JPH0452144B2 - - Google Patents

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention is an image intensifier that uses an (Hereinafter referred to as "II".)
Regarding an X-ray diagnostic device, which converts the optical image into an optical image, inputs the optical image with a television camera (hereinafter referred to as "TV camera"), and displays the fluoroscopic image or the photographed image on a monitor or records the image. In particular, TV
X suitable for cameras using solid-state image sensors such as CCD (Charge Coupled Device) image sensors
The present invention relates to radiation diagnostic equipment.

(Prior Art) This type of X-ray diagnostic apparatus will be described by way of example when performing gastrointestinal system diagnosis. That is, for a subject who has swallowed a contrast agent, a fluoroscopic image is obtained using an X-ray TV image under low-energy X-ray irradiation in a fluoroscopic mode. This fluoroscopic image is used exclusively by the operator to confirm the imaging position and timing for obtaining a diagnostic image. Then, by observing this fluoroscopic image and turning on the imaging switch at the desired imaging timing (for example, when the contrast agent reaches the stomach, which is the target of diagnosis), high-energy X-ray exposure is performed as the imaging mode. Obtain images taken with X-ray film, etc. under As mentioned above, this imaging mode is set to X-ray conditions that are completely different from those of the fluoroscopic mode, so the captured images have much better resolution than fluoroscopic images, and can be used as diagnostic images. can.

Furthermore, in this type of X-ray diagnostic equipment, an image pickup tube has been used as the image pickup element of the TV camera;
There are naturally limits to characteristics such as the number of pixels and readout speed, and solid-state image sensors such as CCD image sensors, which have emerged in conjunction with recent advances in semiconductor technology, are about to replace these limits.
In addition to obtaining fluoroscopic images as TV images, there is a trend toward obtaining captured images as TV images without using X-ray film.

(Problem to be solved by the invention) Here, a TV camera using a CCD image sensor,
Consider application to an X-ray imaging apparatus having this type of fluoroscopy mode and imaging mode. That is,
TV cameras using CCD image sensors have frame accumulation interlace mode and field accumulation interlace mode, and although the image input method for ordinary TV cameras can obtain high-resolution images, there is the problem of frame afterimages. Field accumulation interlace modes are sometimes used to avoid certain frame accumulation interlace modes. Since the perspective mode does not require high-resolution images, there is no problem with field accumulation interlaced mode, which is the normal image input method, but the photography mode requires high-resolution images. , resolution is a problem with normal image input.

Therefore, an object of the present invention is to make it possible to obtain optimal diagnostic information by appropriately using the frame accumulation interlaced mode and the field accumulation interlaced mode according to the fluoroscopy mode and the imaging mode. It is an object of the present invention to provide an X-ray diagnostic apparatus which can obtain optimal diagnostic information by appropriately using a frame accumulation interlaced mode and a field accumulation interlaced mode, and which can easily rearrange data.

[Structure of the Invention] (Means for Solving the Problems) The present invention is characterized by taking the following measures in order to solve the above problems and achieve the objects. That is, the present invention provides an X-ray diagnostic apparatus in which an output image of an image intensifier is inputted by a television camera to obtain an X-ray fluoroscopic image or an X-ray photographed image. When using a solid-state imaging device to obtain at least an X-ray image, the solid-state imaging device is operated in a frame storage interlace mode, and the first field shift pulse after the end of X-ray exposure is always of the same field. The invention is characterized in that it is equipped with a control means.

(Function) According to such a configuration, the frame storage interlaced mode, which can obtain high-resolution images but requires processing of afterimages, is used in the shooting mode, and the perspective mode does not require high-resolution images. There is no problem with the interlaced field accumulation mode, which allows optimal diagnostic information to be obtained.

Furthermore, by making the first field shift pulse after the end of X-ray exposure always for the same field, the data of the same field is always available after the end of exposure, regardless of the timing or exposure time of the X-ray exposure. This means that the data will be output first, so that data can be rearranged in only one way.

(Embodiment) An embodiment of the X-ray diagnostic apparatus according to the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the X-ray imaging apparatus of this embodiment uses
The line image is converted into an optical image by II2 and output.
After passing through the optical system 3, this optical image is photographed by a TV camera 5 that uses a CCD image sensor 4 as a solid-state image sensor, and the video signal is converted into a digital signal by an A/D converter 6, and the video signal is converted into a digital signal by an A/D converter 6. After being subjected to appropriate signal processing at 7, the signal is converted into an analog signal at a D/A converter 8, and displayed on a monitor 9 in television format.

On the other hand, the control system includes a photo timer 10 provided in the optical system 3 to detect an appropriate exposure amount.
It has an X-ray controller 11 that sets various exposure conditions for the X-ray source 1, and a system controller 12 that performs overall control.

Here, the characteristics of the CCD image sensor 4 used in the apparatus of this embodiment will be explained with reference to FIG. That is, FIG. 2 shows the frame accumulation interlace mode of the CCD image sensor 4, which has two fields A and B as photosensitive accumulation sections, and which is synchronized with the vertical transfer pulse VDP shown in FIG. 2a. By applying field shift pulses to fields A and B as shown in b and c, the second
As shown in FIG. d, a signal (charge) is output to the transfer section after the field shift pulse is output from the A and B fields. The A and B fields enter a light accumulation state after the field shift pulse is output.

In the above configuration, the image input operation in the photographing mode is as follows. That is, when an X-ray exposure signal is given to the X-ray source 1 at time t1 according to an instruction from the system controller 12, as shown in FIG. X-rays are irradiated under the X-ray conditions of voltage and current, pass through the subject P and reach II3, where they are converted into an optical image. The output image of the II 3 is guided to the photo timer 10 through the optical system 3, and when the photo timer 10 detects that the appropriate exposure amount has been reached, it gives a command to the system controller 12, which causes the system controller 12 to The X-ray exposure signal is stopped for (time t2).

During the above X-ray exposure period t1 to t2, as shown in FIG. 3a, the VDP of the CCD image sensor 4 is operating normally, but as shown in FIG. 3c, the field pulse is inactive. By outputting a field pulse after the X-ray exposure end time t2, a captured image is obtained by reading one frame in the frame accumulation interlaced mode, which is converted into a digital signal by the A/D converter 6, and then sent to the video signal processor. 7 performs appropriate signal processing, and then a D/A converter 8 converts the signal into an analog signal, and a monitor 9 displays the photographed image in television format.

On the other hand, during the X-ray exposure period t11 to t2, although the field pulse is inactive, VDP is output normally, so the read operation from the transfer section continues, thereby suppressing the increase in dark current noise. It becomes what it is. Therefore, the captured image obtained by reading out one frame as described above has high image quality.

Here, the frame storage interlace mode and the field storage interlace mode will be explained.
Figures 4 and 5 show light received by a photodiode,
An interline transfer method that uses CCD to transfer signals.
The operation of the CCD image sensor is shown, with FIG. 4 showing the operation in the frame storage interlace mode, and FIG. 5 showing the operation in the field storage interlace mode.

As shown in FIG. 4, in the frame storage interlaced mode, photodiodes A1, A2, A
3. The signal (charge) received by B1, B2, B3, ... is accumulated in both fields A and B in synchronization with VDP, and the field is given to both fields A and B at each frame period. The accumulated signal is taken out by the shift pulse to obtain the output signal.

As shown in FIG. 5, in the field accumulation interlaced mode, the photodiodes A1, A2,
The signals (charges) received by A3,...B1, B2, B3,... are accumulated in both fields A and B in synchronization with VDP, and are commonly given to both fields A and B at the field period. An output signal is obtained by extracting the accumulated signal using a field shift pulse.

In this case, in the frame accumulation interlaced mode, since the charge accumulation time of the photodiode is a frame, an afterimage will appear due to dark current between one field. The afterimage caused by this dark current is canceled by continuing the read operation even during the field pulse pause period as described above, and therefore no afterimage occurs. Of course, in the field accumulation interlaced mode, this problem of image retention does not occur. however,
For the same device, the frame storage interlaced mode has twice the vertical resolution as the field storage interlaced mode. Therefore, in this embodiment, since the frame accumulation interlaced mode is used as the photographing mode, it is advantageous that a high-resolution image can be obtained. In the perspective mode, since it is not necessary to obtain a high-resolution image, the field storage interlace mode, which does not have the problem of afterimage processing, is sufficient, but the frame storage interlace mode may be used if necessary.

Furthermore, in the above embodiment, a field shift pulse is issued in the frame storage interlaced mode immediately after the end of X-ray exposure;
It is assumed that the pulse of a specific field (A or B) is specified. Here, it is assumed that a shift pulse of the A field is generated.

This is due to the following reason. In other words, when reading an output signal, the outputs of both fields A and B are combined to generate one image, so it is determined which part of the image memory is written depending on which field, A or B, was output first. It depends on what you do. In this case, if it is not known in advance which field A or B will be output first, then A or B will be output first.
A means for detecting which field is being output is required, and two means for recording in the image memory are also required.

On the other hand, if the A field is always output first as in this embodiment, then the A,
B: There is no need for means for detecting which field is being output, and only one means for recording in the image memory is required, which is advantageous.

Also, when reading from field A to field B, and from field B to field A, the same image may not be obtained (for example,
noise, spatial frequency characteristics, afterimages, etc.). Even in such a case, by fixing the reading from the A field to the B field, the instability of the image quality described above can be resolved.

FIGS. 6 and 7 are diagrams explaining the fixed field readout system of this embodiment, respectively. FIGS. 6a and 7a are for VDP, and FIGS. 6b and 7b are for X-ray exposure. Firing signal, Figure 6c and Figure 7c
6d and 7d show field shift pulses for the A field, FIGS. 6e and 7e show the output signals, respectively.

FIG. 6 shows a case where the X-ray exposure ends while the B field is being read out, and since the first field shift pulse after the end of the X-ray exposure is for the A field, it is output as is.

FIG. 7 shows a case where X-ray exposure ends while the A field is being read, and the next B field shift pulse is not output, but the next A field shift pulse is output.

The present invention can be implemented with various modifications other than the above embodiments without departing from the gist thereof.

[Effects of the Invention] As described above, in the present invention, a solid-state image sensor is used as an image sensor of a television camera, and at least when obtaining an X-ray image, the solid-state image sensor is operated in a frame storage interlace mode. Furthermore, since it is equipped with a control means that always makes the first field shift pulse after the end of X-ray exposure the same field, it is possible to obtain a high-resolution image, but it is not possible to use the frame accumulation interlaced mode, which requires processing of afterimages. In the imaging mode, and in the fluoroscopy mode, since high-resolution images are not required, there is no problem with the field accumulation interlaced mode, which allows optimal diagnostic information to be obtained.

Furthermore, by making the first field shift pulse after the end of X-ray exposure always for the same field, the data of the same field is always available after the end of exposure, regardless of the timing or exposure time of the X-ray exposure. This means that the data will be output first, so that data can be rearranged in only one way.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the X-ray diagnostic apparatus according to the present invention, and FIG. 2 is a diagram showing the configuration of an embodiment of the
FIG. 3 is a diagram showing the characteristics of the CCD image sensor, FIG. 3 is a diagram explaining the operation of the same embodiment, FIG. 4 is a diagram showing the frame accumulation interlaced mode, FIG. 6 and 7 are diagrams for explaining the fixed field readout method of the same embodiment. 1... X-ray source, 2... Image intensifier (II), 3... Optical system, 4... CCD image sensor, 5... TV camera, 6... A/D conversion section, 7
...Video signal processing section, 8...D/A conversion section, 9...
...Monitor section, 10...Photo timer, 11...X
line controller, 12... system controller.

Claims (1)

[Claims] 1. In an X-ray diagnostic apparatus in which an output image of an image intensifier is inputted by a television camera to obtain an X-ray fluoroscopic image or an X-ray photographed image, a solid-state image pickup device is used as an image pickup device of the television camera. , comprising a control means for operating the solid-state imaging device in a frame accumulation interlaced mode at least when obtaining an X-ray image, and for always making the first field shift pulse after the end of X-ray exposure to be of the same field. An X-ray diagnostic device characterized by: