JPH0767150B2 - X-ray fluoroscopic image processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray fluoroscopic image processing apparatus for performing image processing of an X-ray fluoroscopic image obtained by an X-ray fluoroscopic system, and particularly to a plurality of continuous frames obtained under X-ray fluoroscopy. The present invention relates to an X-ray fluoroscopic image processing device that processes an image.

[0002]

2. Description of the Related Art An X-ray TV fluoroscopic system converts an X-ray fluoroscopic image obtained by irradiating X-rays from an X-ray tube into a video signal by combining an image intensifier and a TV camera, which is then used as a TV monitor. Sent to the device for display,
What to observe. In this X-ray TV fluoroscopic system, a fluoroscopic image is obtained in a state where the X-ray dose is small, and therefore has a lot of quantum noise. Therefore, conventionally, a noise reduction process such as a recursive filter process is often performed for recording / reproducing a perspective image.

[0003]

However, in the prior art, since only the recursive filter processing is performed, only a noise reducing effect can be obtained, and there is a problem that the contrast of an image is insufficient. In particular, in a region such as a chest where a bright portion such as a lung field and a dark portion such as a heart coexist, it is difficult to understand a fine structure portion that overlaps both. In such a case, it is desirable that the contrast processing for clearly displaying the coexisting fine structures at the same time be automatically performed, and unsharp masking processing can be considered as the processing, but since the processing time is long, It is difficult to execute in real time at the frame rate of the TV fluoroscopy system, and there is a drawback that the processing cannot be performed in real time when observing an X-ray fluoroscopic image while displaying it on a TV monitor in real time.

An object of the present invention is to provide an X-ray fluoroscopic image processing apparatus capable of obtaining an unsharp masking image of high contrast in which a fine structure can be easily observed in a short time.

[0005]

In order to achieve the above object, in the X-ray fluoroscopic image processing apparatus according to the present invention,
The recursive filter processing is performed by weighting and adding the video signals of the X-ray fluoroscopic image while matching the corresponding pixel positions among a plurality of frames, and by performing the weighted addition while shifting the corresponding pixel positions. Perform processing. In the former process, a normal recursive filter processed image, that is, an image in which noise is reduced by having an integration effect in the time direction, is obtained, and in the latter process, a time direction image with smoothing in the plane direction of the screen is added. A blurred image is obtained by integration. Each of these images is weighted and then subtracted. These two
Since different types of recursive filter processing can be performed in parallel at the same time, these images can be obtained at high speed, and an unsharp masking image can be obtained in a short time, which is almost the same as in the case of conventional ordinary recursive filter processing alone. Obtainable.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 1, a video signal of an X-ray fluoroscopic image is sequentially transmitted frame by frame from a TV camera of an X-ray fluoroscopic TV system (not shown).
This video signal is converted into a digital signal in the A / D converter 10. The digitized image data is sent to the recursive filter circuits 20 and 30. The recursive filter circuits 20 and 30 have multipliers 21 and 2 respectively.
2, 31, 32, adders 23, 33, frame memory 2
4 and 34 are provided. Then, the frame memory 24,
The read address of 34 is controlled by the memory address controller 80. The output image data of the recursive filter circuits 20 and 30 are multiplied by multipliers 41 and 42, respectively, and then subtracted from each other by a subtractor 50, passed through a window processor 60 and a D / A converter 70, and converted into analog signals. TV (not shown) converted to video signal
Displayed by sending to a monitor device.

The recursive filter circuit 20 is an ordinary recursive filter circuit. When the image data of a new frame is output from the A / D converter 10, the data of the pixel position corresponding to each pixel is stored in the frame memory 24. Read from. This read address is controlled by the memory address controller 80 as described above. The data of these corresponding pixel positions are respectively converted into the coefficient A and the coefficient (1-A) by the multipliers 21 and 22.
Are weighted by being respectively multiplied and then added by the adder 23. The data after the addition is written in the frame memory 24 at the address of the corresponding pixel position. Since such an operation is repeated for each frame, a kind of weighted integration of the image in the time direction is performed, and a kind of weighted integrated image (recursive filter processed image) is formed in the frame memory 24. It

On the other hand, the recursive filter circuit 30 is a recursive filter circuit with pixel shift. That is, when the image data of a new frame is output from the A / D converter 10, the data of the pixel position corresponding to each pixel is not read from the frame memory 34, but
The read address is the memory address controller 8
By controlling with 0, the data of the shifted pixel position is read. For example, the A / D converter 10
Pixels in the 3 × 3 template of the n-th frame image input from are set to A (n) to I (n) as shown in FIG.
If the pixels of the 3 × 3 template of the image stored in the frame memory 34 at the time of inputting the nth frame image are a (n) to i (n) as shown in FIG. 3, the pixels corresponding to the pixel En As a result, a (n) is read from the frame memory 34 in the nth frame, b (n + 1) is read from E (n + 1) in the next n + 1th frame, and E (n) is read in the (n + 2) th frame. c (n + 2) is read for (n + 2),
In the +3 frame, d (n + 3) is read for E (n + 3), in the n + 8th frame, i (n + 8) is read for E (n + 8), and the n + 9th frame Then, for E (n + 9), a (n +
9) is read out and sequentially shifted frame by frame.

The pixel data thus read out from the frame memory 34 while the pixel position is being shifted is weighted by being multiplied by the coefficient (1-B) in the multiplier 32. The inputted pixel data is multiplied by the coefficient B in the multiplier 31.
Is multiplied and weighted. These weighted pixel data are added by the adder 33. The pixel data after the addition is written in the frame memory 34 at an address corresponding to the pixel position (for example, E position) of the input image. By repeating this operation for each frame, a blurred image is formed in the frame memory 34.

The recursive filter processed image output from the recursive filter circuit 20 is multiplied by a coefficient C in a multiplier 41 and weighted, and the blurred image output from the recursive filter circuit 30 is multiplied by a coefficient (1-C) in a multiplier 42. Is multiplied and weighted. These weighted images are subtracted from each other by the subtractor 50. The image data sequentially obtained from the subtractor 50 is sent to the window processor 60. The window processor 60 receives a window process (a kind of gradation conversion) in which only a predetermined window of the gradation is emphasized, and the contrast, brightness, etc. are adjusted, and then the D / A converter 70. And is converted back to an analog video signal.

Since the blurred image is subtracted from the recursive filter processed image in this manner, the unsharp masking process is performed and an image with high contrast can be obtained. In addition, since the recursive filter processed image and the blurred image are simultaneously processed in parallel by the same recursive filter processing operation, it takes exactly the same processing time as the conventional recursive filter processing alone, and the X-ray TV It can be performed in real time at the system frame rate.

Although a 3 × 3 template blurred image is obtained by the recursive filter circuit 30 with pixel shift in the above, the pixel shift amount is arbitrarily changed to 5 ×.
Of course, it is also possible to obtain a blurred image with a large template such as 5, 7 × 7, 9 × 9, 11 × 11, 25 × 25 and perform the unsharp mask processing.

[0013]

As described above with reference to the embodiments,
According to the X-ray fluoroscopic image processing apparatus of the present invention, since an unsharp masking image can be obtained at high speed, an X-ray fluoroscopic image that clearly shows the fine structure most desired by the operator can be obtained only by the conventional recursive filter processing. It can be obtained in exactly the same processing time as that of, and can be processed at the frame rate of the X-ray TV system, and can be processed in real time while being seen through.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing each pixel of an input image in the embodiment.

FIG. 3 is a diagram showing each pixel of a stored image in the embodiment.

[Explanation of symbols]

10 A / D converter 20 Ordinary recursive filter circuit 30 Recursive filter circuit with pixel shift 21,22,31,32,41,42 Multiplier 23,33 Adder 24,34 Frame memory 50 Subtractor 60 Window processor 70 D / A converter 80 Memory address controller

Claims (1)

[Claims] 1. A first recursive filter means for weighting and adding a video signal of an X-ray fluoroscopic image while matching corresponding pixel positions between a plurality of frames, and weighting and adding while shifting the corresponding pixel position. An X-ray fluoroscopic image processing apparatus comprising: a second recursive filter means, a means for weighting respective integration results thereof, and a subtracting means for subtracting both weighted integration results.