JPH105206A - Digital x-ray photographic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately obtain three-dimensional information on an affected part with X-ray images projected on monitor screens. SOLUTION: In a digital X-ray photographic apparatus, an observer distance measuring part 13 measures a distance between monitors LM, RM for carrying out the stereo display and an observer of the X-ray image, and an image distance controlling part 14 adjusts automatically a distance between centers of 2 X-ray images stereo displayed on the screens of the monitors LM, RM such that an observation parallax and a radiographic parallax with regard to the stereo display become substandially equivalent on the basis of a distance detected with the observer distance measuring part 13. Thereby, the stereo display is made to be adequately stereoscopic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a so-called rotation D
A (Digital Angiography) or rotating DSA (Di
The present invention relates to a digital X-ray imaging apparatus configured to be capable of stereoscopic display of an X-ray image by an angiography method such as gital subtraction angiography, and particularly to a technique for appropriately performing stereo display of an X-ray image.

[0002]

2. Description of the Related Art In a digital radiography apparatus as digital radiography, an X-ray tube and an image intensifier, which are supported opposite to each other with a subject interposed therebetween, are rotated around the subject by a holding mechanism so that various types of radiography are performed. While the imaging angle is set, the imaging is repeated for each imaging angle, while the X-ray images captured at various imaging angles are stored in the image memory in the form of digital signals, and after (or during) the imaging. An appropriate one of the stored X-ray images is read out and displayed on a screen of a display monitor. In addition, in this digital X-ray imaging apparatus, X-ray images are captured and displayed by an angiography method called rotation DA or rotation DSA.

In the case of the former rotational DA imaging method, after a contrast agent is injected into a blood vessel, an X-ray tube and an image intensifier are imaged at various imaging angles while rotating around an object to obtain a large number of X-rays. A line image is obtained and stored, and a large number of X-ray images are sequentially and successively projected on a display monitor after or during imaging, and a moving image is observed.

In the latter rotational DSA imaging method, before injecting a contrast medium into a blood vessel, an X-ray tube and an image intensifier are imaged at various imaging angles while rotating around an object to obtain a large number of images. An X-ray image (mask image) is obtained and stored in advance, and after a contrast agent is injected into a blood vessel, the image is obtained from the X-ray image (live image) in the same manner as in the DA imaging method, and each live image is obtained. Then, a DSA image is obtained by subtracting the mask image obtained at the same photographing angle from the above, and a DSA image is displayed on a screen of a display monitor, and a moving image of only a blood vessel image is observed. In any case, three-dimensional information on the affected part is obtained by, for example, subjectively confirming the anteroposterior relationship between the positions of the blood vessel images by observing a moving image. The three-dimensional information about the affected area is very useful for making an accurate diagnosis.

Further, as a method of obtaining three-dimensional information on an affected part, there is a stereoscopic observation of an X-ray image in addition to the above-mentioned moving image observation. That is, three-dimensional information is obtained by binocularly viewing two X-ray images obtained by using a bifocal X-ray tube and having different imaging angles arranged side by side and simultaneously displayed on a monitor. The method of obtaining three-dimensional information on an affected part by stereo observation of an X-ray image is based on the principle of stereoscopic vision by a human eye, and is a method of easily grasping a sense of depth. It is appropriate as a method for obtaining important information.

[0006]

However, the above-mentioned moving image observation and stereo observation have a problem that it is difficult to accurately obtain three-dimensional information on the affected part. When obtaining three-dimensional information by moving image observation of the former X-ray image,
It is necessary to determine the difference in the moving speed between several images shown on the screen, but it is an expert to quickly determine the difference in the moving speed between the images by looking at the moving screen. However, it is not easy, and it is difficult to obtain three-dimensional information accurately.

In the latter case of stereo observation of X-ray images, 3
When obtaining dimensional information, in order to perform appropriate stereoscopic viewing, a difference in the viewing angle of each eye of the observer who observes the stereo display of the X-ray image (hereinafter, abbreviated as “observation parallax” as appropriate). When,
The difference in the imaging angle of each X-ray image to be stereo-displayed (hereinafter referred to as
(Abbreviated as “photographing parallax” as appropriate), but actually, the observation parallax does not coincide with the photographing parallax, and there is often a considerable shift between the two parallaxes. It is difficult to obtain accurate information accurately.

The present invention provides a digital X-ray imaging apparatus capable of accurately obtaining three-dimensional information on an affected part by observing an X-ray image projected on a monitor screen in view of the above circumstances. The task is to

[0009]

A digital X-ray apparatus according to the present invention employs the following configuration to solve the above-mentioned problems. That is, the present invention is carried out for each of the imaging angles set by the holding mechanism for setting the X-ray tube and the image intensifier, which are opposed to each other across the subject, at various imaging angles. Video signal detecting means for obtaining an X-ray image in the form of a digital signal from the image intensifier with X-ray irradiation on a subject, and image storing means for storing the X-ray image obtained by the video signal detecting means And a display monitor for displaying an X-ray image stored in the image storage means, wherein the two X-ray images having different imaging angles set by the holding mechanism are stored in the image storage device. Stereo display means for reading from the means and displaying stereo on a screen of the monitor, and an observer distance for measuring a distance between the monitor and an observer of the X-ray image And a difference (observation parallax) between an angle at which each eye of an observer observing the two X-ray images of the stereo display is observed based on the distance measured by the observer distance measurement means. An image distance control means is provided for adjusting the distance between the centers of two X-ray images on the monitor screen so that the difference between the imaging angles of the line images (imaging parallax) becomes substantially equal.

[0010]

The operation of obtaining three-dimensional information on the affected part by the digital radiography apparatus of the present invention is as follows. In the digital X-ray imaging apparatus according to the present invention, the X-ray tube and the image intensifier supported opposite to each other across the subject are rotated around the subject by the holding mechanism, and at least two X-rays to be stereo-displayed are provided. While the image is set to the imaging angle at which the image is obtained, the X-ray image is obtained in the form of a digital signal from the image intensifier with the X-ray irradiation on the subject at each imaging angle by the video signal detection means, The obtained X-ray image is stored in the storage means. On the other hand, when two stored X-ray images having different imaging angle settings are stereo-displayed on the screen of the display monitor by the stereo display means of the digital X-ray imaging apparatus, measurement is performed by the observer distance measurement means. Based on the distance between the display monitor and the observer, the image distance control means automatically adjusts the center-to-center distance between the two X-ray images in the stereo display, so that each observer observes the stereo display. The difference between the angles (observation parallax) and the difference between the imaging angles of each X-ray image (imaging parallax) are made substantially equal. That is, in the digital X-ray imaging apparatus of the present invention, the observation disparity is proportional to the distance between the centers of the two X-ray images stereo-displayed on the monitor screen, and the observation disparity is determined by the imaging disparity. Is automatically changed so that the distance between the centers of the two X-ray images coincides with each other.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main configuration of an embodiment of a digital X-ray imaging apparatus according to the present invention. As shown in FIG. 1, the digital X-ray imaging apparatus according to the embodiment includes an X-ray tube 1 and an image intensifier 2 supported opposite each other across a subject M, and the X-ray tube 1 and the image intensifier. 2 is provided with a holding mechanism 3 for setting various shooting angles. The holding mechanism 3 has a C-shaped arm 3a in which the X-ray tube 1 and the image intensifier 2 are fixed to both ends, and has, for example, a rack and pinion driving unit (not shown) for rotating the C-shaped arm 3a. ing. The X-ray tube 1 and the image intensifier 2 maintain the counter installation in conjunction with the rotation of the C-arm 3a (for example, 90 ° rotation) by the rack and pinion drive unit under the control of the holding mechanism control unit 5. The patient rotates around the subject (patient) M who lies on the table 4 while keeping the position. The rotation operation is intermittent, repeating movement and stop, and connects a straight line connecting the X-ray tube 1 and the image intensifier 2 at the reference position and connecting the X-ray tube 1 and the image intensifier 2 at each stop position. The angle between the straight lines is the shooting angle. The X-ray tube 1 emits X-rays to the subject M by applying a high voltage by the X-ray emission control unit 6. Then, while the X-ray tube 1 and the image intensifier 2 are sequentially set at various imaging angles by the holding mechanism 3, X-ray irradiation to the subject M is performed at each imaging angle,
X-ray photography will be repeated.

A video signal detecting section (video signal detecting means) 9 is connected to the image intensifier 2 via an optical system 7 and a stop 8. The X-rays transmitted through the subject M are converted and multiplied into visible light by the image intensifier 2, and thereafter, an X-ray image is output in the form of a digital signal from the video signal detection unit 9 via the optical system 7 and the aperture 8. You. The video signal detection unit 9 includes a television camera and a CCU that performs processing such as amplifying an output signal of the television camera.
(Camera control unit) and CC
It has an A / D (analog-to-digital) converter for converting an output signal subjected to processing such as amplification in U into a digital signal.

The apparatus according to the embodiment includes an image processing unit 10 for performing enhancement and subtraction processing on the X-ray image in the digital signal format obtained by the video signal detection unit 9 as necessary.
Further, the image processing apparatus includes an image memory 11 such as a magnetic disk for storing an X-ray image after image processing. In the image memory 11, each X-ray image is stored in association with its imaging angle.

Further, the apparatus according to the embodiment has a stereo display section (stereo display means) 12, an observer distance measurement section (observer distance measurement means) 13, an image distance control section for performing stereo display of an X-ray image. Unit (image distance control means) 1
4, two frame memories Lm and Rm, two display monitors LM and RM, and an operation console 15 for operating the apparatus. Operation console 1
5 is provided with an operation switch (not shown) for selecting a stereo display and setting a shooting angle and a shooting parallax of the stereo display. The shooting parallax is usually 6 ° ~
It is selected from a range of 10 °. The image processing unit 1 described above
0, stereo display unit 12 or image distance control unit 14
Is mainly composed of a CPU (microprocessor) and a control program. Furthermore, examples of the observer distance measuring unit 13 include a distance sensor using an infrared ray and a distance sensor using an ultrasonic wave.

When the stereo display is selected on the console 15, the stereo display unit 12 stores two frame memories L.
The X-ray images stored in m and Rm (as will be described later) are simultaneously displayed on the monitors LM and RM, and stereo display by the intersection method is performed in a still image mode. The observer distance measuring unit 13 measures the distance between the monitors LM and RM and the observer (doctor or photographer) of the X-ray image. Based on the distance (detection distance) measured by the observer distance measurement unit 13, the image distance control unit 14 determines that the observation parallax of the observer and the imaging parallax of both X-ray images for the two X-ray images in the stereo display are substantially equal. It has a function of adjusting the center-to-center distance between both X-ray images during stereo display so as to be equal,
Specifically, when storing two X-ray images to be stereo-displayed in the frame memories Lm and Rm, the storage area (address) is shifted by an amount corresponding to the detection distance of the observer distance measurement unit 13.

Next, a specific description will be given of a case where the digital X-ray imaging apparatus of the embodiment performs stereoscopic display by the rotating DSA imaging method as an example. When performing rotational DSA imaging, the X-ray tube 1 and the image intensifier 2 are rotated around the subject M by an appropriate angle (for example, 90 °) by the holding mechanism 3 before the contrast medium is injected into the blood vessel. The X-ray images obtained at various photographing angles are subjected to enhancement processing and the like by the image processing unit 10 while being associated with the photographing angles in the image memory 11 as mask images. And memorize one after another.

Next, after the contrast medium is injected into the blood vessel of the subject M, the X-ray tube 1 and the image intensifier 2 are similarly rotated around the subject M by the holding mechanism 3 from various photographing angles. The image processing unit 10 performs imaging, performs an emphasis process or the like on the X-ray image (live image) obtained at each imaging angle, and forms a mask image at the same imaging angle from the live image obtained at each imaging angle. Image processing to be subtracted is performed, and this is sequentially stored as a DSA image in the image memory 11 in association with the photographing angle.

In this manner, the DS to the image memory 11 is
When the storage of the A image is completed, the stereoscopic display is selected on the console 15 and the photographing angle (photographing angle θ1) and the photographing parallax θa of the stereoscopic display object are set. As shown, monitor L
Distance between M, RM and observer of X-ray image (detection distance)
Measure A. The detection distance A measured by the observer distance measurement unit 13 is immediately sent to the image distance control unit 14.

On the other hand, two DSA images to be stereo-displayed are sequentially read from the storage memory 11 and sent to the image distance control unit 14. One of the two DSA images (D
As shown in FIG. 2, the SA image L) is an image at an imaging angle θ1 at a position where the X-ray tube 1 and the image intensifier 2 are connected by a straight line ma, and the other (DSA image R) is As shown in FIG. 2, the DSA image L is an image at a shooting angle (θ1 + θa = θ2) at a position where the X-ray tube 1 and the image intensifier 2 are connected by a straight line mb.
And the DSA image R have a relationship of the shooting parallax θa. The shooting parallax θa is represented by θa = V × F ÷ r (1) V is the rotation speed (V ° / sec), that is, the rotation angle per second by the holding mechanism 3, and r is the image acquisition speed (r fr / sec), that is, the number of X-ray images collected per second. And F is the number of image steps, that is, the number of X-ray images between the DSA images L and R. Therefore, the DSA image L at the photographing angle θ1 is read from the image memory 11.
And the DSA image R after F (= θa × r ÷ V) steps are read from the DSA image L.

On the other hand, the image distance control unit 14 stores the DSA image L in the frame memory Lm while taking into account the displacement corresponding to the detection distance A of the observer distance measurement unit 13, and stores the DSA image R
Is stored in the frame memory Rm. The relationship between the detection distance A and the storage area of each DSA image L, R in the frame memories Lm, Rm is as follows. As shown in FIG.
Observation parallax θb of the observer, detection distance A, distance between both eyes of the observer (that is, the distance between human eyes) B, DSA images L, R
, A relation C = 2Atan (0.5 × θb) -B (2) is established between them. Since the detection distance A and the distance B in the equation (2) have already been determined, the value of the center-to-center distance C is calculated as follows.
It can be seen that the observation parallax θb can be determined.

If θb = θa, an appropriate stereo display is obtained in which the observation parallax and the shooting parallax are equal. This θb
= Θa, referring to the relationship of the above equation (1),
The expression (2) can be expressed by the following expressions (3) to (4). C = 2Atan (0.5 × θa) −B (3) C = 2Atan (0.5 × V × F ÷ r) −B (4) The right side of the above equations (3) and (4) Parameters A, B, θ
The values of a, V, F, and r have already been determined. Therefore,
If the distance C between the centers of the remaining DSA images L and R is equal to the value on the right side, an appropriate stereo display in which the observation parallax is equal to the shooting parallax will be realized. The image distance control unit 14
The value on the right side of the above equation is calculated, and the following control is performed so that the center-to-center distance C becomes the calculated value.

As shown in FIG. 4, each of the frame memories Lm and Rm has addresses 0 through m in the X direction and addresses 0 through m in the Y direction.
The image distance control unit 14 has an effective area of address n.
When the detection distance A is the reference distance A0, as shown by the solid line in FIG. 4, the DSA images L, R are arranged such that the centers LC, RC of the DSA images L, R are located at the centers of the frame memories Lm, Rm.
Is stored in the frame memories Lm and Rm. The stereo display in this storage state is represented by DSA as shown by the solid line in FIG.
The centers of the images LC and RC are located at the centers of the monitors LM and RM, and the distance between the centers of the DSA images L and R is adjusted to be the reference center distance C0 where θb = θa. Also,
The center LC, RC of the DSA images L, R is the frame memory L
When they are coincident with the centers of m and Rm and the monitors LM and RM, there is still enough room left and right in both the storage area and the display area.

However, when the detection distance A is smaller than the reference distance A0 (A <A0), the distance between the centers of the DSA images L and R at which the observation parallax and the photographing parallax become equal is apparent from the equation (3). , 2 [A0tan (0.5 × θa) -At
an (0.5 × θa)] = Ca is the distance C0 between the reference centers.
Less. Therefore, when storing the DSA images L and R in the frame memories Lm and Rm, the image distance control unit 14 stores the centers LC and RC of the DSA images L and R in the frame memories Lm and Rm, as indicated by the dashed line in FIG. The storage address is changed so as to shift to the right (larger address) in the frame memory Lm and to the left (smaller address) in the frame memory Rm by an amount corresponding to the distance 0.5Ca from the center of Rm. Then, as shown by the one-dot chain line in FIG. 5, in the stereo display on the screen of the monitors LM and RM, the LC and RC of both DSA images L and R are respectively set to 0.
By approaching the center by 5Ca, the distance between the centers of the DSA images L and R decreases by the distance Ca, and the observation parallax and the imaging parallax become equal.

Conversely, when the detection distance A is larger than the reference distance A0 (A> A0), as is apparent from the equation (3), the distance between the centers of the DSA images L and R at which the observation parallax and the photographing parallax are equal. Is 2 [Atan (0.5 × θa) −A0t
an (0.5 × θa)] = Cb by reference distance C0
More. Therefore, when storing the DSA images L, R in the frame memories Lm, Rm, the image distance control unit 14 stores the center LC, RC of the DSA images L, R in the frame memory Lm, as indicated by the two-dot chain line in FIG. , Rm from the center of the monitor LM, RM on the left side (smaller address) in the frame memory Lm by an amount equivalent to 0.5 Cb.
In the frame memory Rm, the storage address is changed so as to be shifted to the right (the side with the larger address). Then, as shown by a two-dot chain line in FIG.
In the stereo display on the screen of M, both DSA images L,
The LC and RC of R are separated from the center by 0.5 Cb, respectively, and the distance between the centers of the DSA images L and R is increased by the distance Cb, so that the observation parallax and the imaging parallax become equal.

In the apparatus of the embodiment, as described above, by adjusting the distance between the centers of the DSA images L and R by the image distance control unit 14, the observation parallax in the stereo display automatically becomes equal to the photographing parallax. By always observing both DSA images L and R with an appropriate sense of depth, it is possible to accurately obtain three-dimensional information on the affected part.

The present invention can be modified as follows. (1) In the embodiment, the adjustment of the distance between the centers of the DSA images L and R is realized by shifting the storage area of the frame memory. Modified examples include a configuration in which the beam is shifted left and right or the entire monitor is shifted left and right.

(2) In the case of the embodiment, stereo display is performed by using two display monitors. However, only one display monitor is used, and two X-ray images are simultaneously projected on one screen and stereo display is performed. Can be cited as a modification.

(3) In the embodiment, a stereo display of a DSA image has been described as an example. However, the present invention is of course also effective for a stereo display of a different type of image such as a DA image.

(4) In the embodiment, the X-ray and the image intensifier are rotated by 90 ° around the subject M. However, in the present invention, the X-ray and the image intensifier are not necessarily rotated by 90 °, but may be stereoscopically displayed. It may be possible to rotate a narrow range only between two photographing angles necessary for the camera.

(5) In the embodiment, the stereo display is a static display, but the stereo display may be a moving image display.

[0031]

As is apparent from the above description, the digital X-ray imaging apparatus according to the present invention has a structure capable of stereoscopic display of an X-ray image in which a sense of depth can be easily grasped, and an X-ray image. Since the configuration that automatically controls the observation parallax and the shooting parallax to be substantially equal in accordance with the distance between the observer of the image, the observer can perform appropriate stereoscopic viewing, Three-dimensional information on the affected part can be obtained accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of a digital X-ray imaging apparatus according to an embodiment.

FIG. 2 is a schematic diagram illustrating imaging parallax in a digital X-ray imaging apparatus.

FIG. 3 is a schematic diagram illustrating observation parallax in a digital X-ray imaging apparatus.

FIG. 4 is a schematic diagram showing a specific example of storage in a frame memory of the embodiment device.

FIG. 5 is a schematic diagram showing a specific example of displaying an X-ray image on a display monitor of the apparatus according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... X-ray tube 2 ... Image intensifier 3 ... Holding mechanism 9 ... Video signal detection unit 11 ... Image memory 12 ... Stereo display unit 13 ... Observer distance measurement unit 14 ... Image distance control unit LM ... Monitor for display RM … Monitor for display

Claims (1)

[Claims] 1. A holding mechanism for setting an X-ray tube and an image intensifier, which are opposed to each other with a subject interposed therebetween, at various photographing angles, and an object for each photographing angle set by the holding mechanism. Image signal detecting means for obtaining an X-ray image in the form of a digital signal from the image intensifier with X-ray irradiation on a sample; and image storing means for storing the X-ray image obtained by the image signal detecting means. A digital X-ray imaging apparatus having a display monitor for displaying an X-ray image stored in the image storage means, wherein two X-ray images having different imaging angles set by the holding mechanism are stored in the image storage means. Stereo display means for reading from the monitor and displaying stereo on the monitor screen, and observer distance measuring means for measuring the distance between the monitor and the observer of the X-ray image. And a difference (observation parallax) between an angle at which each eye of an observer observing the two X-ray images of the stereo display is observed, based on the distance measured by the observer distance measurement unit, and an observation angle of each X-ray image. Two X's on the monitor screen are set so that the difference between the shooting angles (shooting parallax) is approximately equal.
A digital X-ray imaging apparatus comprising image distance control means for adjusting a center distance of a line image.