JPH01212569A - Device for indicating x-ray image - Google Patents

Abstract

PURPOSE:To make it possible to clearly observe the tip end position of a subject to be photographed by automatically recognizing radiophotographically impermeable material provided in proximity to the tip end of the subject in a line or pipe form, and thereby magnifying it to a specified size so as to enable it to be indicated. CONSTITUTION:Radiophotographically obtained image data on a balloon catheter provided with a marker such as gold in proximity to the tip end of it are housed in an image memory 2, read-out data from them are issued to an automatic marker recognition circuit 3 so as to let the minimum picture element concentration in an image be detected so that data in a range less than a threshold level are recognized on the basis of both the picture element concentration set based on the minimum value and the picture element concentration set based on the minimum value and the picture element concentration read-out of the memory 2. Then, picture element data corresponding to the shadow of the marker are extracted so as to be housed in a plane memory 4. And concurrently an address is read out by a marker position address read-out circuit 5, and information obtained through performing operations by means of an enlargement ratio and an enlargement center determination circuit 6 is issued to an image enlarging circuit 7 so that data for the shadow of the marker is enlarged so as to be indicated on a monitor.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to X-ray photography using a linear or tubular object as a subject;
Alternatively, the present invention relates to an X-ray image display device capable of extracting an X-ray opaque substance from image data obtained through X-ray fluoroscopy and displaying an input image obtained by enlarging the substance to a predetermined size.

(Prior Art) When performing a catheter test using an X-ray diagnostic device, a doctor needs to quickly and safely insert a catheter or a balloon catheter into a patient's blood vessel. In addition, percutaneous angioplasty, which has recently become rapidly popular, (
Percutaneous Translumina
l A ngioplasty Hereinafter simply referred to as PTA °
), it is necessary to insert a guide wire (with a diameter of about 0.3 mm) in addition to the catheter.

By the way, when such a catheter, balloon catheter, or guidewire is inserted into a blood vessel and its image is displayed on the monitor of an X-ray diagnostic device, the catheter or guidewire itself is exposed to weak Since it is difficult to project against the line, it is difficult to confirm whether the tip has been inserted to the desired position within the blood vessel.

For this reason, conventional catheters, balloon catheters,
Alternatively, as shown in Figures 8(a) to (c), the guide wire may be coated with an X-ray opaque material such as gold or platinum near its tip.
A substance with a large attenuation coefficient.

(hereinafter referred to as markers) was provided to make the position of the tip of the marker easier to recognize on the display screen of the monitor. In this case, the gold X, which is usually used as a marker,
The linear absorption coefficient reaches about 160-170,
Absorbs X-rays very strongly. For example, even with a thickness of about 0.2 m+s, X-rays passing through gold are attenuated to 0.04 (4%). If this is converted to the equivalent thickness of water in terms of X-ray attenuation, the thickness would be approximately 15 cm. Moreover,
The spatial size of the marker is approximately 1 mm in width or less.
It is a small one, 2 to 3 dragons or less in height. Therefore, when such a marker is displayed as an image, its pixel density is extremely small, and is often the smallest pixel density within the field of view.

Furthermore, during PTA, a contrast agent is injected into the balloon part of a balloon catheter inserted into a blood vessel to inflate the balloon, and the pressure is used to spread the narrowed part of the blood vessel. In the present invention, it is also necessary to display an image with only the area magnified and to observe the state in which the balloon is pushing and spreading the blood vessel wall.

Therefore, conventionally, when enlarging and displaying this balloon part, the operator creates a region of interest (R1g1on of interest) so as to surround the balloon part on the screen.
st (hereinafter simply referred to as ROI), and set the ROI
The image in I was enlarged and displayed.

(T!a problem that the invention aims to solve) However, the diameters of current catheters and guide wires are becoming smaller and smaller, and the markers provided near their tips are also becoming smaller accordingly. In the case of a patient with a thick body, it is difficult to distinguish the markers even if the markers are displayed on the monitor screen under transparent light. In particular, if the catheter, guide wire, or tip position cannot be determined,
Physicians are unable to properly manipulate catheters and guidewires.

Furthermore, when it is desired to display an image by enlarging the balloon portion, such as during PTA, operations such as ROI setting must be performed, which places a burden on the operator and the image itself is not easy to view.

The present invention enables X-ray imaging or X-ray fluoroscopy to be performed using a linear or tubular object as a subject.
By automatically recognizing a radiopaque substance, extracting only this radiopaque substance, and displaying it as an image enlarged to a predetermined size, it is possible to provide two things to the operator. It is an object of the present invention to provide an X-ray image display device capable of displaying the position of the distal end of a subject in an easy-to-see manner without imposing any burden.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a linear or tubular object having at least one X-ray opaque substance at its tip. An image memory for storing image data obtained by X-ray photography or X-ray fluoroscopy as a subject; a detection means for reading the image data from the image memory and detecting the minimum pixel density in the X-ray image; Threshold level setting means for setting pixel density and threshold level based on the detected minimum value, and when the pixel density of the image data read from the image memory is in an area below the threshold level. , an image recognition circuit comprising an extraction means that recognizes that there is an X-ray opaque substance provided near the tip of the subject in this area and extracts pixel data corresponding to the X-ray opaque substance; The magnification rate and the center of expansion are determined from the spatial size and position on the image of the pixel data corresponding to the X-ray opaque substance extracted by this image recognition circuit, and the magnification is determined to correspond to the X-ray opaque substance. A configuration comprising an image enlarging means for enlarging pixel data, and a display means for selecting either the image data enlarged by the image enlarging means or the image data read from the image memory and displaying the input image. That is.

(Function) In such an X-ray image display device, when the pixel density of the X-ray image is below a threshold level set based on the minimum pixel density value in the X-ray image, this region It is recognized that there is at least one X-ray opaque substance provided near the tip of the linear or tubular object, and pixel data corresponding to this X-ray opaque substance is extracted. Then, the magnification rate and center of expansion are determined from the spatial size of this pixel data and the position on the image, and the pixel data corresponding to the X-ray opaque material is expanded. By displaying an enlarged image of only the X-ray opaque material, it is easy to check the condition of the tip of a linear or tubular object, and the linear or tubular object can be manipulated quickly and easily. It's going on.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit showing an example of the configuration of an X-ray image display device according to the present invention. In Fig. 1, reference numeral 1 indicates an image in which a fluoroscopic X-ray image obtained by, for example, X-ray fluoroscopy is inputted while inserting a balloon catheter, which has gold at two places near its tip and gold as a force, into a blood vessel. This image processing apparatus 1 digitally converts this fluoroscopic X-ray image using an A/D converter to obtain image data. Reference numeral 2 denotes an image memory for storing image data obtained from the image input device 1, and reference numeral 3 recognizes a marker provided near the tip of the balloon catheter from the image data read out from the image memory 2, and calculates the shadow of the marker. This is an automatic marker recognition circuit whose details for extracting only pixel data will be described later. Also,
4 is a brain memory that stores the pixel data of the two marker shadows extracted by this automatic marker recognition circuit 4; 5 is a brain memory that reads the memory addresses of the two marker shadow areas from the pixel data stored in this plain memory 4; There is a marker position address reading circuit that stores the marker position address in a register. Furthermore, 6 is 2 from the address of pixel data corresponding to each marker shadow stored in this marker position address reading circuit 5.
7 is an enlargement rate and enlargement center determining circuit which selects the middle point of two marker shadows as the enlargement center, calculates the area of each marker shadow and the enlargement center, and determines an image enlargement rate such that the image does not protrude from the screen; When the image enlargement rate and enlargement center are determined by the enlargement rate and enlargement center determining circuit 6, the image memory 2
The image enlarging circuit 7 reads out and enlarges the corresponding image data from the image data, and the image enlarging circuit 7 may be a conventional affine transformation or the like. Reference numeral 8 denotes a selection circuit that selects and reads out either the image data enlarged by the image enlargement circuit 7 or the image data stored in the image memory 2 in response to an operation signal issued by the operator, and displays this on a monitor (not shown). .

FIG. 2 is a block circuit showing a detailed configuration example of the automatic marker recognition circuit 3 described above. In FIG. 2, 31 is a histogram calculation circuit that takes in the image data read out from the image memory 2, and this histogram calculation circuit 31 calculates the pixel density distribution of the image data and detects the minimum pixel density value. It is something to do. Although it is possible to detect this minimum pixel density value without performing histodarum calculation, a general-purpose configuration is shown here as an example.

32 is a value 2 that is slightly larger than the minimum pixel density value when the minimum pixel density value is detected by the histogram calculation circuit 31.
For example, this is a threshold level determining circuit in which a threshold level is set by adding an amount corresponding to the actual value of the noise amount of the image. In this case, there are various other methods of determining the threshold level; for example, the minimum pixel density value may be multiplied by a factor determined in advance experimentally, such as 1.1 times. 33 is a binarization processing circuit which compares the threshold level set in the threshold level determining circuit 32 with the pixel density of the image data read out from the image memory 2 and performs binarization. , this binarization processing port 33 performs binarization processing by setting "0" to a pixel with a density higher than the threshold level and "1" to a pixel having a lower density. 34
is a plain memory that stores the processing results of this binarization processing circuit 33. Furthermore, 35 and 36 read out the processing data stored in the block lane memory name, filter the pixel data of all lines in the horizontal and vertical directions of the screen, and leave candidate points for markers. This is a logic filter circuit that removes unnecessary parts such as noise, and one of the logic filter circuits 35 has a filter size of 5th size (for pixel density below the threshold level, for the upper limit of the area of a certain area). ) are used,
As the other logical filter circuit 36, one having the second smallest filter size (for the lower limit of the area of the region where the pixel density is below the threshold level) is used. 3
7 and 38 are inverse logic filters that return the pixel data filtered by the logic filter circuits 35 and 36 to the original pixel data, and these inverse logic filters 37 and 3
As the filter size 8, filters having a filter size of 3 to 4 are used.

39 is a black and white inversion circuit that inverts the pixel data output from one inverse logic filter 37; 40 is a combination of the data inverted by this black and white inversion circuit 39 and the other inverse logic filter 38;
This is an AND circuit that performs AND of data obtained from .

Firstly, the operation of the X-ray image display device configured as described above will be explained.

First, the operation of recognizing and extracting a marker shadow by the automatic marker recognition circuit 3 will be described. Now, when the image data stored in the image memory 2 is read from the image input device 1 and input to the histogram calculation circuit 31 shown in FIG. 2, the histogram calculation circuit 31 calculates the pixel density distribution of the image data. Then, the minimum pixel density value is detected. When the minimum pixel density value is detected by the histogram calculation circuit 31, the threshold level determination circuit 32 generates a value 2 slightly larger than the minimum pixel density value, for example, by adding an effective value of the amount of image noise to the minimum pixel density value. Set the superimposed threshold level. When this threshold level is set, the binarization processing circuit 3
The pixel density of the image data read out from the image memory 2 in step 3 is compared with the threshold level, and pixels larger than the threshold level are binarized as "0-" and pixels smaller as "1". , and store the results in the plain memory 34. In this case, since the marker candidate point is set to be "1" by the threshold level, it goes without saying that the plain memory 34 contains this marker candidate point as "1". However, in addition to this marker candidate point, there may be noise or overlapping parts of bones that have high attenuation in the human body, and the binarization process may cause
There is a possibility that a point where the angle is 1° is also included. Therefore, 2
The pixel data that has been converted into a value and stored in the plain memory 34 is applied to logic filter circuits 35 and 36 to perform filter processing, and the filtered pixel data is further applied to inverse logic filters 37 and 38 for inverse filter processing. is being carried out.

Here, the function of the logic filter circuit will be described with reference to FIGS. 3 and 4. When the “1°, 0” image is read out from the plane memory 34 and subjected to a logical filter,
The part A shown in FIG. 3 is attenuated, but 1. Part B remains. The filter function at this time will be explained in one dimension with reference to FIG. 4 as follows. In other words, applying data from No. 1 to No. 0.10 to a filter whose filter size is 3 (a, b, and c are all 1 degree) means that these No. 1 to No. 0.10 data are This means that "1" will not be output unless at least three consecutive II II II out of the data of Since the three are not consecutive (only one is independent), the output after passing the data of No. 2 through the filter is "0". On the other hand, the data consecutive with No. 4, 5, and 6 are No. 4. is “0”
, No. 5 is "1" and No. 6 is "1", so the data of No. 5 at the center position is output as 0.

However, all the data connected to No. 5.6.7 are “1”.
”, so the output of NO, 6 at the center position becomes “1”. If the filter size is n, the output becomes “1” only when n consecutive data are “1”.

To make this two-dimensional, first apply a filter as shown in FIG. 4 to each and every line (■, ■, . . . ) in the horizontal direction of the screen. As a result, the filter output is
As shown in the upper part of the right side of the figure, (■, 7), (■, 7),
Four pixels (■, 6) and (■, 7) become "1". Furthermore, this time a vertical line row (1, 2, 3,...
If the data of ) is similarly filtered, the resulting filter output will be (■, 8), (■, 6), (■, 7), as shown at the bottom of the right side of Figure 2. (■, 8
) become "1".

Therefore, by filtering each and every line of the horizontal edge of the screen and each and every line of the vertical direction in this way, the filter size is smaller than the filter size as shown in A shown on the left side of Figure 3. Small parts will be erased.

Next, the function of the inverse logic filter circuit will be described with reference to FIG. Here, a case where the filter size is 3 is shown as an example. That is, applying an inverse filter to the pixel data from the logic filter circuit using an inverse logic filter is an operation similar to reversing the data. However, what disappears due to the operation of the logic filter circuit (operation from the left side to the right side in Figure 4) cannot be restored, so the pixel data after applying the inverse filter are No. 2 of the pattern on the left side of Figure 4. The pixels that are "1" are erased.

In other words, the inverse logic filter circuit has a function of expanding the region of "1" around "1" on the target pattern by the filter size.

Therefore, by performing an inverse logic filter operation on all six lines in the horizontal and vertical directions of the screen using an inverse logic filter circuit, the pan pixel data shown on the left side of FIG. 5 becomes pixel data of the pattern shown on the right side. By calculating the logical sum of these, pixel data of a pattern as shown in part B of FIG. 3 is completely restored.

The above are the functions of the logic filter and the inverse logic filter, but if the filter size is as large as 5 as in one of the logic filter circuits 35 as in this example, then B in FIG.
Patterns such as portions are erased, and those with a filter size of 5 or more remain as portions that extend in either the horizontal or vertical direction of the screen. Furthermore, if the filter size of the other logic filter 36 is as small as 3, part A in FIG. 2 is removed and pixel data with a pattern like part B remains.

In this example, a logic filter circuit 35 with a large filter size
The reason why the logic filter circuit 36 with a small filter size is provided and the inverse logic filter circuits 37 and 38 with a filter size of about 3 are provided is as follows. In other words, since the physical size of the target marker shadow is known in advance, the size of the image when X-ray photography is taken can be calculated from the magnification ratio, etc., and therefore the pixel size of the marker can be known. can. However, since effects such as blur are added, the pixel size must be approximately 3 to 4 pixels in both the horizontal and vertical directions of the screen.

Therefore, it is necessary to erase noise with a size of 2 pixels or less, and also to erase object shapes with a size of 5 pixels or more.

Therefore, by filtering the pixel data read out from the brain memory 34 using the logic filter circuit 35 with a large filter size, pixel data in an area with a filter size of 5 or more is extracted, and these logic filter circuits 35
The pixel data extracted from the inverse logic filter circuits 37 and 36 are added to the inverse logic filter circuits 37 and 38 respectively, and the image data of only the object shape is extracted from the inverse logic filter circuit 37 by the inverse filter function, and the image data of only the object shape is extracted from the inverse logic filter circuit 38. Extract image data of both the marker salt and the object shape. and,
The pixel data of only the object shape extracted from the inverse logic filter circuit 37 is converted into "
01. The marker salt extracted from the inverse logic filter circuit 38 by inverting "1" and the image data of the person painting the object are ANDed by the AND circuit 40, so that only the marker salt from which the object shape and noise have been removed. Image data representing the position and size of the image on the screen is obtained, and this image data is stored in the brain memory shown in FIG.

In this way, when the image data of only the marker salt is extracted by the automatic marker recognition circuit 3 and stored in the brain memory 4, the automatic image enlargement circuit performs the following processing.

When the image data of only the marker salt is stored in the brain memory 4, the position and size of the marker salt stored in the brain memory 4 are as shown in FIG. It looks like this.゛Therefore, the marker position address reading circuit 5 accesses all of the brain memory 4 and reads "1" on the memory.
It recognizes and reads the address of the pixel that is , and stores these addresses in an internal register. When the marker position address reading circuit 5 reads the address of a pixel that is "1", the enlargement rate and enlargement center determination circuit 6 determines the enlargement rate and enlargement center based on the address stored in the register. . For example, when there is one marker salt, the center of expansion may be an address near the center of its shadow, and when there are multiple marker salts, the center of expansion may be the center address (Xo,) Fo), (x
l.

It may be given as the average position of yl), ..., (xa, ym), and it may also be given as a more complicated formula. In the example of FIG. 6, there are two regions, so in this case, the midpoint between the regions may be given.

On the other hand, the magnification rate must be 6 to include all of the marker salt when the marker salt is expanded. However, the expansion center (x, y) obtained as above and each address (x'i
, yl) is calculated so that is a predetermined value. Here, γ is the maximum distance between the image enlargement center and each address. For example, in a 100OX100O matrix image, if it is γ-100, then the 7th
As shown in the figure, marker salt is displayed when the magnification is 5 times or less. In fact, if you enlarge it to its fullest extent,
In many cases, the displayed image becomes difficult to see, so in the case of the example shown in FIG. Then, the image enlarging circuit 7 reads out the image/image data corresponding to the marker salt from the image memory 2 based on the information number, and enlarges the image by increasing the speed.

The image data corresponding to the marker salt enlarged by the image enlarging circuit 7 is selected by the operator (i) inputted to the selection circuit 8 by the operator and displayed on the monitor. In this case, the selection circuit 8 Since the image data stored in the image memory 2 can also be selected, when it is necessary to view the subject with a wide field of view, it is possible to display an image without enlarging it.

As described above, in this embodiment, image data obtained by X-raying a balloon catheter with a marker such as gold near its tip is stored in the image memory 2, and the image data read out from the image memory 2 is stored in the image memory 2. The minimum pixel density in the X-ray image is detected by the automatic marker identification circuit 3, and the pixel density threshold level set based on this minimum value and the pixels of the image data read out from the image memory 2 are The pixel data in the area below the threshold level is recognized from the concentration, and the pixel data corresponding to the marker shadow provided near the tip of the balloon catheter is extracted and stored in the brain memory 4. The marker position address reading circuit 5 recognizes the marker position and reads its address from the pixel data stored in the pixel data stored in 4.
The enlargement center determination circuit 6 calculates the enlargement center and enlargement rate of the marker shadow, and provides this information to the image enlargement circuit 7 to enlarge the image data corresponding to the marker shadow read from the image memory 2. It can be displayed on a monitor.

Therefore, even when performing X-ray photography or X-ray fluoroscopy using a balloon catheter as a subject, the marker shadow provided near the tip of the balloon catheter is automatically recognized, and this marker shadow is extracted and enlarged to a predetermined size. Since it is possible to display an image of the tip of the balloon catheter, the position of the distal end of the balloon catheter can be displayed in an easy-to-see manner without placing any burden on the operator. Particularly during PTA, when a contrast agent is injected into the balloon part of a balloon catheter inserted into a blood vessel, the balloon part is inflated, and the pressure is used to spread the narrowed part of the blood vessel. This makes it possible to control the inflation of the balloon, or to appropriately judge whether to continue inflation by applying more pressure or to stop it. In addition, patients do not suffer from ischemia unnecessarily, and PT due to insufficient inflation
Failure of A can be reduced.

In addition, as in percutaneous transcutaneous angioplasty (PTCA), the balloon part moves with the movement of the blood vessels on the heart, and even in such cases, the enlargement rate and enlargement center determination circuit 6 determines the enlargement center of the marker shadow. is selected, the balloon can be displayed as if it were stationary, allowing extremely detailed observation.

Furthermore, when it is necessary to view the subject in a large field of view due to a request from the operator, the selection circuit 8 selects the image data read out from the image memory 2 and displays it on the monitor, so that no enlargement processing is performed. Images can also be observed.

[Effects of the Invention] As described above, according to the present invention, even when a linear or tubular object is taken as a subject for X-ray photography or X-ray fluoroscopic photography, the X-ray opacity provided near the tip of the object The system automatically recognizes the substances in the image, extracts only these radiopaque substances, and displays them as images enlarged to a predetermined size, without placing any burden on the operator. X-ray that can clearly display the tip i position of the subject□
An image display device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an X-ray image display device according to the present invention, FIG. 2 is a block diagram showing a detailed configuration of an automatic marker recognition circuit in the same embodiment, and FIGS. 3 to 5 6 is a functional explanatory diagram of a logic filter circuit and an inverse logic filter circuit, FIGS. 6 and 7 are diagrams for explaining the operation of the same embodiment, and FIG. 8 is a diagram showing an example of a guide wire, a catheter, and a balloon catheter. It is. 1... Image input device, 2... Image memory, 3... Automatic marker recognition circuit, 4...
・Brain memory, 5...Marker position address reading circuit, 6...Enlargement ratio, enlargement center determining circuit, 7...Image enlargement circuit, 8... selection circuit. Applicant's agent Patent attorney Takehiko Suzue (Ludesiste 4) No. 1rXI Figure 4 Figure 6 (C)

Claims (1)

[Claims] X-ray photography or
An image memory for storing image data obtained by fluoroscopy, a detection means for reading the image data from the image memory and detecting the minimum pixel density in the X-ray image, and a detection means for detecting the minimum pixel density in the X-ray image based on the minimum value detected by the detection means. Threshold level setting means for setting a threshold level of pixel density, and when the pixel density of the image data read from the image memory is in an area below this threshold level, the vicinity of the tip of the subject is placed in this area. an image recognition circuit comprising an extraction means for recognizing the presence of an X-ray opaque material and extracting pixel data corresponding to the X-ray opaque material; Image enlarging means for determining an enlargement ratio and an enlargement center from the spatial size of pixel data corresponding to the X-ray opaque substance and the position on the image, and enlarging the pixel data corresponding to the X-ray opaque substance. and display means for selecting either the image data enlarged by the image enlargement means or the image data read from the image memory and displaying the input image. Device.