JP4740348B2 - X-ray diagnostic equipment - Google Patents

Description

The present invention relates to an X-ray diagnostic apparatus for supporting, for example, catheter examination or treatment using a catheter.

Conventionally, for example, when treating an aneurysm, it is surgically open to reach the affected area, and the aneurysm neck is clipped to prevent blood from flowing into the aneurysm. Treatment has been carried out. However, in recent years IVR (Interventional Radiolo
A very less invasive therapy such as gy) has been developed. For example, a treatment method for an aneurysm will be briefly described. First, a contrast image taken by angiography is displayed as a road map, and a catheter inserted from the base of the foot, for example, under the fluoroscopy using the image as a guide, is used. Then, an occlusive substance 200 such as a coil is placed in the aneurysm from the distal end of the catheter as shown in FIG.

This placement treats the blood flow in the aneurysm, thereby treating the blood by coagulating the blood in the aneurysm. At this time, since it is necessary to grasp the three-dimensional structure of the aneurysm in order to determine the appropriate diameter of the coil to be placed, the rotation DSA (Digital Subtractio)
n Angiography) may be performed. Similarly, in order to confirm the therapeutic effect three-dimensionally, rotational DSA may be performed after the placement of the occlusive substance. In such a case, generally, even in the rotation DSA after the placement of the occluding substance, an image of the same region as the visual field area at the time of the rotation DSA before the placement of the occluding substance is taken.
International Publication No. 99/1066 JP-A-8-280657

However, in complex cerebral blood vessels, it is difficult to identify the target blood vessel due to overlapping blood vessels, or there is no information in the depth direction, so the catheter cannot be operated properly, and it takes a lot of time to reach the lesion. There was a problem. You can also find the best angle with few overlapping blood vessels,
In order to obtain depth information, imaging from multiple directions is indispensable, and there is a problem of increasing the exposure dose of the subject.

In the treatment using the catheter, for example, whether or not the aneurysm is appropriately placed by the occlusive substance 200 is confirmed by rotating DSA or the like, but there is a change in the rotating DSA images before and after placement. In the case of an aneurysm due to an occlusive substance, an image of the same area as the visual field area at the time of rotation DSA before placement was taken even during rotation DSA after placement. There was a problem of giving unnecessary exposure to these parts.

The present invention has been made in view of the above-described problems, and facilitates the grasping of the blood vessel structure in the vicinity of the target site, thereby facilitating the catheter operation and shortening the catheter examination time and the treatment time using the catheter. An object of the present invention is to provide an X-ray diagnostic apparatus capable of reducing the exposure of a subject through shortening of examination time and treatment time.

It is another object of the present invention to provide an X-ray diagnostic apparatus that can reduce useless exposure during rotation DSA after treatment.

An X-ray diagnostic apparatus according to the present invention includes a bed on which a subject is placed, X-ray generation means for exposing X-rays to the subject placed on the bed, and the X-ray generation means. X-ray shielding means for adjusting the X-ray exposure area by shielding X-rays exposed to the subject, and X-rays from the X-ray generation means to the subject via the X-ray shielding means In an X-ray diagnostic apparatus comprising: an X-ray detection means for capturing an X-ray image formed by exposure to X-rays; an X-ray generation means; and a mechanism for rotating the X-ray detection means. A three-dimensional image obtained by reconstructing a mask image taken for the subject before injecting the contrast agent and a live image taken for the subject after injecting the contrast agent by the X-ray detection means Attention area setting means for setting an attention area based on an image, and the mechanism The X-ray shielding unit is rotated so that the X-ray shielding unit rotates the X-ray generation unit and the X-ray detection unit, and X-rays are exposed only to a portion of the subject corresponding to the target region set by the target region setting unit. Control means for controlling, and reconstruction means for forming a reconstructed image by performing reconstruction processing based on the X-ray image captured by the X-ray detection means.

The X-ray diagnostic apparatus according to the present invention limits an X-ray exposure region so that X-rays are only exposed to a portion of a subject corresponding to a region of interest during rotational imaging for obtaining a reconstructed image. Thus, useless exposure of the subject can be reduced.

1 is a block diagram of an X-ray diagnostic apparatus for a circulatory organ that is a first embodiment of an X-ray diagnostic apparatus according to the present invention. It is a figure which shows a mode that X-ray exposure is performed only to the site | part corresponding to ROI in the X-ray diagnostic apparatus of the said 1st Embodiment. It is a figure for demonstrating the distortion correction process at the time of providing an image intensifier as a X-ray detection means. It is a figure which shows a mode that it controls so that the center of ROI may be located in the center of an X-ray flat panel detector in all the imaging angles in the modification 1 of 1st Embodiment. FIG. 11 is a block diagram of an X-ray diagnostic apparatus that forms a reconstructed image for ROI setting by reducing a subtraction image in Modification 2 of the first embodiment. FIG. 10 is a block diagram of an X-ray diagnostic apparatus that performs ROI setting based on two or more images captured from different imaging angles in Modification 3 of the first embodiment. It is a figure for demonstrating a mode that ROI is set based on the 2 or more image image | photographed from the different imaging | photography angle in the X-ray diagnostic apparatus of the modification 3 of 1st Embodiment. It is a block diagram of the X-ray diagnostic apparatus for circulatory organs which becomes 2nd Embodiment of the X-ray diagnostic apparatus of this invention. It is a block diagram of the X-ray diagnostic apparatus which becomes 3rd Embodiment of the X-ray diagnostic apparatus of this invention. It is a block diagram of the X-ray diagnostic apparatus of the biplane structure used as the modification 1 of 3rd Embodiment. It is a figure which shows the occlusive substance indwelled in an aneurysm from the front-end | tip of a catheter in catheter treatment.

Hereinafter, preferred embodiments of an X-ray diagnostic apparatus according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
The X-ray diagnostic apparatus according to the present invention can be applied to a circulatory X-ray diagnostic apparatus as shown in FIG. The X-ray diagnostic apparatus according to the first embodiment of the present invention includes an imaging unit 1 that performs X-ray imaging, and an A / D that digitizes a captured image supplied as analog information from the imaging unit 1.
A converter 2, a shooting condition memory 3 that stores shooting conditions from the shooting unit 1, a subtraction unit 4 that performs subtraction processing on collected images obtained in different shooting sequences, and image reconstruction processing based on the subtraction image. An image reconstructing unit 5 to perform, an image memory 6 for storing the collected image and the reconstructed image, a comparison processing unit 7 for processing two or more reconstructed images so as to be easily compared, and the comparison processed image A D / A converter 9 which is converted into an analog signal and supplied to the display unit 8.

In addition, this X-ray diagnostic apparatus is based on the reconstructed image formed by the image reconstruction unit 5.
A stereoscopic image creation unit 15 that forms an image of a three-dimensional imaging region, a region of interest determination unit 10 (ROI determination unit) that determines a region of interest using an image displayed on the display unit 8, and a region of interest A diaphragm / bed operation determining unit 11 that determines the optimum diaphragm and bed movement based on the movement and controls the movement of the diaphragm and bed is provided.

The imaging condition memory 3 stores imaging conditions such as patient name, patient ID, imaging date and time, imaging angle, imaging mode (detector field of view size), tube voltage, tube current, pulse width, and the like. It has become.

The image reconstruction unit 5 performs image reconstruction by a filtered back projection method with weight correction proposed by, for example, Feldkamp and the like, and information such as a photographing angle and a photographing mode obtained from the photographing condition memory 3 The image reconstruction process is performed based on the above.

The imaging unit 1 has a rotating arm 14 having a substantially C-shape. This rotating arm 14
The X-ray generator 12 and the X-ray flat detector 13 are provided at opposite ends of the two so as to face each other. The X-ray flat panel detector 13 converts X-rays into light by an X-ray-light converting member, and converts this light into an electrical signal (imaging signal) by the light-electric converting member, thereby depending on the X-ray dose. A shooting signal is formed.

The rotating arm 14 can move along the shape direction of the arm, and can also rotate in a direction perpendicular to the moving direction. In general, the former rotation is called slide rotation, and the latter rotation is called main rotation. Shooting (rotating shooting) is performed while performing the rotational movement of the arm that combines either the slide rotation or the main rotation, or both. Then, rotating DA (Digital Angiogram), which is imaging while injecting a contrast medium.
phy), and rotation DSA (Digital Subtraction Angi) that performs imaging before and after the contrast agent and performs subtraction of the images before and after that to obtain an enhanced image of only the blood vessel
ography).

In addition, as the imaging unit 1, a so-called X-ray CT apparatus may be provided in which the imaging is performed while the X-ray tube and the X-ray detector are rotating inside the gantry rotating unit (gantry). Good.

The X-ray diagnostic apparatus includes a distance between the X-ray focal point of the X-ray generation unit 12 and the X-ray flat panel detector 13, a distance between the X-ray focal point and the subject, and a size of the X-ray flat panel detector 13. A plurality of three-dimensional images are projected in accordance with the observation angle by the X-ray optical system determined by.

Next, the operation of the X-ray diagnostic apparatus according to the first embodiment having such a configuration will be described.

First, in the X-ray diagnostic apparatus according to the first embodiment, the rotation DS before the placement of the occluding substance is performed.
A blood vessel and aneurysm image are reconstructed from the A image. Specifically, the imaging unit 1 performs rotational imaging before and after contrasting, and collects 360 degrees of rotated DSA images, for example, by 3 degrees, thereby obtaining 120 patterns of projection data. The projection data is A / D converted by the A / D converter 2 and stored in the image memory 6.

The subtraction unit 4 performs subtraction between the images having the same imaging angle among the pre-contrast images stored in the image memory 6 and supplies the subtraction image to the image reconstruction unit 5. When the subtraction image is supplied, the image reconstruction unit 5 reads the corresponding shooting condition from the shooting condition memory 3, and displays the SID (distance from the tube focus to the detector), the shooting mode, the shooting angle, and the like. Use this to perform image reconstruction processing.

That is, the reconstruction area is defined as a cylinder inscribed in the X-ray flux in all directions exposed from the X-ray generator 12. The inside of this cylinder is discretized three-dimensionally with a length d at the center of the reconstruction area projected onto the width of one detection element of the X-ray flat panel detector 13, for example, and a reconstruction image of data at discrete points is obtained. Need to get. However, although an example of the discrete interval is shown here, this may differ depending on the device or manufacturer, so basically, the discrete interval defined by the device may be used. As an example of the reconstruction method, the Feldkamp method is shown here. For example, a Shepp & Logan or Ramachandra is applied to a 120-frame subtraction image.
After applying a suitable convolution filter such as n, a three-dimensional backprojection operation is performed while multiplying a coefficient for correcting the three-dimensional spread of the beam. Reconstructed image (1)) is formed. The reconstructed image (1) is temporarily stored in the image memory 6 and supplied to the stereoscopic image creating unit 15.

Next, when the reconstructed image is supplied from the image memory 6, the stereoscopic image creating unit 15 extracts the surface shape of the blood vessel or aneurysm by threshold processing, and then performs a shadow based on the surface shape and depth information. A three-dimensional image (image that appears three-dimensionally) of blood vessels and aneurysms observed from an arbitrary direction is formed, and this is converted into, for example, a CRT (cathode ray tube) or LED (liquid crystal) via a D / A converter 9. To the display unit 8 such as a display unit). As a result, stereoscopic images of blood vessels and aneurysms observed from an arbitrary direction are displayed on the display unit 8.

Although an example using surface rendering as a stereoscopic display method is shown here, the present invention is not limited to this, and other stereoscopic display methods such as volume rendering may be used.

Next, the region of interest (RO) including the aneurysm is displayed on the blood vessel and aneurysm image displayed on the display unit 8.
The ROI determination unit 10 performs the determination of I). The ROI determination unit 10 is configured by an input device such as a mouse device, a trackball, or a keyboard, for example, and sets the ROI by designating the center position and radius of the ROI.

Specifically, first, for example, a position that is considered to be the center of the aneurysm is indicated by a mouse device. From the indicated position, a straight line formula is obtained in a direction perpendicular to the image. A search for a three-dimensional image is performed while sequentially moving the pixel width along the straight line, and the coordinates A of the position exceeding the threshold value are first stored. Then, the search is further continued, the coordinates B of the position below the threshold value are stored, and the midpoint of the positions of the points A and B is set as the center of the aneurysm.

Note that the method for obtaining the center of the aneurysm is not limited to this method. For example, after obtaining a straight line expression in a direction perpendicular to the image from the position indicated by the mouse device, the same processing is performed for an image observed from another angle. The intersection of the obtained straight lines (in reality, the midpoint between the closest points of the straight lines) may be obtained as the center of the aneurysm. The radius may be input from a keyboard, or a circle indicating an ROI drawn on an image may be enlarged or reduced with a mouse. Here, the ROI is considered as a sphere, but an ROI having a shape other than this may be used. Furthermore, the display color of the part in the ROI may be changed, the display density may be reversed, or dots and stripes may be pasted and displayed. As a result, the set ROI range can be easily recognized. When the ROI is set in this way, the ROI determining unit 10 narrows down the information (center and radius) of the ROI and the bed operation determining unit 11.
To supply.

Next, when the information on the ROI is supplied, the aperture / bed motion determination unit 11 is configured so that X-rays are exposed only to the part of the subject corresponding to the ROI at an arbitrary imaging angle based on the information. X-ray shielding part (pre-collimator: hereinafter simply referred to as “aperture”) provided in the X-ray generation part 12.
To control.

For example, referring to the example of FIG. 2, in the rotation DSA before the placement of the occlusive substance, the diaphragm 16 is hardly closed so that the entire blood vessel and aneurysm are imaged as shown in FIG. But RO
When the ROI as shown in FIG. 2B is set by the I determining unit 10, the diaphragm 16 is narrowed so that the X-ray flux circumscribes the spherical ROI. Data indicating the diaphragm operation determined in this way is supplied to the imaging unit 1 and used at the time of rotational imaging after occlusion substance placement described below.

Next, imaging after placement of an occlusive substance will be described. After placement of the occlusive substance, the imaging unit 1 performs rotational imaging again before and after contrasting to obtain 120 patterns of projection data. At the time of this photographing, based on the data indicating the diaphragm operation from the diaphragm / bed operation determining unit 11, FIG.
As shown in FIG. 4, rotational imaging is performed while closing the diaphragm 16 so that X-rays are only exposed to the ROI. The projection data obtained by this photographing is A / D converted and stored in the image memory 6.

The subtraction unit 4 performs subtraction between images having the same imaging angle among the pre-contrast images stored in the image memory 6 and supplies the subtraction image to the image reconstruction unit 5. However, the subtraction is performed only in the ROI projection area. The other areas are treated as having no value. However, if the blood vessel has spread in the direction perpendicular to the rotation axis and as a result projected from the ROI, the value of the contrast image before placement of the occluding substance may be placed outside the ROI projection area.

The set of photographed images supplied to the subtraction unit 4 is initially a live image and a mask image before and after placement of the occluding substance. Based on these subtraction images, the image reconstruction unit 5 forms a reconstructed image of only ROI as described above. As a result, an aneurysm image with reduced blood vessels and blood flow (hereinafter, this aneurysm image is referred to as a reconstructed image (2)) is reconstructed. This reconstructed image (2) is temporarily stored in the image memory 6.

The set of photographed images supplied to the subtraction unit 4 next is a mask image after placement of the occluding substance and a mask image before placement. Based on these subtraction images, the image reconstruction unit 5 forms a reconstructed image of only ROI as described above. As a result, an image showing the distribution of the occluding substance (hereinafter, an image showing the distribution of the occluding substance is referred to as a reconstructed image (3)) is reconstructed. This reconstructed image (3) is also temporarily stored in the image memory 6.

Next, the operation of the comparison processing unit 7 will be described. First, reconstructed images to be compared are selected using an input device such as a keyboard. For example, assuming that the reconstructed image (1) and the reconstructed image (2) are selected, the three-dimensional image creation unit 15 determines from various directions based on the reconstructed image (1) and the reconstructed image (2). An observed three-dimensional stereoscopic image is formed and supplied to the comparison processing unit 7.

The comparison processing unit 7 supplies the two sets of stereoscopic images from the stereoscopic image creation unit 15 to the display unit 8 via the D / A converter 9 and displays them side by side. By observing the arranged three-dimensional images, the examiner can grasp the change in blood flow before and after placement of the occlusive substance.

When each stereoscopic image is displayed on the display unit 8, the stereoscopic image of the reconstructed image (1) may be displayed in one display area, and the stereoscopic image of the reconstructed image (2) may be displayed in the same area. . This
Changes in two images can be observed with a small display area.

Alternatively, the three-dimensional image of the reconstructed image (1) and the three-dimensional image of the reconstructed image (2) may be displayed in different colors. Thereby, the change of both images can be made easier to understand. Also,
At this time, the overlapping part of the stereoscopic image of the reconstructed image (1) and the stereoscopic image of the reconstructed image (2) may be displayed at the same time, or one of the stereoscopic images may be displayed with priority. good. This priority image switching can be easily performed by instructing by the input device (in this case, it is preferable that the stereoscopic image of the reconstructed image (2) is displayed with priority).

In addition, when a stereoscopic image is formed by the stereoscopic image creation unit 7, not only information resulting from the structure but also density information thereof may be displayed simultaneously. Thereby, the change of both images can be made easier to understand. For example, the information resulting from the structure is displayed with luminance as before, and the density information is displayed in color, so that both pieces of information can be grasped at once.

Furthermore, when displaying at least two sets of three-dimensional images formed by the three-dimensional image creation unit 7, the images may be displayed in an angle-synchronized manner. Thereby, each stereoscopic image can be observed at the same angle.

Next, a case where the reconstructed image (1) and the reconstructed image (3) are selected will be described. Based on the reconstructed image (1) and the reconstructed image (3), the stereoscopic image creating unit 15 forms a stereoscopic image observed from various directions, and supplies these to the comparison processing unit 7.

The comparison processing unit 7 combines the three-dimensional images of the reconstructed image (1) and the reconstructed image (3) into one,
This composite image is supplied to the display unit 8 via the D / A converter 9. At this time, the three-dimensional image creation unit 15 uses the center coordinates of the ROI obtained by the ROI determination unit 10 to obtain a plane perpendicular to the observation direction and passing through the center coordinates, and data in front of the plane. Erase. As a result, as shown in FIG. 11, the state of the occluding substance occupying the aneurysm can be observed from all directions, facilitating the effect of the occluding operation and selection of the occluding substance when performing the occluding substance placement again. can do.

Note that when only the reconstructed image (1) and the reconstructed image (3) are to be compared, it is not necessary to take a live image after placement of the occluding substance.

Here, in the description of this embodiment, the X-ray flat detector 13 is provided as the X-ray detection means, but this may be provided with an image intensifier (II). This I.I. I. Converts X-rays into light, optically expands and reduces the distribution of the converted light,
The light distribution is converted into an analog signal by photographing with a V camera. This I.I. I. Even if provided, the same effect as described above can be obtained.

However, this I.D. I. Is provided, a distortion correction unit 18 is required as indicated by a dotted line after the subtraction unit 4 in FIG. That is, I.I. I. The image collected in (1) is distorted as shown in FIG. 3A when a mesh pattern composed of a square lattice is photographed. This is mainly due to I.D. I. This is because the shape of the X-ray detection surface is spherical and the image is distorted into a pincushion shape. This is also due to the occurrence of S-shaped distortion due to the bending of the electron beam trajectory due to the influence of magnetism such as geomagnetism.

The corrected images corresponding to arbitrary position coordinates (i _d , j _d ) in FIG. 3A should be arranged two-dimensionally from the center at regular intervals. Therefore, the position coordinates of the corrected image are (i
, J). (I _d , j _d ) and (i, j) indicate image coordinates on the acquired image and on the image with corrected distortion, respectively. For image coordinates, the upper left corner of the image is the origin, and the upper right corner is (N
−1, 0), the upper left is (0, N−1), and the lower right is (N−1, N−1). N
Represents the matrix size of the image, generally N = 512 or 1024 [pi ×
el]. I. I. Image distortion correction is achieved by substituting the (i, j) data on the corrected image into the (i _d , j _d ) data value on the collected image.

(I, j) and (i _d , j _d ) are related to the installation location of the apparatus, the shooting angle, the SID, the I.D.
I. Determined by size. Even if these conditions are exactly the same, these relationships are related to I.D. I.
Depending on the details, it will be different. Therefore, I. I. Therefore, it is necessary to grasp in advance the relationship between (i, j) and (i _d , j _d ) under each condition. In general, this is determined experimentally.

For example, a grid of grids I. After being attached to the front surface, a grid is photographed for each angle required for the inspection, and the position of the lattice point (intersection of wire and wire) is obtained from the grid projection image. Since these lattice points should be two-dimensionally arranged at regular intervals on the image if there is no original distortion, the lattice points are rearranged every known lattice point interval centered on the lattice point closest to the image center. Then, the image distortion is corrected. In addition, the positions of points other than the lattice points can be obtained approximately based on the positions of surrounding lattice points surrounding the points. The distortion correction unit performs such an operation for each shooting angle. By providing such a distortion correction unit 18, I.D. I
. Even when using, a display image without distortion can be obtained, and an accurate observation of a treatment site or the like can be performed.

In the first embodiment, an example in which a diaphragm is used as a means for shielding X-rays has been described. However, this may be a wedge filter that partially attenuates the X-ray distribution. Good.

[Modification 1 of the first embodiment]
After setting the ROI in the ROI determining unit 10, the diaphragm / bed operation determining unit 11 instructs to move not only the diaphragm 16 but also the bed or the photographing unit 1, and the ROI center P is set as shown in FIG. You may control so that it may be located in the center O of the X-ray plane detector 13 with every imaging | photography angle. In this case, since the control of the diaphragm 16 is symmetrical left and right with respect to the center O of the X-ray flat detector 13, the control of the diaphragm 16 can be facilitated.

In addition, the subtraction unit 4 temporarily subtracts each image and forms a stereoscopic image based on the subtraction image. However, before the subtraction process, each stereoscopic image is formed, You may make it perform a subtraction process between stereo images. That is, a three-dimensional image is separately reconstructed from the mask images before and after the change, and the reconstructed images are subjected to subtraction processing to form a reconstructed image of only “indwelling substance”, for example.

[Modification 2 of the first embodiment]
In the first embodiment described above, the ROI is set based on the reconstructed image.
It takes a lot of time to obtain a reconstructed image. For example, even when a device dedicated to reconstruction is used, 256 × 256 × 256 [pi × el ³ ] Takes about 6 minutes. If the collected image resolution is 1024 × 1024 [pi × el ² ] Or 2048 × 2048 [pi
Xel ² ] 1024 × 1024 × 1024 [pi × el ³
] Or 2048 × 2048 × 2048 [pi × el ³ ] Is obtained with an apparatus having the same reconstruction speed, 384 minutes (6.4 hours) or 3072 minutes (
51.2 hours). In addition, 512 × 512 [pi × el ² ] 512 × 512 × 512 [pi × el ³ ], It takes 48 minutes to obtain a reconstructed image. This is not practical because it is too long compared to the time from the end of imaging before placing the occlusive substance to the time when rotational imaging is performed again after placing the occluding substance.

Therefore, as shown in FIG. 5, an image reduction unit 20 is provided in the subsequent stage of the subtraction unit 4, and this image reduction unit 20 enables distortion correction from the subtraction image (or distortion correction unit 18) in image reconstruction before the occlusion substance placement. Image) is reduced, and the image reconstruction unit 5 performs image reconstruction processing based on the reduced image obtained by the reduction processing. For example, 1024 × 1024 [pi × el
² ] 256 × 256 [pi × el ² ] Or 128 × 128 [pi × el ²
The image reconstruction unit 5 performs image reconstruction processing based on the reduced data.

As a result, the processing that should be performed by the X-ray diagnostic apparatus after the imaging before the placement of the occlusive substance is completed and before the rotational imaging is performed again after the occluding substance is placed can be greatly reduced. Therefore, before the rotational imaging is performed again, the X-ray diagnostic apparatus can complete the determination up to the diaphragm / bed operation.

This reduction process reduces the resolution of the image observed when setting the ROI.
When setting this ROI, it is sufficient to know only the approximate position and size of the aneurysm, so a reconstructed image formed from a reduced image is sufficient. Instead, it is necessary to reconstruct the reconstructed image (1) only for the ROI. The timing for reconstructing this ROI is R
It is desirable to do this immediately after OI designation. At this time, it is preferable not to perform the reduction process. In addition, the reconstructed image (2) is provided after rotational imaging after placing the occluding substance.
The reconstruction image (3) is reconstructed.

[Modification 3 of the first embodiment]
In Modification 3 described above, the time is reduced by reducing the resolution of the reconstructed image when setting the ROI. However, the ROI is set based on two or more images taken from different shooting angles. Also good. The apparatus configuration in this case is as shown in FIG.

In FIG. 6, first, an aneurysm is photographed from two directions, and the photographed image is converted into a digital signal by the A / D converter 2 and then supplied to the ROI determination unit 21. At this time, the X-ray generator 12 and the X-ray
With a biplane system having two sets of line plane detectors (or II), a target image can be obtained with a single photographing.

The ROI determination unit 21 supplies the image to the display unit 8 via the D / A converter 9. For example, a front image (Frontal) shown in FIG. 7A and a side image (La) shown in FIG.
If (talal) is displayed, the ROI determination unit 21 sets the ROI (center and radius) for each displayed image.

Specifically, a point K that is considered to be the center of the aneurysm is designated on one of the images (for example, a front image this time) (FIG. 7A). The ROI determination unit 21 calculates a straight line (epipolar line) connecting the point K and the focal point of the X-ray generation unit 12 as shown by a dotted line in FIG. Projection is performed by the unit 12 (here, the side image side). Then, the projected linear image is superimposed on the image.

Since the center of the aneurysm should be on this epipolar line, FIG.
A center point H as shown in FIG. As described above, a straight line connecting the point H and the focal point of the X-ray generation unit 12 is obtained by calculation, and the intersection of the two straight lines is determined as the center point of the ROI. In addition, since these straight lines may not cross, in that case, it calculates | requires as a midpoint of the nearest points. The radius is also specified by either a front image or a side image. The ROI is determined by correcting the radius in consideration of the geometric magnification of the X-ray.

Next, when the ROI information from the ROI determining unit 21 is supplied to the aperture / bed motion determining unit 11, the aperture / bed motion determining unit 11 determines the aperture at an arbitrary shooting angle based on the ROI information. Determine the action or position of the bed or photographic system.

Specifically, as described with reference to FIG. 4, the bed or the imaging unit 1 is moved so that the center of the ROI is always located at the center of the X plane detector 13 during the rotational imaging, and only the ROI is X only.
The diaphragm 16 is controlled to be closed so that the line is exposed. Thus, the reconstructed image (1) to
By capturing only the ROI area in (3), ROI is also possible in rotational imaging before the placement of the obstructing substance.
It is possible to irradiate only X-rays, and it is possible to reduce unnecessary exposure of the subject.

[Second Embodiment]
Next, a second embodiment of the X-ray diagnostic apparatus according to the present invention will be described. In the description of the second embodiment, the same reference numerals are given to the portions showing the same operation as in the first embodiment, and the detailed description thereof will be omitted.

The X-ray diagnostic apparatus according to the second embodiment is an X-ray diagnostic apparatus for a circulatory organ as shown in FIG. 8, and is supplied as analog information from the imaging unit 1 that performs X-ray imaging. An A / D converter 2 that digitizes the captured image, a shooting condition memory 3 that stores shooting conditions from the shooting unit 1, a geometry processing unit 30 that performs image conversion processing so that the shot image can be easily viewed, and a floor A tone conversion processing unit 31 and an edge enhancement unit 32, and a D / A converter 33 that converts a digital image subjected to image conversion processing by the processing units 30 to 32 into an analog signal for display on the display unit
And have.

The geometry processing unit 30 performs linear transformation such as enlargement, rotation, and movement, and the X-ray detection unit 1
2 is I.I. I. In the case of an image intensifier, distortion correction processing is performed.

The gradation conversion processing unit 31 adjusts the display density so that the target structure can be easily seen, and the edge enhancement unit 32 performs edge enhancement processing using a high-frequency enhancement filter (edge enhancement filter) such as a Laplacian or a differential filter. These processes can be varied stepwise by an input device (not shown), and each process can be selectively executed.

The image collected by the X-ray flat detector 13 is A / D converted by the A / D converter 2 and then stored in the image memory 6. This image memory 6 is not only a two-dimensional image collected by the cardiovascular X-ray diagnostic apparatus, but also an X-ray CT apparatus 36 and a nuclear magnetic resonance apparatus 37 (MRI) connected to the X-ray diagnostic apparatus and the bus line 35. 3D images reconstructed with other modalities such as SPECT apparatus 38, 3D CT apparatus 39 obtained by, for example, the cardiovascular X-ray system described in the first embodiment and similar systems 3D images are also recorded.

These three-dimensional images are projected by the projection conversion unit 40 at angles and positions that match the image currently being shot based on the shooting conditions recorded in the shooting condition memory 3 from the shooting unit 1 for each shooting. The image is converted into an analog form by the D / A converter 41 and displayed on the display unit 42.

In addition, in this 2nd Embodiment, although it has a total of two display parts, the display part 34 and the display part 42, you may make it provide any one display part.

In this case, the captured image is displayed side by side with the projection image or displayed in an overlapping manner.

Next, the operation of the second embodiment having such a configuration will be described. In the second embodiment, first, the catheter is operated while being advanced to the affected area under fluoroscopy (imaging with a low dose and without performing contrast). In such a case, the catheter cannot be advanced unless the blood vessel running is grasped. This is particularly noticeable when the structure is complicated. Therefore, in general, before the catheter is advanced, the contrast medium is flowed and photographed, and the contrast image (still image) is displayed side by side with the photographed image (moving image: currently captured image) or displayed in a superimposed manner. Thereby, the blood vessel traveling can be grasped even if the contrast is not always performed. The examiner (operator) advances the catheter based on the contrast image (using the contrast image as a guide). This contrast image is called a road map. However, in order to create a road map, it is necessary to perform imaging with a contrast and a somewhat high dose.

Therefore, in the second embodiment, a three-dimensional image such as a CT image, an MRI image, and a three-dimensional CT image of the same subject that has already been photographed and the current photographing conditions (SID, photographing angle, photographing). The projection conversion unit 40 performs projection conversion processing of the three-dimensional image based on the mode, the shooting position, and the like, and provides this as a road map via the D / A converter 41 and the display unit 42. This projection conversion process is performed every time the shooting angle or position changes. This can reduce contrast and exposure for roadmap creation.

At this time, the projection conversion unit 40 first extracts a blood vessel portion by threshold processing from a CT image, an MRI image, a three-dimensional CT image, etc., and projects only the extracted blood vessel. If extraction with a simple threshold is difficult, an interactive region growing method may be used. By replacing the value in the blood vessel extracted in this way with an arbitrary absorption coefficient value and projecting other parts with an absorption coefficient of 0, it is possible to create a projection image like a DSA image. D
The CT image and the three-dimensional CT image reconstructed from the SA image are projected and converted as they are.

If there is a shift in the imaging angle with respect to the patient due to movement of the patient between the acquisition of the 3D image and insertion of the catheter, etc., there are 3 or more transferred to the 3D image and the captured image observed from two or more directions. It can be corrected using the marker. This marker may be photographed with a high absorption coefficient attached to the outside of the body, or a characteristic structure in the body such as a branch of a blood vessel. Specifically, if three or more marker positions can be specified on a three-dimensional image and a photographed image observed from two or more directions, the coordinates of the three markers in the coordinate system defined by the three-dimensional image are used. Then, the coordinates in the coordinate system defined in the imaging system can be calculated. The correction can be performed by obtaining the rotation angle of the three-dimensional image so that the three markers coincide. The operation for obtaining such a correction angle may be performed only once before the road map is created. Although only the angles are matched here, the positions may be matched.

[Modification of Second Embodiment]
In the description of the second embodiment, the road map is created every time the shooting position changes. This is because the road map is moved in parallel in an area where the change in the shooting position (translation) is small. You may respond. Also, in a region where the change in the shooting angle is small, the change in the road map due to the change in the angle is not as great as the change in the road map due to the position movement, and can be dealt with to some extent without changing. Therefore, the road map is recalculated and created only when there is a change beyond a predetermined range from the shooting position or angle at which the previous road map was created. As a result, in a region where there is little change in the shooting position and shooting angle, it is possible to deal with the previously created road map without creating a new road map.

[Third Embodiment]
Next, a third embodiment of the X-ray diagnostic apparatus according to the present invention will be described. In the description of the third embodiment, the same reference numerals are given to the portions showing the same operations as those in the first and second embodiments, and the detailed description thereof is omitted. .

If a road map is created by the procedure of the second embodiment, blood vessels may overlap depending on the imaging angle, and it may be difficult to identify the target blood vessel structure. The third embodiment solves this problem.

That is, the apparatus configuration of the third embodiment is as shown in FIG. 9, and the three-dimensional image stored in the image memory 6 is processed by the three-dimensional image creation unit 50 by the above simple threshold processing,
Alternatively, after the target region is extracted by the region growing method or the like, it is shaded on the surface structure, converted to analog via the D / A converter 52 and displayed on the display unit 53. By observing the stereoscopic image from various directions, the operator can grasp the three-dimensional structure of the target region.

Next, as described in the first embodiment, the ROI determination unit 51 performs R processing on this stereoscopic image.
Set OI. When the ROI is set, the ROI determination unit 51 displays the information easily, for example, by changing the color inside the ROI. Here, the ROI shape is considered to be spherical, but this may be a ROI shape other than spherical. A plurality of ROIs can be specified. When a plurality of ROIs are specified, the final ROI is determined as an overlap of the ROIs.

The ROI information set by the ROI determination unit 51 is supplied to the projection conversion unit 40. Based on this ROI information, the projection conversion unit 40 calculates a projection image so that data other than the ROI is not projected onto the projection area corresponding to the ROI, and displays this via the D / A converter 41. Part 4
2 is displayed.

Alternatively, based on the ROI information, the projection conversion unit 40 attenuates data other than the ROI with a weighting factor in the region captured by the ROI, and clarifies the projected image in the ROI and displays it on the display unit 42. To do.

In this way, by omitting the display of the overlapping blood vessel structure on the road map or weakening the display, it is possible to easily specify the blood vessel structure that is overlapping and difficult to specify on the road map. For this reason, it becomes possible to advance the catheter quickly, shortening the examination (treatment) time and reducing the exposure dose.

[Variation 1 of the third embodiment]
In the above-described third embodiment, the ROI is manually specified. This is because an X-ray diagnostic apparatus 61 that can be observed from two directions with a biplane configuration as shown in FIG. Based on the image coordinates of the catheter tip, which is a characteristic structure in the captured image extracted from the images in two directions, the three-dimensional position coordinates where the catheter is present are calculated, and the ROI is set around that point. May be. As a technique for extracting the catheter tip, a technique for detecting a substance with a high absorption coefficient attached to the catheter tip, or a technique for taking a time difference can be used. Thereby, automatic setting of ROI can be enabled.

[Modification 2 of the third embodiment]
In the first modification of the third embodiment described above, the ROI is automatically set using the X-ray diagnostic apparatus 61 having the biplane configuration. However, this uses a single-plane X-ray diagnostic apparatus. The ROI can be automatically set in the same way.

In this case, the catheter tip is specified in the captured image, and the image is back-projected in the three-dimensional image coordinate system from that point. At that time, the blood vessel structure intersecting with the reverse translucency line is set as the ROI center candidate.

Specifically, the density distribution is searched along the backprojection line, and the points exceeding the density value of the first blood vessel and the points below the density value are recognized as the boundaries of one blood vessel structure. The midpoint is set as an ROI candidate point. This operation is repeated on the line to obtain a plurality of candidate points. The line segment connecting the ROI center one frame before or several frames before is searched in the same manner, and if there is a region other than the blood vessel between them, it is removed from the candidate points. The candidate points can be reduced by the operation as described above. However, in this method, candidate points may not be uniquely identified. In this case, a plurality of ROIs are set. The operator selects one desired ROI from the plurality of designated ROIs. Thereby, even when a single plane X-ray diagnostic apparatus is used, the ROI can be set semi-automatically.

[Modification 3 of the third embodiment]
In the third embodiment described above, the density of the three-dimensional blood vessel image is projected.
It may be the distance from the line focus or detector to the surface of the target area. Since the information projected at this time always overlaps, only the smallest or largest value is projected. By such an operation, depth information can be added to the two-dimensional road map, so that the catheter operation becomes easier, and the examination time can be shortened and the exposure dose can be reduced.

[Modification 4 of the third embodiment]
In the third modification of the third embodiment described above, the distance from the boundary of the target region to the X-ray generator 12 or the X-ray detector 13 is projected and displayed. It may be displayed. Further, the depth information of the position indicated by the ROI on the color bar may be displayed in an easy-to-understand manner using arrows or the like.

[Modification 5 of the third embodiment]
In Modification 3 and Modification 4 of the above-described third embodiment, the distance from the boundary of the target region to the X-ray generator 12 or the X-ray detector 13 is projected and displayed. The display density or display color may be updated around the current position. For example, the display color is dynamically changed so that the current position is always displayed as the center color of the color bar.
Or, if the color is constantly changing, it will be difficult to grasp the structure in areas where the change in depth is severe, so either one of every certain time, every certain change in depth, every change in shooting angle or position One or a combination thereof may be used. Further, a reset switch or the like may be provided and changed when the switch is pressed. Thereby, the depth information in the vicinity of the ROI can be displayed more easily.

[Modification 6 of the third embodiment]
In the third modification, the fourth modification, and the fifth modification of the third embodiment described above, the distance is projected for the entire blood vessel structure (the central axis and others), but the depth information is only for the central axis. Therefore, only the central axis of the blood vessel is first extracted from the three-dimensional image by the thinning method, only the extracted center line is projected as distance information, and density information may be projected otherwise. Note that three-dimensional thinning processing can also be performed basically by expanding two dimensions to three dimensions. Thereby, since the conventional road map and depth information can be observed simultaneously, depth information can be provided while preventing confusion of the operator (examiner). It will be easier to understand if the center line projected at this time is a little thicker.

Further, the density information of the projected center line may be used as the blood vessel boundary. If it is at the center of the blood vessel, it is difficult to understand depending on the density of the road map around it, but it is easier to understand if it is at the boundary. This can also be done by thinning the roadmap, associating it with the projected centerline, and then finding both boundaries that are closest in the direction perpendicular to the thinned centerline.

Finally, the present invention is not limited to each of the embodiments described above, and can be adapted to the design, etc., even if other than each embodiment, as long as it does not depart from the technical idea according to the present invention. Of course, various modifications are possible.

For example, in the description of each embodiment described above, treatment and occluding substance placement are given as examples. However, this is merely an example for facilitating the explanation of the present invention, and the present invention is not limited to these treatments. Not only, but add that it will be useful before and after any situation change.

DESCRIPTION OF SYMBOLS 1 ... Imaging | photography part, 2 ... A / D converter, 3 ... Memory for imaging | photography conditions, 4 ... Subtraction part, 5
Image reconstructing unit 6 Image memory 7 Comparison processing unit 8 Display unit 9 D / A converter
DESCRIPTION OF SYMBOLS 10 ... ROI determination part, 11 ... Diaphragm / bed operation determination part, 12 ... X-ray generation part, 13 ... X-ray plane detector (or image intensifier), 15 ... Three-dimensional image creation part, 18 ... Distortion correction part,
16 ... X-ray shielding unit (pre-collimator or diaphragm), 20 ... Image reduction unit, 21 ... ROI determination unit, 30 ... Geometry processing unit, 31 ... Tone conversion processing unit, 32 ... Edge enhancement unit, 35 ... Bus line, 36 ... X-ray CT apparatus, 37 ... Nuclear magnetic resonance apparatus (MRI apparatus), 38 ... SPECT apparatus, 39 ... Three-dimensional X-ray CT apparatus (3DCT apparatus), 40 ... Projection conversion unit, 50 ... Three-dimensional image creation unit, 51 ... ROI determination unit, 200 ... occlusion substance

Claims (3)

A bed on which the subject is placed, X-ray generation means for exposing X-rays to the subject placed on the bed, and X which is exposed to the subject from the X-ray generation means An X-ray shielding unit that shields a ray and adjusts an X-ray exposure area, and an X-ray is emitted from the X-ray generation unit to the subject through the X-ray shielding unit. In an X-ray diagnostic apparatus comprising an X-ray detection means for capturing an X-ray image, and an X-ray generation means and a mechanism for rotating the X-ray detection means
The X-ray generation means and the X-ray detection means reconstruct a mask image taken for the subject before the contrast agent is injected and a live image taken for the subject after the contrast agent is injected. Attention area setting means for setting the attention area based on the three-dimensional image obtained in the above,
The X-ray generation means and the X-ray detection means are rotated by the mechanism, and the X-ray is exposed only to the part of the subject corresponding to the attention area set by the attention area setting means. Control means for controlling the X-ray shielding means;

An X-ray diagnostic apparatus comprising: reconstruction means for forming a reconstructed image by performing reconstruction processing based on an X-ray image captured by the X-ray detection means.   The reconstructing means generates an occluding substance distribution image based on the first photographed image before placing the occlusive substance and the photographed image before injecting the contrast agent after placing the occlusive substance. The X-ray diagnostic apparatus according to claim 1.   The control means controls the X-ray shielding means so that X-rays are exposed only to a portion of the subject corresponding to the region of interest when the X-ray image after the placement of the occluding substance is rotated. The X-ray diagnostic apparatus according to claim 2, wherein the X-ray diagnostic apparatus is controlled.

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