JPH04129391A - Ray picture processor - Google Patents

Abstract

PURPOSE:To attain a vein image easily observed especially by comparing a subtraction picture data with a prescribed value so as to extract an area in which a vein exists, obtaining a histogram of the extracted area and processing only a live picture data corresponding to the area based on a window generated in response to the histogram. CONSTITUTION:A video data of a TV camera 18 is converted into a digital data and the signal is connected to a live memory 22 and a mask memory 24. A logarithmic transformation device 26 applies logarithmic transformation to a live picture data L and the data L subjected to logarithmic transformation is fed to a subtractor 30, a logarithmic transformation device 28 applies logarithmic transformation to a live picture data M and the data M subjected to logarithmic transformation is fed to the subtractor 30. The subtractor 30 obtains a difference between the data L and M and gives a subtraction picture data S to a vein area extraction circuit 32. The circuit 32 compares data S with a prescribed value to extract an area exceeds the prescribed value among the data S. A histogram circuit 34 obtains a histogram H of a live picture data corresponding to the area fetched from the circuit 32 among the data L fetched from the memory 22 and gives the obtained histogram H to a window circuit 36.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a radiation image processing apparatus that displays image data with appropriate brightness or contrast.

(Prior Art) Conventionally, in image processing apparatuses, there is a method called histogram flattening (histogram equalization) as a method for displaying image data with appropriate brightness or contrast. This histogram flattening method calculates the histogram of the image data, and uses this histogram to create a window unique to the image so that the brightness histogram of the image to be displayed is flat (flat characteristic). The image data is processed using the window provided, and the processed image data is displayed on a TV monitor or the like with appropriate brightness.

FIG. 3 is a diagram for explaining the histogram flattening method. A case will be described in which the histogram flattening method is applied to angiography image data. As shown in the same figure, live image data L after angiographic agent injection. (
Angiography image data L in which a bone part A and a blood vessel B are present. Also called. ) to obtain a histogram H of the live image data L using a histogram circuit (not shown). Here, the horizontal axis of the histogram H is the pixel value, and the vertical axis is the pixel value.
degree. This histogram shows the relatively small image value E
, has a peak frequency H3.

Using the histogram H of the image data obtained in this manner, a window W(g) is created using the following equation so that the histogram of the angiography image data LIO to be displayed on the TV monitor is flat.

W (g) -jh (q) d q Here, the horizontal axis of the window W is the histogram h (q), and the vertical axis is the window W (g).

Therefore, since the image data is subjected to window processing using the created window W (g), the angiography image data LIO can be displayed with appropriate brightness or contrast.

(Problem to be Solved by the Invention) However, when the above-described histogram flattening method is directly applied to an angiography image, the brightness or contrast of the entire image becomes appropriate, and the bone area A
The brightness and contrast of the images are relatively improved.

However, since the brightness and contrast of blood vessel B are reduced, it becomes difficult to see the blood vessel image that should be of interest.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a radiation image processing apparatus that can display an image of a blood vessel of interest in an easy-to-see manner.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems and achieve the objects, the present invention takes the following measures. That is, the present invention provides subtraction means for obtaining subtraction image data by determining the difference between mask image data before angiographic contrast agent injection and live image data after angiographic contrast agent injection; an extraction means for extracting a region in which a region exists; a histogram means for obtaining a histogram of the live image data corresponding to the extracted region; The present invention is characterized by comprising a window means for performing window processing on data.

(Effects) By taking such measures, the following effects are achieved. When the subtraction image data is compared with a predetermined value by the extraction means, a region where a blood vessel exists is extracted,
A histogram of the live image data corresponding to the extracted region is obtained, and only the live image data corresponding to the region is processed using a window created based on this histogram, so only the brightness of the blood vessel image is emphasized. Among angiographic images displayed on a TV monitor or the like, blood vessel images are particularly easy to see.

(Example) FIG. 1 is a diagram showing a schematic configuration of an X-ray image processing device as an embodiment of the radiation image processing device according to the present invention, and FIG. 2 is a diagram for explaining the operation of the embodiment. be. In FIG. 1, an X-ray image processing device 2 is an image data supply device 2.
It takes in image data from the computer, processes the image data, and supplies the processed image data to the TV monitor 3 for display.

The image data supply device 1 is configured as follows. X
The ray tube 10 irradiates X-rays to the subject 12, and includes an image intensifier 14 (hereinafter referred to as 1.1.
That's what it means. ) detects the X-rays transmitted through the subject 12 and converts the detected X-rays into an optical image. The TV left camera 8 converts the optical image incident from 1.1.14 into TV video data through an optical system 16 such as lenses 16a and 16b, and supplies the TV video data to the image processing device 2. It is.

The image processing device 2 is configured as follows.

Analog/digital converter (hereinafter referred to as ADC) 2
0 converts analog format TV video data captured from the TV left camera 8 into digital format TV video data (
Hereinafter, this is referred to as image data. ). A
The output terminal of the DC 20 is the live memory 22. It is connected to the mask memory 24.

The mask memory 24 is a memory having a pixel matrix size, and stores mask image data M before angiographic contrast agent injection.

The live memory 22 is a memory having the size of a pixel matrix, and stores the live image data L taken in from the ADC 20 after the angiographic contrast agent has been injected.

A logarithmic converter 26 logarithmically transforms the live image data L and supplies the logarithmically transformed live image data L to a subtracter 30. A logarithm converter 28 logarithmically transforms the mask image data M and provides a logarithmically transformed mask image. The data M is supplied to the subtracter 30.

The subtractor 30 calculates the difference between the logarithmically transformed live image data L and the logarithmically transformed mask image data M, obtains subtraction image data S, and supplies this subtraction image data S to the blood vessel region extraction circuit 32. It is.

The blood vessel region extraction circuit 32 compares the subtraction image data S with a predetermined value and extracts a region of the subtraction image data S in which the subtraction image data S exceeding the predetermined value exists.

The histogram circuit 34 calculates a histogram H of the live image data corresponding to the area taken in from the extraction circuit 32 out of the live image data L taken in from the live memory 22, and supplies the found histogram H to the window circuit 36. do.

The window circuit 36 uses the histogram H corresponding to the area taken in from the histogram circuit 34 to
A window W1 is created such that the brightness histogram of the image L20 to be displayed on the TV monitor 3 is flat, and the window W1 allows the window W1 to display the live image data L20 corresponding to the area out of the live image data L taken in from the live memory 22. Window the image data.

Digital/analog converter (hereinafter referred to as DAC) 3
8 is connected to the window circuit 36, converts digital image data into analog image data, and supplies the converted image data to the TV monitor 3.

Next, the operation of the embodiment configured as described above will be explained with reference to FIGS. 1 and 2. First, the X-rays emitted from the X-ray tube 10 pass through the subject 12, and the transmitted X-rays are 1.1.1
4 into an optical image. The optical image is a lens 16a,
16b, the TV left camera 8 converts the data into TV video data, and the ADC 20 converts the TV video data into digital image data. Then, the mask image data M of only the bone portion A before the contrast agent injection is stored in the mask memory 24, and the live image data L after the contrast agent injection is stored in the live memory 22.

Then, the live image data L and the mask image data M are logarithmically converted by the logarithmic converters 26 and 28 according to the following equation.

M, mlogM LlmlogL If a conversion table is prepared in advance and the live image data L and mask image data M are logarithmically converted using this conversion table, high-speed processing can be performed.

These image data are then supplied to a subtracter 30.

Next, subtraction image creation by the subtractor 30 will be explained. The mask image data M and live image data L after log conversion are subtracted by the subtracter 30 using the following equation, thereby creating subtraction image data S.

S-M, -L.

Next, the operation of the blood vessel region extraction circuit 32 will be explained.

(1) First, blood vessels are extracted.

Based on the subtraction image data S, a region having image data larger than a certain threshold (threshold level) is extracted by the blood vessel region extraction circuit 32. So-called binarization processing is performed, and as a result, the vixels in which blood vessels exist can be identified. Note that the threshold level varies depending on the number of bits of image data and the coefficient at the time of log conversion, but it is a positive value close to zero.

(2) Next, a blood vessel region is extracted.

The area around a certain vixel where a blood vessel exists (for example, 9×9 vixels for a certain vixel) is defined as a blood vessel area. Then, the blood vessel region extracting circuit 32 extracts a blood vessel region C by including a certain range around one pixel in the blood vessel region.

Next, a histogram circuit 3 based on the extracted blood vessel region C
Live image data L taken in from the live memory 22 by 4. Among them, a histogram is created within the area C.

Next, the operation of the window circuit 36 will be explained.

An image L of the blood vessel region to be displayed by the window circuit 36
The window W1 is created so that the histogram of the brightness of 20 is flat. This window W1 is created in the following manner based on the histogram H obtained using the histogram 34.

for example The pixel value of the image data is q(q-0,1 The minimum value of brightness is Pl Characterized by maximum brightness The requested histogram with h Ru.

If the created window is W(i), i-0,1...4095, then...4095) (q) and W (i)-P, + (P2-PI) ・Σh (q
) /Σh (q).

The window W thus obtained converts the live image data L corresponding to the area into luminance, and the converted live image data L is converted into analog data by the DAC 38 and supplied to the TV monitor 3. ,
You can create images to display.

According to this embodiment, when the subtraction image data S and the threshold are compared by the blood vessel region extraction circuit 32, the region C in which the blood vessel exists is extracted, and the live image data L corresponding to the extracted region is extracted. A histogram H is obtained, and only the live image data L corresponding to the area is processed using the window Wl created based on this histogram H, so only the brightness of the blood vessel B is emphasized. Among the displayed angiographic images, blood vessel B becomes particularly easy to see.

Furthermore, since an easy-to-see image can be obtained, misdiagnosis can be prevented and a good diagnosis can be made. Furthermore, since easy-to-see images can be automatically created, the operational burden on the operator can be significantly reduced.

Note that the present invention is not limited to the embodiments described above. Although the above-mentioned embodiment describes an X-ray image processing device in an X-ray diagnostic device, the present invention can also be applied to, for example, a radiation diagnostic device using gamma rays.

Further, in the blood vessel region extraction circuit 32 of the embodiment, a predetermined threshold is used to extract the blood vessel region, but the edges of the blood vessel may be extracted using, for example, a Sobel filter. , or others may be used.

It goes without saying that various other modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, when the subtraction image data is compared with a predetermined value by the extraction means, a region where a blood vessel exists is extracted, and a histogram of live image data corresponding to the extracted region is determined. Since only the live image data corresponding to the region is processed using a window created based on this histogram, only the brightness of the blood vessel image is emphasized. It is possible to provide a radiation image processing device in which images are particularly easy to see.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a radiation image processing apparatus according to the present invention, FIG. 2 is a diagram for explaining the operation of the embodiment, and FIG. 3 is a diagram for explaining a histogram flattening method. This is a diagram for 1... Image data supply device, 2... X-ray image processing device, 3... TV monitor, 10... X-ray tube, 12...
・Subject, 14... Image intensifier, 1
6a, 16b--lens, 18-=TV camera,
20...ADC, 22...Live memory, 24...
・Mask memory, 26.28... Logarithmic converter, 30・
...Subtractor, 32...Vessel region extraction circuit, 34...
Histogram circuit, 36... Window circuit, 38...
・AC0

Claims (1)

[Claims] a subtraction means for obtaining subtraction image data by determining the difference between mask image data before angiographic contrast agent injection and live image data after angiographic contrast agent injection; an extraction means for extracting, a histogram means for obtaining a histogram of the live image data corresponding to the extracted region, a window is created based on the histogram, and the live image data corresponding to the region is subjected to window processing using the window. A radiation image processing device comprising: window means.