JP2012176082A - X-ray diagnostic apparatus and x-ray diagnostic program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray diagnostic apparatus and an X-ray diagnostic program attaining simultaneous observation of a portion extracted by subtraction processing, and a high contrast object and a low contrast object in a background.SOLUTION: A subtraction image creating section 35 creates a subtraction image by carrying out subtraction processing from a mask image acquired based on the output of an X-ray detector 7 and on a live image acquired based on the output of the X-ray detector 7. In parallel with the subtraction processing, a dynamic range compressed image creating section 37 creates a dynamic range compressed image using one of the mask image and live image and carrying out dynamic range compression only to low frequency components out of the low frequency components and high frequency components included in the image. A composite image creating section 43 creates a composite image by superimposing the subtraction image and the dynamic range compressed image.

Description

  The present invention relates to an X-ray diagnostic apparatus and an X-ray diagnostic program for displaying an image of a part extracted by digital subtraction processing and a background image which is information other than the extracted part.

  In conventional X-ray diagnostic apparatuses, digital subtraction angiography (DSA) is used as an imaging method for clearly viewing a blood vessel into which a contrast medium has been injected (see, for example, Patent Document 1). In DSA imaging, a mask image, which is an image in which no contrast medium is injected, and a live image, which is an image in which a contrast medium is injected, are subtracted by image processing, and only the blood vessels into which the contrast medium is injected are extracted. By creating a DSA image that is an image, blood vessels can be easily visually recognized. At this time, information other than blood vessels such as organs and bones (hereinafter abbreviated as “background”) is erased by image processing subtraction and cannot be seen.

  However, in the diagnosis, the positional relationship between the blood vessel and the background may be important. Live images can be observed with both blood vessel and background information, but generally the blood vessel contrast is often lower than the background, making it difficult to see the blood vessel and the background at the same time. It is. Conventionally, as shown in FIG. 6, first, DSA is performed on a live image and a mask image to create a DSA image. Contrast adjustment is performed on the DSA image to increase (high) the contrast of the blood vessel and enhance the blood vessel. The blood vessel image extracted by the DSA process and the mask image as the background are displayed in an overlapping manner. By this method, the blood vessel and the background can be easily observed simultaneously.

  Patent Document 2 discloses contrast adjustment. According to this, the contrast adjustment is performed in the direction of clarifying the difference in brightness between the region to be diagnosed and the surrounding region. Contrast adjustment includes a window width (window width: WW) for arbitrarily setting the width of the density value when displaying an image, and a window level (WL) for setting the center value of the window width. , Two parameters are adjusted.

  Also, cited document 3 discloses a technique for applying dynamic range compression processing to an image. According to this, for example, predetermined processing is performed on the lowest frequency band image of the lowest frequency band among the images of a plurality of frequency bands obtained by converting the image into a multi-resolution space. Then, by performing demultiplex resolution conversion on the lowest frequency band image subjected to this processing and an image in another frequency band, a processed image subjected to dynamic range compression processing corresponding to the image area is obtained. .

JP 2009-50379 A JP-A-8-96125 JP-A-9-44656

  As described above, by displaying the blood vessel image extracted by DSA and the mask image as the background in an overlapping manner, the blood vessel and the background can be observed simultaneously. However, it is difficult to observe simultaneously high-contrast objects (such as lungs and diaphragm) in the background and low-contrast objects (devices (such as catheters, guidewires, balloons or stents), tumors or bone contours). . Note that a high-contrast object indicates a portion where the difference in pixel value is larger than others. For example, since the lungs easily transmit X-rays, the lungs are brighter than other parts, and the difference in pixel values is large. On the other hand, a low-contrast object indicates a portion where the difference in pixel values is smaller than the others.

  That is, in actual use, a blood vessel and a region of interest in the background to be observed simultaneously are selected, contrast adjustment is performed according to the region of interest, and a blood vessel image extracted by DSA and a mask image as a background are selected. It was necessary to create a superimposed composite image. For example, FIG. 7 shows an example of a conventional composite image. In FIG. 7, the contrast is adjusted in accordance with a relatively bright area (center right part) in the high contrast object. Therefore, it is difficult to observe the blood vessel running in a dark area (upper center). That is, when it is adjusted to the bright area, the dark area becomes too dark and difficult to observe, and when it is adjusted to the dark area, the bright area becomes too bright and difficult to observe. In addition, when the entire image is adjusted, the light gray area becomes thin and difficult to observe. Therefore, for an area that is not focused on in the background information, it is difficult to observe the area that is not focused on and the blood vessels that travel there. That is, conventionally, image information obtained from only blood vessels and high-contrast objects or only blood vessels and low-contrast objects is limited. Therefore, when the operator tries to observe each of the bright area, the dark area, and the light gray area, the operator adjusts the contrast according to each area and prints, for example, an image a plurality of times.

  Further, if dynamic range compression processing is performed on one or both of the mask image and the live image, a false image is generated. Further, when a DSA image is created using them, there is a problem that a false image is further generated.

  The present invention has been made in view of such circumstances, and can simultaneously observe a portion extracted by subtraction processing, a high-contrast object in the background, and a low-contrast object in the background. An object of the present invention is to provide an X-ray diagnostic apparatus and an X-ray diagnostic program.

  In order to achieve such an object, the present invention has the following configuration. That is, an X-ray diagnostic apparatus according to the present invention includes an X-ray irradiation unit that irradiates a subject with X-rays, an X-ray detector that detects X-rays transmitted through the subject, and an output of the X-ray detector. A subtraction image creation unit that creates a subtraction image by performing a subtraction process on a mask image obtained based on the live image obtained based on an output of the X-ray detector, and the mask image is performed in parallel with the subtraction process. Alternatively, using either one of the live images, dynamic range compression that creates a dynamic range compressed image by performing dynamic range compression on only the low frequency component of the low frequency component and high frequency component included in the image. An image creation unit, and a composite image that creates a composite image by superimposing the subtraction image and the dynamic range compressed image And it is characterized in that it comprises an image creation unit.

  According to the X-ray diagnostic apparatus of the present invention, the subtraction image creation unit performs subtraction processing from the mask image acquired based on the output of the X-ray detector and the live image acquired based on the output of the X-ray detector. To create a subtraction image. In parallel with this subtraction processing, the dynamic range compressed image creation unit uses only one of the mask image and the live image and applies only the low frequency component of the low frequency component and high frequency component included in the image. Perform dynamic range compression to create a dynamic range compressed image. Then, the composite image creation unit creates a composite image by superimposing the subtraction image and the dynamic range compressed image.

  The dynamic range compressed image creation unit uses either a mask image or a live image as a background to be combined with the subtraction image, and the low frequency component included in the low frequency component and high frequency component included in the image. Only dynamic range compression is performed. When dynamic range compression is performed only on the low frequency components, the contrast of a small region (device, tumor, bone contour, etc.) remains unchanged, and the contrast of a large region (lung, diaphragm, etc.) can be reduced. As a result, the overall contrast can be reduced. For this reason, when a composite image is created, it is possible to simultaneously observe an image of a portion extracted by subtraction processing, a low-contrast object in the background, and a high-contrast object in the background. In addition, the dynamic range compression processing is performed in parallel with the subtraction processing. Since the dynamic range compression is performed separately from the subtraction process, the false image generated by the dynamic range compression process is not a big problem, and the composite image can be created by performing the subtraction process without considering the false image.

  In other words, a portion extracted by subtraction processing, a high-contrast object in the background, and a low-contrast object in the background can be observed at the same time, and a composite image with a larger amount of information obtained than before can be obtained. Can do.

  An example of the X-ray diagnostic apparatus according to the present invention is that the mask image is an image in which no contrast medium is injected, and the live image is an image in which a contrast medium is injected. As a result, the subtraction image creation unit obtains an image obtained by extracting a portion into which the contrast medium is injected, such as a blood vessel, from the mask image in which the contrast medium is not injected and the live image in which the contrast medium is injected. can do.

  In addition, the X-ray diagnostic apparatus according to the present invention preferably includes a first contrast adjustment unit that enhances a portion extracted by subtraction processing of the subtraction image. Thereby, when a composite image is created by superimposing a subtraction image and a dynamic range compressed image, a subtraction image in which the extracted portion is emphasized can be given.

  In addition, the X-ray diagnostic apparatus according to the present invention preferably includes a second contrast adjustment unit that adjusts the contrast of the created dynamic range compressed image. As a result, the contrast of the dynamic range compressed image used as the background is adjusted, and a composite image can be created by distinguishing from the portion extracted by the subtraction process.

  The X-ray diagnostic program according to the present invention also includes a mask image acquired based on an output of an X-ray detector that detects X-rays transmitted through a subject and a live image acquired based on the output of the X-ray detector. A step of creating a subtraction image by performing a subtraction process on the image, and a low-frequency component included in the image using either one of the mask image or the live image, performed in parallel with the subtraction process, and A step of creating a dynamic range compressed image by performing dynamic range compression only on a low frequency component of high frequency components, and a step of creating a composite image by superimposing the subtraction image and the dynamic range compressed image. These steps are executed by a computer.

  According to the X-ray diagnostic program of the present invention, using either a mask image or a live image as a background to be combined with a subtraction image, a low-frequency component and a high-frequency component included in the image are included. Among them, dynamic range compression is performed only on low frequency components. When dynamic range compression is performed only on the low frequency components, the contrast of a small region (device, tumor, bone contour, etc.) remains unchanged, and the contrast of a large region (lung, diaphragm, etc.) can be reduced. As a result, the overall contrast can be reduced. For this reason, when a composite image is created, it is possible to simultaneously observe an image of a portion extracted by subtraction processing, a low-contrast object in the background, and a high-contrast object in the background. In addition, dynamic range compression is performed in parallel with the subtraction process. That is, since the dynamic range compression process is performed separately from the subtraction process, a false image generated by the dynamic range compression process does not become a big problem, and a composite image can be created without considering this false image.

  In other words, a portion extracted by subtraction processing, a high-contrast object in the background, and a low-contrast object in the background can be observed at the same time, and a composite image with a larger amount of information obtained than before can be obtained. Can do.

  According to the X-ray diagnostic apparatus and the X-ray diagnostic program of the present invention, a low-frequency component included in an image using either a mask image or a live image as a background to be combined with the subtraction image. Dynamic range compression is performed only on the low frequency component of the high frequency component. When dynamic range compression is performed only on the low frequency components, the contrast of a small region (device, tumor, bone contour, etc.) remains unchanged, and the contrast of a large region (lung, diaphragm, etc.) can be reduced. As a result, the overall contrast can be reduced. For this reason, when a composite image is created, it is possible to simultaneously observe an image of a portion extracted by subtraction processing, a low-contrast object in the background, and a high-contrast object in the background. In addition, the dynamic range compression processing is performed in parallel with the subtraction processing. That is, since the dynamic range compression is performed separately from the subtraction process, the false image generated by the dynamic range compression process does not become a big problem, and a composite image can be created without considering this false image.

  In other words, a portion extracted by subtraction processing, a high-contrast object in the background, and a low-contrast object in the background can be observed at the same time, and a composite image with a larger amount of information obtained than before can be obtained. Can do.

It is a block diagram which shows schematic structure of the X-ray diagnostic apparatus which concerns on an Example. (A) is a figure which shows an example of the one-dimensional image before dynamic range compression, (b) is a figure which shows an example of the low frequency component of the image of (a), (c), It is a figure which shows an example of the high frequency component of the image of a), (d) is a figure which shows the image after dynamic range compression. It is a figure where it uses for description of contrast adjustment. It is a flowchart which shows operation | movement of the X-ray diagnostic apparatus which concerns on an Example. It is a photograph which shows an example of the synthesized image produced with the X-ray diagnostic apparatus which concerns on an Example. It is a figure where it uses for description of the method of displaying the conventional blood vessel and its background superimposed. It is a photograph which shows an example of the synthesized image produced with the conventional X-ray diagnostic apparatus.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a schematic configuration of the X-ray diagnostic apparatus according to the embodiment.

  Please refer to FIG. The X-ray diagnostic apparatus 1 is disposed so as to face the X-ray tube 5 with the subject M interposed therebetween, an X-ray tube 5 that irradiates the subject M with X-rays, and the subject M. And an X-ray detector 7 for detecting X-rays transmitted through the subject M. The X-ray tube 5 corresponds to the X-ray irradiation unit in the present invention.

  The X-ray tube 5 is subjected to control necessary for X-ray irradiation by the X-ray tube control unit 9. The X-ray tube control unit 9 includes a high voltage generation unit 11 that generates a tube voltage and a tube current of the X-ray tube 5. The X-ray tube control unit 9 emits X-rays from the X-ray tube 5 in accordance with X-ray conditions such as a tube voltage, a tube current, and an irradiation time set by an input unit 25 described later.

  An injector 13 is disposed at a position adjacent to the top plate 3. A catheter 15 is connected to the injector 13, and a contrast agent is injected into the subject M through the catheter 15. The injection is started, for example, when a signal is given from the main control unit 21 described later, and is similarly stopped by a signal given from the main control unit 21.

  The X-ray detector 7 detects X-rays emitted from the X-ray tube 5 and outputs an X-ray detection signal that is a signal corresponding to the X-ray intensity distribution. The X-ray detector 7 includes a flat panel X-ray detector (FPD), an image intensifier, and the like.

  An A / D converter 17 and an image processing unit 19 are provided following the X-ray detector 7. The A / D converter 17 converts the analog X-ray detection signal output from the X-ray detector 7 into a digital signal. The image processing unit 19 performs various processes on the image based on the digital X-ray detection signal output from the X-ray detector 7. The X-ray diagnostic apparatus 1 includes a main control unit 21 that comprehensively controls each component of the apparatus 1, an output unit 23 that outputs an image processed by the image processing unit 19, and an operator who performs input settings and An input unit 25 for performing various operations and a storage unit 27 for storing processed images are provided.

  The main control unit 21 includes a central processing unit (CPU) and the like, and executes various programs. In addition, the main control unit 21 performs control to move the top 3, the X-ray tube 5 or the X-ray detector 7 on which the subject M is placed to a predetermined position, for example. The output unit 23 includes a display unit such as a monitor and a printer that prints an image. The input unit 25 is configured with a keyboard, a mouse, and the like. The storage unit 27 includes a storage medium such as a read-only memory (ROM), a random-access memory (RAM), or a hard disk.

  The image processing unit 19 includes a mask image creation unit 29, a mask image storage unit 31, a live image storage unit 33, a subtraction image creation unit 35, and a dynamic range compressed image creation unit (hereinafter abbreviated as “DR compressed image creation unit”) 37. The first contrast adjusting unit 39, the second contrast adjusting unit 41, and the composite image creating unit 43 are provided.

  The mask image creation unit 29 creates a mask image in which no contrast agent is injected from a plurality of images acquired based on the output of the X-ray detector 7 with the injector 13 stopped. The mask image is created, for example, by performing a process of averaging a plurality of images obtained continuously at a predetermined timing. The created mask image is stored (collected) in the mask image storage unit 31.

  The live image storage unit 33 displays an image injected with a contrast agent acquired based on the output of the X-ray detector 7 in a state where the contrast agent is injected from the injector 13 into the subject via the catheter 15. Remember. The image is not limited to a single image (frame), but a plurality of images acquired continuously at a predetermined timing set in advance are collected in the live image storage unit 33.

  The subtraction creation unit 35 creates a subtraction image by performing subtraction processing on the mask image acquired based on the output of the X-ray detector 7 and the live image acquired based on the output of the X-ray detector 7. That is, the subtraction image creation unit 35 is read and supplied with the mask image stored in the mask image storage unit 31 and the live image stored in the live image storage unit 33, respectively. The live images are read one by one. The mask image and the live image are taken at the same position of the subject M, and the subtraction processing unit 35 is taken at the same position of the subject M corresponding to the mask image and the mask image. Subtraction processing (DSA processing) is performed on the live image to create a subtraction image.

  The DR compressed image creating unit 37 is performed in parallel with the subtraction process, and dynamic range compression is performed only on the low frequency component of the low frequency component and the high frequency component included in the mask image (hereinafter abbreviated as “DR compression” as appropriate). To create a dynamic range compressed image (hereinafter abbreviated as “DR compressed image” as appropriate). A mask image stored in the mask image storage unit 31 is read and given to the DR compressed image creation unit 37. The DR compression is performed on a predetermined low frequency component included in the mask image.

  Reference is made to FIGS. FIG. 2A is a diagram illustrating an example of a one-dimensional image before dynamic range compression, and FIG. 2B is a diagram illustrating an example of a low-frequency component of the image of FIG. FIG. 2C is a diagram illustrating an example of high frequency components of the image of FIG. 2A, and FIG. 2D is a diagram illustrating an image after DR compression. 2A to 2D indicates the pixel (density) value of each pixel.

  The DR compressed image creation unit 37 performs DR compression on the mask image, that is, the image of FIG. 2A, and a low frequency component based on the line of the symbol r like the line indicated by the symbol p of FIG. Only compresses vertically. The compressed low frequency component is combined with the high frequency component shown in FIG. 2C to obtain a DR compressed image with a reduced contrast as a whole as shown in FIG. The DR compressed image creation unit 37, for example, performs Fourier transform on the mask image to extract low frequency components by a filter (for example, a low pass filter LPF), performs DR compression, and compresses the low frequency components and high frequency components of the mask image. A DR compressed image is created by performing inverse Fourier transform on the synthesized image. The DR compression may use other known methods.

  When DR compression is performed on a low-frequency component included in the mask image, the low-frequency component, that is, the dynamic range of a relatively large region (such as the lung or the diaphragm) is compressed, and the contrast is reduced. By performing DR compression on low frequency components, the overall contrast can be reduced. The high-frequency component is a relatively small region (a portion showing a relatively fine structure such as a device, a tumor, or a bone contour). Since DR compression is performed only on the low frequency component, the contrast of the high frequency component is maintained. That is, it is possible to reduce the contrast of the low frequency component while keeping the contrast of the high frequency component in a relatively small region as it is. Thereby, the high-contrast thing and low-contrast thing of the mask image used as a background can be displayed simultaneously.

  Returning to FIG. The first contrast adjustment unit 39 emphasizes the blood vessel portion extracted by the subtraction processing of the subtraction image. That is, the first contrast adjustment unit 39 adjusts the contrast of the created subtraction image to emphasize the extracted blood vessel portion. The second contrast adjusting unit 41 adjusts the contrast of the created DR compressed image. In contrast adjustment, window processing is performed as described above. The window processing is shown in FIG. In the window processing, a pixel having a pixel value that is equal to or higher than a threshold value for each pixel (density) value of pixels constituting the image is extracted, and a histogram is created. Within the histogram, the window width (WW) and the window level (WL) which is the center value thereof are adjusted.

  The composite image creation unit 43 creates a composite image by superimposing the subtraction image and the DR compressed image. The composite image creation unit 43 superimposes the blood vessel extracted by the subtraction processing of the subtraction image and the DR compressed image of the mask image as a background. A composite image having a blood vessel and its background in the same image is created.

  Next, the operation of the X-ray diagnostic apparatus will be described with reference to the flowchart with reference to FIG.

  X-rays are emitted from the X-ray tube 5 in accordance with X-ray conditions such as tube voltage, tube current, and irradiation time set by the X-ray tube controller 9. X-rays irradiated from the X-ray tube 5 pass through the subject M and enter the X-ray detector 7. The X-ray detector 7 outputs an X-ray detection signal corresponding to the X-ray intensity distribution.

[Step S01] Creation of Mask Image The mask image creation unit 29 is a plurality of images that are acquired based on the output of the X-ray detector 7, for example, continuously at a predetermined timing in a state where the injector 13 is stopped. A mask image is created by performing the process of averaging. The created mask image is stored in the mask image storage unit 31.

[Step S02] Injection of contrast medium A signal is given from the main control unit 21 at a timing set by the operator, whereby a contrast medium is injected from the injector 13 into the blood vessel of the subject M via the catheter 15.

[Step S03] Collection of Live Image The image acquired based on the output of the X-ray detector 7 is stored in the live image storage unit 33 while the contrast agent is injected. In addition, you may make it memorize | store in the live image memory | storage part 33 the image acquired continuously at the predetermined timing set beforehand.

[Step S04] Subtraction Processing The subtraction creation unit 35 creates a subtraction image by performing subtraction processing on the mask image in which no contrast agent is injected and the live image in which the contrast agent is injected. By this process, an image in which only the blood vessel into which the contrast medium is injected is extracted is acquired.

[Step S05] Contrast Adjustment The first contrast adjustment unit 39 adjusts the contrast of the subtraction image so as to enhance the blood vessels extracted by the subtraction processing of the subtraction image. Contrast adjustment is performed by changing the window width and window level as shown in FIG. Thereby, when a composite image is created by superimposing a subtraction image and a DR compressed image, a subtraction image in which the extracted blood vessel portion is emphasized can be provided.

[Step S14] Dynamic Range Compression Processing The DR compressed image creation unit 37 performs DR compression on the low frequency components included in the mask image in parallel with the subtraction processing in Step S04 to create a DR compressed image (FIG. 2 (a)). ), FIG. 2 (d)). The DR compression is performed on a predetermined low frequency component included in the mask image. The DR compression may be performed before, after, or at the same time as the subtraction process.

[Step S15] Contrast Adjustment The second contrast adjustment unit 41 adjusts the contrast of the created DR compressed image. Contrast adjustment is performed by changing the window width and window level as shown in FIG. Thereby, the contrast of the DR compressed image used as the background is adjusted, and a DR compressed image distinguished from the blood vessel portion extracted by the subtraction process can be provided.

[Step S06] Composition Processing The composite image creation unit 43 creates a composite image by superimposing the subtraction image and the DR compressed image. As a result, a composite image (FIG. 5) is obtained in which the extracted blood vessel portion obtained by performing the subtraction processing of the subtraction image and the DR compressed image (the mask image subjected to the DR compression processing) as the background of the blood vessel portion can be observed simultaneously. Compared to the conventional FIG. 7, FIG. 5 has no halation, and can easily observe high-contrast objects in the background. For example, low-contrast objects in the background (for example, bone edges and stents (center: S in FIG. 5)). The blood vessel portion can also be observed at the same time, and the symbol T in FIGS.

[Step S07] Output / Save The acquired composite image is displayed on the monitor or printed by a printer in the output unit 23 and output. The composite image is stored in the storage unit 27.

  According to the X-ray diagnostic apparatus 1 according to the present invention, the subtraction image creation unit 35 includes a mask image that is acquired based on the output of the X-ray detector 7 and is not injected with the contrast agent, and the output of the X-ray detector 7. A subtraction image is created by performing a subtraction process from a live image injected with a contrast medium acquired based on the above. Performed in parallel with this subtraction process, the DR compressed image creation unit 37 creates a DR compressed image by performing DR compression only on the low frequency component of the low frequency component and high frequency component included in the mask image. Then, the composite image creation unit 43 creates a composite image by superimposing the subtraction image and the DR compressed image.

  The DR compressed image creating unit 37 performs DR compression only on the low frequency component among the low frequency component and the high frequency component included in the mask image used as a background to be combined with the subtraction image. When DR compression is performed only on the low frequency component, the contrast of a small region (device, tumor, bone contour, etc.) remains unchanged, and the contrast of a large region (lung, diaphragm, etc.) can be reduced. As a result, the overall contrast can be reduced. For this reason, when a composite image is created, it is possible to simultaneously observe an image of a portion extracted by subtraction processing, a low-contrast object in the background, and a high-contrast object in the background. Also, DR compression processing is performed in parallel with the subtraction processing. That is, since the DR compression is performed separately from the subtraction process, the false image generated by the DR compression is not a big problem, and the composite image can be created by performing the subtraction process without considering the false image.

  Here, the false image will be briefly described. When the DR compression process is performed, a false image is generated. That is, when DR compression is performed, noise is generated in the compressed image as indicated by a broken line indicated by a symbol n in FIG. When DR compression processing is performed on one or both of the mask image and the live image and a subtraction image is created using them, a false image is further generated. Therefore, normally, the subtraction process is not performed using the DR-compressed image. However, in this embodiment, the DR compression process is performed only on the mask image to be combined as the background. For this reason, a false image is generated in the mask image, but it is not a false image that causes a serious problem.

  That is, according to the X-ray diagnostic apparatus 1, the portion extracted by the subtraction process, the high-contrast object in the background, and the low-contrast object in the background can be observed at the same time. A large amount of composite image can be acquired.

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

  (1) In the above-described embodiment, the image processing unit 19 includes a control unit configured by a CPU or the like for executing a program, and a storage unit configured by a storage medium such as a ROM or RAM that stores the program or the like. May be provided. A program for the operations of steps S01 to S07, S14, and S15 is stored in the storage unit and executed by the control unit. Then, necessary operations are input through the input unit 25, and the generated composite image is output through the output unit 23. The storage unit may include the mask image storage unit 31 and the live image storage unit 33, or may be configured separately.

  (2) In the above-described embodiment, the operation of each of steps S01 to S07, S14, and S15 is not limited to the image processing unit 19, and a program of the operation is stored in the storage unit 27 and executed by the main control unit 21. You may do it. Then, necessary operations may be input through the input unit 25, and the generated composite image may be output through the output unit 23. The operation program may be executed on a personal computer connected to the X-ray diagnostic apparatus 1 in a network system such as a LAN.

  (3) In the above-described embodiment, the mask image is used as the background, but a live image may be used. That is, in FIG. 1, a live image is read from the live image storage unit 33 and provided to the DR compressed image creation unit 37. Then, the composite image creation unit 43 creates a composite image by superimposing the blood vessel portion extracted by the subtraction process and the DR-compressed live image as a background thereof.

  (4) In the above-described embodiment, the second contrast adjustment unit 41 is provided. However, when the created DR compressed image does not require contrast adjustment, the configuration may not be provided.

  (5) In the above-described embodiment, first, a subtraction process is performed on the mask image in which the contrast agent is not injected and the live image in which the contrast agent is injected. Then, a composite image is obtained by superimposing the extracted subtraction image including the blood vessel portion and the DR compressed mask image as the background. However, the subtraction image for creating a composite image is not limited to the presence or absence of a contrast agent. For example, it may be an X-ray image obtained by photographing the same position of the subject M, and an image obtained by subtracting an X-ray image obtained at a certain time and an X-ray image obtained at a different time from this image. . In this case, the mask image is an X-ray image taken at a certain time, and the live image is an X-ray image taken at a different time from the mask image.

DESCRIPTION OF SYMBOLS 1 ... X-ray diagnostic apparatus 5 ... X-ray tube 7 ... X-ray detector 19 ... Image processing part 21 ... Main control part 29 ... Mask image creation part 31 ... Mask image storage part 33 ... Live image storage part 35 ... Subtraction image creation Unit 37... Dynamic range compressed image creation unit 39... First contrast adjustment unit 41... Second contrast adjustment unit 43.

Claims (5)

An X-ray irradiation unit that irradiates the subject with X-rays;
An X-ray detector for detecting X-rays transmitted through the subject;
A subtraction image creation unit that creates a subtraction image by performing a subtraction process on a mask image obtained based on the output of the X-ray detector and a live image obtained based on the output of the X-ray detector;
Performed in parallel with the subtraction processing, and using either the mask image or the live image, dynamic range compression is performed only on the low frequency component of the low frequency component and high frequency component included in the image. A dynamic range compressed image creating unit for creating a dynamic range compressed image by performing,
A composite image creating unit that creates a composite image by superimposing the subtraction image and the dynamic range compressed image;
An X-ray diagnostic apparatus comprising: The X-ray diagnostic apparatus according to claim 1,
The X-ray diagnostic apparatus according to claim 1, wherein the mask image is an image in which no contrast medium is injected, and the live image is an image in which a contrast medium is injected. The X-ray diagnostic apparatus according to claim 1 or 2,
An X-ray diagnostic apparatus, comprising: a first contrast adjustment unit that emphasizes a portion extracted by subtraction processing of the subtraction image. In the X-ray diagnostic apparatus according to any one of claims 1 to 3,
An X-ray diagnostic apparatus comprising a second contrast adjustment unit for adjusting the contrast of the created dynamic range compressed image. A step of creating a subtraction image by subtracting a mask image acquired based on an output of an X-ray detector that detects X-rays transmitted through a subject and a live image acquired based on an output of the X-ray detector. When,
Performed in parallel with the subtraction processing, and using either the mask image or the live image, dynamic range compression is performed only on the low frequency component of the low frequency component and high frequency component included in the image. Performing a dynamic range compressed image, and
Creating a composite image by superimposing the subtraction image and the dynamic range compressed image,
An X-ray diagnosis program characterized by causing a computer to execute these steps.