JPS5958990A - X-ray tv signal processor - Google Patents

Abstract

PURPOSE:To obtain a subtraction image having a high diagnostic ability, with less motion artifact, by detecting the time point of the movement of a personnel to be inspected at an electronic circuit automatically if the personnel is moved after the injection of a contrast medium and replacing the image into a new mask image. CONSTITUTION:If the motion artifact exists, the signals A, B of the motion artifact are outputted in addition to the contrast medium C. The signals A, B are the pictures having a different code and an equal amount theoretically. Since the signal B shows the same density trend as the contrast medium, it is not discriminated from the signal shown by the contrast medium, but the signal A shows the opposite density trend as the contrast medium to discriminate the picture to be the motion artifact. The region of the signal A is measured to know the point of a time when the personnel to be inspected moves and to mask. The region to which the contrast medium flows is limited and its address is preset to a preset 28. The same address of the mask image memory 14 and the live image memory 16 is inputted to an address comparison circuit 26. Further, a switch 13 is switched to the live image memory 16 after the data write. Further, 50 is a circuit detecting the fluctuation of each picture before and after timewise movement and detecting the end of the movement of the motion artifact.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray TV signal processing device having a subtraction function.

X-ray TV equipment subtracts images before and after contrast agent injection,
The so-called subtraction method, which displays a difference image using only a contrast agent, has been frequently used in recent years. As the image before this contrast agent injection, an image (mask image) at a fixed time in a series of X-ray sequences was used, so from that point on, the contrast agent actually flows in. The patient's movements during the scan caused motion artifacts that overlapped with the contrast agent-only image, making interpretation difficult. For this reason, it has been desired to display subtraction images with fewer motion artifacts. Conventionally, the mask image has been recorded on a VTR, VDR, etc., played back, visually inspected to detect motion artifacts caused by the patient's movements, and then replaced with a new mask image, which is inaccurate and manual operation. It was an inconvenience or a hassle.

The purpose of the present invention is to
An object of the present invention is to provide an X-ray TV signal processing device that can obtain a subtraction image with few motion artifacts and high diagnostic ability by automatically detecting that point using an electronic circuit and replacing it with a new mask image.

The purpose of this is to create a circuit that selects an arbitrary area from the image obtained by subtracting the mask image from the live image, and compares each pixel of the selected image with a preset value, and determines whether the level exceeds that level. A circuit that adds pixel values, a circuit that compares the summed value with a preset value and, when it exceeds that level, generates a pulse that outputs a first signal and writes data from the live image memory to the mask image memory. This is achieved by having the following. Alternatively, this can be achieved by adding a circuit that compares the above-mentioned added values for each image and outputs a second signal when the variation is less than a preset value, and using this signal to transfer between the two memories. Ru. Furthermore, when there is a first signal and a second signal is generated, zero
Next, the gist and preferred embodiments of the present invention will be explained with reference to the drawings.

Figure 1 shows one of the subtraction images that are absorbed in the present.
Give an example. The image obtained with pulse 1 is referred to as an image before contrast agent inflow (mask image), and the images obtained with subsequent pulses are referred to as live images, and a difference image between the live image and the mask image is displayed. For example, if the subject moves at pulse 3.4 (in the figure, S indicates stationary and D indicates movement), after 0 pulse 3, motion artifacts are superimposed on the contrast agent image, making the image difficult to see. be done. Therefore, as a conventional means, a remasking method is used in which the image of pulse 3 or pulse 4 in which the subject has moved is replaced with a new mask image. Conventionally, this timing has been manually determined by visual judgment.

Kinoe BA is an automated version of Toku.

In short, all that is required is to obtain a signal indicating that the subject has moved. Figure 2 shows the case where there is no such movement, and Figure 3 shows the case where there is a motion artifact. Contrast medium C
In addition, a motion artifact signal ASB is output. The signals A and B are images with theoretically opposite signs and equal amounts. Of the signals A and B, signal BU shows the same concentration tendency as the contrast agent, and therefore cannot be distinguished from the signal indicated by the contrast agent. However, since signal A shows a concentration trend opposite to that of the contrast agent,
It turns out that this is an image of the motion artifact itself. By measuring the area of this signal A, it is possible to know when the subject moves. Actually, in order to separate it from noise, it is sliced and shaped at a certain level as shown in FIG. In this first example, motion due to internal gas movement
There is a risk of malfunction due to artifacts, etc., so the average value of the shaped signals is calculated (added), and when it exceeds a certain level, the first signal is output, it is determined that the subject has truly moved, and remasking is performed. do.

The implementation is remasking at the time when the subject starts moving. After this movement is completed, in order to perform remasking, the above-mentioned addition signal is obtained for each image and its temporal change is observed. Furthermore, if the first signal is present (a signal indicating that the subject has moved) and the temporal fluctuations in the added value (for each opening) are small, the subject's movement will decrease and the movement will end. I decided that it was and remasked it.

A configuration example of the present invention is shown in FIG.

10 is an image pickup tube, 12 is an A/D converter, 14 is a mask image memory, 16 is a live image memory, 18 is a subtracter, 20 is a sharpening processing circuit, 22 is a TV monitor, and 24 is an arbitrary area of the image. 26 is an address comparison circuit, 28 is a preset, 30 is an AND circuit, 32 is an adder, 34 is a comparator, 36 is a preset, 38 is an AND circuit, 40 is a /ft circuit, 42 is a subtracter , 44 is a comparator, and 46 is a preset.

In the preset 28, the address of a region into which the contrast agent will flow is limited and set in advance. Although not shown in the figure, the same addresses of the mask image memory 14 and the live image memory 16 are also input to the address comparison circuit 26 under the control of an address counter. In the illustrated example, the switch 13 is connected to the mask image memory 14, but after writing the data,
The image is switched to the live image memory 16. Furthermore, 5o is a circuit that detects the fluctuation of each image before and after the time, and detects the point at which the movement of the motion artifact ends. Therefore, in FIG. 5, one embodiment is constructed by removing the circuit 50, and another embodiment is constructed by adding the circuit 50 and removing the AND circuit 38.
Furthermore, the circuit 50 and the AND circuit 38 are connected as shown in the illustrated example, and the output signal WR2 of the comparison circuit 44 is supplied to the AND circuit 38.
8 to form another embodiment.

Still another embodiment is constructed by means of switching the data in the mask image memory to the minuend side instead of rewriting the data from the live image memory to the mask image memory. Other modification means, such as providing a buffer memory, are also conceivable. Further, when adding pixels, it is not necessary to add all the pixels in the area selected by the circuit 24, but it is also possible to appropriately sample and add them. Furthermore, in that case, the addition and accumulation of pixel values may be replaced by counting the number of pixels.

Although the contrast agent level is shown to be lower than the normal level in Figures 2 to 4, and the explanation is based on this assumption, in the opposite case, the logic is simply reversed.

[Brief explanation of the drawing]

Fig. 1 is an illustration of the conventional method, Fig. 2 is an illustration of signal generation due to the inflow of contrast medium, Fig. 3 is an illustration of signal generation when there is a motion artifact, and Fig. 4 is an illustration of signal shaping processing. FIG. 5 is a block diagram showing a configuration example of the present invention. 14 is a mask image memory, 16 is a live image memory, 18 is a subtracter, 24 is a circuit for selecting an arbitrary area, 32 is an adder, 34 and 44 are comparators, 36 and 46 are Bricents, 40
is a shift register, 42 is a subtracter, and WR is a write signal.

Claims (2)

[Claims] (1) X-ray TV with subtraction function
In the signal processing system, a mask image memory before contrast agent injection, a live image memory after injection, a circuit for subtracting mask image data from live image data, and in this case, the subtracted image data are On the other hand, the arbitrary area is input to a circuit that selects it, compares each pixel of the selected image with a preset value, and adds pixel values exceeding that level; An X-ray TV signal processing device comprising a circuit that compares an integrated value with a preset value, and a circuit that controls writing of data from a live image memory to a mask image memory based on an output signal of the comparison circuit. (2) Instead of writing data from the live image memory to the mask image memory, the first claim is characterized by having means for switching the data in the mask image memory to the minuend side.
The X-ray TV signal processing device described in 2.