JPH10136262A - X-ray defocus subtraction video device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve time resolution by switching a focus image and a defocus image at high speed. SOLUTION: An optical system 30 is constituted of a focus lens 31 which is focused and a defocus lens 32 which is defocused by installing them on a rotary frame 33. The focus lens 31 and the defocus lens 32 are alternately positioned between the output face 22a of an image intensifier 22 and a television camera 23 by rotating the rotary frame 33. Then, the focus image and the defocus image are transmitted to the television camera 23 at every radiation of an X-ray by rotating the rotary frame 33 in synchronizing with the radiation of the X-ray. The video signal of the focus image and the video signal of the defocus image, which are alternately switched, are outputted from the television camera 23. Thus, the image of high time resolution can be provided and the device is useful for the diagnosis of a part which requires clinically minute resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray imaging apparatus used for medical diagnosis and the like, and particularly to an X-ray defocus subtraction imaging apparatus.

[0002]

2. Description of the Related Art An X-ray subtraction imaging apparatus is capable of converting an X-ray image with a contrast agent injected into an X-ray image without a contrast agent.
This is an apparatus for extracting an image of a contrast agent portion by subtracting a line image (mask image), and is an effective apparatus for angiography.
However, when moving the imaging system with respect to the subject to obtain a wide range of images or images from various angles, it is actually necessary to capture the image at the time of injection of the contrast agent and the mask image at the same position and direction. Subtracting between these images will result in artifacts due to the misregistration. Since this problem also occurs when the subject moves while capturing the contrast agent injection image and the mask image, it cannot be applied to a patient who is difficult to stay still for a certain period of time or a moving organ.

[0003] An X-ray defocused subtraction image apparatus has been proposed to fundamentally solve this difficulty. That is, extracting a blood vessel image filled with a contrast agent by using an X-ray subtraction imaging device
Focusing on the fact that the rough part that is the background is erased from the image at the time of injection of the contrast medium and extracting the fine parts such as blood vessels, the blurred image at the time of injection of the contrast medium is also obtained, and this blurred image Is used as a mask image, and an image similar to a conventional subtraction image is obtained by subtracting it from an image without blur. According to this, since the mask image can be obtained at the same time as the image at the time of injection of the contrast agent, it is possible to fundamentally avoid the problem of positional displacement.

[0004]

However, in the conventional X-ray defocus subtraction image apparatus, the focus of the image intensifier is controlled so that the focus image and the defocus image are switched and output. In addition, there is a problem that a high-speed switching is limited due to a capacitance or the like based on an electrode structure in an image intensifier, and a defocus subtraction image with high time resolution cannot be obtained.

SUMMARY OF THE INVENTION In view of the above, the present invention provides an X-ray defocus subtraction image apparatus improved so that the focus image and the defocus image can be switched at high speed to improve the time resolution of the defocus subtraction image. Aim.

[0006]

In order to achieve the above object, in an X-ray defocus subtraction image apparatus according to the present invention, an X-ray generating means, an X-ray transmitted through a subject, and an X-ray image Conversion means for converting the light image into an optical image and outputting the light image; optical transmission means for transmitting the optical image by switching between a focus state and a defocus state; and an electric video signal for transmitting the optical image transmitted by the optical transmission means. And a means for subtracting the video signal of the defocused image from the video signal of the focused image.

Optical transmission means for transmitting an optical image converted from an X-ray image by switching between a focused state and a defocused state, for example, mechanically switches a focused lens system and a defocused lens system. Switching, or distributing the optical image to the in-focus lens system and the out-of-focus lens system, taking images with separate imaging means, and simultaneously obtaining the focus image and defocus image video signals, In any case, it is easy to configure to switch at high speed. Therefore, since the focus image and the defocus image can be obtained by switching at high speed, a subtraction image with high time resolution can be obtained, and even when the organ moves at high speed, or when the imaging system is moved or rotated at high speed, etc. ,
A subtraction image without artifacts can be obtained.

[0008]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of an optical system used in an X-ray defocus subtraction image apparatus according to the present invention. FIG.
Is incorporated in an X-ray defocus subtraction imaging apparatus as shown in FIG. Referring to FIG. 3, the subject 10 is placed on the examination table 12 of the examination table 11. An X-ray tube 21 and an image intensifier (II) 22 are opposed to each other so as to sandwich the subject 10. In this example, the X-ray tube 21 and the image intensifier 22 are attached to both ends of a C-arm 24, respectively. A television camera 23 is connected to the image intensifier 22 by an optical system 30.

The C-arm 24 is held by a holding device 25, which is attached to a stand 26. The holding device 25 allows the C-arm 24
As shown by an arrow, the C-arm 24 rotates in a circular direction with respect to the stand 26, rotates around the horizontal horizontal axis of the circular arc, and moves linearly in the front-rear direction and the vertical direction. It is possible to move and rotate. Also,
The X-ray tube 21 and the image intensifier 22 are also held at the tip of the C-arm 24 so as to be movable in the direction of approaching and moving away from each other, as indicated by arrows. The stand 26 has wheels so that it can freely move on the floor of the examination room. An X-ray high-voltage device that supplies a high-voltage tube voltage or a filament current to the X-ray tube 21 is housed in the stand 26.

The optical system 30 switches the focus image and the defocus image at a high speed in synchronization with the X-ray exposure and transmits the same to the television camera 23. TV camera 2 for each X-ray exposure
From 3, video signals of the focus image and the defocus image are output alternately. These video signals are sent to the image processing device 40 and are converted into digital data by the A / D converter 41. Assuming that a video signal of a defocused image is obtained by a certain X-ray exposure, the data is stored in the frame memory 42. Next, a video signal of a focus image is obtained by X-ray irradiation, and the data is sent to the subtractor 43. At this time, the data of the previous defocused image is read from the frame memory 42, and subtraction between the focus image and the defocused image is performed by the subtractor 43. Thus two X's
Subtraction image data as a result of the subtraction is obtained for each line exposure, and this image data is converted back to an analog video signal by the D / A converter 44, sent to the image monitor device 50, and displayed.

As shown in FIG. 1, the optical system 30 has a focus lens 31 that is in focus and a defocus lens 32 that is out of focus mounted on a rotary frame 33. Is rotated, the output surface 22a of the image intensifier 22 is rotated.
The focus lens 31 and the defocus lens 32 are alternately positioned between the camera and the television camera 23. Therefore,
As the rotating frame 33 rotates in synchronization with the X-ray exposure, a focus image and a defocus image are alternately transmitted to the television camera 23 for each X-ray exposure, and the television camera 23
Thus, a video signal of a focus image and a video signal of a defocus image that are alternately switched are output.

In this case, the signal switching speed is determined by the rotation speed of the rotating frame 33. Therefore, by increasing the rotation speed, high-speed switching between the focus image and the defocus image can be performed. Therefore, if the X-ray irradiation is synchronized with the television synchronization signal and the rotation of the rotating frame 33 is also synchronized with the television synchronization signal, for example, a video signal of a focus image and a video signal of a defocus image are obtained alternately for each frame of the television. You can also.

Therefore, when the examination table 12 on which the subject 10 is placed is moved at a high speed, subtraction images are sequentially obtained at each position, or the C-arm 24
When sequentially obtaining subtraction images of the subject 10 in various angular directions while rotating at a high speed, it is possible to obtain those subtraction images free of artifacts due to displacement.

FIG. 2 shows another example of the optical system. In FIG. 2, the output image of the image intensifier 22 is split 1: 1 using the spectroscope 35, and the split images are respectively transmitted to the two television cameras 23a and 23b via the focus lens 31 and the defocus lens 32. Then, the video signal of the focus image and the video signal of the defocus image are simultaneously obtained. These video signals are alternately switched by the video signal switch 36 and sent to the A / D converter 41 of the image processing device 40 as shown in FIG. By switching the video signal switching unit 36 in accordance with the timing of X-ray exposure, it is possible to alternately output the video signal of the focus image and the video signal of the defocus image for each X-ray exposure.

The present invention is not limited to the above, and various modifications are possible. For example, the configuration of the image processing device 40 is not limited to that shown in FIG. In addition, as the television cameras 23, 23a, and 23b, an imaging tube, a CCD camera, or the like can be used.

[0016]

As described above, according to the X-ray defocus subtraction video apparatus of the present invention, the video signal of the focused image and the video signal of the blurred image can be alternately switched at high speed. This makes it possible to obtain a defocused subtraction image with a higher temporal resolution, which is useful for diagnosing a site that requires clinically fine temporal resolution.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of an optical system according to an embodiment of the present invention.

FIG. 2 is an exemplary block diagram showing another example of the optical system according to the embodiment;

FIG. 3 is an exemplary block diagram illustrating the entirety of an X-ray defocus subtraction video apparatus according to the embodiment;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Examinee 11 Examination table 12 Examination table 21 X-ray tube 22 Image intensifier 22a Image intensifier output surface 23, 23a, 23b Television camera 24 C-arm 25 Holding device 26 Stand 30 Optical system 31 Focus lens 32 Defocus lens 33 Rotating frame 35 Spectroscope 36 Video signal switch

Claims (1)

[Claims] 1. An X-ray generating unit, a converting unit that receives an X-ray transmitted through a subject, converts an X-ray image into an optical image and outputs the optical image, and converts the optical image into a focus state and a defocus state. An optical transmission means for switching and transmitting, an imaging means for converting an optical image transmitted by the optical transmission means into an electric video signal, and a means for subtracting a video signal of a defocused image from a video signal of a focus image An X-ray defocus subtraction imaging apparatus, characterized in that: