JPH0444476A - X-ray television receiver - Google Patents

Abstract

PURPOSE:To obtain sufficient contrast resolution by providing a lst image pickup means picking up a picture with a low gain and a 2nd image pickup means picking up a picture with a high gain sequentially at each prescribed timing and synthesizing each picture picked up by both the image pickup means so as to reconstitute the picture as one picture. CONSTITUTION:An X-ray tube 1 is controlled by an X-ray generator 10. A camera output corresponding to a short X-ray exposure time 1 is read as a low gain picture (lst L picture : VIEW1). Succeedingly a camera output corresponding to a long X-ray exposure time t. is read as a high gain picture (lst H picture : VIEW1). Similarly, VIEW2 and succeeding pictures are repeated. Thus, the pictures of high and low gain are picked up by controlling the X-ray exposure time and the pictures are synthesized and reconstituted into one picture, then the dynamic range of a television camera is widened. Thus, sufficient contrast resolution is obtained.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Industrial Application Field) The present invention converts X-rays transmitted through a subject into an optical image, and captures this optical image to produce an X-ray image for visualization. Related to television equipment.

(Prior art) After exposing the subject to X-rays and inputting the transmitted X-rays to an image intensifier (I, r, ) to convert the X-rays into an optical signal, output based on this optical signal. 2. Description of the Related Art An X-ray television apparatus is known in which an optical image formed on a surface is photographed by a television camera and displayed on a monitor. FIG. 10 shows the configuration of an example of a conventional X-ray television device, in which 1 is an X-ray tube, 2 is a subject, and 3 is an I/O device that inputs the X-rays that have passed through the subject 2 and converts them into optical signals. , I, , 4a, 4b are first and second condensing lenses; 5 is an image pickup tube that operates as a television camera that inputs the optical signal through the condensing lenses 4a, 4b and converts it into an electric signal; 6; 7 is an A/D converter that converts the output signal of the image pickup tube 5 into a digital signal, 7 is a signal processing system that processes the digital signal into a necessary signal, and 8 is a signal processing system that converts the output of the signal processing system 7 into an X-ray image. This is the monitor that displays the image.

FIG. 11 shows the image pickup tube 5 using such an X-ray television device.
This shows a timing chart for taking images by the X-ray tube 1, in which the image of the subject 2 taken by the image pickup tube 5 while being continuously exposed to X-rays is frame-framed at the timing of the generation of the vertical synchronization signal VD. It is designed to scan and output each time. VIEWI, 2.3... indicate images corresponding to each frame.

(Problem to be Solved by the Invention) However, in conventional X-ray television equipment that uses an image pickup tube as a television camera, there is a problem in that sufficient contrast resolution cannot be obtained due to the narrow dynamic range of the television camera. .

The present invention has been made in response to the above-mentioned problems.
It is an object of the present invention to provide an X-ray television apparatus that can obtain sufficient contrast resolution.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention converts X-rays transmitted through a subject into an optical image, and visualizes it by photographing this optical image. In the X-ray television apparatus provided, the first imaging means sequentially takes low gain images at predetermined timings, the second imaging means takes high gain images, and the first and second imaging means each The present invention is characterized by comprising an image reconstruction means for combining a photographed low-gain image and a high-gain image into one image.

(Function) After sequentially capturing low-gain images and high-gain images at predetermined timings, such as vertical synchronization signal generation timings,
These images are combined and reconstructed as one image.

By repeating such imaging and reconstruction in the same manner, necessary X-ray images are created and displayed on the monitor. As a result, the dynamic range of the television camera can be widened, and sufficient contrast resolution can be obtained.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the X-ray television apparatus of the present invention. - This shows an example of application to a CT device, where 1 is an X-ray tube, 2 is an object to be examined, and 3 is an input device that inputs the X-rays that have passed through the object 2 and converts it into an optical signal.
4b is a first and second condenser lens; 9 is a condenser lens 4a for transmitting the optical signal;

4b is a CCD (charge coupled device) that operates as a television camera that inputs the signal and converts it into an electrical signal; 6 is an A/D converter that converts the output signal of CCD 9 into a digital signal; 8 is a monitor. . As will be described later, the CCD 9 operates to sequentially take a low gain image and a high gain image at each vertical synchronization signal generation timing.

10 is an X-ray generator that controls the X-ray exposure timing of the X-ray tube 1; 11 is a system controller including a CPU (central processing unit) that controls the entire structure of the X-ray television apparatus; and 12 is a system controller that controls the operation of the CCD 9. A TV camera controller 13 is used to synthesize a low gain image and a high gain image photographed by the CCD 9 into one image, and 14 is an X-ray C
This is a reconstruction device that reconstructs a T image.

Next, the operation of this embodiment will be explained.

FIG. 2 shows a timing chart for photographing images by the apparatus of this embodiment, in which the TV left camera ITCCD is used to scan in non-interlace mode.

First, X-rays are generated from the X-ray tube 1 in a pulse shape as shown in the figure. In this case, the X-ray tube 1 is placed between the
controlled by In response to such X-ray exposure, I,
The transmitted X-rays input to I, 3 are converted into an optical image and output, and this optical image is passed through the first and second condensing lenses 4.
The signal is inputted to the CCD 9 via signals a and 4b, converted into an electrical signal, and accumulated every vertical synchronization signal period. This accumulated electric signal is read out by a field shift pulse (FS) generated in synchronization with the vertical synchronization signal VD, thereby obtaining a camera output. The camera output corresponding to the short X-ray exposure time t1 is read out as a low-gain image (first L image: VIEWI), and then the camera output corresponding to the long X-ray exposure time t2 is read out as a high-gain image. (First 8 images: VI EWI). Similarly, when the reading of the low gain and high gain images of the first image is completed, the next low gain image (second L image: VI EW2) is read out as the next camera output, and then the high gain image is read out as the next camera output. image (second 8 images: VI
EW2) is read out. Similarly, VI EW3
Reading of subsequent images is repeated.

FIG. 3 shows the camera output characteristics of low-gain and high-gain images sequentially read out in this manner.

Here, the gain ratio G between the low gain image and the high gain H image of each image (VI EW) is expressed as the ratio of the X-ray exposure time jl+t2 as follows.

The low-gain image and the high-gain image output from the CCD 9 are each converted into digital signals by the A/D converter 6, and then the two-image synthesizer 13 first converts them into a first L image and a first 8 images. are combined into one image, then the second image and the second eight images are combined into one image, and the third and subsequent images are combined into one image in the same manner.

The image synthesized in this way is converted to X by the reconstruction device 14.
After being reconstructed as a line image, it is displayed on the monitor 8.

Here, signals that are not saturated among the first eight images (VI EWI) are adopted as they are, and for saturated portions, the corresponding first L image (VI EWI) is multiplied by the value of G. Adopted as the signal value of the part. Below is the second image (
The same applies to VI EW2), the third image (VI EW3), and so on. Further, the distinction between H and L may be made based on a specific threshold value set as shown in FIG. 4, rather than whether or not it is saturated.

According to such an embodiment, by controlling the X-ray exposure time, a low gain image and a high gain image are respectively taken, and then these images are combined and reconstructed as one image. The dynamic range of the TV camera can be widened. Therefore, sufficient contrast resolution can be obtained. Note that the apparatus of this embodiment can also be applied to the case of performing transmission image photography, and in this case, the reconstruction device 14 with the configuration shown in FIG. 1 is unnecessary. Further, although the X-ray pulse may be repeatedly exposed, the image may be imaged with only one shot.

As a second embodiment of the present invention, a CCD 9 having the configuration shown in FIG.
This shows an example in which X-ray exposure is performed continuously by using the electronic shutter function of the CCD 9, and low-gain images and high-gain images are sequentially photographed by the CCD 9. Also, X-ray exposure may be performed in a pulsed manner, but in this case, the fifth
As shown in the figure, it is desirable that the control be such that X-ray exposure is performed during the integration time of the electronic shutter.

In this case, the gain ratio G is expressed as follows.

X-ray amount (light amount) of VI EWI L Also, the low gain and high gain image synthesis methods are performed in the same manner as in the first embodiment.

FIGS. 6 and 7 are block diagrams and timing charts showing a third embodiment of the present invention, and show an example in which low-gain images and high-gain images are sequentially photographed using an optical aperture. . 15 is the first and second condensing lens 4a, 4b
An optical diaphragm 16 is placed between the two, an aperture controller that controls the degree of aperture of the optical diaphragm 15, and a television camera 17 consisting of a CCD or an image pickup tube.

With X-ray irradiation being performed continuously as shown in FIG. The camera output corresponding to the large aperture is read out as a low gain image (first L image: VIEWl), and then the camera output corresponding to a large aperture is read out as a high gain image (first 8 images: VI EWI). Similarly, the second image (VI EW2) is output as the next camera output.
is read out, and the third image (VI EW3) and subsequent images are read out. Here, the gain ratio G is expressed as in the following equation.

Further, the low gain and high gain image synthesis methods are performed in the same manner as in the first embodiment. Note that the optical diaphragm 15 may be of a mechanical type or an electronic type (for example, one using liquid crystal).

FIGS. 8 and 9 are block diagrams and timing charts showing a fourth embodiment of the present invention, in which two television cameras with different gains are used simultaneously to sequentially capture low-gain images and high-gain images. This is an example of how to do this. 4a, 4b,
4c is the 1st. 2nd ° 3rd condensing lens, 6a, 6b are A
/D converter; 17a, 17b are first and second television cameras constructed from CCDs or image pickup tubes; 18, half mirrors 19a, 19b disposed between the first and second condensing lenses 4a, 4b; are the first and second television cameras 1, respectively.
These are first and second optical apertures that narrow down the optical signals input to 7a and 17b.

As shown in FIG. 9, with continuous X-ray irradiation, the optical signals input to the first and second television cameras 17a and 17b are alternately thickened at each generation timing of the vertical synchronization signal VD. At the same time, the same image (for example, VI EWI) is controlled so that one image (for example, VI EWI) is apertured large and the other is apertured small. A gain image and a high gain image are sequentially photographed by the first and second television cameras 17a and 17b.Here, the gain ratio G is expressed as in the following equation.

The aperture difference is between the first and second optical apertures 19a.

This can also be realized by a difference in the opening degree of the openings 19b.

It can also be realized by appropriately selecting the ratio between the transmittance and the reflectance of the half mirror 18.

As described above, according to the embodiment of the present invention, 1.1. When taking X-ray images using a television camera, two images with different gains of the same body part are taken by various means, and then these are combined into one, so the dynamic of the television camera is The range can be expanded. The television camera used in the present invention is not limited to a solid-state image pickup device such as a CCD, and similar effects can be obtained by using a commonly used image pickup tube.

[Effects of the Invention] As described above, according to the present invention, after taking a low gain image and a high gain image, each image is combined and reconstructed as one image, so that the television camera The dynamic range can be widened and sufficient contrast resolution can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the X-ray television apparatus of the present invention, FIG. 2 is a timing chart explaining the operation of the first embodiment, and FIG. 3 is an image photographed by the present invention. FIG. 4 is an explanatory diagram of a modification of the first embodiment, and FIG.
The figure is a timing chart explaining the operation of the second embodiment of the present invention, FIGS. 6 and 7 are block diagrams showing the third embodiment of the invention and a timing chart explaining the operation, and FIG. 9 is a block diagram showing a fourth embodiment of the present invention and a timing chart explaining its operation, and FIGS. 10 and 11 are a block diagram showing a conventional device and a timing chart explaining its operation. . 3...r, r, (image intensifier)
, 9...CCD, 13...2 image synthesis device,
14... Reconstruction device, 15.19a, 19b-optical aperture, 17.17a, 17b... TV camera, 18...
Half mirror 1

Claims (1)

[Claims] In an X-ray television apparatus that converts X-rays transmitted through a subject into an optical image and provides visualization by photographing this optical image, a first photographing means for sequentially photographing low-gain images at predetermined timing; A second photographing means for photographing a high gain image; and an image reconstruction means for combining a low gain image and a high gain image respectively photographed by the first and second photographing means into one image. An X-ray television device characterized by: