JPS59158687A - X-ray image processing device - 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 (a) Industrial Field of Use The present invention is used in the field of digital subtraction systems for d1 X-ray TV equipment.

The present invention relates to an X-ray image processing device attached to a digital Zabtraction system of an X-ray TV device.

(o) Conventional technology A digital subtraction system displays differential images before and after injection of a contrast medium, but image enhancement processing is particularly important when reducing contrast, so that images can be displayed or recorded in an easily viewable state. Since the entire process is done in real time, it is too slow to adjust the degree of image enhancement visually. Therefore, the degree of image enhancement needs to be set in advance and currently relies on the experience or intuition of the surgeon.
In some cases, the optimal degree of image enhancement cannot be obtained, and another X-ray irradiation is required.

(c) Purpose A. The purpose of 56 is to create an X-ray image in which the degree of image enhancement in the digital subtraction system is not required to be set in advance, and image enhancement is automatically set in parallel with real-time processing. The purpose of the present invention is to provide a processing device.

The purpose of the above-mentioned structure is to have two histogram generating means representing the number of pixels for each image value, one of which is stored in the mask image data memory of the digital subtraction system or its input bus, and the other is stored in the mask image data memory of the digital subtraction system or its input bus. A subtraction means is connected to the live image data memory or its input bus, and extracts a change between both histograms, and calculates the center of gravity of a positive area area and a negative area area of the change, This can be achieved by adding an emphasis degree determining means connected to the image intensifier of the system, which determines the distance between the centers and determines the degree of emphasis using this distance as an element.

(e) Example A preferred embodiment of the invention will be described with reference to the drawings.

FIG. 1 is a diagram of each frame image and its corresponding histogram. (a) shows the lr mask image; a') shows the histogram of pixels, which shows the pixel I for each pixel value (brightness), and represents the area of the closed surface or the number of pixels per frame. A represents the spine, B represents intestinal gas, and C represents the blood vessel (contrast medium). Live image 1d: shows a motion artifact (false image) due to the movement of the subject,
The second live image is an image taken when the contrast agent arrived.

As shown in the figure, in the histogram according to the present invention, the horizontal axis represents pixel color (brightness), and the vertical axis represents the value of each pixel in the image.
This is a graph showing the number of pixels. This histogram has the following characteristics.

(1) Movement in a small area, such as the movement of intestinal gas B (the d histogram does not change); (2) ``fi, statistically large movements such as parallel movement and rotation of the specimen; , there is no increase or decrease in the number of pixels for any pixel value, so there is no change in the histogram; (3) The histogram changes only with the arrival of the contrast agent.

Therefore, the invention A consists of extracting such changes in the histogram, determining the vibration [1] of the subtraction image from this, and automatically setting the degree of image enhancement.

As mentioned above, in FIG. 1(b), the movement of the spine A',
Even if intestinal gas moves B', the number of pixels does not increase or decrease for any pixel value, whether the image is bright or dark, and whether the dark area becomes bright or not, and the histogram is There is no change as shown in (b'). However, as shown in Figure 1 (C), when the contrast agent arrives, only bright areas or dark areas appear due to the contrast agent, and as shown in Figure 1 (C'), pixels shift within the histogram. occurs, and the histogram is distorted. The moving distance of this pixel in the horizontal axis direction becomes the change in amplitude due to the contrast agent, that is, the amplitude of the subtraction image. Figure 1(d') shows the subtraction between the histograms of the mask image and the live image 2 (the areas of the positive part molecule and the negative part S are equal), and the subtraction of the positive part molecule and the negative part S is shown. The distance e in the horizontal axis direction between each center of gravity GLGZ approximates the average amount of pixel movement, that is, the average amplitude of the blood vessel image appearing in the subtraction image "1".The value of this distance β is used as the reference value for the degree of image enhancement. For example, it is good to decide the window width to be 2 to 3 times the distance e.The way you decide is U, but only on the upper side.

FIG. 2 is a configuration block diagram showing an embodiment of the present invention. Inside the dotted line is a conventional digital subtraction system, 11 is a logarithmic converter, 12 is A/
D converter, 13 is a mask image data memory, 14 is a live image data memory, 15 is a subtracter on the system, 1G is an image enhancement device, 17 is a D/A converter, 18 is a display or recording device. It is a vessel.

The data of the mask image and the live image are stored in the memory 13 and the memory 14, respectively, the contents of both memories are subtracted by the subtractor 15, and after being emphasized by the image intensifier 16,
Displayed or recorded.

According to the present invention, the histogram of the contents of the memory 13 is created by the histogram creation means 20, and the histogram of the contents of the other memory 14 is created by the histogram creation means 22.
Each histogram is created, and the subtraction means 24 subtracts both histograms. Further, according to the subtraction result, the emphasis degree determining means 26 determines the distance n, determines the degree of emphasis of the image intensifier 16, and operates the image intensifier 16.

The histogram creation means 20, 22, the subtraction means 24, and the emphasis level determining means according to the present invention can all be achieved by calculations and can be configured with software, but they can also be configured with hardware capable of high-speed operation in accordance with the real-time processing of the system. It is preferable. Note that when creating a histogram, it is not necessary to immediately display it, although it may be possible to provide a separate display and display it on this. Further, if the histogram creation means is connected to the output of the A/D converter, its processing is performed in parallel with the data writing processing of the memory.

(F) Effect A unique effect of the present invention is that image enhancement is automatically set in real time without being affected by the presence of motion artifacts, and an optimal degree of enhancement can be obtained.

[Brief explanation of drawings]

Figure 1 shows the frame image and its hiffs, l-grams,
FIG. 2 is a configuration block diagram showing one embodiment of the present invention. A and A'd spine, B and B' are intestinal gas, C is blood vessels, 13
is a mask image data memory, ]4 is a live image data memory, 20 and 22 are histogram creation means, 24 is a subtracter,
26 IC1 emphasis level determining means.

Claims (1)

[Claims] (]) It has two histogram creation means in which the horizontal axis corresponds to the pixel value and the vertical axis corresponds to the number of pixels, one of which is stored in the mask image data memory of the digital subtraction system, and the other is stored in the mask image data memory of the digital subtraction system. are respectively connected to the live image data memory of the system; and a subtraction means for extracting the change between both histodarams; G2, the distance l on the horizontal axis between the centers of both types is determined, and the emphasis degree determining means is connected to the image intensifier of the system, which determines the degree of emphasis using this distance l as an element. X
Line image processing device. (2) Digital subtraction system A/
2. The X-ray image processing apparatus according to claim 1, further comprising a histogram creation means connected to a data bus between the D converter and the memory.