JPS58116890A - Digital subtraction type x-ray device and x-ray picture processing system - Google Patents

Abstract

PURPOSE:To improve the quality of X-ray diagnosis and X-ray transmission inspection by removing the influence of scattered X-rays while utilizing digital subtraction picture processing technique, and outputting a clear picture formed by only direct X-rays. CONSTITUTION:Generated X rays from an X-ray tube 1 are passed through an object S and a scattered X-ray removing grid 2 to form a transmission image at a video detection part such as the input screen of an image tube 3, and image pickup tube 5 extracts a picture signal through a diaphragm 4 to reproduce and display the picture on a monitor TV6. Through a logarithmic amplifier 9, analog conversion is performed by a D/A converter 10 and the result is stored by the 1st picture memory 12 after being integrated through an arithmetic unit 11. Said operation is controlled under the instruction of a control unit 7 and a switch S1 is placed at a side (d) to remove the grid 2 automatically, storing a current video on the image pickup tube 5 in the 2nd picture memory 13. Then, digital subtraction picture processing is carried out to output a clear picture formed by only direct X-rays.

Description

[Detailed Description of the Invention] This invention is capable of reproducing and displaying X-ray images for medical diagnosis or X-ray fluoroscopy using a digital sub-transmission system to remove the influence of scattered radiation and display clear images. The present invention relates to an X-ray apparatus and an image processing method thereof.

Generally, when an image is formed using X-rays transmitted through an object, the image is strongly influenced by the scattered X-rays in addition to the image formed by the direct X-rays of the object due to scattered X-rays from various parts of the object.

That is, as shown in Figure 111 (1), one point 0 on the image plane P
The blackening is due to scattering from the subject (5) in addition to the direct X-ray person
Blackening due to IB and C is weighted. Generally, the 0-point image is
It would be more accurate to say that the desired image of X1iA is formed in the scattered X-ray image. In order to improve this problem, as shown in (b), a grid G for removing scattered rays is inserted into the rudder of the image plane to reduce the influence of scattered rays and strongly reduce the proportion of direct X-rays incident on the image. Efforts are also being made to increase the contrast.

However, even in this case, scattered radiation cannot be completely removed. That is, if the scattered ray removal rate of the grid is α, conceptually the degree of blackening at 0 point is (1) in the case of figure A0B0C...
・・・・・・・・・(1) (b) In the case of figure '(B+C
)+A river... control... river (2), and the influence of scattered radiation can only be reduced to l/α.

In principle, the present invention is realized by substituting an image of (a) a figure and an image of (b) a figure.

This is based on the idea of almost completely eliminating the influence of scattered radiation. In other words, (multiplying equation 21 by α and subtracting equation (1) yields (B+C)+aA1-(B0C+A1=aA-person=A(
As shown in (E-1) -・-・-・-13), the effects of scattered radiation (B+C) are almost completely removed from images processed in this way, and sharp images created only by direct X-rays are obtained. can get.

The present invention will be described below with reference to Examples.

Figure 2 shows X1i9! The X-rays generated from iz are passed through the object 8° scattered ray removal grid 2 and a transmitted image is transmitted to the image detection unit such as the input screen of the image tube (3).

A device is shown in which the image on the output screen is taken out as an image signal by an image pickup tube 5 via a suitable diaphragm 4 as required, and is reproduced and displayed on a Moyuku TV 6.

First, an explanation will be given of an image storage operation (first operation) c hereinafter referred to as a mask creation operation on a letter with a grid inserted as shown in FIG. 1 (bl). In Fig. 2, when the switch S1 of the control unit 7 is turned to the C side, the grid 2 is automatically inserted as shown in the figure via the grid insertion machine @17, and when the X-ray exposure switch (not shown) is pressed, the grid 2 is automatically inserted as shown in the figure. X-rays are emitted from the X-ray tube 1 in synchronization with the vertical synchronization signal of the composite video signal from the camera control unit. The X-ray emission time due to this is controlled to a time corresponding to several frames of Monique TV (determined by the scattered ray removal rate α of the grid). The video signal is transmitted to the image pickup tube 5. Camera control unit 8
．． The signal is converted into a digital signal by the Φ converter lO via the log amplifier 9, integrated into the image memory 12 of @1 via the arithmetic unit 11, and stored. (In this case, the arithmetic unit works as an adder) These series of operations, 1
Input switching to the memory 11, signal synchronization processing, etc. are performed accurately in synchronization with imaging scanning of the imaging tube according to commands from the control unit 7. With the above steps, the mask creation operation by grid insertion is completed.

Next, while keeping the same subject, the switch S1 is moved to the d side to perform an operation corresponding to FIG. fa1 (a). When the switch S+ is switched to the d side, the grid 2 shown in FIG. 2 is automatically removed, and X-ray radiation is performed by the same operation as described above. However, in this case, the X-ray emission time is
1 frame scanning time (approximately 1730 seconds). In this case, the output of the image pickup tube is processed in the same manner as described above, but is stored in the second image memory 13 according to instructions from the control unit.

Next, the sub-truncation operation of both image signals will be explained.

When the subtransmission switch S2 is turned on after all X-ray radiation has been completed, the arithmetic unit 11 becomes a subtracter according to a command from the control unit 7, and the reproduced signals of both image memories 12 and 13 are subtracted through this subtracter. and output. This subtraffic signal is applied as a luminance signal to the ↓ monitor TV via the D/A conversion $14 synchronization signal addition circuit 15, and a transparent image of the subject is reproduced on the CRT.

In the above, the selection of the X-ray radiation time with and without inserting grid 2 is determined by the scattered ray removal rate of the green node, as mentioned earlier. In the case of Gri-Rad, the X-ray irradiation time during mask creation operation is 2 frames on the TV monitor (
145 seconds) and 4 when the scattered radiation removal rate is 1/4.
frame (4/30 seconds). This determines the integration time of each image signal, but if the correct number of frames cannot be obtained due to the scattered radiation removal rate or the number of frames cannot be selected at an integer magnification, the reproduction subtract of the stored image In this case, this can be corrected by applying an appropriate magnification to one of the reproduced signals. Reference numeral 16 in FIG. 2 is the magnification adjustment command device, and by adjusting this, the reproduced signal of the image memory 12 is appropriately multiplied by the arithmetic unit 11 according to a command from the control unit, and then the two are subtracted.

In the above embodiment, the video signals of the first operation and the second operation are stored in two image memories.

We have explained an example in which an image is obtained by reproducing the image by subtracting this, but in the process of omitting the image memory #I2 and applying the video signal of the second operation to the CRT online,
CR with the image memory playback output and timing result signal
It is also possible to display an image on the T. In this way, image sharpening processing can be performed in real time.

As detailed above, one aspect of the present invention utilizes digital subtraction image processing technology to remove the influence of scattered X-rays,
It is possible to obtain clear images using almost only direct X-rays, and the quality of X-ray diagnosis or X-ray fluoroscopy has been dramatically improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention, and FIG. 2 is a circuit diagram explaining the operation of the embodiment. 1...X-ray tube 2...Scattered X-ray removal grid 3...Image tube 5...Image tube 6...Monique TV 7 ... Control unit 10 ... 4θ converter 11 ... Arithmetic unit 12 ... First image memory 13 ...
...Second image memory patent applicant Shimadzu Corporation

Claims (1)

[Claims] (1) Xla equipped with a device that displays the transmitted X-ray image of the subject on a CRT via a video detector and an imaging device
*In the system, a device for digitally converting the image output signal of the imaging device, and an arithmetic device for subtracting the reproduced image outputs of the first and li2 image memory devices and the 0th memory device for storing this digital signal are provided respectively. , an image signal taken by inserting a scattered radiation removal grid in the front of the image detection device is stored in a second memory device, and an image signal taken by removing the grid is stored in a second memory device. (2) An X-ray image processing system that displays a transmitted X-ray image of a subject on a CRT via an imaging device. , a first operation involves inserting a scattered radiation removal grid in front of the image detection unit to take an X-ray image, converting the image signal into a digital signal, and then storing it in a storage device; a second operation of taking a line image and converting the image signal to digital; a third operation of generating a playback output by subtracting the image signal stored in the first operation from the image signal based on the second operation; A digital subtraction-based X-ray image processing method characterized by sequentially performing the following operations and displaying an image of the object on a CRT using an output signal based on the third operation.