JP2005198975A - X-ray diagnostic apparatus and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display an image enabling diagnostic reading to be done without being affected by halation generated on the image due to mechanical slackness of an X-ray irradiation field aperture or distortion caused by introducing I.I. <P>SOLUTION: The output side of an X-ray tube 20 is provided with: an X-ray irradiation field aperture 23 to narrow an X-ray to prevent unnecessary sections from being irradiated; an X-ray irradiation field aperture control section 33 to control the degree of the aperture of the X-ray irradiation field aperture 23; a blackening means 55 to calculate an X-ray irradiation field aperture edge coordinate, corresponding to the end section at the aperture side of the X-ray irradiate field aperture 23, from an image photographed and to recognize an X-ray irradiation field aperture area based on the X-ray irradiation field aperture edge coordinate and blacken it; a gradation blackening means 56 to calculate a halation edge coordinate from the image photographed and to recognize a halation area based on the halation edge coordinate and the X-ray irradiation field area; and a gradation blackening function DB57 housing a plurality of gradation blackening functions to do gradation blackening of the halation area. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for acquiring an image of a required part of a subject based on transmitted X-rays, interpreting the image, and diagnosing the subject. In particular, the present invention performs blackening processing on halation generated on an image. The present invention relates to an X-ray diagnostic apparatus and method that can reduce the occurrence of halation.

  In an X-ray diagnostic apparatus that fluoroscopically / photographs a required part of the digestive tract or the like with X-rays, the subject is irradiated with X-rays, and the transmitted X-rays that have passed through the subject are incident on the X-ray TV apparatus and converted into optical signals The optical signal is converted and photographed as an optical image by the TV camera. When this imaging is performed under a predetermined fluoroscopic condition (X-ray exposure by fluoroscopy with a predetermined intensity), a fluoroscopic image of the subject can be displayed almost in real time on the screen of the display device.

  An X-ray diagnostic apparatus is an apparatus that performs indirect imaging of a subject, and an operator can observe the flow and movement of contrast medium inside the subject on a screen of a display device in time series. Recently, flat detector devices that convert transmitted X-rays transmitted through a subject into electrical signals have been commercialized. The X-ray diagnostic apparatus can also perform so-called direct imaging, in which transmitted X-rays are directly exposed to an X-ray film to obtain an X-ray image.

  In image processing of images, enlargement / gradation / spatial filter processing that handles transmission images, minimum / maximum value tracing processing of images accumulated in time series, subtraction processing, and addition for removing noise There are processing.

  Then, an example of the procedure at the time of image | photographing a transmission X-ray image using an X-ray diagnostic apparatus is demonstrated.

  The operator determines the tube voltage on the basis of information such as patient age, sex, required region to be examined and special items (patient status, pregnancy status, medical precautions, contrast agent allergy and special assistance). Furthermore, the operator sets fluoroscopic conditions such as tube current and fluoroscopic pulse time (hereinafter referred to as “initial fluoroscopic conditions”), and the subject is irradiated with X-rays that match the initial fluoroscopic conditions. A fluoroscopic image is displayed on the screen of the display device. Then, the operator can set the X-ray tube, I.D. I. Position (Image Intensifier) etc.

Further, the imaging X-ray switch is pressed to irradiate the subject with imaging X-rays, and the subtraction between the mask image and the contrast image stored for each imaging position / angle is performed. In vascular examinations that display subtraction images almost in real time and non-vascular digestive tract examinations that use contrast agents such as barium, diagnosis is performed while displaying images on the screen of the display device in real time. Printing is performed as necessary (see, for example, Patent Document 1).
JP 2000-354593 (page 3 to page 5, FIG. 1)

  In an X-ray diagnostic apparatus that continuously inspects under fluoroscopic imaging, the shape of a part to be diagnosed and the angle of transmitted X-ray that passes through the subject (the sagittal plane (CRA / CAU) and cross section of the indicator (RAO / LAO)) Depending on the angle), mechanical sagging (deviation from the set position) of the lead feathers constituting the X-ray irradiation field stop becomes a problem. In examinations such as gastrointestinal tract examination and DSA (Digital Subtraction Angiography), sagging cannot be corrected during X-ray irradiation. It was practically difficult to obtain a transmission image.

  Therefore, in reality, when the negative display image has a higher diagnostic effect, it may be difficult to see the image due to halation when viewed with the negative display image. At this time, there is a clinical problem as a restriction of the apparatus, such as having to display the negative display image positively and interpret it with a reduced diagnostic effect (or vice versa).

  Further, in order to take into account the sagging of the X-ray irradiation field stop, when taking an image so that the direct line is ignored and the aperture of the X-ray irradiation field stop is widened to give priority to the transmission image in the vicinity of the direct line, The exposure of the subject due to scattered radiation and the halation near the transmission image expose the drawback of hindering diagnosis. In particular, halation is likely to occur in images of parts such as the head, neck, chest, and extremities.

  On the other hand, when taking a picture so that the aperture of the X-ray field stop is narrowed and the exposure and halation of the subject are reduced so that no direct line is generated even if the sagging of the X-ray field stop is taken into consideration, There is a disadvantage that an image of a required part corresponding to the vicinity of the X-ray irradiation field stop is missing.

  In order to make the aperture of the X-ray irradiation field stop wide or narrow, a technique for delicately controlling the aperture of the X-ray irradiation field stop is required. Further, when the aperture of the X-ray irradiation field stop cannot be controlled, it is necessary to take a wide viewing angle. However, advanced inspection techniques are required to instantaneously determine and implement this viewing angle. Therefore, while confirming the patient's body position and position in advance, the greatest common divisor X-ray field stop is such that the image of the required part to be diagnosed is not lost in the direction of opening the aperture of the X-ray field stop. It was only possible to set the opening degree. If control is difficult, the examination can be stopped and imaging can be performed by irradiating the subject with X-rays via an appropriate compensation filter.

  That is, when trying to widen or narrow the aperture of the X-ray irradiation field stop, an extra operation (labor) is required to prevent halation due to sagging of the X-ray irradiation field stop. Cause overexposure.

  Moreover, since the halation area near the X-ray irradiation field stop cannot be recognized by ABC (Auto Brightness Control) control while irradiating fluoroscopic X-rays, the X-ray irradiation field stop is readjusted again by intuition. Work is required. In addition, advanced techniques are required to set the aperture of the X-ray irradiation field stop with high reproducibility in accordance with the movement of the subject P and the movement of the holding device for each imaging.

  Therefore, halation in the vicinity of the X-ray irradiation field stop when displaying an actually captured image, and output to a film etc. in a form that is easy to diagnose by display that has been blackened including the sagging of the X-ray irradiation field stop. It was impossible.

  In addition, I.I. I. Due to the nature of the image, distortion in the periphery of the output image (pincushion distortion) results in a stretched image in the periphery of the image compared to the center, and the X-ray irradiation field stop cannot be adjusted well, causing halation. It becomes. The strain is I.V. I. The image distortion rate is about 5% at a size of 12 inches and about 3% at a size of 9 inches.

  The present invention has been made in consideration of the above-described circumstances. I. It is an object of the present invention to provide an X-ray diagnostic apparatus and method capable of blackening a halation on an image caused by distortion caused by the use of the image and displaying an image that can be interpreted.

  Another object of the present invention is to provide mechanical sagging of the X-ray irradiation field stop and I.I. I. It is an object of the present invention to provide an X-ray diagnostic apparatus and method that can reduce halation on an image caused by distortion due to the adoption of the image and display an image that can be interpreted.

  In order to solve the above-described problems, an X-ray diagnostic apparatus according to the present invention irradiates a subject with X-rays emitted from a radiation source, and enters the transmitted X-rays that pass through the subject, thereby An X-ray diagnostic apparatus comprising: a holding device that sees through and images a subject; and a main body control unit that controls the holding device and displays an image that has been seen through and taken by the holding device on a screen. And an X-ray irradiation field stop for controlling the X-ray irradiation field stop on the exit side of the radiation source to prevent irradiation of unnecessary portions by limiting the X-ray, and an X-ray irradiation field stop control unit for controlling the aperture of the X-ray irradiation field stop, X-ray irradiation field stop edge coordinates corresponding to the opening side end of the X-ray irradiation field stop are calculated from the photographed image, and an X-ray irradiation field stop area is recognized from the X-ray irradiation field stop edge coordinates. Blackening processing means for blackening processing and halation from the photographed image A gradation blackening processing means for calculating a gradation coordinate and recognizing a halation area from the halation edge coordinates and the X-ray irradiation field stop area, and gradation blackening processing; and a plurality of gradations for gradation blackening processing of the halation area A gradation blackening processing function DB storing blackening processing functions is provided.

  Further, the X-ray diagnostic apparatus according to the present invention irradiates a subject with X-rays emitted from a radiation source, enters the transmitted X-rays that pass through the subject, and sees and images the subject. An X-ray diagnostic apparatus comprising: a holding device; and a main body control unit that controls the holding device and displays a fluoroscopically / photographed image on the screen. In addition, an X-ray irradiation field stop for narrowing the X-ray to prevent irradiation of unnecessary parts, an X-ray irradiation field stop control unit for controlling the aperture of the X-ray irradiation field stop, and a positive display under fluoroscopic imaging And P / N inversion processing means for converting the image to negative display.

  In order to solve the above-described problem, the X-ray diagnostic method according to the present invention irradiates a subject with X-rays and fluoroscopically images the subject based on transmitted X-rays transmitted through the subject. In an X-ray diagnostic method for displaying a fluoroscopic / photographed image on a screen, X-ray irradiation field stop edge coordinates corresponding to the opening side end of the X-ray irradiation field stop are calculated from the captured image. An X-ray irradiation field stop area recognition step for recognizing an X-ray irradiation field stop area from the X-ray irradiation field stop edge coordinates, and calculating a halation edge coordinate from the photographed image, the halation edge coordinates and the X-ray irradiation field stop A halation area recognition process for recognizing a halation area from edge coordinates, a gradation blackening process for gradation blackening the halation area, and an X-ray irradiation field stop area. It has a blackening treatment step of treating of, and an image display step of displaying the gradation blackening treatment and the blackened image on the screen.

  The X-ray diagnostic method according to the present invention irradiates a subject with X-rays, and sees and images the subject based on transmitted X-rays transmitted through the subject. In the X-ray diagnostic method displayed on the screen, a negative conversion step of converting a positive display image displayed on the screen under fluoroscopy into a negative display, and the opening side of the X-ray irradiation field stop from the negative display image An X-ray irradiation field stop edge recognition step for calculating an X-ray irradiation field stop edge coordinate corresponding to the end of the X-ray irradiation field, and recognizing the X-ray irradiation field stop area from the X-ray irradiation field stop edge coordinate, and the negative display image The halation edge coordinates are calculated from the halation edge coordinates and the halation area recognition step for recognizing the halation area from the halation edge coordinates and the X-ray irradiation field stop edge coordinates, and until the halation area becomes a predetermined size. , And an X-ray irradiation field aperture adjustment process for adjusting the opening of the aperture the X-ray irradiation field.

  According to the X-ray diagnostic apparatus and method therefor according to the present invention, mechanical sagging of the X-ray irradiation field stop, I.V. I. It is possible to blacken the halation on the image generated due to distortion due to the adoption of the image, and display an image that can be interpreted.

  In addition, according to the X-ray diagnostic apparatus and method of the present invention, mechanical sagging of the X-ray irradiation field stop, I.V. I. It is possible to reduce the halation on the image caused by distortion due to the adoption of the image, and to display an image that can be interpreted.

  An embodiment of an X-ray diagnostic apparatus and method according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing this embodiment of the X-ray diagnostic apparatus according to the present invention, and FIG. 2 is a perspective view showing a holding device.

  As shown in FIG. 1, the X-ray diagnostic apparatus 10 mainly includes a holding device (also called a fluoroscopic imaging table) 11 and a main body control unit 12. The holding device 11 is installed in the X-ray television room where the subject P actually enters the room and receives fluoroscopy and imaging, while the main body control unit 12 is installed in the operation room. Note that a proximity console may also be installed in the X-ray television room.

  As shown in FIG. 2, the holding device 11 includes a holding device main body 14 fixed to the floor, and a vertical movement (I direction in the drawing) and a rotational movement (J in the drawing) with respect to the holding device main body 14. A top plate holding mechanism 15 that is movably attached to the top plate holding mechanism 15, and a left-right movement (C-LAT: H direction in the figure), a vertical movement (C-VERT: G direction in the figure), and A top plate 16 that allows rolling (ROLL: F direction in the figure), a C arm holding mechanism 17 that is slidably attached to the holding device main body 14 in a direction substantially parallel to the floor (A direction in the figure), Long manual operation (C-LONG: A direction in the figure), rotation (LAO / RAO: B direction in the figure), and circular motion (CRA / CAU: C direction in the figure) around the attachment position with the C arm holding mechanism 17 ) Is freely provided.

  An X-ray tube 20 as a radiation source is provided at one end of the C arm 18, and a transmitted X-ray is provided at a position facing the X-ray tube 20 so as to sandwich the top plate 16 at the other end of the C arm 18. Is input, and an X-ray TV device 19 is provided for outputting a TV video signal.

  As shown in FIG. 1, the X-ray tube 20 provided at one end of the C-arm 18 is supplied with high-voltage power from a high-voltage generator 22 provided in the main body control unit 12, and this high voltage X-rays are exposed according to power conditions. On the emission side of the X-ray tube 20, an X-ray irradiation field stop 23 configured by a plurality of lead feathers to restrict X-rays generated in the X-ray tube 20 to prevent X-ray irradiation to unnecessary portions is provided. A compensation filter that is formed of acrylic or the like and attenuates a predetermined amount of irradiated X-rays may be provided on the emission side of the X-ray irradiation field stop 23 to prevent halation.

  Further, the X-ray TV apparatus 19 provided at the other end of the C-arm 18 is irradiated with transmitted X-rays. I. (Image Intensifier) 21 is installed. I. 21 has an X-ray grid 26 for cutting scattered X-rays transmitted through the subject P. I. 21 is provided with an optical system 27 that corrects the converted optical image to an appropriate size, and a TV camera (or imaging element) 28 that converts the corrected optical image into a TV video signal. I. I. 21 is composed of a large vacuum tube composed of an input phosphor screen, a photocathode, a focusing electrode, an anode and an output phosphor screen (not shown), an input window, a high voltage power source, and the like. It is sent to the main body control unit 12. I.I. I. The video system from 21 to the TV camera 28 may be replaced with a flat detector.

  Next, the main body control unit 12 includes an X-ray controller 32 that controls the high-voltage generator 22 that generates a high voltage to be applied to the X-ray tube 20 around the system controller 31, and an X-ray irradiation field stop 23. An X-ray irradiation field stop control unit 33 for controlling the aperture of the projector, a holding device control unit 36 for controlling the movement of the top 16 and the like; I. I. I. The control unit 41, the TV camera control unit 48 for controlling the TV camera 28, the TV video signal converted by the TV camera 28 and the imaging conditions such as the X-ray control condition, the holding control condition, and the image processing condition are associated with each other. A storage unit 51 for storing, a display device 52 for displaying an image stored in the storage unit 51 and an image obtained by the TV camera 28 in real time, and an enlarged / tone / space for the obtained image of the subject P An image processing unit 53 that performs filter processing, addition processing for removing noise, and the like, and an X-ray irradiation field stop area that is an area narrowed by the X-ray irradiation field stop 23 of the fluoroscopic image is recognized and blackened. Blackening processing means 55 for processing, and gradation blackening processing for recognizing a halation area generated inside the X-ray irradiation field stop 23 of the fluoroscopic image and performing gradation blackening processing Stage 56, gradation blackening processing function DB 57 storing a plurality of gradation blackening processing functions, and P / N inversion processing means 58 for inverting a fluoroscopic image, which is generally P (positive) display, to N (negative) display. Are provided.

  The main body control unit 12 is provided with an operation panel 61 such as a keyboard and a mouse that can be input by an operator, and an input signal from the operation panel 61 can be input to the system controller 31.

  Next, the operation of the X-ray diagnostic apparatus 10 will be described.

  First, as shown in FIG. 1, after the subject P is placed on the top 16, normal imaging is performed independently of images captured in the past of the subject P, and then in the past. Follow-up imaging is performed based on the captured image of the subject P. The description of this embodiment is for the case of rotating DSA (Digital Subtraction Angiography) imaging.

  A method related to the subject P to be imaged is input to the system controller 31 via the operation panel 61 provided in the main body control unit 12 by the operator. The input of this information is performed directly by the operator on the operation panel 61, or information input in advance from a predetermined terminal is indirectly performed via a network (not shown) or the like. When the operator confirms the subject P, the operator selects whether to perform normal imaging or follow-up imaging. This selection is set for each subject P by the operator based on information on the subject P.

  Next, the normal imaging operation in the X-ray diagnostic apparatus 10 will be described with reference to the flowchart shown in FIG.

  Prior to taking a mask image and a contrast image, fluoroscopic imaging of a required part of the subject P is performed with fluoroscopy X-rays having a relatively low X-ray intensity compared to taking a mask image and a contrast image ( Step S1). Specifically, the operator uses the system controller 31, the X-ray controller 32, and the high-voltage generator 22 to see through the subject P from the X-ray tube 20 after the subject P is placed on the top 16. X-rays are irradiated. While irradiating the subject P with the fluoroscopy X-ray, the operator can transmit the X-rays that pass through the subject P so that the portion through which the fluoroscopy X-ray is transmitted through the holding device control unit 36 is maximized. The angle (LAO / RAO, CRA / CAU) is determined.

  The transmitted X-rays transmitted through the subject P by the fluoroscopic X-rays irradiated on the subject P are subjected to removal of scattered rays by the X-ray grid 26 of the X-ray TV apparatus 19. I. 21 is incident. I. I. In 21, an optical signal corresponding to the incident X-ray dose is generated. This optical signal is corrected by the optical system 27, and then converted into an electric signal which is a TV video signal by the TV camera 28. The TV video signal converted by the TV camera 28 is converted into a digital signal by an A / D converter (not shown), subjected to desired image processing, and then again TV by a D / A converter (not shown). Converted to video signal. This TV video signal is sent to the display device 52 provided in the main body control unit 12, and is displayed on the screen of the display device 52 in real time as a fluoroscopic image (step S2).

  A real-time image displayed in real time on the screen of the display device 52 or an image obtained by fluoroscopic imaging is temporarily stored in the storage unit 51 while performing fluoroscopic imaging in step S1, and is read out from the storage unit 51 for reproduction display. The operator sets X-ray control conditions and holding control conditions suitable for capturing a mask image and a contrast image in rotating DSA imaging with reference to the image thus obtained (step S3). Here, the X-ray control condition is a condition for determining what kind of X-ray is irradiated to the subject P. For example, the tube voltage and tube current of the X-ray tube 20 and the control condition of the X-ray irradiation field stop 23 are determined. It is. The holding control condition is a condition for controlling the holding device 11 and is, for example, a position condition of each part shown in FIG. Note that the X-ray control conditions and the holding control conditions for the mask image and the contrast image in the rotation DSA imaging are substantially the same conditions (the C arm 18 may have different slide movements in the arc direction or the like). is there.

  Here, in particular, the setting of the X-ray irradiation field stop 23 among the X-ray control conditions will be described. On the fluoroscopic image of the subject P, X-rays are irradiated to unnecessary portions that do not need to be imaged. If so, the position of the X-ray irradiation field stop 23 is set so that X-rays are not irradiated to unnecessary portions. In addition, among the holding control conditions, the setting of the position conditions of the respective parts is performed by the operator operating the operation panel 61 so that a required part of the subject P to be observed is photographed.

  Next, rotating DSA photographing is performed, and a mask image and a contrast image are photographed (step S4). Here, the mask image and the contrast image are X-ray images that are substantially perpendicular to the body axis direction of the subject P. The system controller 31 automatically sets the top plate 16 and the C arm 18 at appropriate positions based on the holding control condition set in step S3. During photographing of the mask image and the contrast image, the top plate 16 does not move, and the C arm 18 does not move other than slide in the arc direction. That is, before the X-ray tube 20 emits X-rays, the top plate 16 and the C-arm 18 move in the A, B, D, and J directions, respectively, and are fixed during imaging.

  During the capture of the mask image and the contrast image, the C arm 18 slides only in the C direction, so that X-rays are intermittently emitted at every predetermined slide angle, and a plurality of times of photographing are performed. A mask image and a contrast image are created based on the image data obtained by the plurality of times of photographing. This slide movement is automatically performed at a rotation speed set in advance by the operator.

  FIG. I. It is the schematic which shows the locus | trajectory of 21. FIG.

  The X-ray diagnostic apparatus 10 shown in FIG. 4 shows a holding device body 14 and a top plate 16 on which a subject P is placed. The imaging of the mask image in the X-ray diagnostic apparatus 10 is performed by the I.D. I. Is performed from the initial position (Start Position) to the end position (Final Position). As described above, the mask image is an I.D. I. Is created from the image data obtained when moving from Start Position to Final Position. I. May be created from image data obtained when starting from Final Position and moving to Start Position.

  Here, when image processing such as P / N conversion is performed on the basis of image data obtained by a plurality of times of shooting, a mask image created based on the image data, and a contrast image, the image processed image is processed. , Mechanical sagging of the X-ray irradiation field stop 23 due to the angle of the holding device 11 and gravity; I. The halation occurs due to the distortion caused by the adoption of 27. The halation changes in size and position depending on the shape of the required part.

  Therefore, it is determined whether or not a gradation blackening processing function at a required slide angle for performing gradation blackening processing on the halation area (hereinafter referred to as “halation area”) is stored in the storage unit 51 (step S51). S5). If the determination in step S5 is Yes, that is, if it is determined that the gradation blackening function at the required slide angle is not stored in the storage unit 51, the blackening processing unit 55 uses the image data, mask image, or contrast image. Is used to detect the X-ray irradiation field stop edge on the image corresponding to the opening side end portion of the lead feather constituting the X-ray irradiation field stop 23 by a general mathematical method. By detecting the X-ray irradiation field stop edge, the X-ray irradiation field stop area affected by the sagging of the X-ray irradiation field stop 23 is recognized (step S6). Since the change of the pixel value indicating the light amount value (0 to 256 gradations) of the pixel (coordinates (X, Y)) on the screen of the display device 43 is large, the X-ray irradiation field stop edge corresponds to the change of the pixel value. Thus, it can be detected by performing a differential (difference) operation.

  For example, according to the differential operation, the differential value of the pixel of interest is obtained from the pixel value change in the horizontal (X-axis) direction and the pixel value change in the vertical (Y-axis) direction using 8 pixels surrounding the pixel of interest. And among the obtained differential values, a differential value exceeding a required threshold value for the X-ray irradiation field stop edge is obtained. The coordinates (X, Y) of the pixel having this differential value are set as X-ray irradiation field stop edge coordinates (c, 1, 2) (c = 1, 2,..., D = 1, 2,...). Then, the outside of the polygon formed by the plurality of X-ray irradiation field stop edge coordinates (c, d) is recognized as an X-ray irradiation field stop area. As the pixel value of the target pixel, the pixel value of the target pixel and the pixel values of the neighboring pixels are averaged, and the X-ray irradiation field stop edge coordinates (c, d) are obtained from the averaged differential value of the average pixels. May be.

  Further, the gradation blackening processing unit 56 uses the image data, the mask image, or the contrast image as in step S6, and the halation generated on the image inside the X-ray irradiation field stop 23 by a general mathematical method. The halation edge is detected. By detecting the halation edge, the halation area is recognized (step S7). For example, according to the differential operation, the differential value of the target pixel is obtained from the change in the pixel value in the horizontal direction and the change in the pixel value in the vertical direction using eight pixels surrounding the target pixel. Of the obtained differential values, a differential value exceeding a required halation edge threshold is obtained. The coordinates (X, Y) of the pixel having this differential value are set as halation edge coordinates (e, f) (e = 1, 2,..., F = 1, 2,...). Then, the outside of the polygon formed from the plurality of halation edge coordinates (e, f) and the inside of the X-ray irradiation field stop area recognized in step S6 is recognized as a halation area. As the pixel value of the target pixel, the pixel value of the target pixel and the pixel values of the neighboring pixels may be averaged, and the halation edge coordinates (e, f) may be obtained from the differential value of the averaged average pixels.

  Subsequently, the halation area recognized in step S7 is superimposed on the image as a graphic, and is drawn or displayed in color on the screen of the display device 52 (step S8). The operator can check the position and size of the halation area while looking at the image in which the halation area is graphicized.

  Next, when the operator operates a pointing device such as a mouse, the plurality of gradation blackening processing functions (secondary or higher order functions) stored in the gradation blackening processing function DB 57 are recognized in step S7. A required gradation blackening function corresponding to the size of the halation area (the coordinate difference between the X-ray irradiation field stop edge coordinates (c, d) and the halation edge coordinates (e, f)) is selected (step S9). .

  FIG. 5 is a graph showing an example of a gradation blackening function.

  The horizontal axis of FIG. 5 shows the coordinate difference between the halation edge coordinates (e, f) and the X-ray irradiation field stop edge coordinates (c, d) when the halation edge coordinates (e, f) are set to the reference “0”. The vertical axis indicates the pixel value. The gradation blackening function is shown as a function that attenuates as the coordinate difference between the X-ray irradiation field stop edge coordinates (c, d) and the halation edge coordinates (e, f) increases. In step S9, among the plurality of gradation blackening functions shown in FIG. 5, the X-ray irradiation field stop edge coordinates (c, d) and the halation edge coordinates (e, f) recognized in steps S6 and S7. A gradation blackening function corresponding to the coordinate difference is selected.

  When a desired gradation blackening function is selected from among a plurality of gradation blackening functions, the selected gradation blackening function is selected from the X-ray irradiation field stop edge coordinates (c, d) and the halation edge coordinates. Applied to the coordinates between (e, f), the pixel value of the coordinates between the X-ray irradiation field stop edge coordinates (c, d) and the halation edge coordinates (e, f) is transformed, and the halation area on the image Is subjected to gradation blackening processing (step S10).

  FIG. 6 is a graph showing the relationship between coordinates (X, Y) on the screen and pixel values.

The horizontal axis of the graph shown in FIG. 6 represents the coordinates (X, Y) on the screen, for example, X when Y = y, and the vertical axis represents the pixel value for each coordinate. Coordinates between the X-ray irradiation field stop edge coordinates (c ₁ , y) and the halation edge coordinates (e ₁ , y) when Y = y, the X-ray irradiation field stop edge coordinates (c ₂ , y) and the halation edge It can be seen that pixel values vary greatly at coordinates between the coordinates (e ₂ , y). In step S10, coordinates between the X-ray irradiation field stop edge coordinates (c ₁ , y) and the halation edge coordinates (e ₁ , y), the X-ray irradiation field stop edge coordinates (c ₂ , y) and the halation edge coordinates ( The necessary gradation blackening function selected is applied to the coordinates between e ₂ and y).

  Next, in the graph shown in FIG. 6, the case of Y = y is shown, but the pixel value of the coordinate between the X-ray irradiation field stop edge coordinate (c, d) and the halation edge coordinate (e, f) is It is determined whether the image has been converted over all the Y-axis other than Y = y on the screen and the gradation blackening process of the image has been performed (step S11). In the determination of step S11, Yes, that is, the pixel values of the coordinates between the X-ray irradiation field stop edge coordinates (c, d) and the halation edge coordinates (e, f) are converted over all the Y axes on the screen. If it has been done, the gradation blackening function and the slide angle corresponding to all the Y axes are stored in the storage unit 51 (step S12). Then, the blackening processing means 55 performs blackening processing on the X-ray irradiation field stop area recognized in step S6 (step S13).

  On the other hand, the determination in step S11 is No, that is, the pixel values of the coordinates between the X-ray irradiation field stop edge coordinates (c, d) and the halation edge coordinates (e, f) are all over the Y axis on the screen. If not converted, the pixel values of the coordinates between the X-ray irradiation field stop edge coordinates (c, d) and the halation edge coordinates (e, f) are converted for the entire halation area, and the halation area of the image is gradation. Blackening processing is performed (step S10).

  The image processing unit 53 performs image processing on the image that has been subjected to the gradation blackening process of the halation area in step S10 and the blackening process of the X-ray irradiation field stop in step S13 (step S14). This image processing may be processing performed manually by an operator or may be processing performed automatically. This image processing includes subtraction processing in addition to enlargement / gradation / spatial filter processing, minimum value / maximum value trace processing of X-ray transmission images accumulated in time series, and addition processing for removing noise. included. The subtraction process is performed between the mask image and the contrast image. A plurality of mask images, contrast images, and subtraction images are created in the body axis direction of the subject P. Further, the subtraction image subjected to the subtraction process in the image processing unit 53 is displayed on the screen of the display device 52 and printed on an imager or the like as necessary (step S15).

  The mask image, contrast image, and subtraction image that have been subjected to image processing are stored in the storage unit 51 (step S16). In addition, information on the subject P, X-ray control conditions, holding control conditions, and image processing conditions are stored corresponding to these images.

  On the other hand, if the determination in step S5 is No, that is, it is determined that the gradation blackening processing function at the required slide angle is stored in the storage unit 51, the gradation blackening processing function is read from the storage unit 51. Then, the gradation blackening processing means 56 applies the image to the image displayed in real time, and gradation blackening processing is performed on the halation area on the image (step S18).

  Subsequently, follow-up photography is performed after a predetermined period after normal photography, for example, about several days to several months, but since it is the same as general follow-up photography, description of follow-up photography is omitted. To do.

  According to this embodiment, the X-ray irradiation field stop area 23 and the halation area are automatically recognized, the halation area is gradation blackened, and the X-ray irradiation field stop area is blackened. Mechanical sagging and I. I. 21 can reduce the halation on the image caused by distortion due to the adoption of the image 21 and display an image that can be interpreted.

  FIG. 7 is a flowchart showing a modification of the present embodiment and showing a method for controlling the X-ray irradiation field stop 23. Note that the configuration of the modification of the present embodiment is the same as the configuration of the X-ray diagnostic apparatus 10 shown in FIGS.

  The flowchart shown in FIG. 7 shows fluoroscopic imaging in step S1 of the flowchart shown in FIG.

  The X-ray diagnostic apparatus 10 shown in FIG. 1 performs fluoroscopic imaging, and the obtained image is subjected to P / N reversal processing by the P / N reversal processing means 58, and is generally a positive display image under fluoroscopic radiography. Is converted into a negative display (step S21). A positive display image such as a fluoroscopic image has a fact that it is difficult to determine whether a black portion on the image is at a black level or is stuck to black by the X-ray irradiation field stop 23. When the image is reversed to a negative display, the X-ray irradiation field stop 23 sticks to white, so that it is easy to distinguish.

  Using the image converted to the negative display, the X-ray irradiation field stop area on the image is recognized as in step S6 (step S22), and subsequently, using the positive display image as in step S7. Then, the halation area on the image is recognized (step S23).

  Next, the X-ray irradiation field stop control unit 33 is controlled to adjust the position of the lead feathers of the X-ray irradiation field stop 23. For example, in step S21, the X-ray irradiation field stop is subjected to fluoroscopic imaging with a relatively wide aperture of the X-ray irradiation field stop 23 so that X-rays are also widely irradiated to unnecessary portions of the subject P. In the position adjustment of the lead feathers 23, the X-ray irradiation field stop 23 is automatically slid stepwise in the direction of narrowing the opening (step S24).

  Here, the system controller 31 determines whether or not the halation area in the image has a predetermined size that does not interfere with image interpretation (step S25). If the determination in step S25 is Yes, that is, if the halation area in the image is determined to have a predetermined size that does not interfere with image interpretation, the automatic slide of the X-ray irradiation field stop 23 is terminated, and X The fluoroscopic imaging is performed at the adjustment end position of the line irradiation field stop 23 and displayed as a fluoroscopic image on the screen of the display device 52 (step S2 in the flowchart shown in FIG. 3).

  FIG. 8 shows a fluoroscopic image displayed on the screen of the display device 52, and FIG. 8A shows an ideal fluoroscopic image of the subject imaged in step S1 of the flowchart shown in FIG. FIG. 8B shows an actual fluoroscopic image of the subject imaged in step S1, and FIG. 8C shows a fluoroscopic image of the subject imaged by the flowchart shown in FIG.

  FIG. 8A shows an X-ray irradiation field stop edge J1 corresponding to the opening side end of the X-ray irradiation field stop 23 set by the X-ray irradiation field stop control unit 33, and the X-ray irradiation field. An X-ray irradiation field K1 formed from the diaphragm edge J1 and a fluoroscopic image L1 of the subject displayed in the X-ray irradiation field K1 are shown. FIG. 8B shows the X-ray irradiation field stop edge J1 similarly to FIG. 8A, and in addition, the actual X-ray irradiation field stop 23 is affected by the sagging of the X-ray irradiation field stop 23. X-ray irradiation field stop edge J2 corresponding to the edge of the X-ray, an X-ray irradiation field K2 formed from the X-ray irradiation field stop edge J2, and a fluoroscopic image L2 of the subject displayed in the X-ray irradiation field K2 It shows.

  FIG. 8C shows X-ray irradiation field stop edges J1 and J2 as in FIG. 8B. In addition, the opening of the X-ray irradiation field stop 23 is narrowed, and FIG. X-ray irradiation field stop edge J3 in which the X-ray irradiation field stop edge J2 is automatically slid inward, an X-ray irradiation field K3 formed from this X-ray irradiation field stop edge J3, and this X-ray irradiation A perspective image L3 of the subject displayed in the field K3 is shown.

  As shown in FIG. 8A, when the fluoroscopic imaging is performed by setting the position of the X-ray irradiation field stop 23 according to the subject as in the imaging in step S1 of the flowchart shown in FIG. A fluoroscopic image L1 of the subject is obtained in an X-ray irradiation field K1 formed by an ideal X-ray irradiation field stop edge J1 corresponding to the X-ray irradiation field stop 23. However, in reality, when the sagging of the X-ray irradiation field stop 23 occurs and the fluoroscopic imaging is performed in the state where the sagging of the X-ray irradiation field stop 23 is generated, as shown in FIG. The edge of the irradiation field stop 23 becomes the position of the X-ray irradiation field stop edge J2, and the X-ray irradiation field K2 is formed. As described above, when the sagging of the X-ray irradiation field stop 23 occurs, the difference between the pixel values increases in the vicinity of the X-ray irradiation field stop edge J2, causing halation, and the fluoroscopic image L2 of the subject in the X-ray irradiation field K2. Is difficult to interpret.

  On the other hand, in the imaging according to the flowchart shown in FIG. 7, first, fluoroscopic imaging is performed with the aperture of the X-ray irradiation field stop 23 set relatively wide according to the subject, as shown in FIG. 8B. In addition, a fluoroscopic image L2 of the subject in the X-ray irradiation field K2 is obtained. Then, in step S24, the left and right lead feathers of the X-ray irradiation field stop 23 are automatically slid asymmetrically (may be a target) in the direction of narrowing the opening degree of the X-ray irradiation field stop 23. When fluoroscopic imaging is performed by adjusting the aperture of the X-ray irradiation field stop 23, the edge of the X-ray irradiation field stop 23 becomes the position of the X-ray irradiation field stop edge J3 as shown in FIG. A line irradiation field K3 is formed. In this way, when fluoroscopic imaging is performed by adjusting the aperture of the X-ray irradiation field stop 23, halation areas having a large difference in pixel values in the vicinity of the X-ray irradiation field stop edge K3 are reduced, and the X-ray irradiation field K3 is within the X-ray irradiation field K3. Interpretation of the fluoroscopic image L3 of the subject.

  On the other hand, when the determination in step S25 is No, that is, when it is determined that the halation area in the image has a size that hinders interpretation of the image, the X-ray irradiation field stop 23 is further set in the X-ray irradiation field. The slide is automatically slid stepwise in the direction of narrowing the opening of the diaphragm 23 (step S24).

  Note that the halation on the negative display image in step S21 is easier to identify than the halation on the positive display image. Therefore, the automatic slide of the X-ray irradiation field stop 23 in step S24 can be manually performed while the operator looks at the image.

  Further, in FIG. 8C, the fluoroscopic imaging is performed by adjusting the opening degree in the left-right direction of the X-ray irradiation field stop 23, but it is assumed that it can be automatically slid in the vertical direction as well as the left-right direction.

  According to the second modification of the present embodiment, the X-ray irradiation field stop area and the halation area are automatically recognized, the halation area is gradation blackened, and the X-ray irradiation field stop area is blackened. The mechanical sagging of the irradiation field stop 23 and I.I. I. Therefore, it is possible to blacken the halation on the image generated due to the distortion caused by the use of 21 and display an image that can be interpreted.

  Further, according to the second modification of the present embodiment, the X-ray irradiation field stop 23 is converted by converting a positive display fluoroscopic image into a negative display under fluoroscopic imaging and adjusting the aperture of the X-ray irradiation field stop 23. Mechanical sagging and I. I. 21 can reduce the halation on the image caused by distortion due to the adoption of the image 21 and display an image that can be interpreted.

The block diagram which shows this embodiment of the X-ray diagnostic apparatus which concerns on this invention. The perspective view which shows the holding | maintenance apparatus of the X-ray diagnostic apparatus which concerns on this invention. The flowchart which shows the operation | movement of normal imaging | photography in an X-ray diagnostic apparatus. I. I. Schematic which shows the locus | trajectory of. The graph which shows the example of a gradation blackening process function. The graph which shows the relationship between the coordinate on a screen, and a pixel value. The flowchart which shows the modification of this embodiment. (A), (b), (c) is a perspective image displayed on the screen of the display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 X-ray diagnostic apparatus 11 Holding | maintenance apparatus 12 Main body control part 19 X-ray TV apparatus 23 X-ray irradiation field stop 33 X-ray irradiation field stop control part 51 Memory | storage part 52 Display apparatus 55 Blackening process means 56 Gradation blackening process means 57 Gradation Blackening function DB
58 P / N inversion processing means

Claims (8)

A holding device that irradiates the subject with X-rays emitted from a radiation source, and enters the transmitted X-ray that passes through the subject to see through and image the subject, and controls the holding device; In an X-ray diagnostic apparatus comprising a main body control unit that displays an image fluoroscopically / photographed by the holding device on a screen,
An X-ray irradiation field stop for narrowing the X-rays on the radiation side of the radiation source to prevent irradiation of unnecessary parts;
An X-ray irradiation field stop controller for controlling the aperture of the X-ray irradiation field stop;
X-ray irradiation field stop edge coordinates corresponding to the opening side end of the X-ray irradiation field stop are calculated from the photographed image, and an X-ray irradiation field stop area is recognized from the X-ray irradiation field stop edge coordinates. Blackening processing means for blackening,
A gradation blackening processing unit that calculates halation edge coordinates from the captured image, recognizes the halation area from the halation edge coordinates and the X-ray irradiation field stop area, and performs gradation blackening processing;
An X-ray diagnostic apparatus, comprising: a gradation blackening processing function DB storing a plurality of gradation blackening processing functions for performing gradation blackening processing on the halation area. A holding device that irradiates the subject with X-rays emitted from a radiation source, and enters the transmitted X-ray that passes through the subject to see through and image the subject, and controls the holding device; In an X-ray diagnostic apparatus comprising a main body control unit that displays an image fluoroscopically / photographed by the holding device on a screen,
An X-ray irradiation field stop for narrowing the X-rays on the radiation side of the radiation source to prevent irradiation of unnecessary parts;
An X-ray irradiation field stop controller for controlling the aperture of the X-ray irradiation field stop;
An X-ray diagnostic apparatus, comprising: P / N inversion processing means for converting a positive display image into a negative display under fluoroscopic imaging. X-ray irradiation field stop edge coordinates corresponding to the opening side end of the X-ray irradiation field stop are calculated from the fluoroscopic image, and an X-ray irradiation field stop area is recognized from the X-ray irradiation field stop edge coordinates. Then, the blackening processing means for performing blackening processing and the halation edge coordinates are calculated from the fluoroscopic image, and the gradation blackening processing is performed by recognizing the halation area from the halation edge coordinates and the X-ray irradiation field stop area. The X-ray diagnostic apparatus according to claim 2, further comprising gradation blackening processing means. In an X-ray diagnostic method of irradiating a subject with X-rays, fluoroscopically imaging the subject based on transmitted X-rays transmitted through the subject, and displaying the fluoroscopically / photographed image on a screen,
X-ray irradiation field stop edge coordinates corresponding to the opening side end of the X-ray irradiation field stop are calculated from the photographed image, and X-rays for recognizing the X-ray irradiation field stop area from the X-ray irradiation field stop edge coordinates Irradiation field stop area recognition process,
Calculating a halation edge coordinate from the photographed image and recognizing a halation area from the halation edge coordinate and the X-ray irradiation field stop edge coordinate;
A gradation blackening process for gradation blackening the halation area;
A blackening treatment step of blackening the X-ray irradiation field stop area;
An X-ray diagnostic method comprising: the gradation blackening process; and an image display step of displaying the blackened image on a screen. 5. The X-ray diagnosis method according to claim 4, wherein the halation area is displayed in a graphic or color display. In the gradation blackening processing step, a coordinate difference between the halation edge coordinates and the X-ray irradiation field stop edge coordinates is obtained, and a gradation blackening processing function corresponding to the coordinate difference is obtained from a plurality of gradation blackening processing functions. 5. The X-ray diagnosis method according to claim 4, wherein a gradation blackening process is performed between the coordinates using the gradation blackening processing function. In an X-ray diagnostic method of irradiating a subject with X-rays, fluoroscopically imaging the subject based on transmitted X-rays transmitted through the subject, and displaying the fluoroscopically / photographed image on a screen,
A negative conversion process for converting a positive display image displayed on the screen under fluoroscopic imaging into a negative display;
X-ray irradiation field stop edge coordinates corresponding to the opening side end of the X-ray irradiation field stop are calculated from the negative display image, and an X-ray irradiation field stop area is recognized from the X-ray irradiation field stop edge coordinates. A line irradiation field stop area recognition process;
A halation area recognition step of calculating a halation edge coordinate from the negative display image and recognizing a halation area from the halation edge coordinate and the X-ray irradiation field stop edge coordinate;
An X-ray diagnostic method comprising: an X-ray irradiation field stop adjusting step of adjusting an opening of the X-ray irradiation field stop until the halation area becomes a predetermined size. 8. The X-ray diagnostic method according to claim 7, wherein in the X-ray irradiation field stop adjusting step, the X-ray irradiation field stop adjusting step automatically slides stepwise in a direction of narrowing an opening degree of the X-ray irradiation field stop.

Images