JP2005205086A - X-ray diagnosis apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an X-ray radiographing diagnosis apparatus in which the resolution of an X-ray flat panel detector is quickly checked. <P>SOLUTION: The X-ray radiographing diagnosis apparatus thins X-ray image data to an image of a size equivallent to e.g., a preview picture size and displays the thinned X-ray image data on the preview picture in order to detect the resolution of the X-ray image data which is detected and acquired by the X-ray flat panel detector 4. A part with a high spatial frequency, which is the optimum part to determine the resolution, is selected from the displayed image and extracted from the image data from the detector 4. An FFT processing is applied to the extracted partial image, and comparison is made between the above FFT processing result and the FFT processing result of a reference image to thereby judge the resolution. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an X-ray diagnostic apparatus that diagnoses a subject from an X-ray image.

In the X-ray imaging diagnosis apparatus, it is assumed that imaging is performed normally. However, there are actually examples of abnormal shooting. For example, an example of underexposure or the occurrence of blurring due to movement of the imaging part during imaging is called abnormal imaging.
As a conventional example for quickly evaluating immediately after photographing whether there is an abnormal photographing, there is Patent Document 1. Patent Document 1 is an example in which after completion of digital X-ray imaging, an instant image is displayed by a preview to determine whether or not proper exposure is performed and whether or not an object is completely urged.
JP 2002-186606 A

In Patent Document 1, image data is thinned out to 1/2 or 1/3 to obtain low-resolution image data, which is displayed as an instant image. By thinning out and reducing the amount of data, it is possible to quickly display immediately after shooting, and the background is that it is possible to determine whether or not normal shooting is possible even with low resolution images (see above document) (See item number 0036).
However, since the resolution is low, Patent Document 1 cannot evaluate the resolution of the captured image.

  An object of the present invention is to provide an X-ray imaging diagnostic apparatus that enables easy evaluation of the resolution of a captured image.

  The present invention relates to an X-ray source that irradiates a subject with X-rays, an X-ray plane detector that is disposed opposite to the X-ray source and detects transmitted X-rays of the subject as an X-ray image, and the X-ray plane. A first means for displaying and / or storing output image data of the detector or a processed image thereof, and a high space which is a part of the output image data of the X-ray flat panel detector and is used for blur detection due to movement of the subject. A second means for extracting partial pixel data of a part having a frequency; a third means for calculating a spatial frequency spectrum of the extracted partial image data; and a spatial frequency of reference image data of the same part as the part. The fourth means for storing the spectrum, the fifth means for comparing the spectra of the third and fourth means to determine the resolution of the X-ray flat panel detector, and the result of the determination is lower than the predetermined resolution If the resolution is low resolution Discloses an X-ray diagnostic apparatus characterized by comprising a sixth means demonstrating a.

  Furthermore, the present invention provides an X-ray source that irradiates a subject with X-rays, an X-ray flat panel detector that is disposed opposite to the X-ray source and detects transmitted X-rays of the subject as an X-ray image, and the X-rays The flat detector display output image data and / or the processed image data is displayed on a display screen and stored in a memory, and the image data of the detector is thinned to obtain image data with a small image size. The second means, a third means that is a part of the image being displayed on the small-screen display and that is selected as a part for detecting a shake due to the movement of the subject, and a shake detection method selected by the third means And a fourth means for determining the resolution of the X-ray detector based on the part to be used, and a fifth means for clearly indicating the state of the resolution if the result of the determination is a resolution lower than the predetermined resolution. An X-ray diagnostic apparatus is disclosed.

  According to the present invention, it is possible to determine whether or not the imaging result is technically good in a short time after the X-ray imaging is completed. Therefore, it is possible to determine whether or not it is necessary to repeat imaging before the subject leaves the imaging room. Accordingly, the waste of time required for re-imaging can be minimized, so that the X-ray inspection workflow can be improved.

FIG. 1 is a diagram showing a configuration example of an X-ray imaging diagnostic apparatus according to the present invention. An X-ray generator (X-ray source) 1 irradiates a subject 3 with X-rays, and an X-ray flat detector 4 takes the transmitted X-rays and detects a fluoroscopic image.
The image processing device 5 captures fluoroscopic image data (image data) from the detector 4 and performs various noise removal and preprocessing to obtain regular fluoroscopic image data. The image observation monitor 6 displays this.
The output device 7 is a laser printer, for example, and outputs an image to a film or the like. The X-ray flat panel detector 4 uses a digital output type, but may be an example of a conventional analog output type.
The imaging operation device 2 with a preview display device is a device that includes an imaging condition input function and a man-machine operation function for X-ray imaging, and has a preview processing function, a display function, and the like. Since the display screen by this display function is for preview, the image size (500 pixels × 500 pixels) smaller than the output image size of the X-ray flat panel detector 4, that is, the image size of the monitor 6 (eg, 3000 pixels × 3000 pixels). ).

  The preview processing function is either a method of having the image processing apparatus 5 or a method of having a function means for taking in the image data from the flat detector 4 and performing the preview processing inside the photographing operation device 2 as described above. Can be realized. In the following, the latter example will be described, but in the former example, the preview processing result from the image processing apparatus 5 can be taken into the photographing operating device 2 and displayed on the display unit.

The flow of the preview process is shown in FIG. The image G from the flat detector 4 is a so-called fluoroscopic image, and there are various images depending on the imaging purpose and the imaging site. For example, the image G shown on the right side of FIG. 2 shows a skeleton image, but there is also a mammogram.
In the process F ₁ , the raw image G (for example, 3000 pixels × 3000 pixels) from the detector 2 is captured, and in the process F ₂ , the pre-processing (correction process) is a parameter input from various correction process parameters (F ₃ ). To use. Parameters include offset, gain, and scratches. Thus, to obtain a normalized image _{G 1.} Example of a normal image G ₁ is not subjected to the pretreatment also can be.

Process _{F 4} is thinned out of the image _{G 1} after the correction processing. This thinning out is, for example, 1/6 to be matched with the image size (500 pixels × 500 pixels) of the preview screen. Thus 500 pixels × 500 pixels thinned image G ₂ in obtained are naturally low resolution because it is thinned out. Thinned image _{G 2} is immediately displayed as a preview image on a display screen _(F 6). Since the processing of F ₁ , F ₂ , and F ₃ is possible at high speed, this display can be realized almost simultaneously with photographing.

Process _{F 5} extracts the partial image _{G 3} from the normal image _{G 1.} This display thinned image G ₂ obtained by the process F ₆ was observed by the operator, designated by the operator a portion in the image is performed by extracting the normalized image G ₁ of the specified site . A part is a part having a high spatial frequency component, for example, a part like a clavicle in chest radiography. Even from the thinned image being displayed by the operator, this portion can be sufficiently judged. Partial image G ₃ are, instead of thinning out such processing F _2, full size magnitude, i.e. the image of the specified portion of the normal image G ₁ as it is (1: 1) is obtained by extraction in relation. This designation is designated by the mouse while the operator observes the thinned image G ₂ (F ₆ ) during preview display. Image size of the partial image _{G 3} are, a preview screen image size (500 pixels × 500 pixels). For shorter time until extraction of such partial image G _3, after mice designated operator, but immediately obtained. Partial image _{G 3} are, displayed on the preview screen _(F 10). Or an image to be displayed on the preview screen G ₂ or G ₃ are designated by the operator.

Process _{F 7} is subjected to a 2-dimensional FFT processing to the partial image _{G 3,} obtains the power spectrum of the partial image _{G 3.} There are the following non-patent documents as disclosure documents of the power spectrum by the two-dimensional FFT processing. For example, a comparison is made by paying attention to the power of 2.0 Cycle / mm in FIG.
Nippon Radio Engineering Journal 53 (11) (1977) PP. 1665 to 1672 “Analysis of frequency components of X-ray image” (Matsuo et al.) The power spectrum is data indicating the relationship between the spatial frequency f and its density (power) Power, and can also be displayed as an image. This is shown as an image G4 in FIG. In the present application, such a power spectrum is used for determining blurring of an image due to movement of the subject. A partial image serving as a reference when there is no motion in the same part with respect to the subject is used as a reference image, and a power spectrum serving as a reference is obtained from the reference image (F9).

In process F _8, was obtained in the power spectrum as a reference of the reference image and the processing F ₇ and a power spectrum obtained from the partial image G ₃ of the actual photographed displayed on the same screen, or operator has moved the subject not (That is, whether the resolution is good or bad). Screen _G 4 in FIG. _2, the power spectrum of the _{G 41} the real part _{image, G 42} is a power spectrum of the reference image. If there is a blur due to movement, a difference occurs in the high frequency portion (right direction in the figure) between G ₄₁ and G ₄₂ . Is determined by the operator (F ₁₁ ). In the example of the screen G ₄ in FIG, there as is not negligible motion blur, making a determination as to the photographed image is not reliable. Then, re-photographing is performed. Performs the same checks against the image G ₁ obtained by re-photographing, If there is no difference between the G ₄₁ and G _42, or if there is a difference negligible, it is determined that the normal shooting.
If it is normal photographing, processing is performed by the processing device 5 and displayed on the monitor 6, stored, and output by the printer 7 is also performed. If the photographing is not normal, the processing device 5 deletes the data. However, if there is any usability, it is left as a processing target.
Since each process of F ₅ , F ₇ , and F ₇ is high-speed, if the pass / fail judgment by the operator can be performed quickly, the processes of F _{5 to} F ₁₁ can be performed immediately. Judgment results can be output.

  In the above embodiment, it is determined whether there is a blur due to motion due to a visual difference in the high frequency part of the power spectrum. Since the difference can also be calculated by a calculation formula, the determination software is installed in the apparatus 2 itself. In addition, it can be automatically performed by executing the software.

Next, a visual determination method by image observation, which is a determination example other than the power spectrum, will be described. Rather than calculating the power spectrum of the image G ₃ obtained in the process F ₅ of FIG. 2, the image G ₃ itself or the enlarged image G ₃₁ is obtained and displayed to observe the details, and the blur due to motion is detected. It is determined whether or not there is. These partial images G ₃ and G ₃₁ are positions set in advance for determination of resolution and are of the target part, for example, bone parts, and are displayed in real (G ₃ ) and enlarged (G ₃₁ ). The resolution can be determined. Here, if the size of the enlarged image matches the image size of the preview screen, it can be determined on the preview screen. There is also a display example that matches the screen size of the monitor 6.

According to the above embodiment, after the end of X-ray imaging, whether the resolution of the image is good or not is automatically determined, so that it can be determined whether or not the imaging has been successful. The radiographer can concentrate on helping the subject, reduce the subject's anxiety, and improve the X-ray examination workflow. Furthermore, for example, it is possible to confirm whether or not photographing is possible by enlarging and displaying the bone and observing the image.

  In the above embodiment, the power spectrum has been described as an example. However, the spectrum is not limited to the square power spectrum of the signal but may be a spectrum analysis of the signal itself. In short, it is only necessary to be able to compare the spectrum of the actual image of the spatial frequency analysis and the reference image data.

  The present invention is used in an X-ray fluoroscopic apparatus. Furthermore, since it is possible to easily and quickly determine the shake due to the movement of the subject during imaging, it can be installed and used in fields such as hospitals and group examinations.

It is an example of a structure of the X-ray diagnostic apparatus of this invention. It is a figure which shows the processing flow of this invention.

Explanation of symbols

1 X-ray generator 2 preview display device with a photographing operation unit 4 X-ray flat panel detector 5 image processing apparatus for 6 image observation monitor F ₁ to F ₁₁ treatment

Claims (2)

  An X-ray source that irradiates the subject with X-rays, an X-ray flat detector that is disposed opposite to the X-ray source and detects the transmitted X-rays of the subject as an X-ray image, and an output of the X-ray flat detector A first means for displaying and / or storing image data or a processed image thereof, and a part having a high spatial frequency that is a part of the output image data of the X-ray flat panel detector and that is used for blur detection due to movement of the subject The second means for extracting the partial pixel data, the third means for calculating the spatial frequency spectrum of the extracted partial image data, and the spatial frequency spectrum of the reference image data of the same part as the part are stored. The fourth means, the fifth means for comparing the spectra of the third and fourth means to determine the resolution of the X-ray flat panel detector, and if the result of the determination is lower than the predetermined resolution Clarify its low resolution state X-ray diagnostic apparatus characterized by comprising: the sixth means, a. An X-ray source that irradiates the subject with X-rays, an X-ray flat detector that is disposed opposite to the X-ray source and detects the transmitted X-rays of the subject as an X-ray image, and an output of the X-ray flat detector A first means for displaying image data and / or processed image data on a display screen and storing it in a memory; a second means for thinning out the image data of the detector to obtain image data of a small image size; A part of the image being displayed on the small screen display, based on the third means selected as the part for detecting blur due to the movement of the subject and the part for detecting blur selected by the third means And a fourth means for determining the resolution of the X-ray detector and a fifth means for clearly indicating the state of the resolution if the result of the determination is lower than a predetermined resolution. X-ray diagnostic equipment.

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