JPH02224745A - Defect compensating device for x-ray fluoroscopic image - Google Patents

Abstract

PURPOSE:To obtain a good penetration image and enhance the space resolution of an X-ray TV camera by storing in memory any defective parts in advance, compensating defective part signals in an object penetrative image signal corresponding to the parts with a perimetric image signal, and thereby compensating defects such as black and white spots appearing on the penetration image. CONSTITUTION:Defective positions are stored in memory prior to photographing. At this time, a changeover switch 32 is set on the A-terminal side. An image signal obtained by penetrating a phantom is converted by an A/D converter 31 into digital signal and entered in comparators 33a, 33b. The comparator 33a compares an image signal for calibration with the threshold value and senses defects of white spot. The other comparator 33b compares image signal with the threshold value and senses defects of black spot. The output signals from comparator are fed to an image memory 35 and allocated with an address therein corresponding to the defective position according to an address specifying signal from an address specifying circuit 36, which is to be given dot clock pulses, and the bit '1' is stored in the address region.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention relates to an X-ray fluoroscope using an X-ray image intensifier and an X-ray television camera.

B. Prior art X-ray fluoroscopy equipment includes an X-ray tube device that irradiates X-rays toward a subject, an X-ray image intensifier placed opposite the X-ray tube device, and an X-ray image It includes a television camera that receives an output optical image from an intensifier and outputs an image signal, and a monitor television that receives an image signal from the television camera and displays a perspective image.

The X-rays that have passed through the subject are converted into a light image by an X-ray image intensifier, then overestimated by an X-ray television camera and provided as an image signal to a television monitor. As a result, a fluoroscopic image of the subject is displayed on the monitor television.

C1 Problems to be Solved by the Invention However, the above-mentioned conventional device has the following problems.

■During the manufacturing process of X-ray image intensifiers and X-ray television cameras, dust may get mixed into the X-ray image intensifier or the imaging tube of the X-ray television camera. This dust blocks the flow of the electron beam, causing black dots to appear on the fluoroscopic image displayed on the screen of the monitor television, resulting in the problem that a good fluoroscopic image cannot be obtained.

■In the manufacturing process of image pickup tubes for X-ray television cameras, when forming a photoconductive film on the image pickup surface, it is difficult to deposit the photoconductive film on the periphery of the image pickup surface, and there are areas where the deposition is not applied or scratches occur. there is a possibility. The photoconductive film is a substance whose resistance value changes when exposed to light, so if there is a portion where the photoconductive film is not formed, a white spot will appear on the transparent image displayed on the monitor television. For this reason, only the central portion of the imaging surface excluding the peripheral portion is used, which results in the problem that the imaging surface cannot be used widely and the spatial resolution of the X-ray television camera cannot be increased.

This invention was made in view of the above circumstances, and aims to compensate for defects such as black spots and white spots that appear in fluoroscopic images, obtain good fluoroscopic images, and improve the spatial resolution of an X-ray television camera. It is an object of the present invention to provide a defect compensation device for X-ray fluoroscopic images.

09 Means for Solving the Problems The present invention has the following configuration to achieve the above object.

That is, the present invention provides an image defect compensation device for an X-ray fluoroscopic photographing device in which an output optical image of an X-ray image intensifier is captured by an XM child television camera and displayed on a monitor television, and the present invention is an image defect compensation device for calibrating the X-ray television camera. defective part detecting means for detecting a defective part signal in an image signal; defect position storing means for storing a defect position on the most image screen based on the signal from the defective part detecting means; The present invention is characterized by comprising an image interpolation means for interpolating a defective part signal included in the subject fluoroscopic image signal of the Xg child television camera based on the defective position signal using neighboring pixel signals.

According to the invention of 81 action 2, before taking a fluoroscopic image of the subject,
By comparing the calibration image signal output from the X-ray television camera with a preset threshold, the defect detection means detects the defective part signal in the calibration image signal, and detects the defective part signal. Output to position storage means. The defect location storage means stores the defect location of the image displayed on the screen of the television monitor based on the defect location signal.

When capturing a fluoroscopic image of the object, an image interpolation means interpolates a defect site signal included in the object fluoroscopic image signal with a pixel signal near the defective area based on the defect position data output from the defect position storage means. Process.

F. Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram schematically showing the configuration of an embodiment of the X-ray fluoroscopic image defect compensation apparatus according to the present invention, and FIG. 2 is an explanatory diagram of its operation.

In the figure, numeral 10 is an X-ray image intensifier;
0 is an X-ray television camera, 30 is a defect compensation device, and 40 is a monitor television.

The defect compensation device 30, which is a characteristic part of the present invention, is an A/D converter that converts an image signal from the X-ray television camera 20 into an A/D converter.
A converter 31, a changeover switch 32 for switching and outputting a digital image signal, comparators 33a and 33b for detecting a defective part in the image signal, and a threshold generation country for setting a threshold value for the comparators 33a and 33b. 34, and an image memory 35 of NXNX 1 bit (N indicates the number of vertical and horizontal pixels of the monitor image) for storing the defect position.
, an address designation circuit 36 that counts dot crotters and designates the address of the image memory 35, and an AND gate 3.
7, a latch circuit 38 that latches an image signal, and a D/A converter 39 that converts the output of the latch circuit 3 into an analog signal.

First, the defect position is stored before the ti image.

For example, a homogeneous phantom with uniform thickness, such as an acrylic plate, can be seen through.

At this time, the changeover switch 32 is set to the A terminal side.The image signal obtained by looking through the phantom is
The signal is converted into a digital signal by the /D converter 31 and inputted to the comparators 33a and 33b via the changeover switch 32.

Figure 2 (b) shows the image signal for calibration at this time, and P
+, Pt corresponds to the defective site signal. FIG. 2(a) shows an image on the monitor television 40 when looking through the phantom. The white dots in FIG. 2 are caused by defects in the photoconductive film of the X-ray television camera 20, and the defect site signal P1 is at a positive level, and the black dots are caused by dust, and the defect site signal P1 is at a positive level. ! is at a negative level. The comparator 33a detects a white spot defect (defect site signal P+) by comparing the threshold Va set in the threshold country 34 with the calibration image signal. The comparator 33b detects a black spot defect (defect site signal P2) by comparing the threshold (1[Vb) set in the threshold country 34 with the image signal.

In this way, the comparator output signal that detects each defect is provided to the image memory 35. At this time, as shown in FIG. 2(C), an address in the image memory 35 corresponding to the defective position is designated by an address designation signal from the address designation circuit 36 to which a dot clock pulse is applied, and the comparators 33a, 33b Based on the output signal of , a bit "1" is stored in that address area.

Next, the operation of defect compensation processing of the object fluoroscopic image signal will be explained.

FIG. 2(d) is a waveform diagram of the output signal of the image memory 35, FIG. 2(e) is a waveform diagram of the dot clock, and FIG. 2(f) is an AN
The output waveform diagram of the D gate (6) is an output timing diagram of the latch circuit.

When looking through the subject, the changeover switch 32 is switched to the B terminal side. An image signal obtained by looking through the subject is converted into a digital signal by an A/D converter 31, and then input to a D terminal of a latch circuit 38 via a changeover switch 32. In synchronization with the timing of A/D conversion, the data in the image memory 35 is sequentially read out and input to the A terminal of the AND gate 37.

If there is no defect, bit "0" is read from the image memory 35, so the input to the A terminal of the AND gate 37 is "
LJ (see FIG. 2(d)), therefore, the dot clock is passed through the AND gate 37 to the latch circuit 38.
As a result, the output of the A/D converter 31, which is input to the D terminal of the latch circuit 38, is input to the Q terminal in synchronization with the timing of the dot clock. (See FIG. 2(g)), this image signal is converted into an analog signal by the D/A converter 39, and then displayed on the monitor television 40.

On the other hand, when the image signal reaches the position corresponding to the defect position,
Since the signal manually inputted from the image memory 35 to the AND gate 37 is at rH level (see FIG. 2(d)), the dot clock signal is not outputted from the AND gate 37 (see FIG. 2(f)). ).

The image signals at that time, that is, the defective site signals P+ and Pg are:
It is not latched by the latch circuit 38. therefore,
The image signal immediately before the image signal of the defect position is input is latched and output as it is (see FIG. 2 (see 80)).

Next, when a defect-free image signal is input to the D terminal of the latch circuit 3, the output of the image memory 35 becomes "L", so this image signal is latched by the next dot clock and sent from the Q4 child. Output.

In this way, the defect site signal is replaced with the immediately preceding image signal and output, so that an image free of defects such as black dots and white dots is displayed on the monitor television 40.

Note that this invention can be modified and implemented as follows.

■In the above embodiment, the defect position storage means is used as the image memory 3.
5, but it can also be configured as follows.

That is, a comparator 33a is provided with a counter for counting dot crotters, and is used when a defect is detected.

The count value of the counter at that time is memorized by the output of 33b. At the time of normal I maximum image, the count value of the counter is compared with the count value corresponding to the memorized defect position, and if they match. Sometimes the dot clock pulse is prevented from entering the latch circuit 38 to compensate for the defect.

(2) The image interpolation means can also be configured as follows.

The image signal converted into a digital signal is separated into a low-frequency component and a high-frequency component, and the defect site signal included in the high-frequency component is selectively shielded by data in the image memory 35 indicating the defect position. The compensated image signal may be extracted by adding the high-frequency image signal from which the high-frequency signal has been removed and the low-frequency image signal.

■Also, in the embodiment, the image is compensated by replacing the defective part signal with the image signal immediately before it, but this is not done by replacing it with the average value of a plurality of image signals around the defective part signal. You can.

G1 Effects of the Invention As is clear from the above description, the defect compensation device for X-ray fluoroscopic images according to the present invention stores a defective part in advance, and calculates a defective part signal in a subject fluoroscopic image signal corresponding to the part. Since compensation is performed using peripheral image signals, it is possible to display good fluoroscopic images in real time that are not affected by defective areas.

Furthermore, since defects in the imaging surface of the X-ray television camera are compensated for, a wide area including the periphery of the imaging surface can be used for imaging. Thereby, the spatial resolution of the X-ray television camera can be improved.

[Brief explanation of the drawing]

FIGS. 1 and 2 relate to embodiments of the present invention.
The figure is a block diagram showing a schematic configuration of the device, and FIG. 2 is an explanatory diagram of its operation. 33a, b...Comparator 34...Threshold value country 35...Image memory 37
...AND gate 38...Latch circuit Fig. 1 Fig. 2 (e)

Claims (1)

[Claims] (1) The output light image of the X-ray image intensifier
An image defect compensation device for an X-ray fluoroscopic imaging device that captures an image with a radiographic television camera and displays the image on a monitor television, the defective region detection means for detecting a defective region signal in a calibration image signal of the X-ray television camera; defect position storage means for storing the defect position on the imaging screen based on the signal from the defect location detection means; 1. A defect compensation device for an X-ray fluoroscopic image, comprising: image interpolation means for interpolating a defective part signal included therein by a neighboring pixel signal.