JPS58214846A - X-ray image photographic apparatus - Google Patents

Abstract

PURPOSE:To make it possible to control the optimum exposure of an image part desired in diagnosis, by detecting the quantity of light of the specific part of an image intensifier by moving a light detector corresponding to the positional indication of a display image surface to control a photographic image. CONSTITUTION:When the image surface position of a display apparatus 42 through a light pen 47, a light detector 44 is moved and the light amount at the specific part corresponding to an image intensifier 34 is detected. Corresponding to this detected output, an X-ray generating part 31 and the intensifier 34 are controlled through X-ray image controll apparatuses 32, 35 to carry out the control of a photographic image and the control of the optimum exposure of an image part desired in diagnosis can be automatically carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an X-ray image photographing apparatus, and particularly to an apparatus using an X-ray image intensifier (hereinafter simply referred to as II).

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS THEREOF Conventionally known X-ray imaging apparatuses have been widely used in combination with an X-ray tube, an intensifying screen and a film, or an X-ray television. Figure 1 is an example.
The X-rays emitted from the X-ray tube aυ) pass through the object a3, and depending on the transmittance distribution of the object att to the X-rays, the
An intensifying screen and a film (13 or II (14) 1 m long, with line images indicated by dotted lines, are projected.

In such a device (II), an exposure control mechanism called a Niphoto timer is incorporated in order to obtain the optimum exposure when taking an X-ray image.
4) outputs an output image according to the transmittance of the subject @,
A part of the output light is passed through an optical lens (1sa), (15b)
The reflective prism provided between the photodetector and the reflective prism
It forms part of the exposure control mechanism that sends a signal to the X-ray control device σ9. Photodetector light receiving element (a)
A photomultiplier tube is often used. Figure 2 is an enlarged view of the light-receiving element in Figure 1 (2).
The output light of the output screen of I is guided. Since the light receiving element has a large light field, photometry using the light receiving element is averaged over a wide area over the entire output screen. However, if an abnormality that is not intended for diagnosis (i.e. a high-brightness area, such as a lung field in a human body) falls within the lighting range, the density or brightness or contrast of the area that requires diagnosis may be inappropriate due to the high brightness. Put it away.

On the other hand, proposals have been made to compensate for the above-mentioned shortcomings, and examples thereof are presented on pages 388 to 391 of the proceedings of the 37th General Meeting of the Japanese Society of Radiological Technology. One of them is an automatic X-ray exposure control device that uses an array of photodiodes as a photodetector.The upper and lower limits of each photodiode are set in advance, and the average light intensity of the photodiodes other than those that exceed the limits is determined in advance. This is what we seek. However, this also effectively determines the brightness of the entire screen at once, and is not as suitable as Cf, which adjusts only a limited portion of the screen to the optimum brightness and contrast.

Purpose of the Invention The present invention provides a C double dynamic (controlling the operating voltage, etc. of the dual X-ray generator or The purpose of the present invention is to provide an X-ray image photographing apparatus that can be used in a C2 manner.

SUMMARY OF THE INVENTION The present invention is characterized in that a photodetector having a light field with a sufficiently small area compared to the output screen (II) is divided into two movable sections (C), and a detection signal at a desired position is used to generate an X-ray generator. or I
It is configured to control the operating voltage, etc. of I.

As a result, the image of the part of the output screen that is particularly desired to be diagnosed is automatically adjusted to have the optimum brightness or contrast, allowing high-quality imaging to be achieved in practice.

Examples of the invention The X-ray imaging apparatus shown in FIG. 3 will be explained.

In the figure, reference numeral 311 is a T-ray generator, (9) is its control device, (to) is the subject, @ is II, and ta is its control device (to).

C37), (■) are optical lenses, (to) are...-7 mirrors, (4G is a television camera using an image pickup tube, etc., I is an image signal processing device, and (c) is a television display device. Therefore, the screen for light detection is fixed to the imaging plane (43) by the half mirror (to) and the lens (to).
Hail as the entire output screen. A photodetector with a sufficiently small light field is movable with respect to the screen C2 (two photodetectors are provided). 1451 can be configured with a 2-axis orthogonal stage, a pulse motor, etc. The output signal of the photodetector is applied to a controller to obtain the optimal exposure (brightness, contrast, etc.) and processed electrically. The X-ray generator control device or II control device (G) (2) is transmitted to automatically control the operating voltage, etc. On the other hand, the CRT television display device (43 A light ben (a) n for specifying the position is provided, and a position controller (c) c2 is added to use the position as an electrical signal to drive the moving mechanism (sand).

In this device, the output image of II is displayed on the television display device τ
2 is displayed on the screen, and when the light ben is operated on the area desired to be diagnosed on the screen, the photodetector is automatically moved to a position corresponding to the area on the imaging plane, and the position is selected. In this way, the position selection device is configured.Then, the detection signal C2 is determined by the photodetector with a narrow light field.The operating voltage of the X-ray generator and/or The condition C obtained is double dynamic!two controlled.

Note that when considering the image characteristics of II and the lens, there are problems with II] pincushion distortion and vignetting of II and the lens.

When receiving light with a photodetector, the above-mentioned pincushion distortion and vignetting may be corrected using an electric circuit, but the configuration described in [2] below is simple. In order to correct the pincushion distortion of II, the lens 1 and 2 may be provided with a distortion aberration that compensates for the pincushion distortion. Also, for peripheral light reduction due to II and lens vignetting, it is sufficient to insert an optical filter with a density distribution that compensates for the vignetting immediately before the compensation using an electric circuit, and this method is simpler.

Now, in order to provide the part desired to be diagnosed as two signals using the above-mentioned apparatus, C2 may be obtained by the following method. That is, the photographer determines the part to be imaged while viewing the image on a cathode ray tube type display device. By using the horizontal and vertical deflection signals, it is easy to detect signals that cause the photodetector to move in accordance with the area desired to be diagnosed.

In the above embodiments, the desired part on the output image of II is selected (2. Although a cathode ray tube type output display device and a light vent are used, the image forming surface (screen shown in 43) is not limited to this. , the position may be specified.Furthermore, it is easier to operate if the light field of the photodetector and the area ratio of the light pen to the screen are matched.

Effects of the Invention The inventive feature is that, unlike conventional devices that perform average photometry of most areas of the output image, it detects the light of only a specific part of the output image and measures the brightness, etc. of that part. Optimal (
-1 Since the camera performs dynamic control, appropriate photographing quality can be obtained without being affected by, for example, undesired bright spots. These controls can be configured to be performed automatically and are extremely easy to operate.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a conventional device, FIG. 2 is a perspective view of its main parts, and FIG. 3 is a schematic configuration diagram showing an embodiment of the present invention. Gl)...X-ray generator (B)...X-ray image inch (4z...Display device Insifier...Photodetector (c)...-Movement mechanism C32+, 135+...(X Line image control device) 4 types...
・(Position selection device) (Inquiry...Controller (7317) Representative patent attorney Norikata Chika (and 1 other person) Figure 1 Figure 3 a6 qy

Claims (1)

[Claims] an X-ray image intensifier that receives a portion of the X-rays generated from the X-ray generator; an imaging display device that captures and displays an output image of the image intensifier;
A photodetector for detecting the amount of light of the output image of the image intensifier directly or through another optical element in a limited range smaller than the output image surface, and moving the light-collecting position of the photodetector. a photodetector moving mechanism, a photodetection output signal of the photodetector (secondarily, an X-ray image control device that controls the operating conditions of the X-ray generator or image intensifier to control the brightness of the output image; a position selection device for selecting a position on the screen obtained by the photographing and display device, and a position at which the lighting position of the photodetector corresponds to a desired position on the screen according to a position selection signal from the position selection device. C. An X-ray imaging device configured to move.