JP5361407B2 - X-ray diagnostic imaging apparatus, image processing apparatus, and control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform the pixel replacement processing of a background part of an X-ray image. <P>SOLUTION: A separation part 7a separates signals supplied from a detector into a signal part having useful information of a part of bones or blood vessels, and a background part not having the useful information, which is a part other than the living body. A pixel replacement part 7b performs the pixel replacement processing using random number generation to the background part of the signal part and the background part separated in the separation part 7a, and writes an image subjected to the pixel replacement processing, in a memory 7c. A noise reduction part 7d reads an object image written in the memory 7c, and reduces noise using averaging processing and a recursive filter, etc. A display control part 7e makes a monitor 8 display the object image for which the noise is reduced in the noise reduction part 7d and background processing is performed using a different random number in the preceding stage part of the noise reduction part 7d. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to an X-ray image diagnostic apparatus , an image processing apparatus, and a control program , and more particularly to an X-ray image diagnostic apparatus , an image processing apparatus, and a control program for reducing noise in an X-ray image.

  Conventionally, in fluoroscopy and imaging for moving image observation, the frame rate displayed on the monitor is higher than the X-ray irradiation rate. For example, when an X-ray image taken at an X-ray irradiation rate of 15 frame / s is displayed on a monitor at a frame rate of 30 frame / s, the same image is repeatedly displayed until the image is updated. This is because writing to and reading from the memory are handled at different rates. In this way, it is possible to display an X-ray image by increasing the display frame rate without causing flicker.

  Further, when displaying on a monitor at a display rate higher than the imaging rate by an apparatus other than the X-ray diagnostic imaging apparatus, a signal is detected by motion detection processing using the previous and next frames, and the amount of movement of the detected signal is obtained to obtain an intermediate frame There is a method of generating an image. This method can reduce image noise.

  As described above, various techniques for converting the shooting rate into the display rate have been proposed. For example, Patent Document 1 proposes a technique for converting a frame rate of ultrasonic scanning into a frame rate of a television scan system. With this technology, data with the same ultrasonic scan frame number is not stored redundantly, and data with different ultrasonic scan frame numbers is not mixed in frames and fields after conversion to the TV scan format. It becomes possible to do.

Japanese Patent Laid-Open No. 11-76243

  However, even if the same image is repeatedly displayed in accordance with a high display rate, the observer's view of the frame rate remains at 15 frames / s, and there is a problem that the noise stops and appears.

  Moreover, when using the front and back frames as applied in other than the X-ray image diagnostic apparatus, there is a problem that a frame delay occurs in image processing.

The present invention has been made in view of such a situation, and an object of the present invention is to provide an X-ray image diagnostic apparatus , an image processing apparatus, and a control program capable of reducing noise in an X-ray image without causing a frame delay. Is to provide.

The feature of the invention described in claim 1 is based on X-ray generation means for generating X-rays irradiated on the subject, detection means for detecting X-rays transmitted through the subject, and X-rays detected by the detection means. The X-ray image is separated into an observation area part and a background part that is a part other than the living body, a pixel replacement part that performs pixel replacement processing of the background part separated by the separation part, and a background part by the pixel replacement part Display control means for controlling the display of the X-ray image subjected to the pixel replacement process.

  According to the present invention, it is possible to reduce noise in an X-ray image without causing a frame delay by performing pixel replacement processing in the background portion of the X-ray image.

It is a figure which shows the structural example of an X-ray image diagnostic apparatus. It is a block diagram which shows the function structural example of an image process part. It is a figure for demonstrating a pixel replacement process. It is a flowchart explaining a pixel replacement process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration example of an X-ray image diagnostic apparatus according to the present invention.

  As shown in FIG. 1, the X-ray diagnostic imaging apparatus includes an X-ray generator 1, a detector 2, a high voltage generator 3, a C-arm 4, a support 5, a bed 6, an image processor 7, and a monitor 8. A system control unit 9, a bed control unit 10, a support unit control unit 11, and an operation unit 12 are provided.

  The X-ray generation unit 1 includes an X-ray tube 1a and an X-ray restrictor 1b. The X-ray tube 1 a generates X-rays based on the high voltage and filament current applied by the high voltage generator 3 and irradiates the subject P on the bed 6 with the X-rays. The X-ray diaphragm 1b shapes the X-ray irradiation field of the X-ray tube 1a. The X-ray generation unit 1 functions as an X-ray generation unit that generates X-rays irradiated on the subject P.

  The detector 2 has a plurality of X-ray detection elements arranged two-dimensionally, and functions as an X-ray detection unit that detects X-rays transmitted through the subject P. The detector 2 outputs an X-ray image signal based on the detected X-ray to the image processing unit 7.

  The high voltage generation unit 3 includes an X-ray control unit 3a and an X-ray generator 3b. The X-ray control unit 3a controls high voltage generation of the X-ray generator 3b under the control of the system control unit 9. The X-ray generator 3b applies a high voltage to the X-ray tube 1a and supplies a filament current under the control of the X-ray control unit 3a.

  The C-shaped arm 4 is supported by the support unit 5 so as to be rotatable about at least three orthogonal axes, and holds the X-ray generation unit 1 and the detector 2 so as to face each other with the subject P on the bed 6 interposed therebetween. A subject P is placed on the bed 6.

  The image processing unit 7 is configured by a dedicated image processing device or a general-purpose computer on which a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like are mounted, and is supplied from the detector 2. After the X-ray image signal is separated into a signal part and a background part, a pixel replacement process is performed on the background part. The image processing unit 7 causes the monitor 8 to display the result of the pixel replacement process in the background portion. The signal part has useful information such as a part of a bone or blood vessel, and the background part is a part other than the living body and does not have useful information.

  The system control unit 9 is configured by a general-purpose computer on which a CPU, a ROM, a RAM, and the like are mounted, and comprehensively controls each unit of the X-ray image diagnostic apparatus. Based on the input signal from the operation unit 12, the system control unit 9 controls the X-ray generation of the X-ray generation unit 3, controls the image calculation processing of the image processing unit 7, and controls the movement of the bed 6 of the bed control unit 10. , And arm support control of the support part 5 of the support part control part 11 is executed.

  The couch controller 10 controls the couch 6 to move at a predetermined speed and a predetermined distance under the control of the system controller 9.

  Under the control of the system control unit 9, the support unit control unit 11 controls the support unit 5 to rotate the C-arm 4 at a predetermined rotation speed.

  The operation unit 12 includes a keyboard, a mouse, and the like, and supplies shooting conditions and the like input by the operator to the system control unit 9.

  The image processing unit 7 and the system control unit 9 may be configured by one general-purpose computer or may be configured by separate computers.

  FIG. 2 is a block diagram illustrating a functional configuration example of the image processing unit 7. At least a part of the functional units shown in FIG. 2 is realized by executing an image processing application by the CPU of the image processing unit 7. As shown in FIG. 2, the image processing unit 7 includes a separation unit 7a, a pixel replacement unit 7b, a memory 7c, a noise reduction unit 7d, and a display control unit 7e.

  The separation unit 7a has the signal supplied from the detector 2 as a signal part (observation region part) having useful information such as a part of a bone or blood vessel and a part other than the living body and having useful information. It functions as a separating means that separates into no background part. The separated signal portion and background portion are supplied to the pixel replacement section 7b.

  The pixel replacement unit 7b functions as a pixel replacement unit that performs pixel replacement processing using random number generation for the background portion of the signal portion and the background portion separated by the separation unit 7a. The image subjected to the pixel replacement process is written in the memory 7c.

  For example, when a target image captured at an X-ray irradiation rate of 15 frame / s is displayed on the monitor 8 at a display rate of 30 frame / s, the pixel replacement unit 7b uses the first random number as shown in FIG. The pixel replacement process of the background part B of the image P is performed, and the target image on which the pixel replacement process of the background part B is performed with the first random number is written in the memory 7c. Next, the pixel replacement unit 7b performs pixel replacement processing of the background portion B of the target image P with the second random number, and stores the target image subjected to replacement processing of the pixels of the background portion B with the second random number in the memory 7c. Write to.

  That is, by performing background processing of the same target image P twice using different random numbers and writing them in the memory 7c, the display control processing unit 7e described later reads out and monitors the target images subjected to background processing using different random numbers. 8 can be displayed. For this reason, it seems to the observer that the frame rate is increased only for the background, and as a result, it is synthesized with the afterimage of the observer's eyes and noise is reduced.

  The numbers 1 to 25 shown in FIG. 3 are assigned to each pixel in order to clearly indicate the pixel replacement process. Further, in the example of FIG. 3, in order to make the explanation easy to understand, attention is paid to a part of the background part B, but actually, pixel replacement processing is performed for all the background parts not including the signal part S. Is called. The pixel replacement process may be performed for each block of 5 vertical pixels × 5 horizontal pixels as shown in the example of FIG. 3, or may be performed on all pixels.

  The noise reduction unit 7d reads the target image that has been background-processed using different random numbers and written in the memory 7c. The noise reduction unit 7d performs an averaging process between the same frames on the signal portion of the read target image or reduces noise using a recursive filter or the like, and then supplies it to the display control unit 7e. Note that the averaging process is a process of averaging the noises that are randomly generated by repeatedly adding and averaging the signals so as to approach zero. The recursive filter is a digital filter that is used to suppress image roughness.

  The display control unit 7e functions as a display control unit that causes the monitor 8 to display a target image that has been subjected to noise reduction by the noise reduction unit 7d and subjected to background processing using a different random number in the preceding stage of the noise reduction unit 7d.

  Next, a pixel replacement process executed by the image processing unit 7 will be described with reference to a flowchart of FIG. In this process, a pixel replacement process in a case where a target image captured at an X-ray irradiation rate of 15 frame / s is displayed on the monitor 8 at a display rate of 30 frame / s will be described.

  In step S1, the separation unit 7a separates the target image supplied from the detector 2 into a signal portion and a background portion.

  In step S2, the pixel replacement unit 7b replaces the surrounding pixels with the first random number obtained by the first random number generation for the background portion separated in the process of step S1.

  In step S3, the pixel replacement unit 7b writes, in the memory 7c, the target image that has undergone pixel replacement in the process of step S2.

  In step S4, the pixel replacement unit 7b performs pixel replacement with the surroundings using the second random number obtained by the second random number generation for the background portion separated in the process of step S1.

  In step S5, the pixel replacement unit 7b writes, in the memory 7c, the target image that has undergone pixel replacement in the process of step S4.

  As a result of the above processing, the target image in which the pixels of the background portion are replaced using different random numbers is written in the memory 7c. Although the standard deviation value of the noise is not changed by the replacement process of the pixels in the background portion, the noise frequency is converted closer to a high frequency, so that the noise becomes inconspicuous. Furthermore, after the target image written in the memory 7c is read out by the noise reduction unit 7d and noise is reduced, the target image subjected to background processing using different random numbers is displayed on the monitor 8 by the display control processing unit 7e. Is displayed. As a result, it seems to the observer that the frame rate is increased only for the background, and as a result, it is synthesized with the afterimage of the observer's eyes and noise is reduced.

  In the above, the example of the pixel replacement process when the target image captured at the X-ray irradiation rate of 15 frame / s is displayed on the monitor 8 at the display rate of 30 frame / s has been described. When the target image captured at an X-ray irradiation rate of 10 frame / s is displayed on the monitor 8 at a display rate of 30 frame / s, a different random number is generated three times and the pixel replacement process is performed three times. Well, when a target image captured at an X-ray irradiation rate of 7.5 frame / s is displayed on the monitor 8 at a display rate of 30 frame / s, different random numbers are generated four times to perform pixel replacement processing 4 You can do this once. That is, the pixel replacement unit 7b may generate a different random number a predetermined number of times in accordance with the display rate and repeatedly perform the pixel replacement process using the generated different random number.

  In addition, in the case of taking a DSA (Digital Subtraction Angiography) image, the background portion is uniform, so the signal portion and the background portion can be easily separated. By applying this embodiment, the effect of noise reduction is significant. Become.

  Note that the present invention is not limited to the above-described embodiment as it is, and in the implementation stage, the constituent elements may be modified and embodied without departing from the scope of the invention, or a plurality of configurations disclosed in the above-described embodiment may be used. Various inventions can be formed by appropriately combining elements. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine the component covering different embodiment suitably.

DESCRIPTION OF SYMBOLS 1 X-ray generation part 2 Detector 7 Image processing part 7a Separation part 7b Pixel replacement part 7e Display control part

Claims (6)

X-ray generation means for generating X-rays irradiated on the subject;
X-ray detection means for detecting the X-ray transmitted through the subject;
Separation means for separating an X-ray image based on the X-ray detected by the X-ray detection means into an observation region part and a background part that is a part other than a living body ;
Pixel replacement means for performing pixel replacement processing of the background portion separated by the separation means;
An X-ray diagnostic imaging apparatus comprising: display control means for controlling display of the X-ray image that has undergone pixel replacement processing of the background portion by the pixel replacement means. The X-ray image diagnosis apparatus according to claim 1, wherein the pixel replacement unit generates different random numbers and performs a predetermined number of pixel replacement processes using the different random numbers. The said display control means controls the display of the said X-ray image in which the pixel replacement process of the background part was performed using the said different random number according to a display rate. X-ray image diagnostic apparatus.   The X-ray image is a DSA image
  The X-ray diagnostic imaging apparatus according to claim 1, wherein the diagnostic imaging apparatus is an X-ray diagnostic imaging apparatus.   Separation means for separating an X-ray image based on X-rays transmitted through the subject into an observation region part and a background part that is a part other than a living body;
  Pixel replacement means for performing pixel replacement processing of the background portion separated by the separation means;
  Display control means for controlling the display of the X-ray image that has undergone pixel replacement processing of the background portion by the pixel replacement means;
  An image processing apparatus comprising:   A separation step of separating an X-ray image based on X-rays transmitted through the subject into an observation region part and a background part that is a part other than a living body;
  A pixel replacement step for performing a pixel replacement process of the background portion separated by the separating means;
  A display control step for controlling display of the X-ray image that has undergone pixel replacement processing of the background portion by the pixel replacement means;
  A control program for causing a computer to execute.

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