JPS59155234A - Image input apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] Unexploded BAFi, for example, targets X-ray images obtained based on X-ray exposure, especially images that move with a certain periodicity, such as the heart. This invention relates to an image input device that continuously samples and inputs images.

[Technical Background of the Invention] For example, cardiovascular angiography is known as a method for diagnosing the circulatory system of the human body. This cardiac angiography method uses a technique called cardiac catheterization, in which a catheter called a cardiac catheter is placed at any location within the heart from the femoral artery or vein in the groin, or the brachial artery or cubital vein in the sealed area. A large amount of angiographic contrast agent is injected into the large vascular cavity of the heart through a plastic chip made of synthetic resin, and continuous X-ray imaging such as X-ray movies, direct or indirect continuous imaging is performed. It's a method.

Incidentally, in recent years, a cardiovascular angiography method using deinotal images has been developed, and its spread is attracting attention. This has been made possible by the further development of digital image processing technology as seen in X-ray CT, especially by the development of digital circuit technology such as high-speed analog-to-digital conversion and digital memory, and by the development of television sign technology. With this technology, it has become possible to obtain high-quality radiographic images without using film.

As shown in Fig. 1, this image is converted into a digital signal by amplifying the grayscale information 1 signal of the target image, that is, the video signal of the above image, by an amplifier 2, and converting it into a digital converter by an analog-to-digital converter 3. obtained by doing. This obtained digital signal is then sent to an electronic computer (CPU).
) After being input to 4 and processed, it is transferred to a magnetic disk device or magnetic tape device! 1 (MT) or an external storage device 5 such as a 70 disk drive (FD).

Since the digital signal of the image is converted into data with values corresponding to the gradation level of each pixel, a computer can be used to enhance the outline of the image, erase unnecessary parts, extract and emphasize desired parts, etc. Images can be obtained by making full use of various image processing techniques and output as images that are easy to diagnose.

When inputting a general moving image to a computer for image processing by such a computer, for example, the image is captured by an imaging means such as a television camera, and an analog video signal output from the imaging means. A method is used in which the image data is continuously sampled at a certain time interval, and the signal of one image obtained at each sampling is digitally converted into digital image data. This method takes care not to lose information about the movement of the target area, that is,
The above-mentioned time interval must be appropriately set to correspond to the fastest movement so that the movement of the target region can be sufficiently followed.

Generally, digital image data has an image matrix size of 128X128.256X256 or 51
Although it is 2X512, there is a tendency for even finer multi-IJ sock swaging to improve resolution.

In addition, the bit length of the grayscale information for each pixel is 8 bits, 1
There is a tendency to increase from a 2-bit configuration to 16 bits or more.

This means that the capacity for one digital image data is 256kB7 even if the pixel configuration has a matrix size of 512x512 and the bit length of each pixel is 8 pits.
It becomes a huge thing called t., and there are many pictures in a row! When inputting data to a computer online (0N-Lin@) 7, this means that it is necessary to prepare a storage device with a huge storage capacity on the computer side. In this way, video signals are sent at regular intervals. Obtaining digital image data by sampling not only requires a huge amount of data, but also involves a lot of waste. In other words, if you think about each image one by one, each frame obtained from the video signal may have a series of images that are completely or almost unchanged from the previous one, and these unchanged images are the same as the previous image. Since it is sufficient to use the images as they are, collecting r-innotal image data of such images is a waste of information, which is a problem when considering the effective use of storage media such as disk devices and memory. In addition, handling unnecessary data is a great waste from the point of view of processing digital image data.

Therefore, in order to deal with these problems, a method can be considered in which the sampling interval is changed depending on the degree of change in motion.

That is, this method changes the sampling interval within a range that does not lose motion information, such as decreasing the sampling interval when the motion is fast, and increasing the sampling interval when the motion is slow.

According to this method, only necessary images can be sampled without losing motion information.

[Problems with background technology]

In order to sample the video signal so as not to lose the time information (movement information) of the moving image, it is necessary to sample at a fixed time interval corresponding to the fastest movement of the target part, or to sample the change in the movement of the target part. There are two methods that can be considered: sequentially detecting the movement and sampling at sampling intervals depending on the degree of movement.

However, in the former case, if the sampling time interval is set small enough, each image is extracted at a time interval that does not lose movement information, and this is converted into isotal image data and input. However, if the slow movement is localized, the same screen may continue, which may result in unnecessary input of image data.
Devices that record data have the disadvantage that the stored image data is often wasted.

On the other hand, the latter has the advantage of being able to avoid unnecessary sampling by changing the sampling interval according to the degree of movement, but in reality it is difficult to accurately and instantly measure the degree of movement of the target area. It's almost impossible to calculate.

This is because the time to measure the degree of movement can technically be reduced, but cannot be reduced to zero, so if the degree of movement is large and the sampling interval is very small, the degree of movement must be calculated. The time required for this cannot be ignored, making accurate sampling impossible.

In other words, if the time required to measure the degree of movement is Δt, and the sampling interval at a certain time t is Δ5(t), sufficient sampling is possible without losing time information as long as the following formula is satisfied: Make it.

ΔtkuΔs (t) ・・・・・・・・・(
1) However, as the degree of movement of the target region increases, Δ5(t) inevitably becomes smaller, and therefore, it is difficult to accurately measure the degree of movement at a time that deviates from the condition of Equation 1. To summarize the above, when calculating the degree of movement and extracting dizotal image data by changing the sampling interval and inputting it into a computer, the time to calculate the degree of movement is slow. This is not a problem when inputting something with slow movement, but when inputting something with fast movement, it becomes impossible to ignore, and it becomes impossible to set a sampling interval that sufficiently corresponds to the degree of movement.

[Purpose of the invention]

The present invention has been made in view of the above circumstances. □ For so-called moving images in which the position or size of a target part in an original image changes over time, it is particularly important to understand the periodicity of the movement of the target part. For example, when the heartbeat is accompanied by a regular periodic movement of about 1 to 2 s@e, such as the movement of the heart obtained by cardiovascular angiography, it is necessary to determine the periodicity of the movement of the target region in advance. By measuring the periodicity and controlling the sampling interval of the image manually based on the periodicity information, images can be extracted at sampling intervals that match the movements of the subject without losing information about the movement of the subject image. An object of the present invention is to provide an economical image input device capable of providing deisotal image data.

[Summary of the invention]

That is, in order to achieve the above-mentioned object, the present invention receives a signal of an image of a subject whose target region shows regular movement over time, samples the signal, and processes the image signal obtained at each sampling.
An image input device that converts an image signal for one screen into digital data and outputs the digital data, the image input device includes means for controlling a sampling interval, and sampling the image signal for one screen at a sampling interval given by the sampling interval control means. an image collecting means for converting into digital data based on the digital data; a means for determining the size of the area of change on the screen of the target region image between the images obtained for each sampling based on the digital data; means for obtaining the amount of change in the target region from scratch; controlling the sampling interval control means to obtain a preset short sampling interval for a predetermined period; and controlling the sampling interval control means to obtain information on the amount of change for each sampling within the predetermined period. and means for determining a period of movement of the target region, determining from this a sampling interval according to a transition of the amount of change within the period, and controlling the sampling interval control means accordingly after the predetermined period has elapsed. For a predetermined period of time, images are extracted one screen at a time at short sampling intervals, and the size of the screen white change area of the target area between the extracted images is determined.Based on this, the size of the screen white change area of the target area between each image of the target area is determined. Determine the amount of change, determine the period of movement of the target region from this, further determine a sampling interval according to the transition of the amount of change within the period from this and the amount of change, and control the sampling interval control means in accordance with this. In this way, the sampling interval can be controlled in accordance with the period of movement of the target region and the magnitude of change in the movement,
This makes it possible to reduce the number of sampling screens to the extent that information on the movement of the target body part is not lost, and also to obtain appropriate sampling intervals according to periods of slow movement and periods of fast movement. Since the image will be lost, after the predetermined period of time has elapsed, the output data of the image collecting means is inputted to the device to be imaged manually, thereby providing the necessary image data to the minimum necessary without losing information on the movement of the target region. be able to do so.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 to 6.

FIG. 2 is a block diagram showing one embodiment of the present invention. In the figure, reference numeral 21 denotes an X-ray imaging device equipped with an X-ray i-Level camera, and 22 denotes a video signal outputted from the X-ray television camera of the X-ray imaging device 21, which is obtained after the injection of a contrast medium by the X-ray imaging device 21. An original image acquisition device that collects the saturation image between an image or a mask image and an image after contrast agent injection, and 23 is a time difference between successive images of the collected original images collected and output by this original image acquisition device 22. A time difference device 24 is a time change extraction device that calculates a change from the time difference image obtained by the time difference device 23.

25 calculates the periodicity of the change in the original image based on the change obtained by the time change extraction device 24, and adjusts the magnitude of the change in the movement of the target region in accordance with the calculated periodicity. An electronic computer 26 generates a control output that provides a sampling interval, and also takes in and processes the output of the image acquisition device 22 as image data, and an electronic computer 26 receives the control output of the computer 25 and determines a sampling interval corresponding to this control output. This is a sampling interval control device that controls the X-ray imaging device 21.l!:a!i7 image acquisition device 22 to sample images at .l!:a!i7.

Next, the operation of the present apparatus having the above structure will be explained with reference to FIGS. 3 to 6.

In the present invention, an X-ray imaging device 2 is operated to image a region to be imaged of a subject, for example, the heart.

This is done by the control panel (not shown) of the X-ray imaging device 21, but this device calculates the periodicity of image movement from the The electronic computer 25 controls the X-ray exposure timing of the X-ray imaging device 2 and the image acquisition timing of the image acquisition device 22 to determine the amount of data to be collected. That is, after the start of imaging, the electronic computer 25 sends a signal for sampling control to the sampling interval control device 26 at a predetermined relatively fast period based on an internal clock signal so that sampling is performed at a predetermined relatively fast period for a predetermined period of time. As a result, the sampling interval control device 26 operates the X-ray exposure control of the X-ray imaging device 2 and the image acquisition device 22 at the above-mentioned period.

As a result, the video signal of the subject X-ray image obtained by the Xa television camera of the XW & photographing device 21 is input to the image acquisition device 22, where the video signal and the signal for the sea screen are sampled, and this is digitalized. Convert and collect one screen worth of image data. This image data is given to a time difference device 23. In the same way, image data at the next bringing time is collected and provided to the time difference device 23.
3, the difference between images is determined as a value corresponding to the size of the area. In other words, in the case of an image obtained by cardiac angiography, the X-ray image of the heart region is contrasted black with a contrast agent, and the image data has gradation values that are clearly distinguishable from other regions. Find the area of the part of the image of the old and new images excluding the overlapping part.

For example, the area of the part of the old image that is desired to overlap with the new image, that is, the number of pixels, is determined as a negative value, and the area of the part of the new image that is desired to overlap with the old image is determined as a positive value. This is used as data for determining the time difference.

Furthermore, at the time of the next sampling, the area is determined in the same manner as described above, using the previous new image as the old image and the image obtained this time as the new image. Then, this obtained data is sequentially extracted by the time change extraction device 2.
4, calculate the ratio of the positive and negative areas of the data to the screen, and sequentially calculate the changes in the image. Then, this amount of change is given to the electronic computer 25, and the computer 25 calculates the period of movement of the subject image from the time course of this amount of change. Then, after determining the optimum adjustment/pulling interval that matches the determined period and the transition of the change amount to the magnitude of the movement within the period, that is, the optimal pulling interval that matches the movement, Then, a signal for sampling control is given to the sampling interval control device 26 at the determined sampling interval. Accordingly, the sampling interval control device 26 controls the X-ray imaging device 2 and the image acquisition device 22 at an optimal sampling interval in accordance with the change in the magnitude of movement of the target region, and starts collecting images of the implant surface.

Thereafter, the image acquisition device 2 is operated under the control of the electronic computer 25.
2 is an X-ray imaging device 21 that obtains images at the above-mentioned sampling interval.
Collect images from
Give to 5. Further, if necessary, the image acquisition device [11jj can be configured to obtain and output a mask image and a subtraction image of the image after contrast agent injection under control from the electronic computer 25. The computer 25 runs the image acquisition device 22 after the optimum sampling interval settings have been made.
Collect and store data output from

Although this device does not directly synchronize with the subject,
By using the reference clock or clock function of the electronic computer 25, when the period of image movement is determined from the change in the image, the timing of the period can be grasped, so the predetermined fast sampling is performed for the time necessary to determine the period. After sampling at intervals, the timing is optimized based on the above timing.If you start sampling at grit intervals and collect data, you can obtain image data with the minimum number of images necessary and without losing information about the subject's movement. Collection becomes possible.゛The above action will now be explained in more detail.

When continuously sampling images and inputting them into a device for image processing and storage such as an electronic computer, the method shown in Fig. 3 (b)
), the image acquisition device 22 is operated at the shortest sampling interval (Δtmin) set in advance. If the image data DI, D2゜D"+Dn+1, . . . for each screen obtained at this sampling interval is continuously imported into the computer 25, unnecessary images will also be collected as described above, resulting in a reduction in storage capacity. It just gets bigger.

Therefore, in the present invention, as shown in FIG. 3 (-), the subject image changes from the image 3 obtained at 11 o'clock, the diastolic image 32 at 13 o'clock, the diastolic image 33 at 13 o'clock, and the diastolic image 33 at t4 o'clock. In the case of movement having a certain periodicity, such as the systolic image of No. 34, the sampling interval is controlled based on information on this periodicity.

That is, in order to do this, as shown in FIG. 4, during the preparation period for determining the optimal grid/grit interval, new images sequentially obtained at the shortest predetermined sampling interval Δtmin and old images obtained before that are used. Find the difference between them (time difference).

In other words, if the image H of the heart to be diagnosed changes from image 41 (image at time) to image 42 (image at time 10Δtmin), the difference is that the old image is negative and the new image is negative. When considering the minute as positive, the difference image shown in 43 is obtained.

Here, in the 43 images, 0. The area of e is the area of ■ = the target part is not present at time t, so t + Δ
Region e generated at time tmin = target region is t
The area of the region O that existed at time t+Δtmln disappears at time t+Δtmln=′t, which means an area that does not change at all at time t+Δtmln.

■ Time change extraction device 2 to determine the proportion of the area e on the screen
4 and set as d(It) and dσ), respectively.

In the present invention, since the periodicity of movement is first determined, the change in movement a(t) is defined as follows.

d(t)=d city+d('i) ・・・・・・・・・
(2) This change amount a (t) is determined for a time sufficiently longer than the period of movement of the target part, and the periodicity of the movement is calculated by the electronic computer 25. This calculation method is generally well known, so it will not be explained again here. It is usually sufficient for the period for calculating the change to be about three times the expected period.

FIG. 5 shows an example of a change in the amount of change d(t). t is time, 1 is a short period, and b is a long period.

In a, T is the period, and all the changes a (t) during this determined period T are stored in the electronic computer 25. Although this is just an example, the sampler computer 25 determines the sampling period based on the relationship shown in FIG. 6, controls the sampling interval controller 26, and controls the sampling interval ΔT(t ) to input images and collect image data.

However, the following relationship holds true here.

ΔT(t)=1/Δ5(t)...== (3)
Here, S(t″l/i is the number of samplings per i unit time υ, and ΔT(t), information from t=1 to T can be stored in the storage device via the computer 25 along with the image data. The state of motion can be reproduced.

[Effects of the Invention] As described in detail above, the present invention receives a signal of an image of a subject whose target region moves regularly over time, samples the signal, and processes one screen worth of images obtained for each sampling. In an image input device that converts a signal into digital data and inputs it to a device that is an image input target, the sampling interval is controlled by means for controlling a sampling interval, and the signal of the image is inputted at the sampling interval. an image collection means for sampling, converting it into digital data and outputting it; and means for determining the size of a change area on the screen of the target region image between the images obtained for each sampling based on the digital data; , a means for obtaining the amount of change in the target region according to the determined size; and a means for controlling the sampling interval control means to obtain a preset short sampling interval for a predetermined period, and a means for obtaining the amount of change in the target region according to the determined size; means for obtaining information on the amount of change, determining a period of movement of the target region, determining a sampling interval according to the transition of the amount of change within the toreyoshi period, and controlling the sampling interval control means accordingly; The image is extracted one screen at a time at short sampling intervals for a predetermined period of time, and the size of the internalized area of the target area in the screen between the extracted images is determined.Based on this, the target area is extracted between each image of the target area. , the period of movement of the target part is determined, and from this and the amount of change, a sampling interval corresponding to the transition of the amount of change within the period is determined, and the sampling interval control means is adjusted accordingly. Since the sampling interval can be controlled according to the cycle of the movement of the target area and the amount of change in the movement, the number of sampling screens can be controlled to the extent that information on the movement of the target area is not lost. In addition, since it is possible to obtain an appropriate sampling interval for each period of slow movement, there will be no unnecessary images in the same state, so after the predetermined excitation period has elapsed, the output data of the image collection means is used as the image input target. By inputting it into the device, only the necessary images can be input without losing information on the movement of the target area, and therefore the necessary image data can be provided with the minimum amount of data. It is possible to provide an image input device having excellent features such as being able to effectively utilize a storage device when storing image data and efficiently performing image processing.

It should be noted that the present invention is limited to the embodiments described above and shown in the drawings; however, it may be implemented with appropriate modifications within the scope of the invention; for example, the electronic computer may be replaced with a microprocessor, etc. .

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of a conventional device, Figure 2 is a diagram showing an embodiment of the present invention, Figure 3 is a diagram showing image sampling and the transition of image change, and Figure 4 is a diagram showing the transition of image change. A diagram for explaining the method of obtaining a time difference image in the apparatus of the present invention, FIG. 5 is a diagram showing an example of periodicity obtained from changes in image motion, and FIG. 6 is a diagram showing the magnitude of changes in motion. It is a figure showing the relationship with the number of times. 21... X-ray imaging device, 22... Image collection device, 2
3... Time difference device, 24... Time change extraction device,
25...Electronic calculator, 26...Sangri/g interval control device.

Claims (1)

[Claims] An image input device that receives a signal of an image of a subject whose target area shows regular movement over time, and then converts the signal of one screen worth of images obtained for each sampling into digital data and outputs it. In the apparatus, - means for controlling a sampling interval; and an image collecting means for converting the image signal into digital data by converting it into digital data by converting it into digital data for one screen at the sampling interval given by the sampling interval controlling means; means for determining the size of a change area on the screen of the target region image between the images obtained for each sampling based on the digital data;
means for obtaining the amount of change in the target region from the determined size; controlling the sampling interval control means to obtain a preset short sampling interval for a predetermined period; and controlling the amount of change for each sampling within the predetermined period. obtain the information, determine the period of movement of the target region, determine from this a sampling interval according to the transition of the amount of change within the period, and control the sampling interval control means in accordance with this after the predetermined period has elapsed. An image input device comprising: means.