JP2564313B2 - Stereo photography equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray imaging apparatus using synchrotron radiation, and more particularly to a stereo imaging apparatus suitable for angiographic diagnosis.

[Conventional technology]

Heart disease caused by coronary artery lesions is the leading cause of death in Europe and the United States, and in Japan in 1985, it became the second leading cause of death after a stroke, indicating an ever-increasing trend. For the definite diagnosis of these heart diseases, the technique of imaging the site and degree of coronary stenosis is extremely important. Until now, the technique used for this purpose is to insert a catheter into the artery and advance its tip to the origin of the coronary artery, directly inject the angiographic agent containing iodine into the coronary artery, and before and after the injection. An X-ray absorption image is taken. Since this method is highly invasive, it is not applicable to screening tests, and cannot be used depending on the medical condition of the patient. Therefore, the development of a new diagnostic imaging technique for visualizing the coronary arteries using less invasive and safe venous infusion is strongly desired.

One way to solve this problem is US Pat.
No. 432,370. The method uses synchrotron radiation that is suitable for obtaining monochromatic X-rays that are several orders of magnitude stronger than the X-ray tube used for conventional X-ray diagnosis as an X-ray source. By using the energy difference method based on the large difference in the absorption amount between the upper and lower iodine contrast agents, only the blood vessel image contrasted with iodine is selectively obtained. X-ray absorption data must be acquired in a short time of a few milliseconds in order to image the coronary arteries that are moving with pulsation by the energy difference method without blurring due to motion. A high intensity monochromatic X-ray source is needed. Synchrotron radiation is effective as an X-ray source that can be used for this purpose. Monochromatic X obtained by separating synchrotron radiation
By using the line, the contrast agent in the coronary artery can be detected by the intravenous injection, even though the contrast agent has a low concentration which is 1/10 or less that of the catheter method.

[Problems to be solved by the invention]

Generally, when a contrast medium is injected into a vein, all blood vessels are non-selectively imaged. Therefore, even when it is desired to visualize a coronary artery, the obtained energy difference image includes blood in a ventricle, a large blood vessel, and a lung. Blood vessels and the like will be superimposed and projected. On the other hand, the coronary arteries have many branches and are three-dimensionally distributed so as to wrap the heart as a whole.
Stereo imaging is suitable for three-dimensional visualization of the entire vascular system having such a three-dimensional structure. By adding information on the sense of depth by stereo photography, the coronary arteries can be easily identified. Further, by identifying the directionality of each branch of the coronary artery, the position of the lesion can be accurately known.

From the above, in order to perform coronary angiography by intravenous injection, it is desired to realize stereo imaging using synchrotron radiation and capable of measuring X-ray images at high speed.

However, the beam of the synchrotron radiation is a flat beam with a strong directivity, and since the emitting position and the direction of the beam are fixed, high-speed stereo imaging cannot be easily performed. To date, no method for stereo imaging using synchrotron radiation has been proposed.

An object of the present invention is to realize a method for stereo imaging at high speed by using synchrotron radiation, and to improve the diagnostic ability of coronary lesions.

[Means for solving problems]

The above-mentioned object is to divide flat synchrotron radiation light into two beams by a beam splitting crystal, and to generate two sets of beams having a single energy and a rectangular cross section by a crystal for expanding reflection, and subjecting the rectangular beam to a test object. X-rays which were emitted from different directions and transmitted through the subject using two sets of X-ray image detectors.
It is achieved by measuring the line.

The crystal used here is a single crystal cut so that the surface has an appropriate angle with respect to the diffraction crystal plane, and is arranged at an appropriate angle with respect to the incident beam according to the energy of the X-ray to be obtained. It is assumed that Under these conditions, the X-ray having the desired energy is diffracted by the crystal plane, and the effect that the emitting direction of the beam is changed is utilized.

[Action]

FIG. 2 shows the principle of the present invention. In general,
The cross-sectional shape of the incident synchrotron radiation beam 1 is flat, narrow in the in-plane direction and wide in the direction perpendicular to the plane.
The single crystal 2 is a beam-splitting crystal, and only the lower half of the beam 1 is incident, and the other upper half of the beam 1 passes without being incident.

The surface of the single crystal 2 is cut out in parallel with the diffraction crystal plane, and with respect to the X-ray incident at an angle θ with the diffraction crystal plane,
E = 12.4 / (2d · sin θ), (However, the unit of E is KeV,
d is the crystal lattice plane interval, and the unit is angstrom). Only X-rays with energy of Å are reflected by the Bragg reflection principle. The direction of the reflected beam changes by 2θ with respect to the incident beam. In this way, the beam is divided into two by the action of the beam dividing crystal 2.

The single crystals 3 and 4 are crystals for magnifying reflection, and the crystal plane 8 (shown in FIG. 3) used for diffraction is the same as the single crystal 2, but the crystal surface 9 forms an angle α with the crystal plane 8. It has been cut out.

The direction of the monochromatic beam having the energy E incident on the single crystal 3 changes by −2θ due to the diffraction effect, and finally the beam is emitted in the same direction as the original beam. The height of the cross section of the beam is increased by sin (θ + α) / sin (θ−α) times due to the effect of asymmetrical reflection, resulting in a rectangular beam.

Similarly, the component of the energy E of the beam incident on the single crystal 4 rotates by 2θ with respect to the incident beam. The cross-sectional shape of the beam is similar to the output of the single crystal 3.

Therefore, the two rectangular beams intersect at an angle of 2θ. The crystal diffraction plane is set so that the intersecting angle is about 5 ° to 10 °. Place the subject at the intersecting position,
Stereo imaging is realized by measuring the monochromatic X-rays transmitted through the subject with two sets of X-ray image detectors 6 and 7.

When stereo imaging is performed with different energy, each single crystal is rotated by a small angle, and the viewing angle θ is set according to the energy. The change in θ required to make the energy difference is on the order of 5'at the most.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 11
Is a synchrotron radiation that is flat in the direction perpendicular to the paper, 12
Numerals 14 are three silicon single crystals constituting a monochromator for stereo photography. The subject 15 is fixed on the bed 16. The detector unit for measuring the X-ray image transmitted through the subject is composed of two sets of X-ray image intensifiers 17-1 and 17-2, a tandem lens 18-1 and 18-2, and a television camera 19-. 1 and 19-2. 20 is a data recording device having a frame memory for digitizing the output signal of the television camera and temporarily storing it, 21-1,
Reference numerals 21-2 and 21-3 are pulse motor drive circuits for rotating each single crystal 12 to 14, which are used to measure the oblique angle according to the energy of the X-ray to be obtained, and 22 is data. It is a collection controller for generating a control pulse train signal to 21 and a data collection trigger signal to 20. Reference numeral 23 is an arithmetic unit for reading out data in the frame memory and performing arithmetic operations such as logarithmic conversion and subtraction and image processing, and 24 is a stereo display unit for observing a stereo image.

The single crystals 12 to 14 use the silicon (111) plane as the diffraction plane. The surface of the single crystal 12 is cut out in parallel with the diffraction plane. When X-rays with an energy higher than the K-edge energy of iodine (33.17 KeV) by 30 eV are to be spectrally dispersed, the visual oblique angle is set to be a Bragg angle of 3.4 degrees. Half of the original beam is incident on the single crystal 12. The diffracted X-ray is 6.8
It is directed upwards and enters the single crystal 13. Half of the original beam that is not incident on the single crystal 12 is incident on the single crystal 14. The single crystals 13 and 14 have a surface cutting angle of (111)
It is processed to 3.0 degrees to the surface. 3 from the K edge of iodine
When obtaining X-rays with high energy of 0 eV, the viewing angle is set to 0.4 degree. The height of the beam (length in the plane of the drawing) is expanded 15.6 times due to asymmetrical reflection on the single crystals 13 and 14. Beam emission direction is horizontal for single crystal 13 and single crystal 14
At 6.8 degrees upward. As a result, the output beams meet at a crossing angle of 6.8 degrees. By placing the subject in the area where the beams intersect, stereoscopic imaging of the subject becomes possible.

The present embodiment has a simple structure in which only three single crystals that use the same diffraction surface are used as the single crystals that constitute the monochromator for stereo photography. The beam crossing angle is twice the flag angle. Setting the beam crossing angle to various desired values for X-rays of arbitrary energy can be achieved by using a crystal 12
It is possible by variously selecting the crystal diffraction planes of ˜14. Further, the size of the beam in the height direction can be set to a desired value by setting the cutting angle of the surfaces of the crystals 13 and 14.

In the present embodiment, it is also possible to obtain X-rays having an energy slightly lower than the edge energy in iodine by rotating the single crystals 12 to 14 by the same angle by a pulse motor. For driving the pulse motor, for example, a constant number of pulses from the controller 22 at 3 KHz is applied to the motor drive circuit
By outputting to, the single crystals 12 to 14 can be rotated in several tens of milliseconds. The X-ray transmission image is measured again by the X-ray thus obtained. That is, single crystal 12-
Immediately before rotating 14 the X-ray transmission image by the X-ray having an energy slightly higher than the K-edge energy is used in the first imaging system 17-
Images are similarly picked up by 1,18-1, 19-1 and the second imaging system 17-1, 18-1, 19-1 and the respective images are stored in the data recording device 20. Next, the single crystals 12 to 14 are rotated, and immediately after that, X-ray transmission images by X-rays having an energy slightly lower than the K-edge energy are captured by the first and second imaging systems, respectively, and the data recording device is also used. Accumulate to 20. The images obtained from these first and second imaging systems are respectively subjected to logarithmic conversion and subtraction processing to obtain an energy difference image, and thus two images, that is, 2
Obtain the energy difference image from the direction. These images are displayed side by side on the stereo display device 24, which allows a stereoscopic audience. Further, it is also possible to make appropriate stereoscopic observation by appropriately superimposing the two images and to emphasize only the contrast of a specific depth. In this embodiment, it is also possible to perform real-time monochromatic stereo photography by displaying the two images of the imaging system in real time without taking the energy difference.

Another embodiment of the present invention is shown in FIG. The figure uses four crystals to produce intersecting beams. The crystals (32) and (33) use a silicon (111) plane, and the crystals (34) and (35) use a silicon (220) plane as a diffraction crystal plane. 36 is an absorber that absorbs unnecessary X-rays. In this embodiment, since the intensities of the intersecting beams are balanced, there is an effect of balancing the image quality of the left and right images. Further, since the incident beam is asymmetrically reflected twice, it has an effect of increasing the expansion ratio of the beam height. Also,
The crossing angles of the outgoing beams are the Bragg angle of the crystals 32 and 33 and the crystal 34,
Since it is determined by 4 times the difference from the Bragg angle of 35, the crossing angle can be adjusted by selecting both crystal planes under the condition that the former is larger than the latter.

Another embodiment is shown in FIG. This figure uses thin single crystal Laue reflection to split the original beam. The entire original beam 41 is incident on the single crystal 42. The oblique angle is set to a value at which X-rays of desired energy are diffracted. The thickness of a single crystal is about 50 of the required X-ray energy.
It is desirable to diffract the% and transmit the remaining 50% with as little loss as possible. The transmitted X-rays enter the single crystal 43 and are diffracted. The diffraction angle of the single crystal 43 is made larger than that of 42, and the monochromatic X-ray beams emitted from 42 and 43 have the same wavelength, and the diffraction surfaces of the single crystals 42 and 43 are selected so that they intersect each other. To be done. Also in this embodiment, the single crystals 42 and 43 are rotated by a small angle by a pulse motor, and images are taken before and after the rotation, respectively, so that the images are taken from two directions, and the K-edge energy of the contrast agent is increased or decreased.
Imaging can be performed by using different types of monochromatic X-ray beams.
Although the photographing system and the control system are not shown, they are the same as those of the embodiment shown in FIG. This embodiment has an effect that the white beam 44 other than the monochromatic beam used for stereo photography can be used for another purpose.

Another embodiment is shown in FIG. This figure shows that, with respect to the beam 51 of synchrotron radiation, the single crystals 52 and 53 emit monochromatic light and generate a planar beam, and at the same time, emit the beam not in the vertical direction but in the oblique direction. FIG. 7 shows the position of the reflecting surface of the single crystal 52. The intersection line 63 between the surface 61 and the reflecting surface 62 is not orthogonal to the incident beam 64 and has a certain inclination. As a result, the outgoing beam 65 is also deflected in the horizontal direction. The single crystal 53 is cut out so that the inclination of the reflecting surface is symmetrical with respect to the vertical plane containing the incident beam. As a result, the outgoing beam is tilted in the direction opposite to 52, and the two planar beams intersect. In this embodiment, the single crystals 52 and 53 are arranged on one holding plate, and both are rotated by a small angle to obtain an energy difference image by a monochromatic X-ray beam of two energies. In this embodiment, 1 is used to generate a monochromatic beam.
Since only one Bragg reflection is used, a stronger monochromatic stereo beam can be generated compared to other methods. In addition, the present method is not limited to the case where the light source of the synchrotron radiation is one point, but can also configure a stereo imaging apparatus that uses the synchrotron radiation emitted from different points. FIG. 8 is a modification (top view) of FIG. 6, but shows that stereo imaging can be performed with the same configuration for synchrotron radiation light emitted from separate light emitting points 71 and 72. .

〔The invention's effect〕

According to the present invention, two planar monochromatic X-ray beams that intersect each other can be generated by using synchrotron radiation, and high-speed stereo imaging can be performed. Therefore, the diagnosis of the lesion position of coronary pulsation can be performed accurately. There is.

Moreover, it is extremely effective not only for coronary pulsation but also for general angiographic diagnosis.

Furthermore, since stereo imaging using X-rays of arbitrary energy becomes possible by selecting the diffraction surface of the crystal, it can be applied to a wide range of fields such as imaging using elements other than iodine and selective imaging of various organs. Become.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIG. 2 is a principle view (front view), FIG. 3 is a sketch of a single crystal, and FIGS. 4 to 5 are part of front views of other embodiments. FIG. 6 is a part of a top view and a part of a front view of another embodiment, and FIG. 7 is a sketch of a single crystal,
FIG. 8 is a part of a top view of another embodiment. 1,11,31,41,51 …… Synchrotron radiation, 2,3,4,12,1
3,14,32,33,34,35,42,43,52,53 …… single crystal, 5,15 …… subject, 17-1,17-2 …… X-ray image intensifier, 19 -1,19-2 …… TV camera.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisataka Yokouchi 1-280 Higashi Koigakubo, Kokubunji City Central Research Institute, Hitachi, Ltd. (72) Inventor Yoshio Suzuki 1-280 Higashi Koigakubo, Kokubunji City Hitachi Research Laboratory (72) Inventor Katsuhisa Usami 4026, Kujimachi, Hitachi City Hitachi Ltd. Hitachi Research Laboratory (56) References JP 61-31124 (JP, A) JP 57-207241 (JP, A) Special JP-A-57-93241 (JP, A) JP-A-47-17445 (JP, A) Actual-open Sho-57-3236 (JP, U) Actual-open Sho-48-71775 (JP, U) US Patent 4432370 (US, A) )

Claims (7)

(57) [Claims] 1. An X-ray imaging apparatus for measuring X-rays transmitted through a subject using synchrotron radiation, and means for splitting a synchrotron radiation beam and controlling the energy and emission direction of the split beam. Images of at least one single crystal for generating two monochromatic X-ray beams that intersect each other and are placed in the intersecting portion of the two monochromatic X-ray beams from two directions. A stereo imaging device characterized by simultaneously obtaining 2. The single crystal has a reflecting surface cut out at a predetermined angle with a diffraction crystal surface, and a monochromatic X produced thereby.
The stereo imager according to claim 1, wherein the width of the line beam is wider than that of the incident synchrotron radiation. 3. The single crystal according to claim 1, wherein the single crystal is rotated by a small angle about a predetermined rotation axis to generate a monochromatic X-ray beam having slightly different energies before and after the rotation. The stereo imager described in. 4. The single crystal according to claim 3, wherein the single crystal produces a monochromatic X-ray beam having an energy above and below the K-edge energy of the contrast medium injected into the subject before and after rotation. Stereo photography device. 5. A monochromatic X-ray beam having a desired energy, which is provided along the path of one synchrotron radiation beam and intersects with each other by Laue reflection.
A stereo imaging apparatus having a second single crystal plate and simultaneously obtaining transmission images from two directions of a subject placed at the intersection of the monochromatic X-ray beams. 6. The first and second single crystal plates are each rotated by a small angle about a predetermined rotation axis to divide a monochromatic X-ray beam having slightly different energy before and after the rotation. The stereo imaging device according to claim 5. 7. The first and second single crystals divide a monochromatic X-ray beam having an energy above and below the K-edge energy of the contrast medium injected into the subject before and after rotation, respectively. The stereo imager according to claim 6.