JP3490505B2 - X-ray diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to three-dimensional data of a subject.
The present invention relates to an X-ray diagnostic apparatus for reconstructing an image. [0002] 2. Description of the Related Art This type of X-ray diagnostic apparatus is an X-ray computer.
As with data tomography (X-ray CT),
X-ray tube and image intensifier facing each other
(I.I.) is rotated while rotating within the normal of the subject's body axis.
X-rays of multiple frames with different imaging angles by repeating
Projection images are obtained, and from these X-ray projection images,
Since the original data is reconstructed by back projection or OR, I.
It is also called I.CT. Problems with this I.I.CT
Is described below. The area shown by the dotted line in FIG.
Area. This reconstruction region is represented by a cone X for all directions.
It is defined as a sphere inscribed in a ray bundle. Imaging is subject P
Must be carried out in the reconstruction area.
is there. This is because the subject P is housed in the reconstruction area.
Understand that there is no. As shown in FIG.
As shown in FIG.
Part of the data is taken in from direction b,
It is not taken in from the direction. Therefore, the data in this shaded area
Data appear as artifacts in the reconstructed image.
U. For this reason, I.I.CT requires a large image
A sifier was needed. Also, connect the X-ray tube to the subject.
Close up and image a specific organ within the subject
Could not shadow. Further, an X-ray tube which is a large structure and an image
At least 180 ° rotation with diintensifier
Rotation support mechanism is enlarged, and sufficient rotation
A shooting room with a turning space is required, and the shooting time is longer
There was a problem that time was required. In addition, angiography
In the case of a shadow, a so-called max image before injecting a contrast agent
Must be shot beforehand, and if the shooting time becomes longer,
There was such a problem. [0005] The first object of the present invention
Is an X-ray diagnostic device that can reduce artifacts.
Is to provide an installation. The second purpose is to set the rotation angle to 18
To provide an X-ray diagnostic apparatus capable of making the angle smaller than 0 °.
Is Rukoto. The third objective is to create a mask before injecting the contrast agent.
By providing an X-ray diagnostic device that does not require
is there. [0006] SUMMARY OF THE INVENTION The present invention providesX-ray tube
Defined as a sphere inscribed in a cone of X-rays
Part of the subject with contrast agent injected into the reconstruction area
FitsA portion of the subject from the reconstruction area
Multiple shots from multiple shooting angles
Means for holding data of a first X-ray projection image;
Before imaging from the same multiple imaging angles as the first X-ray projection image of
Holds data of a plurality of captured second X-ray projection images
Means, data of the first X-ray projection image and the second X-ray
Subtract the data of the projected image with the same shooting angle
ByThe shadow of the contrast vessel in the reconstruction area is extracted.
WasMeans for generating a subtraction image for each shooting angle;
Reconstructing three-dimensional data on the contrasted blood vessel from the calculated image
Means. [0007] According to the present invention, an object which protrudes from the reconstruction area is provided.
The image of a part of the specimen is excluded by subtraction,
Eliminate artifacts. In addition, one of the subjects
No artefacts when the part goes out of the reconstruction area
Since three-dimensional data can be obtained, bring the X-ray tube closer to the subject.
The image intensifier away from the subject
A specific organ (in this case, a blood vessel) is geometrically enlarged and taken.
It is also possible to cast shadows. [0008] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
explain. (First Embodiment) FIG. 1 shows an X-ray diagnostic apparatus according to a first embodiment.
1 shows the configuration. X-ray of cone beam type to subject P
X-ray tube 1 to be irradiated and X-rays transmitted through subject P are detected.
Image intensifier 2 sandwiches subject P
While maintaining the facing state with the
Movably (rotatably) supported by a support mechanism (not shown)
You. The optical output surface of the image intensifier 2 is optical
A TV camera 5 such as a CCD camera is attached via the system
Is done. The high voltage generator 3 controls the X-ray controller 4
Thus, a tube voltage and a tube current are applied to the X-ray tube 1 in a pulsed manner. X-ray tube 1 and image intensifier 2
Is repeated while rotating around the subject P.
X of 72 frames whose shooting angles are different by 5 °, for example.
A line projection image is obtained. In addition, regarding all directions of the X-ray tube 1,
Region is defined as a sphere inscribed in the X-ray flux of a conical cone
Then, reconstruction is performed in this reconstruction area. An X-ray projection image signal is analog-digital
Before the injection of the contrast medium via the converter (A / D) 6, the photographing is performed.
The angle is stored in the first image memory 7 as an address,
After the injection of the contrast agent, the second image is taken using the imaging angle as an address.
It is stored in the image memory 8. The first image memory 7 and the second
The X-ray projection image data read from the image memory 8 is
It is sent to the subtraction processing means 9. The subtraction processing means 9 is provided with a photographing angle.
Draws two X-ray projection image data before and after the same contrast agent injection.
Do the subtraction. This allows the shooting angle
72 different frames of subtraction image data
Is done. The three-dimensional reconstructing means 10 has a function of 72 frames.
Suitable convolution for subtraction image data
After applying the filter,
Reconstruct the three-dimensional data of the contrast agent portion. The three-dimensional data is stored in the image memory 11 once.
Remembered. The display image creating means 12 includes an input device (not shown).
For example, a surface image or the like viewed from the viewpoint specified through
Display image data is obtained by using the three-dimensional data of the image memory 11.
To create. Display image data is digital-analog
After being converted into an analog signal by the converter (D / A) 13,
It is displayed on a monitor 14 such as an RT display. Next, the operation of this embodiment will be described. Figure
2 (a) shows the trajectory of the X-ray tube at the time of taking a mask image with a dashed line.
Then, the solid line shows the X-ray tube trajectory during the contrast radiography, and FIG.
In addition, the time-dependent change in the imaging angle is compared with the contrast agent injection timing.
Both are shown. Until reconstructing 3D data in Fig. 3
3 shows the flow of image processing. In FIG. 2A,
In order to distinguish the movement trajectory by both X-ray tubes,
Although it is described without overlapping with the solid line, in actuality both X-ray tubes
Rotate in the same orbit. First, a state in which the contrast agent is not injected into the subject P
In the state, the X-ray tube 1 and the image intensity are supported by the support mechanism.
And around the subject P between the time t1 and the time t2.
Goes around once. During this time, shooting is repeated, and the shooting angle is
For example, 72 frames of X-ray projection images that differ by 5 °
Obtained as a statue. These 72 frame mask image signals
The signal is transmitted through the analog-to-digital
The shadow angle is stored in the first image memory 7 as an address.
You. Next, after the photographing of the mask image is completed, at time t
In 3, the contrast agent is injected into the subject P by a doctor using a syringe.
Or automated by the injector
It is. From time t4 to time t5 when the contrast agent exists in the region of interest
In the meantime, the X-ray tube 1 and the image intensity are supported by the support mechanism.
The wire 2 makes a round around the subject P. During this time,
The shadow is repeated, and the photographing angles are different by, for example, 5 ° each 72
An angiographic image of the frame is obtained as a live image. This
These 72 frames of live image signals are converted to analog digital
Through the camera converter 6, each photographing angle is used as an address.
It is stored in the second image memory 8. A first image memory 7 and a second image memory 8
The mask image data and live image data read from
It is sent to the subtraction processing means 9. Subtraction
2 before and after the injection of the contrast agent having the same imaging angle
The mask image and the live image are subtracted. This takes
Subtraction image data of 72 frames with different shadow angles
Data is created. This subtraction image contains
Only shadowed vessel shadows exist. These 72 frames of subtraction images
The image data is appropriately convolved by the three-dimensional reconstruction means 10.
And then back-projected.
You. As a result, three-dimensional data of only the blood vessel (contrast part) can be obtained.
Reconfigured. The three-dimensional data is stored in the image memory 11.
I will be remembered. Not shown by display image creation means 12
For example, a surface image viewed from the viewpoint specified through the input device
Display image data such as an image is three-dimensional data in the image memory 11
Created from Display image data is digital analog
After being converted to an analog signal by the
It is displayed on a monitor 14 such as a display. [0020] As described above, two images were taken before and after the injection of the contrast agent.
Subtract between the images, and use this subtraction
To reconstruct the 3D data of the contrast agent from the
Then, as described with reference to FIG.
The part of the data of the protruding subject P is subtracted.
Eliminated, thus eliminating artifacts
Is done. Further, as described above, a part of the subject P is
3D data with no artifacts
The X-ray tube is brought close to the subject,
Keep the intensifier away from specific organs within the subject.
In the case of, the blood vessel) can be geometrically enlarged and photographed.
Wear. (Second Embodiment) FIG. 4 shows the configuration of an X-ray diagnostic apparatus according to a second embodiment.
And the same parts as those in FIG.
I do. The second embodiment includes a contrast agent shadow from an X-ray projection image
Extract partial images for each shooting angle, and from these partial images
Reconstructing 3D data of a contrast part
And will be specifically described below. Also here
As in the case of the first embodiment, images are taken every 5 degrees,
72 frame max images, 72 frames with different shooting angles
It is assumed that a live image of the frame is obtained. A max image of 72 frames and a live image
From the subtraction processing means 9, 72 frames
A subtraction image is obtained. Up to here, the first implementation
Same as the example. In this embodiment, a multi-stage slide of X-ray CT is used.
Slice (multi-slice)
Reconfiguration is performed every time. That is, one water of each X-ray projection image
The data sequence on a flat line is the primary in X-ray CT
Handled as original projection data (projection data)
The same horizontal position in the subtraction images at all shooting angles
Reconstruct a tomographic image of one slice plane from the data sequence of line numbers
To achieve. The subtraction image of 72 frames is
Imported into slice dividing means 15 via image memory 15
I will. The slice dividing means 15 calculates each subtraction
For the image, horizontal line number and shooting in horizontal line units
Attribute of angle and area limited hand as one-dimensional data string
Feed into stage 17. The area limiting means 17 has the same horizontal line number.
Of 72 data strings with different shooting angles
When all data indicate 0, the horizontal line number (slice
Do not reconstruct the tomographic image for the
The data of the relevant horizontal line number is excluded from the configuration
The data sequence is not sent to the two-dimensional reconstruction means 18. The diagonal lines in FIG.
The part indicates a region to be removed by the region limiting means 17. Also, territory
The area limiting means 17 has the same horizontal line number,
A non-zero value is added to the data of the 72 data strings having different shadow angles.
When data is included, the horizontal line number (slice
Plane), so that the tomographic image is reconstructed.
The 72 data strings of the in-number are sent to the two-dimensional reconstruction means 18.
send. As described above, data is selected for each horizontal line.
In this way, the region to be reconstructed is
Along the body axis). Site of interest (contrast agent shadow,
(Usually a contrasted blood vessel)
Of interest, usually the lines at the top and bottom of the image
There is no site, and the data is at the 0 level. Each X-ray
Except for the top and bottom lines in the projected image,
This is equivalent to a partial image including a contrast agent shadow. The two-dimensional reconstruction means 18 includes the area limiting means 1
7 and the horizontal line number sent from
Here, a tomographic image is re-created from the 72 data strings of the imaging angle.
Constitute. This reconstruction is sent from the area limiting means 17.
Rows for all horizontal line numbers (slice planes)
Is Thus, a plurality of tomographic images are reconstructed.
  A plurality of tomographic images created in this way are three-dimensional images
Attribute of horizontal line number as slice position in memory 11
Is written. Thereby, the three-dimensional image memory 11
, Three-dimensional data is constructed. As in the first embodiment, the data is written to the image memory 11.
Display image creation 12 from the input 3D data
An image is created and passed through a digital-to-analog converter 13
It is displayed on the monitor 14. According to the second embodiment, the reconstruction area is limited.
Therefore, the reconstruction processing time can be reduced. (Third Embodiment) FIG. 6 shows the configuration of an X-ray diagnostic apparatus according to a third embodiment.
4 and the same parts as those in FIG.
I do. The X-ray diagnostic apparatus according to the third embodiment includes an X-ray tube 1 and an image.
The first consisting of page intensifier 2 and TV camera 5
And an X-ray tube 21 having the same configuration as that of the first imaging system.
From image intensifier 22 and TV camera 25
And two second imaging systems. Figure
As shown in FIG. 7 (b), the image intensity
The center line of the X-ray flux reaching the sapphire 2 and the X-ray tube 21
The center line of the X-ray flux reaching the image intensifier 22
The two photographing systems are rotated (not shown) so that they intersect at an angle α.
Held by the holding mechanism. The smaller this angle α is,
It is effective for shortening time, but large image intensity
3 ° to 45 °
Set to a specific angle within the range. Rotation support mechanism rotates
Then, the first imaging system is the orbit shown by the solid line in FIG.
The road is rotated, and the second photographing system is indicated by the dashed line in FIG.
With a time delay of angle α from the first imaging system
Revolves around the same orbit. The X-ray tube 21 has a high-voltage generator
23 is connected. The injector 27 is an automatic contrast medium injector.
The contrast agent is injected into the subject P via a syringe (syringe) 29.
Is to be injected. The injector 27
During the imaging period, the contrast agent concentration of the subject changes over time.
Inject the contrast agent while changing the instantaneous injection amount every moment
You. The first imaging system does not rotate around the subject P.
Then, repeat the shooting, and the shooting angle differs by 5 °, for example.
72 frames of X-ray projection images (the first X-ray projection image and
Get). These first X-ray projection images are
To the first image memory 31 via the digital-to-digital converter 6.
Sent and stored. Similarly, the second imaging system uses the subject P
Repeat the shooting while rotating around the first shooting system
In the same way as in
X-ray projection image (referred to as a second X-ray projection image)
You. These second X-ray projection images are analog digital
Sent to the second image memory 32 via the
It is memorized. The subtraction processing means 9 calculates the photographing angle.
Draws the same first X-ray projection image and second X-ray projection image
Calculate. As a result, 72 frames with different shooting angles are supported.
A attractions image is created. There is the first shooting system
After taking a picture of the shooting angle, the angle α and the angular velocity
The second imaging system is set to the same imaging angle after a delay time according to
And shoot. The object is manufactured by the injector 27.
Since the contrast agent concentration has changed over time,
Between the first X-ray projection image and the second X-ray projection image
There is a contrast agent concentration difference according to the delay time. Therefore, taking
A first X-ray projection image and a second X-ray projection image having the same shadow angle
By subtracting
Minutes can be extracted. Created by the subtraction processing means 9
The subtraction image of 72 frames is converted to a binarization processing unit.
At 30, binarization is performed. The binarization processing unit 30
Calculate the average pixel value of the
1 for pixels above the threshold and 0 for pixels below the threshold
Assign. As a result, the contrast blood vessel portion has a pixel value of 1,
A binary image having a pixel value of 0 is obtained. The binary image of 72 frames is stored in the image memory 33.
Is stored once. The reconstructing means 34 has a
From the binary image, 3
Reconstruct dimensional data. This 3D data is an image memo
Is temporarily stored in the memory 33. Display image from this 3D data
The display image created by the image creating means 12 is a digital
The information is displayed on the monitor 14 via the log converter 13. Next, the operation of this embodiment will be described. Figure
8 shows the time change of the imaging angle of the first and second imaging systems and the contrast agent injection
The time change of the input is shown. The first imaging system is at time t
During the period from 1 to t4, the imaging angle around the subject is 0 ° to 3 °.
One rotation at 60 °. Is the second imaging system the first imaging system?
From the time t3 to the time t5 with a delay time Δt
One rotation is made around the subject at an imaging angle of 0 ° to 360 °.
The contrast agent is between time t1 and t3, that is, the first imaging system
After passing through 0 °, the second imaging system passes through 0 °.
The injection is started at time t2 between
Continuously during the imaging period while the injection amount is gradually increased
Injected. The first photographing system has a photographing angle of 0 ° to 360 °.
While rotating around the subject P, imaging is repeated at regular intervals
You. As a result, the shooting angle differs by, for example, 5 ° every 72 frames.
First X-ray projection images of the frames are obtained, and these first
The X-ray projection image is transmitted through the analog / digital converter 6
It is sent to the first image memory 31 and stored. Similarly,
The second imaging system rotates the subject P at an imaging angle of 0 ° to 360 °.
The shooting is repeated at regular intervals while rotating the camera. This
The second of 72 frames whose shooting angle differs by 5 ° for example
Are obtained, and these second X-ray projection images are obtained.
Represents the second image via the analog-to-digital converter 26
The data is sent to the memory 32 and stored. First X-ray projection image and second X-ray projection image
Is sent to the subtraction processing means 9. Shooting angle
Are the same as the first X-ray projection image and the second X-ray projection image.
Is calculated. This allows 72 frames with different shooting angles
Is created. When the first photographing system has a photographing angle of, for example, 180 °
, And the second imaging system has the same imaging angle 18
There is a time difference of delay time Δt before shooting at 0 °
You. During this delay time Δt, the contrast injected into the subject
The amount of the drug increases by △ N, and the concentration of the contrast agent at the imaging site is correspondingly increased.
Also increase. Therefore, the first X-ray projection with the same imaging angle is performed.
By subtracting the shadow image and the second X-ray projection image
Therefore, the contrast part is extracted according to this density difference.
You. The data created by the subtraction processing means 9
The subtraction image of 72 frames is converted to a binarization processing unit.
At 30 each is binarized. Threshold for this binarization
Is converted by the binarization processing unit 30 for each subtraction image.
Of pixels. Images above this threshold
Pixels are assigned 1 and pixels below the threshold are assigned 0.
Thus, the contrasted blood vessel portion has a pixel value of 1 and the other portions have a pixel value of 0.
Is obtained. The 72-frame binary image is stored in the image memory 33.
Is stored once. These 72
9 (a) and 9 (b) show the principle from the binary image of the frame.
As shown, the third order of the contrasted blood vessel is obtained by back projection and logical sum processing.
The original data is reconstructed. This 3D data is an image memo
Is temporarily stored in the memory 33. Display image from this 3D data
The display image created by the image creating means 12 is a digital
The information is displayed on the monitor 14 via the log converter 13. What
In this embodiment, since the binarization process is included, the contrast
Although the density information of blood vessels cannot be obtained, the three-dimensional sky
Interim information is obtained. As described above, in this embodiment, the photographing of the mask image is performed.
Since it becomes unnecessary, the photographing time can be shortened. In addition,
This binary subtraction image is back-projected.
By taking the logical sum of the contrast agent, the three-dimensional
3D reconstruction method to identify the optimal position changes the contrast agent concentration
There is no need to limit shooting while the first
Subtract obtained by the X-ray imaging method described in the example
The same processing can be performed by binarizing the
No. At this time, it is desirable that the pitch of the shooting angle is fine
However, when the target blood vessel is one, at least
What is necessary is just to obtain and reconstruct an image in two different directions. Also subject
When there are two or more blood vessels or the target blood vessel is thick,
Using images in at least three directions that do not face each other
Required. (Fourth Embodiment) FIG. 10 shows a main part of an X-ray diagnostic apparatus according to a fourth embodiment.
The structure of the main part is shown, and the same parts as those in FIG.
Description is omitted. The X-ray diagnostic apparatus of the fourth embodiment has a third
As in the embodiment, two imaging systems are provided. FIG.
As shown in (b), the two imaging systems use the center line of each X-ray flux.
So that they intersect at 90 ° + β / 2
Held by the holding mechanism. In addition, as shown in FIG.
When the spread angle of the X-ray flux from 1, 21 is α, β>
β is preferably set to be α. Before imaging, the first image taken by the first imaging system
Are stored in the image memory 41. Imaging
Later, a first X-ray projection image captured by a first imaging system
Are stored in the image memory 42. Before imaging, a second shot
The second X-ray projection image captured by the shadow system is stored in an image memory 4
3 is stored. After contrast, the second image was taken
The second X-ray projection image is stored in the image memory 44. The subtraction processing means 45 has a shooting angle
Subtraction between the two first X-ray projection images before and after contrast with the same degree
Do the calculation. The subtraction processing means 46 determines the shooting angle.
Subtracts between the two second X-ray projection images before and after the same contrast
do. Obtained by the subtraction processing means 45 and 46.
The subtraction image is stored in the
Sent to a three-dimensional reconstruction means (not shown) in the same manner as in the first embodiment.
You. Here, the three-dimensional data of the contrast vessel is reconstructed.
Created from three-dimensional data by display image creation means (not shown)
The displayed image is monitored via a digital-to-analog converter.
Displayed on the screen. Next, the operation of this embodiment will be described. Figure
11 (a) shows the first and second imaging systems (this
Here, the trajectory of the X-ray tube is indicated by a solid line, and a live image after contrast
Trajectories of the first and second imaging systems (here, X-ray tube) during imaging
Is indicated by a dashed line. FIG. 12 shows the photographing of the first photographing system.
The time change of the angle is indicated by a solid line, and the imaging angle of the second imaging system
Is indicated by a one-dot chain line. First, at the time of photographing a mask image, the first and second
Each shooting system has an initial shooting angle (0 °, 90 ° + β / 2)
From 90 ° + β / 2. this
, The imaging angle of the first imaging system is from 0 ° to 90 ° + β
/ 2, and the imaging angle of the second imaging system is 90 ° + β /
It changes from 2 to 180 ° + β. This time t1 to t2
And the first and second photography systems repeat photography,
A plurality of first X-ray projection images, a plurality of second X-ray projection images
Is taken as a mask image. First X as mask image
The line projection image is stored in the image memory 41. Mask image
Is stored in the image memory 43.
Is done. After time t2, at time t3, the contrast medium
Injected into P. The first and second photographing systems are
The shooting angle at the end of the screen image shooting (90 ° + β / 2, 180
° + β), rotate clockwise by 90 ° + β / 2,
Each returns to the initial shooting angle. During this time t4 to t5,
The first and second photographing systems are repeatedly photographed,
Of the first X-ray projection image and a plurality of second X-ray projection images
Photographed as an Eve image (angiographic image). As a live image
All the first X-ray projection images are stored in the image memory 42.
You. The second X-ray projection image as a live image is an image memo
Is stored in the file 44. In this way, rotation by 90 ° + β / 2 is possible.
And the range of 0 ° to 90 ° + β / 2 depending on the first photographing system.
X-ray projection image is obtained, and 90 ° +
X-ray projection image in the range of β / 2 to 180 ° + β is obtained
You. In other words, 0 ° to 180 ° + β
An X-ray projection image of the range will be obtained, and accordingly
By reducing the rotation angle, the shooting time can be reduced.
it can. After contrast recorded in the image memories 42 and 44
Live images are stored in image memory taken from the same shooting angle
It is subtracted from the mask images 41 and 43 before the contrast. Image
The image taken after injection of the contrast agent recorded on the moly 4 is
It is recorded in the image memory 3 and photographed from the same angle.
Subtraction processing with the image before the injection of the contrast agent.
  Multiple subtractions in the range 0 ° -180 ° + β
The image is sent to the three-dimensional reconstruction means, and the three-dimensional reconstruction means
Is an appropriate convolution for subtraction images.
After applying the application filter and back-projecting,
Three-dimensional data of the contrast part is obtained. Three-dimensional data is
A display image is created by the display image creation means. This display
Images are displayed on a monitor via a digital-to-analog converter
Is done. (Fifth Embodiment) FIG. 14 shows a main part of an X-ray diagnostic apparatus according to a fifth embodiment.
The structure of the main part is shown, and the same parts as those in FIG.
The description is omitted. The X-ray diagnostic apparatus of the fifth embodiment includes
As in the third embodiment, two imaging systems are provided. FIG.
As shown in FIG. 5 (b), the two imaging systems have respective X-ray flux centers.
The lines (not shown) intersect at 90 °, that is, perpendicular to each other.
It is held by the rolling support mechanism. At the time of shooting, two shooting systems
Rotates by an angle of 90 ° + β. During this time,
The shooting is repeated. Therefore, the photographing angle is from 90 ° to 9 °.
Between 0 ° and β, both shooting systems shoot at the same shooting angle.
Is performed. In addition, as shown in FIG.
When α is the divergence angle of the X-ray flux from, β> α
Is preferably set as described above. In each of the first and second imaging systems, the imaging angle before contrast
X-ray projection image taken between 90 ° and 90 ° + β
Is sent to the comparison means 51. The comparing means 51 includes first and second
Pixels of two X-ray projection images at the same imaging angle in two imaging systems
Value (pixel values at specific coordinates or pixel value totals)
Compare the two systems so that the sensitivity of both systems is the same.
First and second correction coefficients for each of them are calculated. Correction means
Reference numeral 52 denotes a first photographing system from the image memory 41 before the contrast enhancement.
The captured first X-ray projection image is sent. Correction means 5
2 assigns a first correction coefficient to each pixel of the first X-ray projection image.
The pixel values are corrected by multiplication. Corrected first X-ray
The projection image is stored in the image memory 57 with the shooting angle attributed.
Is done. Similarly, the correction means 53 includes the image memory 43
X-ray projection image taken before imaging with the second imaging system
The image is sent. The correction unit 53 is configured to correct the second X-ray projection image
Correct the pixel value by multiplying each pixel by the second correction coefficient
You. The corrected second X-ray projection image has an imaging angle attribute.
And stored in the image memory 57. The same applies to the first and second imagings after the contrast.
After imaging in each shadow system, the imaging angle is between 90 ° and 90 ° + β
The captured X-ray projection image is sent to the comparing means 54.
The comparing means 54 has two photographing angles of the same in the first and second photographing systems.
Pixel values of two X-ray projection images (pixel values at specific coordinates,
Or the sum of the pixel values), the sensitivity of both shooting systems is the same
The third and fourth correction units for each of the two photographing systems so that
Calculate the number. The correcting means 55
First X-ray projection image captured after imaging with a first imaging system
Is sent. The correction unit 55 is provided for each of the first X-ray projection images.
Correct the pixel value by multiplying the pixel by a third correction coefficient
You. The corrected first X-ray projection image has an imaging angle attribute.
And stored in the image memory 58. Similarly, the correction means 5
6 shows a photograph taken from the image memory 44 by the second photographing system after imaging.
A shadowed second X-ray projection image is sent. Correction means 56
Multiplies each pixel of the second X-ray projection image by a fourth correction coefficient.
Then, the pixel value is corrected. Corrected second X-ray projection
The shadow image is stored in the image memory 58 with the shooting angle attributed.
It is. The subtraction processing means 59 stores an image
X-ray projection images before and after contrast are read from the memories 57 and 58
I will. In the subtraction processing unit 59, before and after imaging
Then, two X-ray projection images with the same shooting angle are subtracted.
You. The subtraction obtained by the subtraction processing means 59
The action image is connected to the previous embodiment via the image memory 47.
Similarly, it is sent to a three-dimensional reconstruction means (not shown). here
Thus, the three-dimensional data of the contrast blood vessel is reconstructed. Not shown
Display created from three-dimensional data by the display image creation means
Images are displayed on a monitor via a digital-to-analog converter
Is done. Next, the operation of this embodiment will be described. Figure
15 (a) shows the first and second photographing systems (this
Here, the trajectory of the X-ray tube is indicated by a solid line, and a live image after contrast
Trajectories of the first and second imaging systems (here, X-ray tube) during imaging
Is indicated by a dashed line. FIG. 16 shows the photographing of the first photographing system.
The time change of the angle is indicated by a solid line, and the imaging angle of the second imaging system
Is indicated by a one-dot chain line. First, at the time of taking a mask image, the first and second
The shooting system starts from the initial shooting angle (0 °, 90 °),
Rotate 90 ° + β counterclockwise. Thereby, the first
The shooting angle of the shooting system changes from 0 ° to 90 ° + β,
The shooting angle of shooting system 2 changes from 90 ° to 180 ° + β
I do. Between the times t1 and t2, the first and second imaging systems
Is repeated, and each of the plurality of first X-ray projection images is
Image and a plurality of second X-ray projection images as a mask image.
You. The first X-ray projection image as a mask image is an image memo.
Is stored in the memory 41. Second X-ray projection as mask image
The image is stored in the image memory 43. After time t2, at time t3, the contrast medium
Injected into P. The first and second photographing systems are
Shooting angle (90 ° + β, 180 ° +
β), rotate clockwise by 90 ° + β, each initial
Return to the shooting angle. During this time t4 to t5, the first and
The photographing is repeated with both photographing systems, and a plurality of first
X-ray projection images, live images of multiple second X-ray projection images
(Angiographic image). No. as a live image
The one X-ray projection image is stored in the image memory 42. La
The second X-ray projection image as the Eve image is stored in an image memory 44
Is stored in Rotating by 90 ° + β in this way
X-rays in the range of 0 ° to 90 ° + β by the first imaging system
A projection image is obtained, and 90 ° to 180 °
An X-ray projection image in the range of ° + β is obtained. That is,
90 ° to 90 ° + during shooting of live images and live images
X-ray projection images of the same shooting angle in both shooting systems in the range of β
Is obtained. The same applies in the range of the photographing angle 90 ° to 90 ° + β.
Whether the mask image taken at the same shooting angle is the first or second shooting system
Are sent to the comparing means 51 at least one by one. Comparison hand
The step 51 allows the first and second photographing systems to have the same photographing angle of two.
Pixel values of two mask images (pixel values at specific coordinates, or
(Total pixel values) are compared, and the sensitivity of both
First and second correction coefficients for each of the two photographing systems.
Is calculated. For example, the first correction coefficient 0.9, the second correction coefficient
A positive coefficient of 1.0 is calculated. The correction means 52 includes the image memory 41
The first mask image taken before imaging by the first imaging system is sent
It is. The correcting means 52 applies the first pixel to each pixel of the first mask image.
To correct the pixel value. Amended
The first mask image is attributed to the shooting angle and stored in the image memory 5.
7 is stored. Similarly, the correction means 53 includes an image memo.
From the camera 43 before the imaging with the second imaging system.
A disk image is sent. The correction unit 53 is configured to correct the second mask image.
Correct the pixel value by multiplying each pixel by the second correction coefficient
You. The corrected second mask image is attributed to the shooting angle.
It is stored in the image memory 57. Similarly, the range of the photographing angle 90 ° to 90 ° + β
Live images taken at the same shooting angle
At least one image from the photographing system is sent to the comparing means 54 at a time.
You. The same photographing is performed by the comparing means 54 in the first and second photographing systems.
The pixel values of the two live images at the shadow angle (the pixel values of the specific coordinates are the same)
And total pixel values) are compared, and the
Third and fourth for each of the two photographing systems so that the degree is the same
Is calculated. For example, the third correction coefficient 0.
9. The fourth correction coefficient 1.0 is calculated. The correction means 55 includes a
The first live image taken after imaging with the first imaging system is sent
It is. The correcting means 55 adds a third pixel to each pixel of the first live image.
To correct the pixel value. Amended
The first live image is stored in an image memory
8 is stored. Similarly, the correction means 56 includes an image memo.
A second laser taken after imaging with the second imaging system from
An Eve image is sent. The correction means 56 is provided for the second live image.
The pixel value is corrected by multiplying each pixel by a fourth correction coefficient.
You. The corrected second live image is attributed to the shooting angle
It is stored in the image memory 58. The post-contrast line recorded in the image memory 57
Image is stored in the image memory 58 photographed from the same photographing angle.
The mask image before contrast is subtracted. This allows the shooting angle
Multiple subtraction images from 0 ° to 180 ° + β
It is created and stored in the image memory 47. Multiple sub
The traction image is sent to the three-dimensional reconstruction means,
In the reconstruction means, appropriate subtraction
Backprojection after applying a convolution filter
Thus, three-dimensional data of the contrast portion of the subject is obtained. 3rd order
The original data is created by the display image creation means.
You. This display image is passed through a digital-to-analog converter.
Displayed on the monitor. In this embodiment, the photographing time is set as in the fourth embodiment.
In addition to shortening the sensitivity, the sensitivity between the two
Non-uniformity can be corrected. (Sixth Embodiment) FIG. 17 shows the structure of an X-ray diagnostic apparatus according to a sixth embodiment.
The same reference numerals are given to the same parts as in FIG.
Abbreviate. The X-ray diagnostic apparatus of the sixth embodiment has the configuration of FIG.
Subtraction processing means 9 and three-dimensional reconstruction means 10
Image memory 60, data correction means 61, image memo
This is a configuration in which a ridge 62 is added. Data correction means 61
Is an example of correcting the subtraction image manually
For example, processing such as removing unnecessary portions is executed. example
For example, to continuously inject the contrast agent for a relatively long time,
In the latter half of the image, the contrast agent may flow into the veins.
You. The purpose is to remove this contrasted vein
ing. The data correcting means 61 is as shown in FIG.
In addition, the subtraction image and the corrected subtraction
Image memory 69 for temporarily storing the
Display device 67 for displaying traction image, subtract
Enter coordinates to specify the part of the image to be removed.
Removal specified via force device 68, coordinate input device 68
CPU 6 that removes the part, that is, converts it to the same 0 value as the background
6 are connected to a data / control bus 65. The image memory 60 has sub-images for all shooting angles.
A traction image is stored. Subtract one by one
The modification image is sent to the data correction means 61 and the display device
67 is displayed. As shown in FIG. 19, the operator displays
Observe the image and enter the coordinates where the unwanted object is shown
For example, it is designated by a rectangular ROI via the device 68. Square
All pixel values in the ROI are replaced with the same 0 value as the background.
It is. Such correction work is necessary as shown in FIG.
Is performed on the correct subtraction image, and
And the unmodified subtraction image are stored in the image memory 62.
It is sent to the three-dimensional reconstruction means 10 via the Three-dimensional
The structuring means 10 applies an appropriate
After applying a convolution filter,
Thus, three-dimensional data of the contrast agent portion of the subject is obtained. As described above, unnecessary portions are eliminated before the reconstruction.
To save labor in the reconstruction process,
Only above mentioned arches due to the presence of contrast veins
The occurrence of a fact can be prevented. Also,
Correct processing is to correct the subtraction image
Is possible. Because the X-ray whose pixel value after correction is unknown
The projection image (shade image) cannot be corrected. (Seventh Embodiment) FIG. 21 shows a main part of an X-ray diagnostic apparatus according to a seventh embodiment.
The configuration of the main part is shown, and the same parts as those in FIG.
The description is omitted. At a certain shooting angle in the reconstruction process
The captured blood vessel part cannot be captured at another imaging angle.
When the subject is out of the reconstruction area
Cause artifacts in the reconstruction results
I will. In the seventh embodiment, the generation of this kind of artifact
Is to prevent. The X-ray diagnostic apparatus according to the seventh embodiment includes:
An image memory 60 and a data correction unit 61 are added to the configuration of FIG.
Between the reconstruction area outside data determination means 72 and the reconstruction
The data correction unit 6 outputs the
Switch 73 for selectively connecting 1 to image memory 62
Is added. FIG. 22 shows the out-of-reconstruction-area data determining means 72.
Is shown in a flowchart. Reconstruction
In step S1, the out-of-area data determination unit 72 determines whether the image
One subtraction image is captured from the memory 60.
In step S2, the peripheral area of the subtraction image
To determine. The input window of the image intensifier
In FIG. 23, the circular subtraction image is hatched.
A peripheral area having a width of one pixel is determined as indicated by. Next, in step S3, the subject (contrast
To determine the pixels where the tube is visible and the pixels where it is not
Is determined. Judgment target is subtraction image
Because it is an image, here it is fixed at 0 value or 0 approximation.
However, for example, the average value of all pixel values of the subtraction image
May be calculated as a reference value. Next,
In step S4, the peripheral pixels of the subtraction image are sequentially
Compare with the reference value. When all peripheral pixels of the subtraction image are
When the value is below the reference value, that is,
All images in the configuration image are within the reconstruction area.
When the subtraction image is
Then, it is sent to the image memory 62 without correction. On the other hand,
At least one peripheral pixel of the traction image has a reference value.
When it exceeds, that is, in the subtraction image
When it is determined that there is an image outside the reconstruction area in
The data of the subtraction image is modified via the switch 73.
It is sent to the corrector 61. That is, there is an image outside the reconstruction area.
Only the subtraction images determined to be
Sent to the correction means 61 to prompt the operator to remove the image.
Can be. Here, the removal surrounded by the dotted line in FIG.
The removal of the blood vessel image to be performed is performed manually by the data correction means 61.
It is done in le. As described above, the image memory 62 is stored outside the reconstruction area.
Maintains subtraction images of all angles where no image exists
Is done. Thus, in this embodiment, the source of the artifact is
The presence or absence of an image outside the reconstruction area that causes the
Can be prompted to the operator. The present invention has been described above.
The present invention is not limited to the embodiment and can be implemented in various modifications.
You. [0067] The present inventionAccording to
Part of the subject is removed by subtraction.
Light artifacts due to the part of the subject
Can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a first embodiment. FIG. 2 is an operation explanatory diagram of the first embodiment. FIG. 3 is a processing outline diagram of the first embodiment. FIG. 4 is a configuration diagram of a second embodiment. FIG. 5 is a diagram showing a removal area. FIG. 6 is a configuration diagram of a third embodiment. FIG. 7 is a diagram showing a rotation trajectory of first and second imaging systems. FIG. 8 is an operation explanatory diagram of the third embodiment. FIG. 9 is a principle diagram of three-dimensional reconstruction. FIG. 10 is a configuration diagram of a main part of a fourth embodiment. FIG. 11 is a diagram showing a rotation trajectory of first and second imaging systems. FIG. 12 is an operation explanatory diagram of the fourth embodiment. FIG. 13 is a diagram showing a spread angle of an X-ray flux. FIG. 14 is a configuration diagram of a main part of a fifth embodiment. FIG. 15 is a diagram illustrating a rotation trajectory of first and second imaging systems. FIG. 16 is an operation explanatory view of the fifth embodiment. FIG. 17 is a configuration diagram of a sixth embodiment. FIG. 18 is a configuration diagram of data correction means of FIG. 17; FIG. 19 is a conceptual diagram of data correction. FIG. 20 is a schematic processing diagram of the sixth embodiment. FIG. 21 is a configuration diagram of a main part of a seventh embodiment. FIG. 22 is a flowchart showing the processing procedure of the data outside the reconstruction area determination unit in FIG. 21; FIG. 23 is a diagram showing a peripheral area. FIG. 24 is an explanatory diagram of one problem in the related art. [Description of Signs] 1 ... X-ray tube, 2 ... Image intensifier, 3 ... High voltage generator,
4 X-ray controller, 5 TV camera,
6 ... analog-digital converter, 7, 8, 11 ... image memory, 9 ... subtraction processing means, 10
... three-dimensional reconstruction means, 12 ... display image creation means, 13 ... digital-analog converter, 14 ... monitor.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Unkun Nakatani 1385-1, Shimoishigami, Otawara City, Tochigi Prefecture, Ltd. Inside the Toshiba Nasu Plant (72) Dr. Nakayama Inventor Dr. Nakayama 1385-1, Shimoishigami, Otawara City, Tochigi Prefecture Stock Company Inside the Toshiba Nasu Plant (72) Inventor Masahiro Ozawa 1385-1, Shimoishigami, Otawara City, Tochigi Prefecture 1 Stock Company Inside the Toshiba Nasu Plant (72) Kunitoshi Matsumoto 1385-1, Shimoishigami, Otawara City, Tochigi Prefecture Toshiba Nasu Plant Company (56) References JP-A-60-220045 (JP, A) JP-A-6-38957 (JP, A) JP-A-62-186374 (JP, A) JP-A-2-230479 (JP, A) JP-A-6-83940 (JP, A) JP-A-56-137145 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 6/00-6/14

Claims (1)

(57) [Claims 1] A conical X-ray flux in all directions of an X-ray tube
Inject contrast into the reconstruction area defined as the inscribed sphere
Means for holding data of a plurality of first X-ray projection images photographed from a plurality of photographing angles in a state where the contrast portion in the entered subject fits in and a part of the subject protrudes from the reconstruction area; Means for holding data of a plurality of second X-ray projection images photographed before imaging from the same plurality of imaging angles as the plurality of first X-ray projection images; and data of the first X-ray projection image and the second X-ray Means for generating, for each imaging angle, a subtraction image in which shadows of contrast-enhanced blood vessels in the reconstruction region are extracted by subtracting the data of the projection image between the same imaging angles, and from the subtraction image. Means for reconstructing three-dimensional data related to the contrast-enhanced blood vessel.