JPH0690939A - Body motion synchronizing recursive filter device - Google Patents

Abstract

PURPOSE:To obtain a distinct image by reducing efficiently a quantizing noise, and also, decreasing a residual image of an image of a motion part. CONSTITUTION:An X-ray image signal of an object 7 to be photographed, outputted from an X-ray radioscopic device 1 by a coefficient circuit 11 is multiplied by a coefficient set in advance, and thereafter, the X-ray image signal outputted from the coefficient circuit 11 and the previous X-ray image signal of the same phase are added by an adding circuit 12, it is outputted as a processed X-ray image signal, and also, the X-ray image signal outputted from the adding circuit 12 is stored at every phase by each image memory 15. Subsequently, the X-ray image signal of the same phase as a phase of the present X-ray image signal is read out, and the X-ray image signal outputted each image memory 15 by a coefficient circuit 17 is multiplied by the coefficient set in advance and fed back to the adding circuit 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a body motion synchronous recursive filter device used in a DF device or the like.

[0002]

2. Description of the Related Art Since it is difficult to completely remove quantization noise in an X-ray fluoroscopic image, a recursive filter device is often used to improve the image quality of the fluoroscopic image. FIG. 4 is a block diagram showing an example of such a recursive filter device.

Recursive filter device 10 shown in this figure
1 is a coefficient unit 102 that multiplies the input current frame image by a preset coefficient, and this coefficient unit 102
103 for adding the output of the image and the feedback image, an image memory 104 for delaying the output of the adder 103 by one frame, and an image output from the image memory 104 (image of the previous frame) and preset And a coefficient unit 105 which feeds back to the adder 103.

Then, X-rays are radiated from the X-ray tube 106 toward the subject 107, and a fluorescent multiplier (II) 108 is emitted.
Goes in, the transmitted X-ray image is converted into a visible light image,
After being converted into a video signal by the TV camera 109,
When the image (digital image) A / D-converted by the A / D converter 110 is input to the coefficient unit 102, the quantization noise is reduced by performing the processing shown in the following equation, and D /
It is supplied to the A converter 111, and the D / A converter D
/ A converted and displayed on the monitor 112. I = (1 / K) I ₀ + (1-1 / K) I _-1 (1) where I: image output from the recursive filter device 101. K: Recursive coefficient value set in advance. I ₀ : This image. I _-1 : Previous image.

[0005]

However, in the above-mentioned conventional recursive filter device 101, the image of the previous frame and the image of the current frame are added at a predetermined ratio, and the random image contained in the image of the current frame is added. Since the quantization noise is canceled to reduce the quantization noise, there is a problem that the moving part between the image of the previous frame and the image of the current frame becomes an afterimage (arcfact).

In particular, the larger the recursive coefficient value and the greater the effect of reducing the quantization noise, the easier it becomes to see the image in the still portion, but conversely, the afterimage becomes noticeable and there is movement. There was a problem that the image of the part became difficult to see.

In view of the above situation, the present invention can efficiently reduce the quantization noise and reduce the afterimage of the image of the moving part, thereby obtaining a clear image. An object is to provide a synchronous recursive filter device.

[0008]

In order to achieve the above object, a body motion synchronous recursive filter device according to the present invention comprises:
A coefficient circuit that takes in an X-ray image signal of a subject obtained by an X-ray fluoroscope and applies a preset coefficient to this X-ray image signal, an X-ray image signal output from this coefficient circuit, and the previous time And an X-ray image signal output from this addition circuit are stored for each phase, and an X-ray image having the same phase as the phase of the X-ray image signal of this time is stored. An image memory for reading out a signal and a coefficient circuit for multiplying an X-ray image signal output from the image memory by a preset coefficient and feeding it back to the adding circuit are characterized.

[0009]

In the above arrangement, the coefficient circuit multiplies the X-ray image signal of the subject output from the X-ray fluoroscope by a preset coefficient, and then the adder circuit outputs the X-rays from the coefficient circuit. The image signal and the previous X-ray image signal having the same phase are added and output as a processed X-ray image signal, and the X-ray image signal output from the addition circuit by the image memory is output for each phase. The stored X-ray image signal having the same phase as the X-ray image signal of this time is read out, and a coefficient circuit applies a preset coefficient to the X-ray image signal output from the image memory. And is fed back to the adder circuit.

[0010]

FIG. 1 is a block diagram showing an example of an X-ray fluoroscopic image system using an embodiment of a body motion synchronous recursive filter device according to the present invention.

The X-ray fluoroscopic image system shown in this figure has an X-ray fluoroscope 1, a biological information detection circuit 2, an A / D conversion circuit 3, a recursive filter device 4, and a D / A conversion circuit 5.
And a monitor 6, the movement of the subject 7 is detected by the biological information detection circuit 2, and an X-ray fluoroscopic image of the subject 7 is created by the X-ray fluoroscopic apparatus 1, and then the recursive filter apparatus 4 is used to detect the subject. 7. The recursive filter processing synchronized with the movement of 7 is performed to reduce the quantization noise, and this is D / A converted by the D / A conversion circuit 5 and displayed on the monitor 6.

The X-ray fluoroscope 1 generates X-rays to generate an object 7
X-ray tube 8 for irradiating the subject, a fluorescent multiplier (II) 9 for converting the X-rays transmitted through the subject 7 into visible light, and a television camera 10 for taking a visible light image of the fluorescent multiplier 9. The X-ray tube 8 irradiates the subject 7 with X-rays, the X-rays transmitted through the subject 7 are converted into visible light by the fluorescent multiplier 9, and then the television camera 10 is provided.
Is converted into a video signal and supplied to the A / D conversion circuit 3.

The A / D conversion circuit 3 is the TV camera 10 described above.
The image output from is taken in, A / D-converted into an image in digital format, and this is supplied to the recursive filter device 4.

Further, the biological information detection circuit 2 uses the subject 7
An ECG waveform indicating the movement of the heart is detected as the body movement of the above, and a synchronization signal having a period up to the next R wave with the R wave of this ECG waveform as a reference is generated and supplied to the recursive filter device 4.

The recursive filter device 4 includes a coefficient circuit 11
It includes an adder circuit 12, a phase detection circuit 13, an input switch group 14, a plurality of image memories 15, an output switch group 16 and a coefficient circuit 17, and is output from the biological information detection circuit 2. The image output from the television camera 10 is subjected to recursive filter processing on the basis of the synchronization signal to generate an image represented by the following equation, and the image is supplied to the D / A conversion circuit 5. I = (1 / K) I _ij + (1-1 / K) I _i-1j (2) where I: image output from the recursive filter device 4. K: Recursive coefficient value set in advance. I _ij : Image of the frame this time. I _i-1j : An image having the same phase one cycle before the image I _ij .

The coefficient circuit 11 takes in the image output from the A / D conversion circuit 3, multiplies the image by a preset coefficient, and supplies the image to the input terminal A of the addition circuit 12.

Further, the phase detection circuit 13 takes in the synchronization signal output from the biological information detection circuit 2 and, based on this synchronization signal, an image of which phase is currently input to the A / D conversion circuit 3. The A / D
A selection signal necessary for selecting the same phase as the phase of the image input to the conversion circuit 3 is generated and supplied to the input switch group 14 and the output switch group 16.

The input switch group 14 includes a plurality of switches 20.
Based on the selection signal output from the phase detection circuit 13, the switch 20 designated by the selection signal is closed and the image output from the addition circuit 12 is stored in one of the image memories 15. Supply one.

The respective image memories 15 are arranged so as to correspond to the respective switches 20 of the input switch group 14 in a one-to-one correspondence, and correspond to the switches 20 when an image is output from the respective switches 20. The image output from the switch 20 is captured and stored by the image memory 15 and is supplied to the output switch group 16. As a result, as shown in FIG. 2, the image of each phase is sequentially stored in each image memory 15 with the R wave of the ECG waveform of the subject as a reference.

The output switch group 16 includes a plurality of switches 21.
Based on the selection signal output from the phase detection circuit 13, the switch 21 designated by the selection signal is closed to select one of the images output from each image memory 15. It is supplied to the coefficient circuit 17.

The coefficient circuit 17 takes in the image output from the output switch group 16, multiplies the image by a preset coefficient, and the image obtained by this multiplication operation is added to the image of the addition circuit 12. Input terminal B
Supply to.

The adder circuit 12 adds the images input to the respective input terminals A and B, supplies the image obtained by this adding operation to the input switch group 14, and
It is supplied to the D / A conversion circuit 5.

The D / A conversion circuit 5 takes in an image in digital format output from the recursive filter device 4, performs D / A conversion on the image, generates an image in analog format, and supplies it to the monitor 6. . The monitor 6 is the D / A
The image output from the conversion circuit 5 is captured and displayed.

As described above, in this embodiment, the input switch group 1 is used with the R wave of the ECG waveform of the subject 7 as a reference.
4 and the switches 21 of the output switch group 16 are sequentially and selectively closed to set the television camera 1
Since the image of the subject 7 output from 0 is stored in each image memory 15 and the recursive filter process is performed, it is possible to cancel only the quantization noise between the images 22 having the same phase as shown in FIG. As a result, the quantization noise can be efficiently reduced, and the afterimage of the moving portion image can be reduced, and as a result, a clear image can be obtained.

Further, in the above-mentioned embodiment, the movement of the heart is taken as an example of the periodic body movement, but another body movement, for example, a movement of the breath is detected, and this is used as the biological information of the recursive filter device 4. It may be supplied to the phase detection circuit 13.

In addition, in the above-described embodiment, a plurality of image memories 15 are used, and the respective image memories 15 are sequentially and cyclically used by the input switch group 14 and the output switch group 16. However, even if one large image memory is prepared and the addresses of this image memory are sequentially switched and used, the same effect as the above-described embodiment can be obtained.

[0027]

As described above, according to the present invention, the quantization noise can be efficiently reduced, and the afterimage of the image of the moving portion can be reduced, whereby a clear image can be obtained. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an X-ray fluoroscopic image system using an embodiment of a body motion synchronous recursive filter device according to the present invention.

FIG. 2 is a schematic diagram showing a phase example of each image stored in each image memory shown in FIG.

FIG. 3 is a schematic diagram showing an operation example of the body motion synchronous recursive filter device shown in FIG.

FIG. 4 is a block diagram showing an example of an X-ray fluoroscopic image system using an example of a conventionally known recursive filter device.

[Explanation of symbols]

 1 X-ray fluoroscope 2 Biological information detection circuit 3 A / D conversion circuit 4 Recursive filter device 5 D / A conversion circuit 6 Monitor 11 Coefficient circuit 12 Addition circuit 13 Phase detection circuit 14 Input switch group 15 Image memory 16 Output switch group 17 Coefficient circuit 20, 21 switch

Claims (1)

[Claims] 1. A coefficient circuit for taking in an X-ray image signal of a subject obtained by an X-ray fluoroscope and applying a preset coefficient to this X-ray image signal, and an X output from this coefficient circuit. An addition circuit for adding the X-ray image signal and the X-ray image signal of the same phase of the previous time, and the X-ray image signal output from this addition circuit is stored for each phase, and the same as the phase of the X-ray image signal of this time. An image memory for reading a phase X-ray image signal, and a coefficient circuit for multiplying an X-ray image signal output from the image memory by a preset coefficient and feeding the multiplied X-ray image signal back to the adder circuit are provided. Characteristic body motion synchronous recursive filter device.