JP2011019712A - X-ray equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To photograph only the circumferential region of guide wires or a catheter by high-strength X-ray, while photographing all the other regions by low-strength X-ray in X-ray equipment. <P>SOLUTION: X-ray having different strength distributions according to its irradiated regions is irradiated on a subject by inserting a filter with its central part thicker than its fringe parts into the X-ray irradiation hole. This more reduces the X-ray irradiation quantity in the fringe areas than in the central area of the irradiation region. A transmittance distribution detection part 22 detects the X-ray transmittance distributions, an X-ray strength correction part 23 corrects the transmittance distribution deviation on a detected image, and an X-ray image composition part 24 removes noises from the detected image, etc. and composes an X-ray photograph. The composed X-ray image has a natural harmony as a whole, because the transmittance distributions are corrected, and has a higher visibility at the central part than at the fringe parts of the image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray fluoroscopic apparatus that captures a fluoroscopic image of a subject with X-rays, and more particularly to a technique for adjusting X-ray intensity.

  A conventional X-ray fluoroscopic apparatus includes an X-ray tube that generates X-rays and irradiates the subject with X-rays, and an X-ray detector that detects X-rays transmitted through the subject. The X-ray tube emits thermoelectrons from the filament by passing a current through the filament, and X-rays are generated when the thermoelectrons collide with the target. The X-ray intensity can be adjusted by the current flowing through the filament.

  Treatment by the IVR (Interventional Radiology) method is actively performed using this X-ray fluoroscopic apparatus. In the IVR method, various treatments can be performed by inserting a catheter or the like into the treatment site. In order to insert this catheter, an ultrafine guide wire is inserted into the treatment site while observing a fluoroscopic image. That is, the guide wire or the catheter is introduced to the treatment site while observing an X-ray fluoroscopic image as a moving image while continuously irradiating the subject with X-rays. At this time, it is necessary to increase the X-ray intensity in order to increase the visibility of the movement of the guide wire or the tip of the catheter.

  Therefore, X-rays with increased intensity are irradiated to the X-ray irradiation region with the same intensity, and the entire X-ray irradiation region is observed in the same situation. In the IVR method, a guide wire or a catheter may be inserted from the base of the thigh of the subject to reach the heart, for example. In the X-ray diagnostic imaging apparatus of Patent Document 1, high energy X-rays in which the number of photons on the low photon energy side is reduced and low energy X-rays on which the photon number on the low photon energy side are not reduced alternately Each of the fluoroscopic images obtained by irradiating was observed and synthesized.

JP 2001-87254 A

  However, since X-rays with increased intensity are irradiated, there is a problem that the patient's exposure dose increases. Moreover, if irradiation is continued from the thigh of the subject to the heart, the exposure dose further increases. Moreover, since high energy X-rays are irradiated to the whole irradiation area | region, the operator's exposure dose by scattered X-rays also increases.

  Further, in the process of introducing the guide wire or the catheter to the treatment site, only the periphery where the guide wire or the catheter is inserted needs to be a highly visible X-ray fluoroscopic image, and it is necessary to improve the visibility of the entire fluoroscopic image. There is no.

  The present invention has been made in view of such circumstances, and provides an X-ray fluoroscopic imaging apparatus in which X-ray intensities irradiated in an X-ray irradiation region to be improved in visibility and other irradiation regions are different. The purpose is to do.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention described in claim 1 is an X-ray fluoroscopic apparatus, an X-ray irradiator that irradiates X-rays, and an intensity converter that converts the irradiated X-rays to different intensities depending on an irradiation region; A radiation detector for detecting the irradiated X-rays; a transmission distribution detection unit for detecting a transmission distribution of the X-rays transmitted through the intensity converter; and the transmission detected by the transmission distribution detection unit And an intensity correction unit that corrects the gradation of the pixel value detected by the radiation detector based on the degree distribution.

  According to the above configuration, the X-rays emitted from the X-ray irradiator can be converted into different intensities depending on the X-ray irradiation region by the intensity converter. X-rays converted to different intensities are detected by a radiation detector, and a transmittance distribution detector detects a different X-ray transmittance distribution depending on the irradiation region. Based on this transmittance distribution, the intensity correction unit corrects the gradation of the pixel value detected by the X-ray detector, so that it is possible to correct the bias of the transmittance distribution by the intensity converter. As a result, it is possible to capture images with different X-ray intensities on the same fluoroscopic image, and to correct the contrast of the fluoroscopic images due to the difference in X-ray intensity. That is, on the same fluoroscopic image, a certain area can improve the visibility, and an area other than the area where the visibility is improved can reduce the exposure amount of the X-ray to the subject. Furthermore, the exposure dose of the scattered X-rays to the practitioner can also be reduced.

  Further, the intensity converter is a filter having different X-ray transmittances in the central portion and the peripheral portion, and it is desirable that the central portion has a higher X-ray transmittance than the peripheral portion. By transmitting X-rays having a uniform intensity distribution through this filter, it can be easily converted into X-rays having a transmittance distribution having a higher X-ray intensity at the center than at the periphery.

  Further, a wire insertion detection unit that detects that a guide wire or a catheter is inserted from a fluoroscopic image of the subject, and a conversion that inserts the intensity converter into the irradiation region of the X-rays irradiated from the X-ray tube It is good also as a structure in which the said transducer insertion part inserts the said intensity | strength converter by detecting that the said wire insertion detection part has inserted the guide wire or the catheter.

  According to this configuration, when the guide wire or the catheter is inserted into the subject, the wire insertion detection unit detects from the fluoroscopic image of the subject that the guide wire or the catheter is inserted, and the transducer insertion unit Automatically inserts the intensity converter into the X-ray irradiation area irradiated from the X-ray tube. Thus, it is possible to reliably reduce the amount of X-ray exposure to the subject without forgetting to insert the transducer when inserting the guide wire or the catheter into the subject.

  Furthermore, an imaging region discriminating unit that discriminates in which part of the subject the guide wire or the catheter is inserted from a fluoroscopic image of the subject, and a guide wire or catheter discriminated by the imaging site discriminating unit are inserted. An intensity converter selecting unit that selects an intensity converter having a different conversion intensity depending on a part may be provided, and the converter inserting unit may be configured to insert the intensity converter selected by the intensity converter selecting unit.

  According to this configuration, the transducer can be adjusted according to the site where the catheter or guide wire is inserted into the subject. As a result, in a part where the visibility does not need to be raised to a high degree, a converter having a low X-ray transmittance as a whole can be used, so that the exposure dose can be further reduced.

  Further, the X-ray fluoroscopic apparatus is an X-ray irradiator that irradiates a subject into which a guide wire or a catheter is inserted, and an intensity conversion that converts the irradiated X-rays into different intensities depending on an irradiation region. A radiation detector that detects X-rays that have passed through the subject into which a guide wire or a catheter has been inserted, a transmittance distribution detector that detects a transmittance distribution of the X-rays that has passed through an intensity converter, It is good also as a structure provided with the intensity | strength correction | amendment part which correct | amends the gradation of the pixel value detected with the X-ray detector based on the transmittance | permeability distribution.

  Furthermore, the transmittance distribution detection unit may detect an edge of the transmittance distribution of the pixel value detected by the radiation detector. According to this configuration, since the transmittance distribution of pixel values is detected each time fluoroscopic imaging is performed, the transmittance distribution can be accurately detected even when the converter is changed.

  Alternatively, the transmittance distribution detection unit may detect the image data based on image data captured in advance without the subject. According to this configuration, since it is not necessary to detect the transmission distribution every time fluoroscopic imaging is performed, it is possible to increase the processing of the detection calculation. This is particularly useful when the transducer is not changed.

  In addition, the intensity correction unit may change the central gradation value of the detection image formed from the pixel values according to the transmittance distribution of the pixel values. According to this configuration, since the central gradation value of the detected image is changed according to each transmittance distribution, fluctuations in the transmittance distribution can be suppressed, and a natural perspective image as a whole can be obtained. Furthermore, an input unit is provided for setting a median gradation value corresponding to regions having different transmittances generated by the intensity converter, and the intensity correction unit is a detection image of each region having different transmittances generated by the intensity converter. By setting the central gradation value to a value set by the input unit, the gradient of pixel values between regions having different transmittances may be reduced. As a result, since the central gradation value of each region having different transparency becomes a value set by the input unit, the gradient of the pixel value between the regions can be reduced, and the perspective due to the difference in transparency can be reduced. The brightness of the image can be reduced.

  Alternatively, the intensity correction unit increases the gain of the pixel value having a low X-ray transmission intensity according to the transmittance distribution of the pixel value, thereby reducing the gradient of the pixel value between the regions having different transmittances generated by the intensity converter. It is good also as a structure. According to this configuration, by increasing the gain of a pixel value having a low X-ray transmittance, it is possible to obtain a fluoroscopic image that does not feel a boundary portion and brightness caused by a difference in X-ray transmittance.

  According to the X-ray fluoroscopic apparatus according to the present invention, it is possible to provide an X-ray fluoroscopic apparatus having different X-ray intensities irradiated in an X-ray irradiation area whose visibility is desired to be improved and other irradiation areas.

1 is an overall view of an X-ray fluoroscopic apparatus according to Embodiment 1. FIG. 1 is a front view showing a filter according to Example 1. FIG. FIG. 3 is a block diagram illustrating a configuration of an image processing unit according to the first embodiment. It is explanatory drawing which shows the irradiation area | region from which the X-ray intensity differs on the flat detector which concerns on Example 1. FIG. 6 is a graph showing pixel values based on X-ray detection values that have passed through a filter according to Embodiment 1. FIG. 6 is a graph showing pixel values based on X-ray detection values that have passed through a filter according to Embodiment 1. FIG. FIG. 6 is a graph showing image correction according to the first embodiment. FIG. 10 is a block diagram illustrating a configuration of an image processing unit according to a second embodiment. It is a graph which shows the image correction which concerns on a modification.

Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall view of a fluoroscopic imaging apparatus, FIG. 2 is a front view showing a filter, and FIG. 3 is a block diagram showing a configuration of an image processing unit.

  As shown in FIG. 1, the X-ray fluoroscopic imaging apparatus 1 converts an X-ray tube 2 that irradiates a subject M with X-rays, and the X-rays irradiated from the X-ray tube 2 into different intensities depending on the irradiation region. A filter 3 and an X-ray flat detector (flat panel detector: hereinafter referred to as FPD) 4 for detecting X-rays transmitted through the subject M are provided. The X-ray tube 2 and the FPD 4 are attached to both ends of the C-type arm 5 so as to face each other. The C-type arm 5 is moved by a C-type arm moving mechanism 6, and the movement amount of the C-type arm moving mechanism 6 is controlled by a C-type arm movement control unit 7.

  The C-type arm 5 is configured to be vertically movable (R1) with respect to the top plate 8 on which the subject M is placed. Further, the arm support 9 that supports the C-shaped arm 5 is attached to be rotatable (R2) around a vertical axis. The C-arm 5 is rotatable around a horizontal axis (R3) and is attached to the arm support 9 so as to be movable in an arcuate shape (R4). Further, in order to adjust the SID (Source Image Distance) that is the distance between the X-ray tube 2 and the FPD 4, the FPD 4 can be moved in the vertical direction (R 5) by the C-type arm moving mechanism 6.

  In addition, the X-ray fluoroscopic apparatus 1 also receives an X-ray tube control unit 10 that controls a tube voltage and a tube current output to the X-ray tube 2 and an analog X-ray detection signal output from the FPD 4. An A / D converter 11 for converting into a digital X-ray detection signal, an image processing unit 12 for performing various image processing from the digital X-ray detection signal, and a main control unit 13 for controlling these components overall. An input unit 14 on which a photographer inputs various imaging conditions, a monitor 15 for displaying an X-ray diagnostic operation screen and an image-processed X-ray fluoroscopic image, an X-ray fluoroscopic image and other imaging data A storage unit 16 to be stored, and a filter insertion unit 17 that performs insertion and extraction of the filter 3 in the X-ray path irradiated from the X-ray irradiation port on the irradiation surface side of the X-ray tube 2 are provided.

  The X-ray tube 2 generates X-rays by causing thermal electrons to collide with the target. The generated X-rays are irradiated toward the FPD 4 from an X-ray irradiation port through which X-rays can be transmitted. The X-ray tube 2 is provided with a soft X-ray removal filter that transmits X-rays in a hard X-ray region effective for X-ray fluoroscopic imaging and removes X-rays in the soft X-ray region. Thus, the X-rays irradiated from the X-ray tube 2 are X-rays in the hard X-ray region. The X-ray tube 2 corresponds to the X-ray irradiator in the present invention.

  As shown in FIG. 2, the filter 3 is provided with a high transmission region 3a having a high X-ray transmission at the center, and the X-ray transmission is higher in the peripheral portion of the high transmission region 3a than in the high transmission region 3a. Low transmission region 3b is provided. The filter 3 is made of Al (aluminum) or the like, and the thickness is different between the high transmission region 3a and the low transmission region 3b. The thickness of the high transmission region 3a is thin, and the thickness of the low transmission region 3b is increased to make a difference in the X-ray transmittance. When X-rays pass through the filter 3, the intensity of the X-rays is reduced regardless of whether they are characteristic X-rays or hard X-rays in proportion to the thickness. The filter 3 corresponds to the intensity converter in the present invention.

  In the FPD 4, for example, 2048 × 2048 detection elements that convert X-rays formed on the active matrix substrate into charge signals are arranged in a two-dimensional array. When this detection element is irradiated with X-rays, it generates a charge signal proportional to the energy of the X-rays. The generated charge signal is read out as an X-ray detection signal for each detection element by the active matrix substrate. The FPD 4 corresponds to the radiation detector in the present invention.

  The main control unit 13 includes a central processing unit (CPU). The input unit 14 includes a pointing device represented by a mouse, a keyboard, a joystick, a trackball, a touch panel, and the like. The photographer can instruct the movement amount of the C-arm and the start of X-ray imaging using the input unit 14.

<Image processing unit>
Next, the image processing unit 12 will be described in detail. As shown in FIG. 3, the image processing unit 12 includes an image memory unit 21 that stores a digital X-ray detection signal converted by the A / D converter 11 as a detection image, and an X converted by the filter 3. A transmittance distribution detecting unit 22 for detecting the transmittance distribution of the line, an intensity correcting unit 23 for correcting the gradation of the detected image based on the transmittance distribution, and a detected image or intensity correcting unit stored in the image memory unit 21 A fluoroscopic image constructing unit 24 that constructs a fluoroscopic image from the detection image corrected by 23, and wire insertion that detects that a guide wire or a catheter is inserted into the subject from the fluoroscopic image obtained by the fluoroscopic image constructing unit 24 And a detection unit 25.

  The transmittance distribution detector 22 detects an edge on the detected image of the X-ray transmittance distribution whose intensity has been converted by the filter 3. As shown in FIG. 4, when the X-rays irradiated from the X-ray tube 2 pass through the filter 3, a high detection region 4a and a low detection region 4b are also generated on the FPD 4 that detects X-rays. The pixel value from the detection element belonging to the low detection region 4b of the FPD 4 irradiated with the X-rays transmitted through the low transmission region 3b of the filter 3 is the high detection of the FPD 4 irradiated with the X-rays transmitted through the high transmission region 3a of the filter 3. It is lower than the pixel value from the detection element belonging to the region 4a. For example, FIG. 5 shows pixel values based on X-ray detection values when the subject M is irradiated on the FPD 4 through the filter 3 without being placed on the top plate 8. .

FIG. 5 is a graph of pixel values based on the detection values from the detection elements in the AA arrow view in the FPD 4 of FIG. Pixel values from detector elements belonging to the high detection area 4a of FPD4 is _{d 1,} the pixel values from the detector elements belonging to the low detection area 4b of FPD4 is _{d 2.} The detected image is also divided into a high detection region and a low detection region, and such a deviation occurs in the detected transmittance distribution. Therefore, the transmittance distribution detection unit 22 detects an edge that is a boundary of each region. Similarly, in the detection image detected through the subject M, the detection transmittance distribution due to the filter 3 is biased, so that an edge that separates the high detection region and the low detection region is detected. Thus, it can be determined whether the pixel value in the detected image belongs to the high detection region or the low detection region.

  The intensity correction unit 23 corrects the bias of the transmittance distribution due to the filter 3 for each pixel value of the detected image. If the detected pixel value is directly configured as a fluoroscopic image, the central portion of the fluoroscopic image is bright and the peripheral portion is dark, and a natural fluoroscopic image cannot be obtained. Therefore, by performing different image processing on each pixel value from the high detection region 4a detected by the transmittance distribution detection unit 22 and each pixel value from the low detection region 4b, an edge that is the boundary between the regions Can be eliminated. By eliminating the edge, it is possible to reduce the gradient of the pixel value between the two regions having different transmittances, and to keep the brightness and darkness of the fluoroscopic image natural.

For this image processing, a Width / Level method for designating the median and width of the gradation of the pixel value is used. FIG. 6 illustrates pixel values of an X-ray detection image transmitted through the filter 3 and the subject M. Pixel value variation in the vicinity of the pixel value d ₃ is detected pixel values from the high detection region 4a of FPD4, pixel value that varies in the vicinity of the pixel value d ₄ was detected in a low detection area 4b of FPD4 It is a pixel value.

Since the edge is detected by the transmittance distribution detection unit 22, each pixel value of the detected image is discriminated into a pixel value detected from the high detection region 4a and a pixel value detected from the low detection region 4b. Yes. Here, when the number of bits of the image data of the detected image is 12, the gradation from black to white can be taken between 0 and 4095. In each pixel value detected from the high-transmission detection area 4a, a corrected image is configured with a pixel value existing in the range of d ₃ ± k as d ₃ as a median value m of the gradation of the image data. Further, a corrected image is configured with the pixel value present in the range of d ₄ ± k in each pixel value detected from the low detection region 4b, and d ₄ as the median value m of the gradation of the image data. On the corrected image, each pixel value detected from the high-transmission detection area 4a is uniformly displayed in white for pixels having a pixel value of d ₃ + k or more, and black for pixels having a pixel value of d ₃ -k or less. Displayed uniformly. In addition, in each pixel value detected from the low detection region 4b, pixels having a pixel value of d ₄ + k or higher are uniformly displayed in white on the corrected image, and pixels having a pixel value of d ₄ −k or lower are displayed. Displayed uniformly in black.

The photographer selects the reference pixel values (Level) d ₃ and d ₄ and the gradation width (Width) k, which serve as the gradation reference in each area, and the corrected image after correcting the different reference pixel values in each area The same median of the gradations. That is, the pixel value of the corrected image is as shown in FIG. Since the edge between the pixel value detected from the high detection area 4a and the pixel value detected from the low detection area 4b can be eliminated, the corrected image becomes an image having natural gradation as a whole. This corrected image is sent to the fluoroscopic image construction unit 24. The reference pixel values d ₃ and d ₄ and the gradation width k are selected by the photographer inputting respective values to the input unit 14. The input value is sent to the intensity correction unit 23 via the main control unit 13. As described above, the intensity correction unit 23 sets the reference pixel value for each region selected by the operator for each pixel value belonging to the two types of regions of the high detection region and the low detection region on one detection image. The corrected image is configured as the central pixel value of the pixel values belonging to the. Thereby, the gradient of the pixel value between each area | region can be reduced.

  The fluoroscopic image construction unit 24 constructs a fluoroscopic image by removing noise from the detected image stored in the image memory unit 21. In addition, when the filter 3 is inserted, noise is removed from the corrected image whose intensity has been corrected by the intensity correcting unit 23 to form a fluoroscopic image. The fluoroscopic image is sent to the wire insertion detection unit 25 and transferred to the main control unit 13. The fluoroscopic image transferred to the main control unit 13 is displayed on the monitor 15 or stored in the storage unit 16.

  The wire insertion detection unit 25 detects a guide wire or a catheter by image recognition from the fluoroscopic image obtained from the fluoroscopic image construction unit 24. When a guide wire or a catheter is detected from the fluoroscopic image, a wire detection signal is output to the main control unit 13. When the wire detection signal is sent, the main control unit 13 controls the filter insertion unit 17 to insert the filter 3 into the X-ray irradiation port of the X-ray tube 2. Thus, when a guide wire or a catheter is inserted into the subject M, the filter 3 is automatically inserted into the X-ray irradiation port of the X-ray tube 2 by the filter insertion unit 17. The filter insertion portion 17 corresponds to the converter insertion portion in the present invention.

  Next, an X-ray imaging operation when a guide wire or a catheter is inserted into a subject will be described.

  When a radiographer instructs the input unit 14 to start X-ray imaging, the main control unit 13 controls the X-ray tube control unit 10 and the FPD 4. The X-ray tube control unit 10 applies a tube voltage or a tube current to the X-ray tube 2 based on an instruction from the main control unit 13, and the subject M is irradiated with X-rays from the X-ray tube 2. X-rays transmitted through the subject M enter the FPD 4 and are detected by the detection element. The X-ray detection signal detected by the detection element is converted from analog to digital by the A / D converter 11. The X-ray detection signal converted into digital is transferred to the image processing unit 12 and stored as a detected image in the image memory unit 21.

  The detected image transferred to the image memory unit 21 is subjected to image processing such as noise removal in the perspective image configuration unit 24 to be formed into a perspective image. This fluoroscopic image is displayed on the monitor 15 via the main control unit 13 so that the photographer and the operator can see the fluoroscopic image of the subject M.

  The fluoroscopic image is also transferred to the wire insertion detection unit 25. The wire insertion detection unit 25 performs image recognition to determine whether a guide wire or a catheter is reflected in the fluoroscopic image. When the image of the guide wire or catheter is recognized and the guide wire or catheter is recognized in the fluoroscopic image, a wire detection signal is output to the main control unit 13 and the intensity correction unit 23.

  When a wire detection signal is input to the main control unit 13, the normal shooting mode is automatically switched to the wire shooting mode. In the wire imaging mode, a high-accuracy image is required only at the center of a fluoroscopic image for imaging a guide wire or a catheter. Thus, the main control unit 13 instructs the filter insertion unit 17 to insert the filter 3 into the X-ray irradiation port of the X-ray tube 2.

  The filter insertion unit 17 inserts the filter 3 into the X-ray irradiation port of the X-ray tube 2 according to an instruction from the main control unit 13. As a result, the X-rays emitted from the X-ray tube 2 have a uniform intensity distribution, but are converted into a transmittance distribution with a high intensity at the center of the X-ray irradiation area and a low intensity at the periphery.

  The detected image with the deviation of the transmittance distribution is corrected by the image processing unit 12. The transmittance distribution detection unit 22 in the image processing unit 12 detects an edge that is a boundary between the high detection region and the low detection region in the detection image.

  When a wire detection signal is input from the wire insertion detection unit 25 to the intensity correction unit 23, the intensity correction unit 23 reads a detection image from the image memory unit 21 and based on the edge detected by the transmittance distribution detection unit 22. Intensity correction of the detected image is performed on the pixel values belonging to each region by using the Width / Level method. The corrected image in which the photographer sets the center value of the gradation of the pixel value in each area from the input unit 14 and the intensity is corrected based on the value of the width of the pixel value stored as the gradation is a perspective image configuration Transferred to the unit 24.

  Further, when a wire detection signal is input from the wire insertion detection unit 25 to the fluoroscopic image configuration unit 24, the fluoroscopic image configuration unit 24 stops reading the detected image from the image memory unit 21 and corrects from the intensity correction unit 23. Read the image. The corrected image is subjected to noise removal or the like to form a fluoroscopic image. The fluoroscopic image is displayed on the monitor 15 via the main control unit 13 and is also transferred to the wire insertion detection unit 25. The wire insertion detection unit 25 again recognizes the guide wire or the catheter in the fluoroscopic image, so that the wire imaging mode is maintained.

  Thus, according to the X-ray fluoroscopic imaging apparatus 1 of Example 1, when a guide wire or a catheter is inserted into a subject, image recognition that the guide wire or the catheter is inserted from a fluoroscopic image of the subject, It automatically shifts to the wire shooting mode. Thus, the filter 3 is inserted into the irradiation port of the X-ray tube 2 from the filter insertion portion 17. On the detection image of the subject by the X-rays transmitted through the filter 3, a difference in transmittance distribution due to the difference in the converted X-ray intensity appears clearly. The central portion of the detected image is an overall bright region, and the peripheral portion of the detected image is an entirely dark region. By detecting the light and dark edges of the detected image divided into light and dark, the photographer sets the center value of the gradation of the pixel value in each region, and sets the width of the pixel value to be stored as the gradation. The gradient of the pixel values of the image of the area and the image of the dark area can be reduced, and the entire image can be displayed as one natural image. In addition, since the discrimination between the high detection area and the low detection area is automatically performed, the operator does not need to specify the area, and only inputs the median gradation value and the width of the pixel value of each area. Therefore, convenience is improved.

  Accordingly, the central portion of the fluoroscopic image in which the guide wire or the catheter is reflected is irradiated with high-intensity X-rays, so that visibility can be improved. Since the X-ray intensity is reduced by the filter 3 in other peripheral portions of the fluoroscopic image, the exposure dose to the region other than the region of interest can be reduced. In addition, since the X-ray intensity is high only in the central portion of the X-ray irradiation region, the scattered X-ray dose with high intensity can be reduced, and the exposure dose of the operator can also be reduced.

  In the first embodiment described above, the filter 3 during insertion of the guide wire or catheter is fixed. However, the type of the filter 3 may be changed depending on the insertion site of the guide wire or catheter. In this case, as shown in FIG. 8, the image processing unit 27 includes an imaging part determination unit 26 that recognizes an image of which part of the fluoroscopic image is acquired. Hereinafter, only differences between the first embodiment and the second embodiment will be described, and description of common items will be omitted.

  The image processing unit 27 according to the second embodiment includes an imaging region determination unit 26 in addition to the components of the first embodiment. When the wire insertion detection unit 25 recognizes an image of a guide wire or a catheter in a fluoroscopic image, a wire detection signal is sent to the imaging region determination unit 26. When the wire detection signal is input, the imaging region determination unit 26 reads out the fluoroscopic image to the fluoroscopic image configuration unit 24 and determines which part of the subject is captured by the fluoroscopic image from which the guide wire or the catheter is detected. Recognize images. Thus, it is possible to determine in which part the guide wire or the catheter is inserted. The determined imaging part information is sent to the filter selection unit 28 as part data.

  The filter selection unit 28 selects the optimum filter 3 from the part data. For example, the required visibility differs when a guide wire or the like is inserted into the base of the thigh and when a guide wire or the like is inserted into the heart. In other words, when a guide wire or the like is inserted into the base of the thigh, visibility may be lower than when a guide wire or the like is inserted into the heart, so overall transmittance is reduced. A low filter 3 can be selected. By selecting the optimum filter 3 according to the part where the guide wire or the like is inserted from among the plurality of filters 3 in which the thickness of the high transmission region 3a of the filter 3 is changed, the minimum X A dose can be irradiated and the exposure dose can be reduced. The filter selection unit 28 corresponds to the intensity converter selection unit in the present invention.

  The filter selection unit 28 sends a selection signal for selecting the optimum filter 3 for the imaging region into which the guide wire or the like is inserted to the filter insertion unit 17 via the main control unit 13. The filter insertion unit 17 inserts or replaces the selected filter 3 into the X-ray irradiation port.

  As described above, according to the X-ray fluoroscopic imaging apparatus of the second embodiment, the imaging region determination unit 26 determines the imaging region from the fluoroscopic image from which the guide wire or the like is detected, so even when the guide wire or the like moves, The filter 3 can be optimally replaced during shooting. As a result, the minimum necessary X-ray dose can be irradiated by the imaging region, and the exposure dose of the subject and the operator can be reduced.

  The present invention is not limited to the above embodiment, and can be modified as follows.

  (1) In the above-described embodiment, the transmittance distribution detection unit 22 detects the edge of the intensity change by the filter 3. However, while the filter 3 is inserted into the X-ray irradiation port of the X-ray tube 2 in advance, The transmittance distribution may be obtained from a detection image taken in a state where the sample M is not placed on the top board 8. That is, the transmittance distribution detection unit 22 multiplies the pixel value of the low transmission region 4b so that the pixel value belonging to the low transmission region 4b and the pixel value belonging to the high transmission region 4a of the detected image have the same value. A correction coefficient is calculated. The calculated correction coefficient is transferred from the transmittance distribution detection unit 22 to the intensity correction unit 23.

  In this case, the intensity correction unit 23 corrects the intensity by increasing the gain, not by adjusting Width / Level. As shown in FIG. 9, in the intensity correction unit 23, when a wire detection signal is input from the wire insertion detection unit, a pixel value belonging to the low transmission region 4b with respect to a detection image sent through the image memory unit 21. Further, the gain is increased by multiplying the correction coefficient transferred from the transmission distribution detector 22 to correct the bias of the X-ray transmission distribution by the filter 3. As a result, the gradient of the pixel value between the regions having different transmittances generated by the filter 3 can be reduced, so that the image of the bright region and the image of the dark region are displayed as one natural image as a whole. Can do. The corrected detection image is transferred to the fluoroscopic image construction unit 24 and configured as a fluoroscopic image.

  (2) In the above-described embodiment, only one filter 3 is inserted into the X-ray irradiation port. However, a plurality of filters may be inserted in a stacked manner. If a plurality of filters having different area areas of the low transmission area 3b are prepared, the adjustment of the areas of the high transmission area 3a and the low transmission area 3b can be simplified. As a result, even if the size of the organ that is desired to avoid exposure varies, the exposure dose can be reduced by selecting a filter having a different area area of the low transmission region 3b.

  (3) In the above-described embodiment, the irradiation intensity of the X-ray tube 2 does not change even when the wire insertion unit 25 outputs a wire detection signal to the main control unit 13. However, the irradiation intensity may be increased. That is, when the wire detection signal is input to the main control unit 13, the main control unit 13 instructs the X-ray tube control unit 10 to increase the tube current of the X-ray tube 2. By this instruction, the X-ray tube control unit 10 can increase the tube current flowing in the X-ray tube 2 and increase the X-ray intensity irradiated from the X-ray irradiation port. Since the filter 3 has already been inserted into the X-ray irradiation port by the wire detection signal, it is possible to increase the X-ray intensity only at the center of the X-ray irradiation region. Further, since the X-ray intensity at the periphery of the X-ray irradiation region is reduced by the filter 3, even if the irradiation amount is the same as when the entire irradiation is uniform, the visibility of the central portion of the X-ray irradiation region Can be improved.

  (4) In the embodiment described above, the filter 3 has a quadrangular shape in the high transmission region 3a, but may be circular. Moreover, not only circular but a polygon may be sufficient.

DESCRIPTION OF SYMBOLS 1 ... X-ray fluoroscope 2 ... X-ray tube 3 ... Filter 4 ... FPD
12, 27 ... Image processing unit
DESCRIPTION OF SYMBOLS 17 ... Filter insertion part 22 ... Transmittance distribution detection part 23 ... Intensity correction part 24 ... Perspective image structure part 25 ... Wire insertion detection part 26 ... Imaging | photography part discrimination | determination part 28 ... Filter selection part M ... Subject

Claims (10)

X-ray fluoroscopic apparatus,
An X-ray irradiator that emits X-rays;
An intensity converter that converts the irradiated X-rays into different intensities depending on the irradiation area;
A radiation detector for detecting the irradiated X-ray;
A transmittance distribution detector that detects a transmittance distribution of the X-rays transmitted through the intensity converter;
An X-ray fluoroscopic apparatus comprising: an intensity correction unit that corrects a gradation of a pixel value detected by the radiation detector based on the transmission distribution detected by the transmission distribution detection unit . The X-ray fluoroscopic apparatus according to claim 1,
The X-ray fluoroscopic imaging apparatus, wherein the intensity converter is a filter having different X-ray transmittances at a central portion and a peripheral portion, and the central portion has a higher X-ray transmittance than the peripheral portion. The X-ray fluoroscopic apparatus according to claim 1 or 2,
A wire insertion detection unit for detecting that a guide wire or a catheter is inserted from a fluoroscopic image of a subject;
A transducer insertion section for inserting the intensity converter into an irradiation region of X-rays irradiated from the X-ray tube;
The X-ray fluoroscopic imaging apparatus, wherein the transducer insertion unit inserts the intensity transducer when the wire insertion detection unit detects that a guide wire or a catheter is inserted. The X-ray fluoroscopic apparatus according to claim 3,
An imaging region discriminating unit for discriminating in which part of the subject a guide wire or a catheter is inserted from the fluoroscopic image of the subject;
An intensity converter selecting unit that selects the intensity converter having a different conversion intensity depending on the part where the guide wire or catheter determined by the imaging region determining unit is inserted;
The X-ray fluoroscopic imaging apparatus, wherein the converter inserting unit inserts an intensity converter selected by the intensity converter selecting unit. X-ray fluoroscopic apparatus,
An X-ray irradiator for irradiating a subject into which a guide wire or catheter is inserted;
An intensity converter that converts the irradiated X-rays into different intensities depending on the irradiation area;
An X-ray radiation detector for detecting X-rays transmitted through the subject into which a guide wire or a catheter is inserted;
A transmittance distribution detector for detecting a transmittance distribution of the X-rays transmitted through the intensity converter;
An X-ray fluoroscopic apparatus comprising: an intensity correction unit that corrects a gradation of a pixel value detected by the X-ray detector based on the transmission distribution. In the X-ray fluoroscopic apparatus according to any one of claims 1 to 5,
The X-ray fluoroscopic imaging apparatus, wherein the transmission distribution detection unit detects an edge of a transmission distribution of pixel values detected by the radiation detector. In the X-ray fluoroscopic apparatus according to any one of claims 1 to 5,
2. The X-ray fluoroscopic apparatus according to claim 1, wherein the transmission distribution detecting unit detects based on image data previously captured without a subject. The X-ray fluoroscopic apparatus according to any one of claims 1 to 7,
The X-ray fluoroscopic imaging apparatus, wherein the intensity correction unit changes a median gradation value of a detection image composed of the pixel values according to a transmittance distribution of the pixel values. The X-ray fluoroscopic apparatus according to claim 8,
An input unit for setting the median gradation value corresponding to regions of different transmittance generated by the intensity converter;
The intensity correction unit is configured to set a central gradation value of a detection image of each region having different transmittances generated by the intensity converter to a value set by the input unit, so that pixel values between regions having different transmittances are set. An X-ray fluoroscopic apparatus characterized by reducing the gradient of the X-ray. The X-ray fluoroscopic apparatus according to any one of claims 1 to 7,
The intensity correction unit reduces a pixel value gradient between regions having different transmittances generated by the intensity converter by increasing a gain of a pixel value having a low X-ray transmission intensity according to the transmittance distribution of the pixel values. An X-ray fluoroscopic apparatus characterized by:

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