JP4245297B2 - X-ray diagnostic imaging equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray image diagnostic apparatus, and more particularly to an X-ray image diagnostic apparatus that performs appropriate image processing according to the brightness portion of a photographed X-ray image.
[0002]
[Prior art]
In recent years, in the medical field, the idea of minimally invasive treatment (MIT) that exerts a sufficient therapeutic effect while minimizing the burden on the patient has attracted attention, and the quality of life of the patient after the operation. Improvement of (Quality of Life: QOL) is also emphasized.
Under these circumstances, a technique called IVR (Interventional Radiology) has been introduced to the examination and treatment of circulatory and gastrointestinal lesions using an X-ray diagnostic imaging apparatus. It was. This technique does not perform surgical laparotomy on patients, but inserts various catheters and endoscopes into the body percutaneously to identify, examine, treat, and monitor the diseased part. To do. Therefore, since this procedure does not involve surgical operation, it is expected to reduce invasiveness to patients, reduce physical risks and mental burdens, and reduce economic burdens. .
In this IVR technique, for example, an inspection jig such as a catheter is inserted into a patient's blood vessel, and the target site is guided to the target diseased part while fluoroscopically imaging the target site with an X-ray diagnostic imaging apparatus. A stenosis portion of a blood vessel is treated by inflating the stenosis portion with a balloon or the like, and the therapeutic effect is confirmed by an X-ray image or the like. The catheter is guided to a target site along a guide wire inserted into the blood vessel through the catheter.
[0003]
FIG. 6 schematically shows an X-ray image from the chest to the waist of the patient (subject) 2 displayed on the monitor 1, together with the spine 3, lung field 4, heart 5, and diaphragm 6. A catheter 7 and a guide wire 8 inserted into the catheter 7 are shown. By the way, when X-ray imaging or fluoroscopic imaging of the target site is performed with a catheter or the like inserted, as is apparent from FIG. 6, the site where X-ray absorption is low (for example, the lung field 4) is bright, and conversely X A region where the line is absorbed much (for example, the diaphragm 6) is displayed darkly. In order to clearly depict the catheter 7 and the guide wire 8 buried in such a background image, conventionally, a spatial filter process has been performed on the original image data.
FIG. 7 shows various characteristics of the spatial filter. The spatial filter having these various characteristics is prepared in advance in the ROM of the image processing unit of the X-ray image diagnostic apparatus and has a desired coefficient as appropriate. You can select and use one.
[0004]
[Problems to be solved by the invention]
By the way, when observing the catheter 7 or the guide wire 8 buried in the background image of the subject 2, there are a bright part and a dark part in the screen, and the catheter 7 and the guide wire 8 are in the screen. It is displayed over various parts of brightness without distinguishing between bright and dark parts. When performing spatial filter processing on an X-ray image, even if a spatial filter having an appropriate coefficient is selected from various characteristics, the entire image is uniformly divided without dividing the bright or dark portion of the image. Is subjected to spatial filtering. Therefore, a bright part (for example, lung field 4) is darker than a dark part (for example, diaphragm 6), and has a lot of X-rays and good S / N. There has been a problem that noise in a dark part of an image is also emphasized.
The present invention has been made to solve such problems.
[Means for Solving the Problems]
In order to solve the above-described problem, the invention described in claim 1 is an imaging unit that images an X-ray image of a subject, and a space that performs spatial filter processing on X-ray image data obtained by the imaging unit. and filtering means, with respect to the original X-ray image data obtained by the X-ray image data and the photographing means after having undergone the spatial filter processing by the spatial filter processing means, of the original X-ray image data A tone conversion processing unit that performs tone conversion processing using a tone conversion coefficient having the same input / output characteristics according to the input level, and one of both X-ray image data processed by the tone conversion processing unit. Subtracting means for subtracting the other and outputting a signal of only the high-frequency component from which the original X-ray image data component has been removed, and the output of this subtracting means as the original X obtained by the imaging means Characterized by comprising adding means for adding the image data.
As a result, it is possible to increase the emphasis on the bright part in the image and suppress the emphasis on the dark part, so that the entire X-ray image can be sharp and easy to see.
[0005]
According to a second aspect of the present invention, in the X-ray diagnostic imaging apparatus according to the first aspect of the present invention, the output signal from the subtracting means is emphasized with a minute signal according to its signal level and suppressed with an excessive signal. And a signal level adjusting means for adjusting to the original X-ray image data. The signal adjusted by the signal level adjusting means is added to the original X-ray image data by the adding means.
This enhances the emphasis on the bright part of the image and suppresses the emphasis on the dark part and does not unnecessarily emphasize the part with a clear outline. A sharp and extremely easy-to-view image can be obtained.
Furthermore, the invention according to claim 3 is the X-ray image diagnostic apparatus according to claim 1 or 2 , wherein the coefficient of the spatial filter processing means is set to an image level of the original X-ray image. It changes according to.
This makes it possible to perform spatial filter processing according to the image level.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an X-ray image diagnostic apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 5.
FIG. 1 is a system diagram showing a schematic configuration of an embodiment of an X-ray image diagnostic apparatus according to the present invention. The X-ray diagnostic imaging apparatus includes, for example, a support 10 that supports an arm 11 that is curved in a substantially C shape, an X-ray tube 20 that is attached to one end of the arm 11, and the other end of the arm 11. X-ray generation for generating desired X-rays from the X-ray tube 20 by controlling output conditions such as the tube voltage, tube current, and X-ray pulse width of the X-ray detector 30 attached and the X-ray tube 20 An apparatus 40, an X-ray controller 50 for calculating and controlling the coefficient of the ND filter, the diameter or sensitivity of the optical aperture for the X-ray detector 30, and image processing for processing an image signal obtained through the X-ray controller 50 An apparatus 60, a monitor 70 for displaying an image or a fluoroscopic image obtained from the image processing apparatus 60, a bed 80 having a top plate 81 on which a subject is placed, the support device 10, the X-ray generator 40, and an X-ray Has controller 50, image processing device 60, bed 80, etc. System controller 90 having a processing unit (CPU) and memory to be controlled automatically, and an operation provided with a keyboard, a mouse, a trackball, etc., for an operator to input appropriate setting values to the system controller 90 Part 91.
The X-ray detector 30 converts the X-ray image into a visible light image by an image intensifier (hereinafter, abbreviated as II). I. In addition to the type in which the visible light image is photographed with a television camera via an optical system that controls the transmission amount of the visible light image formed on the output phosphor screen, for example, a switching element or a capacitor formed on a glass substrate is provided. A flat panel detector (FPD) formed of a semiconductor array that is covered with a photoconductive film that converts X-rays into charges or the like may be used.
[0007]
The image processing apparatus 60 also includes an input interface 61 that receives an image signal from the X-ray controller 50, an X-ray control interface 62 that transmits and receives a control signal to and from the system controller 90, and a filter process that filters the image signal. Unit 63, gradation conversion processing unit 64 that performs gradation conversion processing on image signals and contour signals, arithmetic unit 65 that performs processing for adding and subtracting image signals, and a lookup table unit that is referred to during various processing 66, a memory 67 for storing raw (original) image data obtained through the input interface 61, image data after being processed by the filter processing unit 63 or the calculation unit 65, and the like, and converting the image data into a video signal. A video unit 68 for conversion is included, and these are connected to each other via a bus line 69.
Further, a plurality of monitors 70 are usually provided, and a reference image, a live fluoroscopic image, and the like are simultaneously displayed during clinical practice.
For example, when performing an IVR procedure on a patient's vascular system using the X-ray diagnostic imaging apparatus configured as described above, the patient (subject) placed on the top board 81 percutaneously into the lower limb aorta. The catheter 7 is inserted, and the catheter 7 is guided to the target diseased part (for example, the heart 5) along the guide wire 8 under fluoroscopy. Then, the X-ray fluoroscopic image obtained at this time (the same applies to the X-ray image) is subjected to image processing as follows in the present invention, and several embodiments will be described below.
[0008]
FIG. 2 is an explanatory diagram for explaining the first embodiment of the image processing in the image processing apparatus 60. That is, as Step 1, original image data introduced through the input interface 61 is temporarily stored in the memory 67 (however, it is not always necessary to store it in the memory 67). The waveform of an example of the original image data is as shown in FIG.
Next, as step 2, for the original image data (or the original image data read from the memory 67) introduced via the input interface 61, the filter processing unit 63 performs various coefficients as shown in FIG. A spatial filter having a desired coefficient is selected from the spatial filters having the. FIG. 3B shows a waveform after the spatial filter processing. In step 3, a desired gradation conversion coefficient 65 a is selected from the lookup table unit 65, and the gradation conversion processing unit 64 performs gradation conversion processing on the original image data subjected to the spatial filter processing in step 2. The image data subjected to the gradation conversion process is stored in the memory 67. Therefore, the waveform after the gradation conversion process is as shown in FIG. Here, the image data that has been subjected to the gradation conversion processing in step 3 is referred to as data A.
[0009]
Note that the gradation conversion coefficient 65a has input / output characteristics as shown in FIG. 4A, for example. Although the output hardly changes with respect to a minute input, when the input exceeds a certain level, the output Has such a characteristic that becomes extremely large. As a result, the degree of emphasis by the spatial filter process can be changed in accordance with the brightness of the original image data, the emphasis can be suppressed for the dark part and the emphasis can be strengthened for the bright part. However, since the brightness of the entire image will change if it remains as it is, only the high frequency components are obtained by the processing of step 4 and step 5.
That is, as step 4, the same gradation conversion from the look-up table unit 65 to the original image data (or the original image data read again from the memory 67) introduced through the input interface 61 is performed. The coefficient 65a is selected, and the same gradation conversion processing is performed by the gradation conversion processing unit 64 (this processing can be performed in parallel with step 3 if another hardware is used). Therefore, the waveform after the gradation conversion process is as shown in FIG. This is data B. Then, the process proceeds to Step 5 where the data A and the data B are subtracted by the calculation unit 65 and the result data C is obtained. The waveform after the subtraction process is as shown in FIG. Here, the data C is a signal of only a high frequency component from which the original image data component is removed, that is, a contour signal. When the coefficient of the spatial filter is for high frequency enhancement, the contour signal is obtained as B−A = C, and the spatial filter is obtained. When the coefficient is for low frequency emphasis, the contour signal is obtained as AB = C.
[0010]
Therefore, the process further proceeds to step 6 where the contour signal C is added to the original image data read from the memory 67 by the calculation unit 65. Thus, with respect to the original image data, it is possible to obtain image data in which the emphasis is suppressed in the dark part and the emphasis is enhanced in the bright part while maintaining the brightness of the entire original image. FIG. 3F shows the waveform of the finally obtained image data.
Although explanation is omitted, it is needless to say that a time phase adjusting means such as a delay circuit is inserted as necessary in order to make the time phases coincide with each other at the time of subtraction in step 5 or addition in step 6. Yes.
As described above, according to the present invention, since the conventional spatial filter processing is uniformly performed on the entire image, if the bright portion of the image is emphasized, the noise of the dark portion of the image is also enhanced. The inconvenience is solved, and it is possible to increase the emphasis on the bright part in the image and suppress the emphasis on the dark part, so that the entire X-ray image can be sharp and easy to see.
[0011]
Next, a second embodiment of image processing in the X-ray image diagnostic apparatus according to the present invention will be described with reference to FIG. FIG. 5 is an explanatory diagram for explaining an embodiment of image processing in the image processing apparatus 60 similar to FIG. 2, and steps 1 to 5 are the same as those shown in FIG. The description is omitted.
In the second embodiment, data A and data B are subtracted by the arithmetic unit 65 as step 5 and the result data C is obtained. Then, the process proceeds to step 10 and the desired value is obtained from the lookup table unit 65. The gradation conversion coefficient 65b is selected, the gradation conversion processing unit 64 performs gradation conversion processing again on the data C obtained in step 5, and the data D subjected to the gradation conversion processing is stored in the memory. 67. Note that the gradation conversion coefficient 65b has input / output characteristics as shown in FIG. 4B, for example, and the output changes greatly with respect to a minute input, and when the input exceeds a certain level, the output Has characteristics that hardly change. Therefore, the data D is a contour signal subjected to gradation conversion so as to emphasize only a weak portion of the high frequency component (contour signal) and not emphasize a strong portion of the high frequency component (contour signal).
Therefore, the process further proceeds to step 11, where the arithmetic unit 65 adds the gradation-converted contour signal D to the original image data read from the memory 67. As a result, it is possible to obtain image data in which only the portion where the high frequency component (contour signal) is weak is emphasized in the original image data while the portion where the high frequency component (contour signal) is strong is not emphasized. Note that minute noise can be prevented from being emphasized by changing the gradation conversion coefficient 65b.
[0012]
As described above, according to the present embodiment, it is possible to enhance the bright portion in the image more strongly, suppress the enhancement of the dark portion, and emphasize the portion having a clear outline more than necessary. Therefore, the entire X-ray image can be sharp and extremely easy to see.
[0013]
【The invention's effect】
As described above in detail, according to the inventions described in claims 1 and 2, since the spatial filter processing is uniformly applied to the entire conventional image, if an attempt is made to emphasize a bright portion of the image, the image This eliminates the inconvenience that noise in the dark part of the image is also emphasized, and it is possible to increase the emphasis on the bright part in the image and suppress the emphasis on the dark part. A sharp and easy-to-view image can be obtained throughout. Therefore, the visibility of the guide wire and the catheter is improved during the execution of the IVR procedure, and the burden on the operator can be reduced.
According to the third aspect of the present invention, since the portion with a clear outline is not emphasized more than necessary, the image becomes extremely easy to see. This also improves the visibility of the guide wire and catheter during the IVR procedure, and further reduces the burden on the operator.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a schematic configuration of an embodiment of an X-ray diagnostic imaging apparatus according to the present invention.
FIG. 2 is an explanatory diagram for explaining a first embodiment of image processing in the X-ray image diagnostic apparatus according to the present invention.
FIG. 3 is a waveform diagram shown for explaining the operation of each step of image processing.
FIG. 4 is a characteristic diagram illustrating input / output characteristics of a gradation conversion coefficient.
FIG. 5 is an explanatory diagram for explaining a second embodiment of image processing in the X-ray image diagnostic apparatus according to the present invention.
FIG. 6 is an explanatory view schematically showing an X-ray image from the chest to the waist of a patient (subject) displayed on a monitor.
FIG. 7 is a characteristic diagram shown for explaining various characteristics of the spatial filter.
[Explanation of symbols]
60 image processing device 63 filter processing unit 64 arithmetic unit 65 gradation conversion processing unit 66 lookup table unit 67 memory 69 bus line 70 monitor 90 system controller

Claims (3)

Imaging means for imaging an X-ray image of the subject;
Spatial filter processing means for performing spatial filter processing on the X-ray image data obtained by the imaging means;
Depending on the input level of the original X-ray image data, the X-ray image data after the spatial filter processing by the spatial filter processing means and the original X-ray image data obtained by the imaging means are performed. Gradation conversion processing means for performing gradation conversion processing using gradation conversion coefficients having the same input / output characteristics ,
A subtracting means for subtracting the other from one of both X-ray image data processed by the gradation conversion processing means and outputting a signal of only a high-frequency component from which the component of the original X-ray image data is removed;
An X-ray diagnostic imaging apparatus comprising: an adding unit that adds the output of the subtracting unit to the original X-ray image data obtained by the imaging unit. The output signal from the subtracting means further comprises a signal level adjusting means for adjusting a minute signal to be emphasized and an excessive signal to be suppressed according to the signal level,
2. The X-ray image diagnostic apparatus according to claim 1, wherein the signal adjusted by the signal level adjusting means is added to the original X-ray image data by the adding means.   The X-ray diagnostic imaging apparatus according to claim 1, wherein a coefficient of the spatial filter processing unit is changed according to an image level of the original X-ray image.

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