JPH0537859A - X-ray picture processor - Google Patents

Abstract

PURPOSE:To relieve an artifact of a picture by selecting a mask image with the same pickup condition as that of a live image while a living body signal is used for an index so as to implement subtraction thereby eliminating effectively a background picture. CONSTITUTION:When a mask image and a live image are both collected, the mask image is subtracted from the live image. The live image is sequentially read from a memory 7 and a living body signal stored in relation to the live image is read simultaneously and fed to a controller 8, which controls a memory 6 so that the mask image inked with the living body signal of the same level as that of the living body signal is read from the memory 6. Then the live image and the mask image read simultaneously from the memories 6,7 are fed to a subtractor 9, in which they are subjected to subtraction processing and a digital data of a picture signal after subtraction is restored again into an analog signal by a D/A converter 10 and fed to a picture monitor, on which the subtraction image is displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray image processing apparatus for performing angiography or the like by subtracting images.

[0002]

2. Description of the Related Art In an X-ray image processing apparatus of this type, for example, when angiography is performed, an X-ray image before injection of a contrast agent is stored as a mask image, and then a contrast agent is injected to successively display live images. Then, the mask image is subtracted from these images. Then, since it is considered that the background images are the same among these images, an image in which only the image of the contrast agent is extracted, that is, an image in which only blood vessels appear is obtained.

[0003]

However, in the conventional X-ray image processing apparatus, when the subtraction processing as described above is performed, the subject is periodically moved by respiratory movements or aperiodically by other movements. When moving, the background images do not become the same between the two X-ray images, and as a result, there is a problem that artifacts occur in the image after subtraction.

In view of the above, the present invention effectively removes the background image by subtraction by adjusting the photographing conditions of the mask image and the live image to the periodic or aperiodic movement of the subject. It is an object of the present invention to provide an X-ray image processing apparatus improved so as not to generate an artifact.

[0005]

To achieve the above object, in the X-ray image processing apparatus according to the present invention, a mask image is stored for each biological signal, and a live image is obtained together with the biological signal. The feature is that the mask image of the same imaging condition is selected by using the biomedical signal as an index, and the selected mask image is subtracted from the live image. Thus, when the mask image is subtracted from the live image, In addition, since those images are under the same imaging conditions using the biological signal as an index, the background images are the same, and the background images can be effectively removed by subtraction, and the artifacts due to the movement of the subject are eliminated. It can be lost.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 1, the subject 1 is irradiated with X-rays from the X-ray tube 2, and the X-rays transmitted through the subject 1 are made incident on the image intensifier 3. The X-ray transmission image output from the image intensifier 3 is converted into an image signal by the TV camera 4, and further converted into digital data by the A / D converter 5.

On the other hand, the subject 1 has a biological signal measuring device 1
1 is attached, the desired biological signal is measured,
The biological signal is converted into digital data by the A / D converter 12. The biological signal measuring device 11 is, for example, a respiratory monitor or an electrocardiograph, and measures a respiratory signal representing each state of respiratory motion, an electrocardiogram representing each phase of heart motion, and the like.

In this way, the image signal and the biological signal (digital data of the biological signal) are obtained at the same time. First, the memory 6 stores the mask image together with the biological signal. That is, here, a case of performing angiography will be described. Image signals and biological signals sequentially obtained before the injection of the contrast agent are sent to the memory 6, and each image signal is stored in a form linked to the biological signal at that time. To be done. As a result, a large number of mask images are stored in the memory 6 together with their biomedical signals. When the movement of the subject 1 is a periodic movement such as a respiratory movement, the mask image and the biomedical signal are collected for a period of one cycle or longer, and the images and the biomedical signal are accumulated for each phase. Do. In the case of non-periodic movement, all images and biological signals in the range of the movement are collected only during a period in which they can be accumulated. In the memory 6, as shown in FIG. 2, a large number of mask images M1, M2, ... And biosignal levels S1, S2 ,.

After the mask image has been collected, a contrast material is injected to obtain a live image. Image signals (digital data) of live images sequentially obtained from the A / D converter 5 are sent to the memory 7. At this time, the biological signal at the time when each image signal is obtained is sent from the A / D converter 12 to the memory 7 at the same time as the image signal. As shown in FIG. 3, a large number of live images L1, L2, ... And biosignal levels S1, S
2, ... Are mutually associated and sequentially stored.

After the collection of both the mask image and the live image is completed in this way, the mask image is subtracted from the live image. Live images are sequentially read from the memory 7. At this time, at the same time, the biomedical signal stored in association with the live image is read out and sent to the controller 8. The controller 8 controls the memory 6 so as to read from the memory 6 the mask image linked to the biological signal of the same level as the biological signal. Thus, in the example of FIGS. 2 and 3,
Mask images M1, M2, M3, and M4 are read out from the live images L1, L2, L3, and L4, respectively, and mask images M4 and M1 are read from the live images L5 and L6.
Are read respectively. The live image and the mask image read out simultaneously from the memory 7 and the memory 6 are sent to the subtracter 9 and subjected to subtraction processing, and the digital data of the image signal after the subtraction is returned to the analog signal by the D / A converter 10. After being processed, the subtraction images are sequentially displayed by being sent to an image monitor device (not shown).

Here, the memories 6 and 7 can be used with any storage medium, but if a high-speed accessible semiconductor memory or the like can be used as the memory 6, the above-mentioned offline subtraction is possible. Online subtraction processing is possible instead of processing. In this case, as shown in FIG. 4, the live image memory 7 is omitted. Simultaneous acquisition of the mask image and the biological signal in the memory 6 is the same as in the case of FIG. When the live image is obtained together with the biological signal, the biological signal is directly sent to the controller 8. The controller 8 instantly selects from the memory 6 the mask image stored in association with the biological signal of the level corresponding to the biological signal level. The mask image thus selected and read out from the memory 6 is immediately sent to the subtractor 9 and subjected to subtraction processing with the live image. As a result, a subtraction image can be obtained in real time online.

[0012]

According to the X-ray image processing apparatus of the present invention,
Since the mask image with the same imaging condition as the live image is selected using the biomedical signal as an index and the subtraction between them is performed, the background image becomes the same between the two images subjected to the subtraction processing, The background image can be effectively removed, and the artifacts generated in the subtraction image can be reduced. As a result, it is possible to reduce the artifacts associated with the movement of the diaphragm and the movement of the gas due to the respiratory movement by using a biological signal such as a respiratory signal measured by a respiratory monitor.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a mask image and a biological signal level.

FIG. 3 is a diagram showing a relationship between a live image and a biological signal level.

FIG. 4 is a block diagram of another embodiment.

[Explanation of symbols]

 1 Subject 2 X-ray tube 3 Image intensifier 4 TV camera 5, 12 A / D converter 6 Mask image and bio-signal memory 7 Live image and bio-signal memory 8 Controller 9 Subtractor 10 D / A conversion Device 11 biological signal measuring instrument

Claims (1)

Claim: What is claimed is: 1. Means for storing a mask image for each biological signal together with those biological signals, and a mask image corresponding to the biological image obtained with the live image as an index from the storage means. An X-ray image processing apparatus comprising: a selecting means and a means for performing subtraction between the live image and the selected mask image.