connected form as shown in FIG. 10B. it can. Also in this case, the moving speed of the contrast agent and the like can be displayed in an overlapping manner.

  In addition, it is known that the blood flow velocity is slower at the joints such as the knees and ankles, and the blood flow velocity is slower than at straight parts such as the thighs and shins. ing. Therefore, when it is desired to particularly observe the situation of a joint part such as a knee or ankle, the part is designated in advance, and when the X-ray imaging position reaches the designated position, the X-ray aperture control is performed. It is also possible for the device 55 to control the X-ray diaphragm 21 to have an opening (for example, a narrow opening) suitable for imaging a slow flow of the contrast agent in the region, and in this case, the operation can be performed. The burden on the person can be further reduced.

  In order to specify the specific region, a region to be particularly observed is preset as a region of interest (ROI) using a pointing device provided on the operation panel 52. This setting information may be stored in the imaging parameter storage 64 via the system controller 51. Thus, when the setting information is read from the imaging parameter storage 64 by the imaging parameter controller 65, the setting information is sent to the X-ray aperture controller 55 via the system controller 51. As a result, the aperture of the X-ray aperture 21, that is, the X-ray irradiation range is optimally adjusted in the region of interest according to the setting information. As a result, the X-ray exposure dose can be reduced, and the operation burden on the operator is also reduced.

  When the flow of the contrast agent reaches the specific site where the flow of the contrast agent is slow, the imaging rate may be reduced. As described above, the X-ray exposure rate can be further reduced by controlling the imaging rate of X-ray imaging according to the speed at which the contrast agent flows. Thus, the X-ray imaging conditions can be further optimized according to the flow of the contrast agent.

  An X-ray diagnostic apparatus according to a second embodiment of the present invention will be described with reference to FIGS.

  In the second embodiment, the routine for performing the above-described pre-scan and setting the photographing parameters for the actual photographing from the image obtained by the pre-scan is not a manual process relying on an operator's manual operation, but an automatic process. It is characterized in that it can be executed in a targeted manner.

  In order to perform the automatic setting of the imaging parameters, the X-ray diagnostic apparatus according to the present embodiment newly includes a skeleton processor 70 that extracts and processes a skeleton that is a pattern of a contrast agent, as shown in FIG. I have. Note that the operation panel 52 is additionally provided with a deadman switch 71. Other hardware configurations are the same as those described in the first embodiment.

  The skeleton processor 70 is configured as, for example, a processor having a computer configuration including a CPU and various memories (not shown) for program storage, arithmetic operation, data storage, and the like. When the skeleton processor 70 is activated, a program stored in advance in the program memory is read out to the arithmetic memory, and processing is performed according to a predetermined procedure described in the program. FIG. 12 shows an outline of this processing. That is, as shown in the figure, an image input unit F1 for inputting an image collected by pre-scan, and a skeleton extraction unit F2 for performing a differentiation process for extracting a pattern (hereinafter, referred to as a skeleton) of an input contrast agent. , A storage unit F3 for storing a skeleton image, a detection unit F4 for detecting the position of the image at time tn / tn-1 to be processed as a difference, a difference extraction unit (difference circuit) F5 for performing a difference between the skeletons, and an aperture opening A processing unit F6 for performing calculation and moving speed extraction is functionally provided.

  More specifically, the skeleton processor 70 performs the processing shown in FIGS. 13 and 14 in a time-division manner, for example, and in parallel with the execution of the pre-scan. 13 shows the processing for determining the aperture of the X-ray aperture 21, and the processing shown in FIG. 14 shows the processing relative to one of the C-arm 13 and the top 15. A process for determining an appropriate moving speed (in the embodiment, the C-arm 13 is moved with respect to the top 15) is shown. Note that the scruton processor 70 may execute only one of the processes in FIGS. 13 and 14.

  The skeleton processor 70 inputs image data at a certain imaging position (a plurality of sampling timings tn) collected by the currently performed pre-scan from the image recording unit 60 via the system controller 51 (step S51). . Next, the skeleton processor 70 reads out the image data of the skeleton of the contrast agent that has been processed at the previous photographing position (the plurality of sampling timings tn-1) from the built-in memory (step S52).

  Thereafter, the skeleton processor 70 sequentially performs processes for skeleton extraction, difference image generation, and determination of the aperture.

  First, the skeleton of the contrast agent at the current imaging position (a plurality of sampling timings tn) is extracted by differential processing (pattern recognition), and the image data of each pixel of the skeleton is temporarily stored in the built-in memory (step S53). ). Next, a difference is made for each pixel between the skeletons of the contrast agent between the two photographing positions (each of a plurality of sampling times tn, tn-1), and a difference image is generated (step S54). FIG. 15 shows how the difference image is generated.

  Next, a difference amount (difference area) is calculated for the data of the difference image, and it is determined whether or not the difference amount is equal to or larger than a predetermined threshold (step S55). If the difference amount (difference area) is equal to or greater than the threshold value, the difference amount, that is, the aperture opening of the X-ray aperture 21 corresponding to the skeleton area as the difference result is determined with reference to the first storage table, and Data indicating the aperture degree is stored in the built-in memory (step S56). On the other hand, when the difference amount (difference area) is smaller than the threshold value, the difference amount, that is, the aperture opening of the X-ray aperture 21 corresponding to the skeleton area as the difference result is similarly stored in the second storage table (first storage area). The data is determined with reference to the storage table (data is different from the storage table), and data indicating the aperture is stored in the built-in memory (step S57). As described above, by performing the threshold value processing on the difference amount, the aperture opening can be determined in more detail and easily in accordance with the degree of the flow rate of the contrast agent.

  When the aperture is determined in this way, the prescan image data at the next shooting position (a plurality of sampling timings tn + 1) is input again (step S51). Thus, the above-described processing is repeated.

  With the execution of the pre-scan, a fluoroscopic image is displayed in real time during the execution. For this reason, a skeleton of a contrast agent is extracted at each imaging position by differential processing from data of a fluoroscopic image displayed at a sampling rate planned based on experience values or the like in advance. Among them, a difference image between the skeleton image extracted at the current imaging position (plural sampling timings tn) and the skeleton image extracted at the previous imaging position (plural sampling timings tn-1) is obtained. One example of the generation of the difference image is schematically shown in FIGS. From this difference image, it is possible to determine the aperture opening at a certain imaging position (the area RG indicated by the dotted line in FIG. 15C represents the optimal aperture opening), and it is possible to determine the flow rate of the contrast agent.

  On the other hand, as shown in FIG. 14, the skeleton processor 70 transmits data of an image at a certain shooting position (images at a plurality of sampling timings tn) collected by the currently performed pre-scan from the image recording unit 60 to the system controller 51. Then, the skeleton processor 70 reads out the image data of the skeleton of the contrast agent that has been processed at the previous photographing position (the plurality of sampling timings tn-1) from the built-in memory (step S62). ).

  Thereafter, the skeleton processor 70 sequentially performs processes for skeleton extraction, difference image generation, and determination of the moving speed.

  First, the skeleton of the contrast agent is extracted by differential processing (pattern recognition) at the current imaging position (a plurality of sampling timings tn), and the image data of each pixel of the skeleton is temporarily stored in the built-in memory (step S63). ). Next, a difference is made for each pixel between the skeletons of the contrast agent between the two photographing positions (each of a plurality of sampling timings tn, tn-1), and a difference image is generated (step S64). FIG. 16 shows how the difference image is generated.

  Next, the moving amount of the contrast agent is calculated for the data of the difference image, and it is determined whether the moving amount is equal to or larger than a predetermined threshold (step S65). When the moving amount is equal to or larger than the threshold value, the moving speed of the C arm 13 according to the large skeleton area (large aperture) which is the difference result is determined with reference to the third storage table, and the moving speed is determined. The indicated data is stored in the built-in memory (step S66). On the other hand, when the moving amount of the contrast agent is smaller than the threshold value, the moving speed of the C arm 13 corresponding to the small skeleton area (small aperture) which is the difference result is similarly stored in the fourth storage table (third storage table). (The data is different from the storage table.) The data indicating the moving speed is stored in the built-in memory (step S67). By performing the threshold value processing on the movement amount in this manner, the movement speed of the C-arm 13 can be determined in more detail and easily according to the degree of the movement amount of the contrast agent.

  When the moving speed is determined in this way, prescan image data at the next shooting position (a plurality of sampling timings tn + 1) is input again (step S61). Thus, the above-described processing is repeated.

  With the execution of the pre-scan, a fluoroscopic image is displayed in real time during the execution. For this reason, the skeleton of the contrast agent is sequentially extracted from the data of the image displayed at the sampling rate planned based on the experience value or the like in advance by the differentiation processing. Among them, a difference image between the skeleton image extracted at the current shooting position (a plurality of sampling timings tn) and the skeleton image extracted at the previous shooting position (a plurality of sampling timings tn-1) is obtained at each shooting position. Can be One example of the generation of the difference image is schematically shown in FIGS. 16 (a) to (c) and (d) to (f).

From these difference images, it is possible to determine the aperture (a region P1 (x, y) indicated by a dotted line in FIG. 16C) at a certain photographing position (the photographing time is typically represented by t1), and The aperture opening (region P2 (x, y) indicated by the dotted line in FIG. 16F) at the shooting position (the shooting time is typically represented by t2) can be determined (steps S65 and S66 in FIG. 14). . For this reason, the position of the aperture opening from the photographing position of the C arm 13 (the photographing time is typically t1) to the next photographing position (the photographing time is typically t2), that is, the moving speed V of the C arm 13 ( mm / sec)
V = (P1-P2) / (t1-t2) (2)
(Also executed in steps S65 and S66 in FIG. 14). The moving speed V of the C arm 13 is stored in the photographing parameter storage 64.

  As described above, the photographing parameters necessary for the actual photographing are stored in the photographing parameter storage 64 in the same manner as the main photographing in the first embodiment described above. Therefore, at the time of actual imaging, the imaging parameters are read out by the imaging parameter controller 65, and the aperture of the X-ray aperture 21 is automatically adjusted for each imaging region (position) determined through pre-scanning. At the same time, the C-arm 13 is moved following the contrast agent from the imaging at the desired imaging rate f and the desired imaging interval K in each imaging region toward the next imaging region (position).

  Therefore, according to the second embodiment, during the pre-scan, the skeleton of the contrast agent is recognized as a pattern from the fluoroscopic image obtained by the pre-scan, and the aperture is substantially real-time based on the pattern-recognized information. And stored in the imaging parameter storage 64. For this reason, the imaging parameter controller 65 reads the information on the aperture degree from the imaging parameter storage 64 and passes it to the X-ray aperture controller 55 via the system controller 51. As a result, during the pre-scan, the aperture of the X-ray aperture 21 is adjusted almost in real time to the value designated by the X-ray aperture controller 55, so that the contrast agent has flowed off at each imaging position. The X-ray exposure of the region can be blocked, and the amount of X-ray exposure to the subject can be reduced accordingly. In this way, by automatically recognizing the region where the contrast agent flows from the obtained fluoroscopic image, the flow of the contrast agent can be automatically tracked even during fluoroscopic imaging, and the opening of the X-ray aperture during fluoroscopic imaging can be obtained. Can be adjusted almost in real time. In addition, it is possible to automatically set the imaging parameters such as the X-ray aperture of each imaging position and the relative movement speed between the C-arm and the tabletop in accordance with the flow rate and the amount of movement of the contrast agent tracked. The above burden can be significantly reduced.

  In general, the blood flow at the diseased part, that is, the flow rate of the contrast agent is slowed down. Therefore, by using the automatic tracking function for the skeleton of the contrast agent according to the second embodiment, the X-ray diaphragm 21 is restricted at the position of the diseased part. The opening can be set to a particularly narrow value. For the determination of the diseased part, for example, the threshold value used for the threshold value processing of the difference amount and the movement amount in FIGS.

  Further, the degree of the flow rate of the contrast agent can be predicted using the past determination tendency and the imaging position by the threshold processing, and this prediction information is stored as a part of the imaging parameters. Can be. This prediction information may be incorporated into the control of the aperture of the X-ray aperture and the C-arm at the time of the main imaging, whereby the imaging parameters at the time of the main imaging can be controlled with higher accuracy. The processing of the prediction information can be executed by, for example, the scruton processor 70.

  Further, according to the second embodiment, the skeleton of the contrast agent is recognized as a pattern from the fluoroscopic image obtained by the prescan, and the X-ray diaphragm at each imaging position for the main imaging is recognized from the pattern recognition information. The imaging parameters such as the aperture opening of 21, the flow rate of the contrast agent, and the moving speed of the C-arm 13 are determined and automatically stored in the imaging parameter storage 64. Therefore, unlike the above-described first embodiment, the operator does not need to manually set the imaging parameters for each imaging position, which is performed while displaying the fluoroscopic image after the prescan. Therefore, operational support is significantly enhanced, and operational effort is greatly reduced.

  Further, the imaging parameters automatically set as described above are read out by the imaging parameter controller 65 at the time of actual imaging, and are automatically transmitted to the X-ray aperture controller 55 and the holding device controller 57 via the system controller 51. Sent to For this reason, at the time of the main photographing, the aperture opening and the C-arm moving speed are automatically adjusted using the photographing parameters automatically set from the fluoroscopic image obtained by the pre-scanning, as in the first embodiment. The main shooting is performed.

  As a result, the operator does not need to manually move and operate the C-arm 13 and is released from such operation work, so that the operator can concentrate on the image diagnosis displayed along with the main imaging. For this reason, the operation labor of the operator's operation is remarkably reduced, and the operation efficiency is improved, so that the throughput of the examination can be increased.

  In addition to the above simplification and reduction in operation, the response to the occurrence of an abnormality by the deadman switch 71 is ensured. While the operator (operator) presses the deadman switch 71, the X-ray diagnostic apparatus operates normally. However, if an abnormality such as a failure of the X-ray tube, the C-arm, the top board, or the like occurs, the operator will be notified. By canceling the pressing operation of the deadman switch 71 which has been pressed until then, such an abnormal state can be immediately avoided.

  In each of the above-described embodiments, the X-ray detector 30 is an I.D. I. Although the X-ray detector 31 and the television camera 32 are connected via the optical system 33, the X-ray detector applicable to the present invention is not limited to this. For example, a switching element formed on a glass substrate, A flat panel radiation detector (Flat Panel Detector: FPD) composed of a semiconductor array formed so as to cover the capacitance with a photoconductive film or the like that converts radiation into electric charge or the like may be used. In this case, I. I. The controller 58 and the television camera controller 59 are replaced with an FPD control unit that controls the FPD.

  In each of the above embodiments, it has been described that the top 15 is stopped and the C-arm 13 is moved to perform X-ray imaging. However, in some cases, the C-arm 13 is stopped and the top 15 is moved. It is also possible to perform X-ray photography.

FIG. 2 is a perspective view showing a schematic configuration of a holding device portion in the first embodiment of the X-ray diagnostic apparatus according to the present invention. FIG. 1 is a system diagram showing a schematic configuration of a first embodiment. FIG. 4 is a plan view shown for explaining the operation of the X-ray diaphragm. FIG. 3 is an explanatory diagram illustrating a state in which an X-ray aperture is manually set for each imaging region in the first embodiment. FIG. 3 is an explanatory diagram illustrating a situation in which an appropriate imaging condition for a desired part is set in the first embodiment. FIG. 4 is a diagram illustrating an example of a storage table of setting values (photographing parameters) determined by a setting operation of photographing conditions. 5 is a flowchart illustrating an example of an operation procedure according to the first embodiment. FIG. 6 is an explanatory diagram of a profile display function of a contrast agent moving speed and a C-arm moving speed in the first embodiment. FIG. 7 is a diagram for explaining other functions in the first embodiment. FIG. 9 is a diagram for explaining still another function in the first embodiment. FIG. 7 is a perspective view showing a schematic configuration of a holding device part in a second embodiment of the X-ray diagnostic apparatus according to the present invention. FIG. 13 is a functional block diagram illustrating an outline of processing performed by a scruton processor used in the second embodiment. 9 is a flowchart showing an outline of a process for automatically setting the aperture opening of the X-ray aperture performed by the scruton processor. 9 is a flowchart showing an outline of a process for automatically setting a moving speed of a C-arm performed by a scruton processor. FIG. 9 is a diagram for explaining automatic setting of the aperture of the X-ray aperture by extracting scruton of a contrast agent and performing difference processing. The figure explaining automatic setting of the moving speed of the C arm by scruton extraction of a contrast agent and difference processing.

Explanation of reference numerals

REFERENCE SIGNS LIST 10 holding device 11 holding device main body 12 C arm holding mechanism 13 C arm 14 top holding mechanism 15 top 20 20 X-ray tube 21 X-ray aperture 30 X-ray detector 50 control device 51 system controller 52 operation panel 53 high voltage generator 54 X-ray controller 55 X-ray aperture controller 56 Compensation filter controller 57 Holder controller 58 LL controller 59 Camera controller 60 Image processor 61 Image storage 62 Display device 63 Aperture position / size / angle calculator 64 Imaging parameter storage 65 Imaging parameter controller 70 Skeleton processor 71 Deadman switch

Claims (12)

An X-ray source for generating X-rays,
An X-ray detector for detecting the X-ray;
The X-ray source and the X-ray detector are opposed to each other, and the X-rays are arranged such that a top plate on which a subject is placed is located in a spatial space between the X-ray source and the X-ray detector. Holding means for holding the source and the X-ray detector;
While moving one of the top plate and the holding unit relatively to the other, the contrast agent set to the subject substantially flows into the subject into which the contrast agent has been injected. Perspective imaging means for performing perspective imaging along a direction to obtain a perspective image,
Imaging parameter setting means for setting imaging parameters necessary for main imaging based on the perspective image obtained by the perspective imaging means, at least for each part continuous in the direction,
Based on the imaging parameters set by the imaging parameter setting means, while moving one of the top plate and the holding means relative to the other, the object into which the contrast agent has been injected An X-ray diagnostic apparatus comprising: a main imaging unit that performs the main imaging. The X-ray diagnostic apparatus according to claim 1,
The X-ray diagnostic apparatus, wherein the imaging parameter setting unit is configured to set the imaging parameters according to manual information of an operator. The X-ray diagnostic apparatus according to claim 2,
The main imaging unit controls an irradiation range of the X-rays generated from the X-ray source to the subject in a flow direction of the contrast agent injected into the subject based on the imaging parameters. An X-ray diagnostic apparatus having control means. The X-ray diagnostic apparatus according to claim 3,
The imaging parameter setting unit sets, as one of the imaging parameters, a relative moving speed with respect to one of the top plate and the holding unit according to a speed at which the contrast agent flows in the subject. Means to
The X-ray control device, wherein the irradiation range control means is configured to control the irradiation range according to the moving speed. The X-ray diagnostic apparatus according to claim 3,
The imaging parameter setting means is means for setting an imaging rate of the main imaging according to a speed at which the contrast agent flows in the subject as one of the imaging parameters,
An X-ray control device, wherein the irradiation range control means is configured to control the irradiation range according to the imaging rate. The X-ray diagnostic apparatus according to claim 3,
The apparatus further includes a site specification unit that specifies a specific site of the subject,
The irradiation range control means controls the irradiation range to an opening suitable for imaging the specific part when the position of the X-ray imaging by the main imaging means reaches a specific part set by the part specifying means. X-ray control device having means for performing. The X-ray diagnostic apparatus according to claim 1,
The X-ray diagnostic apparatus, wherein the imaging parameter setting unit is configured to automatically recognize a region where the projecting agent flows from the perspective image obtained by the perspective imaging unit and set the imaging parameter based on a result of the recognition. apparatus. The X-ray diagnostic apparatus according to claim 7,
The photographing parameter setting means includes a calculating means for automatically calculating, by pattern recognition, an area in which the contrast medium flows from the fluoroscopic image obtained by the fluoroscopic photographing means, and the imaging based on the calculation result calculated by the calculating means. Means for setting the aperture of the X-ray for each position as a part of the imaging parameters according to the region where the agent flows,
An X-ray diagnostic apparatus, wherein the main imaging unit includes a unit that controls an X-ray aperture according to the aperture opening of the X-ray. The X-ray diagnostic apparatus according to claim 7,
The photographing parameter setting means includes a calculating means for automatically calculating, by pattern recognition, an area in which the contrast medium flows from the fluoroscopic image obtained by the fluoroscopic photographing means, and the imaging based on the calculation result calculated by the calculating means. Means for setting, as a part of the photographing parameters, a relative moving speed with respect to one of the top plate and the holding means for each of the positions according to a flowing speed of the agent,
The X-ray diagnostic apparatus, wherein the main imaging unit includes a unit that controls a relative moving speed with respect to one of the top plate and the holding unit in accordance with the set relative moving speed. The X-ray diagnostic apparatus according to claim 7,
The photographing parameter setting means, based on the calculation result calculated by the calculation means for automatically calculating the region where the contrast agent flows from the perspective image obtained by the fluoroscopic imaging means by pattern recognition, based on the calculation result calculated by the calculation means, For each of the positions according to the region where the contrast agent flows, the aperture of the X-ray and the relative moving speed of the top plate and the holding unit relative to one of the other are set as part of the imaging parameters. Means for setting,
The main photographing means includes means for controlling an X-ray aperture according to the aperture opening of the X-ray, and one of the top plate and the holding means according to the set relative moving speed. Means for controlling a moving speed relative to the X-ray diagnostic apparatus. The X-ray diagnostic apparatus according to claim 7,
Calculation means for automatically calculating the region where the contrast agent flows from the fluoroscopic image obtained by the fluoroscopic imaging means by pattern recognition,
Based on the calculation result calculated by the calculating unit, the irradiation range of the X-rays generated from the X-ray source to the subject in parallel with the imaging of the fluoroscopic image by the fluoroscopic imaging unit is automatically performed in real time. An X-ray diagnostic apparatus comprising: an irradiation range control unit for controlling. An X-ray source for generating X-rays, an X-ray detector for detecting the X-ray, and the X-ray source and the X-ray detector facing each other; An imaging method executed by an X-ray diagnostic apparatus including: a holding unit that holds the X-ray source and the X-ray detector so that a top plate on which a subject is mounted is located in a spatial space. ,
While moving one of the top plate and the holding unit relatively to the other, the contrast agent set to the subject substantially flows into the subject into which the contrast agent has been injected. Performing fluoroscopic imaging along a direction to obtain a fluoroscopic image;
Setting imaging parameters necessary for main imaging based on the perspective image obtained by the perspective imaging, at least for each part continuous in the direction;
Based on the set imaging parameters, the main imaging is performed on the subject into which the contrast agent has been injected while one of the top plate and the holding unit is relatively moved with respect to the other. And an X-ray imaging method.

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