JP2008122101A - Image measuring method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image measuring method and device capable of acquiring a radiogram of an aiming object having high resolution in a short time by utilizing X-rays having high output, high brightness and excellent parallelism, and applicable to wide medical use or the like. <P>SOLUTION: An energy ray is irradiated from a prescribed energy ray source onto the surface of a target, and X-rays are generated from the target so as to have largeness equivalent to the maximum length of the object. Then, the X-rays are allowed to enter a spectroscope, and a wavelength and a wavelength width are selected from the X-rays, and parallel X-rays becoming parallel are generated. Thereafter, the parallel X-rays are irradiated, while being rotated relatively around the object, and an X-ray image acquired from the object is detected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image measurement method and an image measurement device, and more particularly to an image measurement method and an image measurement device that can be suitably used for medical purposes.

  Conventionally, in medical X-ray imaging, a predetermined X-ray tube is used. The subject is irradiated with X-rays emitted from the X-ray tube, and the X-ray transmitted through the subject is applied to a predetermined film or the like. In this case, the image is detected or detected by the detection unit, and the captured or detected video is analyzed and used for medical purposes.

For example, in a conventional X-ray tube, if X-rays emitted from an effective focal point of 1 mm × 1 mm are spread and expanded to 40 cm × 40 cm and irradiated on a subject, the luminance of the X-ray is (1 mm × 1 mm) / It becomes weak by a ratio of (400 mm × 400 mm). That is, the luminance of the X-rays irradiated to the subject is attenuated to at least 6.25 × 10 ^{−6 as} compared with the luminance immediately after emission.

  In addition, when a conventional X-ray tube is used for medical purposes or the like, most of the cases where unnecessary components are cut with a filter. However, this method is not sufficient for effectively extracting the target wavelength component.

  On the other hand, in the medical field, development of high-speed and high-resolution 3D CT of a subject is desired. That is, if the resolution increases, the discovery of early symptoms such as early cancer progresses, and the cure rate increases dramatically. In order to image a subject with high resolution, it is necessary to expose a high-power and high-intensity X-ray with a short wavelength width and good parallelism for a short time. However, in the conventional X-ray tube, the X-ray luminance at the stage of irradiating the subject is remarkably reduced, and X-rays with high parallelism cannot be obtained.

  In addition, in a conventional CT apparatus using an X-ray tube, when an image of a subject is to be obtained, the X-ray tube must be rotated around the subject several tens of times, which increases the measurement time. There was a problem that.

  As described above, in order to use the conventional X-ray tube particularly for medical purposes, there is a problem that an image of a target subject cannot be obtained in a high resolution and in a short time.

  The present invention has been made under the above-mentioned background, and can be applied to a wide range of medical uses and the like, utilizing X-rays with high output, high brightness, and excellent parallelism. An object of the present invention is to provide an image measuring method and an image measuring apparatus capable of obtaining an X-ray image of a target subject with high resolution and in a short time.

In order to achieve the above object, the present invention provides:
Irradiating the surface of the target with energy rays from a predetermined energy ray source and generating X-rays from the target so as to have a size corresponding to the maximum length of the subject;
Making the X-ray incident on a spectrometer, selecting a wavelength and a wavelength width from the X-ray, and generating parallel X-rays that have become parallel light;
Irradiating the parallel X-rays while rotating around the subject, and detecting an X-ray image obtained from the subject;
It is related with the image measuring method characterized by comprising.

The present invention also provides:
A target for generating X-rays by energy beam irradiation;
An energy ray source for generating energy rays for generating X-rays from the target so that the X-rays have a size corresponding to the maximum length of a subject;
A spectrometer for making the X-ray incident, selecting a wavelength and a wavelength width from the X-ray, and generating parallel X-rays that have become parallel light;
A rotational drive system for generating a relative rotational movement of the parallel X-rays around the subject;
A detector for detecting an X-ray image obtained by irradiating the subject with the parallel X-ray;
It is related with the image measuring device characterized by comprising.

  In the present invention, a special target for generating X-rays is used in place of the conventional X-ray tube, and the target is irradiated with energy rays. Therefore, by appropriately controlling the irradiation intensity and the irradiation area of the energy beam with respect to the target, it has a high output and high luminance that cannot be realized with a conventional X-ray tube, and the size of the subject (X-rays). X-rays having a size substantially equal to or larger than the length on the incident side can be generated.

  In the present invention, X-rays generated from the target are incident on a spectroscope, and only X-ray components that are parallel to the X-ray and within a predetermined wavelength range are extracted. Therefore, due to the use of parallel X-rays that are larger than the subject and have high output and high brightness, the parallel X-rays are rotated around the subject relatively less than half a turn. Then, the whole image of the subject can be obtained. Accordingly, X-ray images of the subject, specifically, three-dimensional X-ray CT image data can be obtained with high accuracy and in a short time. The relative rotation may be performed at a constant speed, or the speed can be arbitrarily changed as necessary.

  In fact, a conventional three-dimensional CT apparatus obtains a three-dimensional image with a computer based on measurement data. At this time, in order to make all the image data have the same magnification (actually magnification 1), in an X-ray tube used in a three-dimensional CT apparatus or the like, the parallel X In order to obtain a line, the parallel X-ray is used as an X-ray beam that is essentially narrowed down to a cross-sectional area having a size of several commas. Therefore, inherently small X-ray luminance results in a further reduction in efficiency.

  Here, the size of the X-ray beam means a characteristic characterizing the size of the X-ray. For example, when the cross-sectional area of the X-ray is rectangular, it means the length of one side thereof. .

For example, as described above, the efficiency of the parallel X-ray is 1 / (400 × 400) = 6.25 × 10 ⁻⁶ as compared with the case where a 40 cm × 40 cm transmission photograph is taken without passing through a 1 mm × 1 mm collimator. It will decrease to. In addition, since the cross-sectional area of the parallel X-ray is extremely limited and a three-dimensional image is obtained by calculation from digital data, it is necessary to scan the subject with the parallel X-ray several tens of times. As a result, when an X-ray image of the entire subject is to be obtained, a time of several tens of seconds is required for one measurement.

  On the other hand, along with the increase in scanning speed, a device that can rotate three times per second is now available, and the time required for the X-ray beam to scan an area of 1 mm x 1 mm at a distance of 200 mm from the center of rotation is only 0.26 milliseconds. Absent. In other words, since exposure is less than millisecond per pixel, exposure is likely to be insufficient, and it is difficult to obtain a high-quality image, that is, a three-dimensional CT image with low noise and good resolution. As a result, in the conventional method, it is necessary to narrow the X-ray beam in order to increase the resolution, and as a result, the measurement time becomes longer. Therefore, there arises a problem that a high-resolution three-dimensional X-ray CT image is practically not obtained.

  On the other hand, in the present invention, since the parallel X-rays having a size corresponding to the maximum length of the subject and having high luminance are used, the parallel X-rays are obtained when obtaining the X-ray image of the subject. A target X-ray image can be obtained by irradiating the subject with a relatively half rotation or less. Therefore, a high-resolution X-ray image of the subject can be obtained on the order of a very short time and a comma second when the high-speed scanning method is used. As a result, in the method and apparatus of the present invention, a high-resolution X-ray image can be obtained for a subject in a short time without depending on the size and shape of the subject.

  In one aspect of the present invention, the X-rays can be easily converted into parallel X-rays by passing through one slit having an interval substantially equal to the width of the energy rays to be irradiated to the target. it can. In this case, it is preferable to select the width of the energy beam and the slit interval so that the X-ray has an effective focal point having a size matching the target resolution in the width direction.

  The spectroscope may include a crystal plate. In this case, two or more crystal plates may be used in combination, and at least one of the crystal plates may function as an X-ray surface reflection type crystal plate. In addition, at least one of the crystal plates can function as an X-ray transmission type crystal plate. Thereby, the target parallel X-ray can be easily obtained. Furthermore, by appropriately setting the combination method of these crystal plates, not only parallel but also monochromatic X-rays can be obtained.

  Further, all of the plurality of crystal plates described above can be X-ray surface reflection type crystal plates, or all of them can be X-ray transmission type crystal plates. Furthermore, these crystal plates can be used in combination.

  For example, when the elongated X-ray is used as in the present invention, the crystal plate can be made of graphite, quartz, etc. in addition to the above-described silicon, germanium, and lithium fluoride (LiF). Accordingly, the parallel X-rays as described above can be easily formed by making the X-rays generated from the target incident.

  Furthermore, the crystal plate can include an X-ray multilayer reflector. Such a multilayer reflector can be configured as a film in which two or more kinds of substances are periodically stacked in layers, and can take out monochromatic or constant width X-rays using the X-ray diffraction phenomenon. Means a membrane. In this case, the relationship between the extracted wavelength and the reflection angle is determined by the period of the multilayer reflector. Also, the reflected X-ray width can be changed by changing the number of layers and the period by a small amount. According to this aspect, the parallel X-rays as described above can be easily formed by causing the X-rays generated from the target to enter.

  Further, as will be described in detail below, the target can be a fixed type or a rotary counter cathode. In the latter case, the energy beam can be irradiated to the target with such an intensity that at least a part of the target irradiation part is melted. Therefore, higher-intensity X-rays can be obtained.

  Further, in one aspect of the present invention, the target is a plurality of targets, and the plurality of targets are irradiated with energy rays and have a size corresponding to the entire length of the incident side of the subject. A plurality of X-rays can be generated, and an X-ray image can be generated and detected from the subject while rotating the plurality of X-rays relatively around the subject. In this case, the relative rotation angle of the parallel X-rays with respect to the periphery of the subject can be further reduced, and an X-ray image of the subject can be obtained in a shorter time.

  As described above, according to the present invention, high-resolution, short-time use of X-rays that can be applied to a wide range of medical uses, etc., has high output, high brightness, and excellent parallelism. Thus, it is possible to provide an image measurement method and an image measurement apparatus capable of obtaining an X-ray image of a target subject.

  Hereinafter, other features and advantages of the present invention will be described based on the best mode for carrying out the invention.

  FIG. 1 is a configuration diagram showing an example of a parallel X-ray generator in the image measuring apparatus of the present invention. As is apparent from FIG. 1, in the present example, the parallel X-ray generator is composed of an X-ray generator main body 10 and a spectrometer 30. The X-ray generator main body 10 is an X-ray generator in the case of using a flat fixed target configured to generate white X-rays from a linear target having a long execution focus.

  In the X-ray generator main body 10 shown in FIG. 1, an anti-cathode 12 is disposed in a vacuum vessel 11, and a cathode 13 is provided so as to face the counter cathode 12. The cathode 13 is fixed to the inside of the Wehnelt 14 with an insulator such as ceramic, and a potential difference is usually given to the cathode and the Wehnelt, and the Wehnelt functions as an electron beam lens.

  An aperture grid 15 and an anode 16 are provided between the counter cathode 12 and the cathode 13. Aperture grid 15 can vary ± 7 kV depending on the conditions depending on the conditions of the cathode, and when it is negative, it blocks electrons, and when it is positive, it neutralizes the space charge of the cathode and effectively draws a large amount of electrons. Used for. The anode 16 is provided for accelerating the electron beam 20 emitted from the cathode 13 and for eliminating the subsequent potential difference and reducing the influence of the target (anti-cathode 12) that has become high temperature. Can be omitted if necessary. The vacuum vessel 11 is provided with an X-ray extraction window 17 so that the X-ray 21 generated from the counter cathode 12 can be extracted to the outside.

  In general, grids are often mesh-like to improve efficiency. However, since a grid-like shading is produced in the electron beam bundle and an excessive current flows through the grid, a cylindrical grid is used. Since 20 passes through the cylinder, it cannot be shaded. Such a grid is called an aperture grid.

  In this example, all of the parts other than the counter cathode 12 and the vacuum vessel 11, that is, the X-ray extraction window 17 are cooled with insulating oil. However, if the counter cathode is directly outside as shown in FIG. 1, the target may be distorted due to the atmospheric pressure. In such a case, the counter cathode 12 is fixed in a vacuum and the atmospheric pressure is not applied. In this manner, a pipe can be attached to the counter-cathode 12, and a predetermined refrigerant can be circulated and cooled.

  A spectroscope 30 is provided outside the vacuum vessel 11 and in the vicinity of the X-ray extraction window 17. The spectroscope 30 is disposed such that the first crystal plate 31 and the second crystal plate 32 form a predetermined angle 2α. Further, a first slit 41 is provided between the first crystal plate 31 and the second crystal plate 32 in the spectroscope 30, and a second slit is provided outside the second crystal plate 32. 42 is provided.

  In the apparatus shown in FIG. 1, the electron beam 20 generated from the cathode 13 is controlled by the grid 15, accelerated by the anode 16, and irradiated on the surface of the counter-cathode 12 in a predetermined shape (rectangular shape). Parallel X-rays 21 are generated. Next, the X-ray 21 is extracted outside from the X-ray extraction window 17, reflected by the first crystal plate 31, and subsequently passed through the first slit 41 to obtain the X-ray 22 parallel to the paper surface. The first slits 41 are configured to have an interval substantially equal to the width of the electron beam 20 to be irradiated to the counter cathode 12. In this case, it is preferable to select the width of the electron beam 20 and the interval between the slits 41 so that the X-ray 22 has an effective focal point having a size that matches the target resolution in the width direction.

  Specifically, when the X-ray 21 is incident on the first crystal plate 31, the X-ray 21 is subjected to Bragg diffraction (2dsin α = nλ), and subsequently passes through the first slit 41 to generate the parallel X-ray 22. And 23 and reflected. When the first crystal plate and the second crystal plate are made of the same material and use the same reflection surface, and both crystal plates are set at an angle of 2α as shown in FIG. 1, the first crystal plate Since the parallel X-rays 22 reflected by the incident light are incident on the second crystal plate 32 at an angle equal to the incident angle and the reflection angle α of the first crystal plate 31, they are similarly reflected on the second crystal plate 32, After that, go straight ahead and reach the subject. On the other hand, the parallel X-ray 22 and the parallel X-ray 23 having a different wavelength have an incident angle and a reflection angle of β in the first crystal plate 31, whereas the incident angle in the second crystal plate 32 is different from the angle γ. Become. Accordingly, the parallel X-rays 23 are not reflected by the second crystal plate 32.

  The X-rays hitting the edge of the first slit 41 are scattered and become stray light, but this stray light is cut by the second crystal plate 32 and the second slit 42.

  As a result, only the parallel X-ray 22 is generated in the spectroscope 30 shown in FIG. This means that no other parallel X-rays at that wavelength are generated. Therefore, in the spectroscope 30 shown in FIG. 1, only the monochromatic parallel X-rays 22 are generated and immediately before the object is irradiated. The cross-sectional shape is almost linear.

  Further, in the example relating to FIG. 1, two crystal plates, a first crystal plate 31 and a second crystal plate 32, are used, and X-ray reflection is performed on any crystal plate, and an X-ray surface reflection type crystal plate is used. It is functioning as. These crystal plates can be made of a material selected from the group consisting of silicon, lithium fluoride (LiF), graphite, germanium, and quartz.

  FIG. 2 is a block diagram showing another example of the parallel X-ray generator in the image measuring apparatus of the present invention. In the parallel X-ray generator shown in FIG. 2, the same X-ray generator main body 10 as that in FIG. 1 is used, and only the configuration of the spectrometer is changed.

  In the X-ray generator shown in FIG. 2 as well, the spectroscope 50 is constituted by two crystal plates 51 and 52. In this example, the crystal plates 51 and 52 are not X-ray reflection type, but transmit X-rays. It is configured as a mold (Laue mold). A first slit 41 is provided between the first crystal plate 51 and the second crystal plate 52, and a second slit 42 is provided behind the second crystal plate 52. Also in this example, when the same kind of crystal plate is used, the reflection surface of the first crystal plate 51 and the reflection surface of the second crystal plate 52 are arranged so as to form an angle 2α. . When different types of crystal plates are used, they are arranged at an angle equal to the sum of the reflection angles.

  In the example shown in FIG. 2, as in the example shown in FIG. 1, white and non-parallel X-rays 21 generated by irradiating the counter-cathode 12 with an electron beam having a predetermined shape (rectangular shape) are converted into the X-ray extraction window 17. Then, the light is made incident on the reflection surface of the first crystal plate 51 at an angle α. At this time, the X-ray 21 is diffracted according to the black diffraction formula 2dsin α = nλ and is transmitted through the first crystal plate 51. At this time, although not clearly indicated, if the black diffraction equation is satisfied when X-rays having different wavelengths λ ′ are incident at an angle β, the first crystal plate 51 can be similarly transmitted. Therefore, the X-rays 21 are still white and non-parallel X-rays only through the first crystal plate 51.

  Note that, since the X-ray 21 is generated from a rectangle having an extremely narrow effective focal point, the X-ray having the wavelength λ has a parallel component along a plane parallel to the paper surface after passing through the first slit 41. In addition, non-parallel components scattered by the first slit 41 also remain. In addition, since the X-rays having the wavelength λ ′ are diffracted in a direction different from the X-rays having the wavelength λ, they are not parallel to each other. In addition, the characteristic requested | required with respect to the 1st slit 41 is the same as the case regarding FIG.

  Next, the X-ray 22 transmitted through the first crystal plate 51 is incident on the second crystal plate 52 at an angle α, similarly diffracted according to the black diffraction formula 2dsinα = nλ, and transmitted through the second crystal plate 52. . On the other hand, the X-ray with the wavelength λ ′ does not satisfy the Bragg diffraction formula for the second crystal plate 52 and therefore does not pass through the second crystal plate 52. Therefore, the X-ray 21 generated from the X-ray generator main body 10 becomes a monochromatic and parallel X-ray 22 after passing through the second crystal plate 52.

  The non-parallel component scattered by the first slit 41 is removed by the second crystal plate 52 and the second slit 42.

  In this example, the first crystal plate 51 and the second crystal plate 52 can be composed of equiaxed crystal plates such as silicon, germanium, and lithium fluoride (LiF). A crystal plate made of the above material can also be used.

  FIG. 3 is a block diagram showing another example of the parallel X-ray generator in the image measuring apparatus of the present invention. In the parallel X-ray generator shown in FIG. 3, the X-ray generator main body 10 similar to that in FIG. 1 is used, and only the configuration of the spectrometer is changed. In this example, only the configuration of the spectrometer is shown in order to clarify the characteristics.

In the X-ray generator shown in FIG. 1, the spectroscope 30 is composed of two reflective crystal plates 31 and 32. However, in the X-ray generator of this example, the spectroscope 70 has two X-ray asymmetries. It consists of cut crystal plates 71 and 72. An asymmetric cut crystal plate is one in which the reflective surface as the crystal outer surface and the reflective surface that reflects X-rays are not parallel but have an inclined crystal surface. Thereby, the cross-sectional area (length in the tilt direction) of the generated X-ray can be changed, and the cross-sectional area of the X-ray can be enlarged or reduced.
The enlargement factor M in this case is M = {sin (α + ε) / sin (α−ε)}. Here, α is a reflection angle and ε is an asymmetric cut angle.

  In the present example, the first crystal plate 71 and the second crystal plate 72 have a reflection surface as the crystal outer surface and a reflection surface that reflects X-rays of several degrees, for example, about ε = 6 degrees (asymmetric angle). It is inclined at an angle of 6 degrees. Further, the reflection surface of the first crystal plate 71 and the reflection surface of the second crystal plate 72 are perpendicular to the paper surface and are arranged so as to form an angle of 2α with each other.

  In the spectroscope 70 shown in this example, the X-ray 21 generated from the X-ray generator main body 10 is reflected on the first crystal plate 71 in a state where the cross-sectional area (only in the long axis direction) is enlarged. Thereafter, the reflected X-ray is reflected on the second crystal plate 72 in a state where the cross-sectional area (only in the long axis direction) is further enlarged. At this time, the reflection surface of the first crystal plate 71 and the reflection surface of the second crystal plate 72 are such that only X-rays incident at a predetermined angle satisfy the Bragg diffraction condition, as in the example of FIG. Monochromatic parallel X-rays 22 can be obtained. Therefore, in this example, it is possible to obtain monochromatic parallel X-rays having an enlarged cross-sectional area as compared with X-rays generated from the X-ray generator main body 10.

  As a specific example, when Si is used as the reflective crystal plate and (440) is selected as the reflective surface, the surface interval is 0.64 mm. When λ = 0.3738Å which is the absorption edge of iodine (contrast agent) is selected as the wavelength, the reflection angle is α = 11226Å according to the Bragg equation. Therefore, the enlargement ratio M is 3.25. That is, the first crystal plate 71 is enlarged 3.25 times in the major axis direction, and then the second crystal plate 72 is further enlarged 3.25 times. As a result, it is magnified 10.56 times. Therefore, when the effective focal length of X-rays emitted from the target is 4 cm, X-rays that can be irradiated onto a subject of about 40 cm are obtained.

  Also in this example, the non-parallel component scattered by the first slit 41 is removed by the second crystal plate 52 and the second slit 42.

  FIG. 4 is a block diagram showing another example of the parallel X-ray generator in the image measuring apparatus of the present invention, and FIG. 5 is a partially enlarged view of FIG. In this example, since the spectrometer having the same configuration as that shown in FIGS. 1 to 3 can be used, only the structure of the X-ray generator in the parallel X-ray generator is shown in FIGS. Show.

  In the X-ray generator shown in FIGS. 4 and 5, the counter-cathode chamber 82 in which the rotary anti-cathode 81 is accommodated, the electron beam source chamber 84 in which the electron beam source 83 is accommodated, and the rotary anti-cathode 81 are rotated. A rotary drive unit 86 provided with a drive motor 85 for driving is formed adjacent to each other and separated by airtight structural members 82a, 84a and 86a. Further, the partition wall 82b that partitions the counter cathode chamber 82 and the electron beam source chamber 84 is provided with a through hole 82c having a size necessary for allowing the electron beam 100 emitted from the electron beam source 83 to pass therethrough. Further, each of the counter-cathode chamber 82 and the electron beam source chamber 84 is provided with vacuum exhaust ports 82d and 84d to which a vacuum exhaust device (not shown) is connected.

  Since the through hole 82c functions as an accelerating electrode (anode), subsequent electron beams pass through a space without an electric field gradient. Therefore, even if the target 91a is heated to the melting point or higher, the risk of discharge is drastically reduced.

  In the drawing, the electron beam 100 is drawn in a linear shape, but the electron beam source 83 may be a wide irradiation area, such as a diode or triode, and is emitted from these. The electron beam 100 has a relatively wide irradiation area. Therefore, although the electron beam 100 actually has a predetermined width, it is simply described in a linear form here. Therefore, the through hole 82c needs to have a predetermined size so that the electron beam 100 can pass through.

  The rotary anti-cathode 81 uses Mo (molybdenum), W (tungsten), or the like in a simple type that radiates heat by radiant heat transfer like a conventional medical valve. The method using an efficient refrigerant is taken as an example. In this case, since this portion does not reach a high temperature, a cylindrical portion 91 made of stainless steel, etc., a disc-shaped portion 92 formed so as to close one opening of the cylinder of the cylindrical portion 91, and a cylinder Rotating shaft portion 93 having a common central axis of disc-like portion 91 and disc-like portion 92 as its central axis is formed continuously and integrally, and the inside is formed in a cavity so that cooling water can flow. The inner wall surface 91a of the cylinder of the cylindrical part 91 is used as an electron beam irradiation part.

  The metal of the electron beam irradiation part is selected depending on the purpose. For example, for physics and chemistry experiments, Cr (chrome), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper), Ag (silver), Mo ( Molybdenum) is used, and metals often used for medical purposes are Mo (molybdenum) and W (tungsten).

  The rotating shaft 93 of the rotating counter cathode 81 is rotatably supported by a pair of bearing members 93 a and 93 b provided in the rotation driving unit 86. Further, a rotor 85a of the drive motor 85 is attached to the outer peripheral portion of the rotary shaft portion 93, and a stator 85b for rotationally driving the rotor 85a is attached to an airtight structure member 86a in the rotary drive portion 86. Yes.

  A rotating shaft seal member 93c that maintains a vacuum between the rotating shaft portion 93 and the airtight structure member 86a and maintains a vacuum in the counter cathode chamber 82 is provided at the base portion of the rotating shaft portion 93 near the disc-shaped portion 92. Is provided.

  Further, a fixed partition member 94 for circulating cooling water on the inner wall surface of the electron beam irradiation unit 91a is inserted and set inside the rotary counter cathode 81. The fixed partition member 94 has a cylindrical shape inside the rotating shaft portion 93, reaches the disc-like portion 92, expands the end of the tube into a disc shape, and the right end portion inside the tubular portion 91. It is extended in front of the inner wall.

  That is, the fixed partition wall 94 divides the hollow portion inside the rotary counter cathode 81 into a so-called double tube structure. The outer pipe portion 94a of the double pipe communicates with the cooling water inlet 96. The cooling water introduced from the cooling water introduction port 96 is introduced into the outer pipe portion 94a of the double pipe so as not to leak into the storage space provided with the bearing member 93b and the drive motor 85. It has become.

  Accordingly, the cooling water introduced from the cooling water introduction port 96 travels through the outer tube portion 94a of the double tube, and is folded back at the inner wall of the right end portion inside the cylindrical portion 91 to the inner tube portion 94b of the double tube. After proceeding and cooling the inner wall surface of the electron beam irradiation part 91a, it further proceeds in the inner tube part 94b and is discharged to the outside through the cooling water discharge port 97.

  An X-ray window for taking out the X-rays 110 generated when the electron beam irradiation unit 91a is irradiated with the electron beam 100 is provided in an airtight structure member 82a in the vicinity of the electron beam irradiation unit 91a of the rotary counter cathode 81. 101 is formed. An X-ray transmission film 102 made of an X-ray transmission material such as a beryllium film or an aluminum film is formed on the X-ray window 101 so that X-rays can be extracted while maintaining the vacuum in the counter-cathode chamber 82. It has become.

  The extracted X-ray 110 is collimated through the spectroscope 30, 50 or 70 as described above, and is monochromatic.

  Next, an X-ray generation method using the X-ray generator shown in FIGS. 4 and 5 will be described. In the above-described configuration, the cooling water is introduced from the cooling water introduction port 96, the rotary counter cathode 81 is rotated at high speed by the disturbance motor 85, and the electron beam is applied from the electron beam source 83 to the electron beam irradiation unit 91a of the rotary counter cathode 81. 100 is irradiated and X-rays 110 are generated. At this time, the intensity of the electron beam 100 is set such that at least a part (a few μm from the surface) or a considerable part (a few hundred μm from the surface) of the electron beam irradiation part 91a is melted. However, it is necessary to prevent the rotating counter cathode 81 from penetrating.

  By irradiating the electron beam 100 having such an intensity that at least a part of the electron beam irradiation unit 91a is melted, high-intensity X-rays can be generated from the electron beam irradiation unit 91a of the rotary counter cathode 81. Become.

  Further, in the conventional method, the electron beam irradiation part is uneven due to thermal stress, and the X-ray is absorbed and the extraction efficiency of the X-ray is lowered. Therefore, the temperature of the electron irradiation part could not be raised so much. By irradiating the electron beam 100 having a strength that melts several tens to several hundreds of μm from the surface of the beam irradiation unit 91a, the electron beam irradiation unit 91a is sequentially melted with the rotation of the rotary counter-cathode 81. A strong centrifugal force (5,000 G to 10,000 G) is applied to sequentially perform the flattening process, so that the surface of the electron beam irradiation part 91 a is always kept flat during the electron beam 100 irradiation. become. Therefore, X-ray absorption due to the roughness of 91a, which is the X-ray generation site, does not occur. As a result, the high-intensity X-ray 110 can be stably generated for a long time.

  In this example, with the melting of the electron beam irradiation part 91a, the surface roughness can be reduced to 1 μm or less, further 100 nm or less in terms of surface average roughness. That is, the surface of the electron beam irradiation part 91a can be kept extremely flat for a long time. On the other hand, in the conventional method, for example, the surface roughness of the rotary counter cathode is about 2 to 10 μm in terms of surface average roughness. Therefore, in the present invention, it can be seen that high-brightness X-rays can be stably generated based on the difference in surface roughness of the X-ray generation site 91a.

  In this example, since the electron beam irradiation part 91a is set on the inner wall surface of the cylindrical part 91 of the rotary counter cathode 81, melting occurs in the inner wall surface of the cylindrical part 91 in this case. . Therefore, the electron beam irradiation part 91a comes to exist against the centrifugal force accompanying the rotation of the rotary anti-cathode 81, and can effectively prevent outward scattering.

  In this example, the cylindrical portion 91 of the rotary anti-cathode 81 is not particularly deformed, that is, the side wall of the cylindrical portion 91 remains parallel to the rotation axis (center axis). The inner wall surface is used as an electron beam irradiation unit 91a. However, the surface contour line of the cross section of the surface of the electron beam irradiation unit 91a can be inclined with respect to the rotation axis by a comma number of degrees to a dozen degrees.

  Specifically, the side wall of the cylindrical portion 91 can be inclined inwardly at an angle of several degrees to several tens of degrees toward the rotation axis. In this case, the electron beam irradiation part 91a can exist more stably against the centrifugal force on the inner wall surface of the cylindrical part 91. Therefore, outward scattering due to melting of the electron beam irradiation portion 91a can be further effectively suppressed.

  On the other hand, the side wall of the cylindrical portion 91 can be inclined outward from the central axis. In this case, it is possible to easily take out the X-rays generated from the rotary counter-cathode 81 in a state in which the outward scattering of the electron beam irradiation unit 91a is suppressed.

  Furthermore, if the cross section of the electron beam irradiation part 91a is formed in a V-shaped groove shape or a U-shaped structure, it is possible to effectively prevent outward scattering due to melting of the electron irradiation part 91a. In this case, it goes without saying that the V-shaped or U-shaped groove width, the inclination angle, the groove depth, and the like are set to dimensions that allow X-ray extraction. Furthermore, if the groove shape is formed in advance in the same surface shape as that of the liquid portion formed by the action of centrifugal force when the surface portion melts and becomes liquid, electron beam irradiation It is possible to reduce surface deformation due to electron beam irradiation of the portion 91a.

  Further, if only the electron beam irradiation portion 91a is made of a target material determined by the type of X-rays to be generated, and its periphery is made of a material having a higher melting point and / or a material having higher thermal conductivity, the rotation It is possible to improve the cooling efficiency of the whole type counter-cathode 81 and to prevent deformation of the whole rotary type counter-cathode 81, and to stably generate high-intensity X-rays for a long time. it can.

  Furthermore, the rotating counter cathode 81, particularly the cylindrical portion 91a irradiated with the electron beam, has a double structure of a target material and a substance having a high melting point and / or a high thermal conductivity provided on the back surface of the target material. The target material is irradiated with 100 to generate X-rays 110, and a coolant for the target material is allowed to flow on the back side of the substance, thereby providing a high heat resistance effect due to the high melting point effect of the substance. And / or the effect of high cooling due to the effect of high thermal conductivity suppresses penetration of the cylindrical portion 91 of the rotating counter cathode 81 by the electron beam irradiation, and effectively suppresses leakage of the refrigerant. Will be able to.

  In addition, as said refrigerant | coolant, liquid things, such as cooling water, antifreeze, and cooling oil, can be used.

  Further, in the present invention, a depth of, for example, several microns to several hundreds of μm is melted from the surface of the electron beam irradiation unit 91a, and therefore the metal constituting the electron beam irradiation unit 91a in the counter cathode chamber 82. In some cases, the X-ray permeable membrane 102 may be contaminated. In order to prevent this, it is desirable to provide a replaceable X-ray transparent protective film on the front surface (in the vacuum) of the X-ray transparent film 102 in the counter-cathode chamber 82. As this protective film, for example, a supply roll obtained by winding a long protective film such as a Ni film, BN film, Al film, Mylar film, etc. that can withstand recoil electrons, and a protective film of this supply roll are wound. A take-up roll to be taken may be provided inside the X-ray window 101, and a protective film stretched between the supply roll and the take-up roll may be disposed on the front surface of the X-ray transmission film 102. Note that the thickness of the protective film is appropriately set in consideration of the recoil electron energy, X-ray absorption, and the like.

  In any of the specific examples described above, an electron beam is used as an energy beam, but other energy beams, for example, an energy beam such as a laser beam or ions can be used as appropriate.

  Further, in order to reduce the evaporation rate from the surface of the target, for example, a film can be provided on the target surface. Such a coating is preferably composed of a substance that absorbs less electron beam, that is, a substance having a small atomic number, has a low vapor pressure even at a high temperature, and does not dissolve in the target metal.

  Specifically, the coating film is formed on the target surface by a method such as vapor deposition. The coating film can be made of a material selected from the group consisting of BN, carbon film, graphite, diamond, DLC, Be, alumina and the like. This film is easily cracked due to the difference in expansion coefficient with a strong electron beam and the target metal, but it is pressed against the target metal by a strong centrifugal force, so it does not easily scatter out of the system. Can last for a long time.

Conventionally, a sealed tube is often used in a medical X-ray generator. In this case, since cooling is performed by radiant heat transfer, the cooling efficiency is much lower than that of the water-cooled type. On the other hand, in the method as shown in FIGS. 4 and 5, since the target is directly water-cooled and the electron beam irradiation unit 91a is dissolved, the temperature of the heat radiation surface is set higher than that of the conventional sealed tube method. It can be at least 500K hot. On the other hand, since the radiant heat is proportional to the fourth power of the absolute temperature, for example, conventionally, the temperature of the irradiated part can be raised only up to 1000K, for example, by electron beam irradiation, but in this method it can be raised to about 1500K. It becomes like this. As a result, the heat radiation effect is improved by about 5 times, that is, (1500/1000) ⁴ = 5.06, and the X-ray generator of the present system is an extremely effective means for producing the sealed tube.

  Next, the image measuring apparatus of the present invention will be described. FIG. 6 is a plan view showing a schematic configuration when the image measuring apparatus of the present invention is arranged with respect to a subject. In this example, a case where a set of image measuring devices is arranged around the subject S is shown.

  In FIG. 6, reference numeral 200 indicates an image measuring apparatus, and reference numerals 211 and 212 are a parallel X-ray generator including a spectroscope and a detector for detecting an X-ray image from the subject S, respectively. .

  In the present invention, the image measuring apparatus 200 is configured to be rotated around the subject S using a rotating means (not shown). Then, during the half rotation, the subject S is irradiated with a monochromatic parallel X-ray having a straight cross section as described above, and an image obtained thereby is detected. Images from various orientations of the subject S can be obtained. Of course, it can also be rotated once. As a result, a three-dimensional X-ray CT image can be obtained.

  In other words, the X-ray image of the subject S can be obtained simply by rotating the image measuring apparatus 200 halfway around the subject S. At this time, since monochromatic high-intensity parallel X-rays are used, if a high-resolution detector suitable for the X-rays of the present apparatus is used, the resolution of the obtained X-ray image is also increased.

  The reason why the image of the subject S can be obtained by such a half rotation is that the parallelism of the X-rays used in this application is high, and therefore the image measuring device 200 is rotated around the subject S from 0 to 180 degrees. Data (half rotation) and data when rotated from 180 degrees to 360 degrees (half rotation) are the same. Therefore, an X-ray image of the subject S can be obtained only by performing a half rotation from 0 to 180 degrees.

  In the above example, the image measuring device 200 is rotated with respect to the subject S. However, in the present invention, it is only necessary that the subject S and the image measuring device 200 rotate relatively. The subject S can be rotated instead of the image measuring apparatus 200. However, when the subject S is a human body or an animal, if the subject S is rotated at a high speed, a heavy burden is imposed on the subject S. In such a case, the image measuring device 200 is rotated as described above. It is preferable to make it. The relative rotation may be performed at a constant speed, or the speed may be changed as necessary.

  In the present invention, the measurement speed can be increased by attaching a plurality of image measuring devices 200. FIG. 7 is a plan view showing a schematic configuration when the image measuring device of the present invention is arranged with respect to a subject. In this example, a case where four sets of image measuring devices are arranged at equal angular intervals (45 degree intervals) around the subject S is shown.

  In FIG. 7, reference numerals 200A, 200B, 200C and 200D indicate image measuring apparatuses, and reference numerals 211, 221, 231 and 241 are parallel X-ray generators including a spectroscope, 212, 222, 232, And 242 are detectors for detecting an X-ray image from the subject S.

  FIG. 7 shows the arrangement at the start of photographing. When four sets of image measuring devices start measurement simultaneously and 200A reaches the 200B position, 200B reaches the 200C position, 200C reaches the 200D position, 200D reaches the 200A position, and 45 degrees respectively. Take an image of the minute. Therefore, a half-round image is obtained as a whole. That is, in this case, each image measuring device only needs to measure 45 degrees, so that the measurement time is ¼ compared to the case of FIG.

  Although not shown, the number of image measuring devices must be an odd number when measuring one round (360 degrees). For example, when three sets of image measuring devices are placed, they are arranged at intervals of 120 degrees. The case where an even number, for example, two units are arranged will be described with reference to FIG. 6. The two units are arranged at positions rotated 180 degrees with respect to each other. As a result, an X-ray generator 211 including a spectrometer and a detector 212 are arranged. Since the same place will be closed and it will be physically impossible to place, even numbers cannot be placed.

  FIG. 8 shows an example in which the one-dimensional detector of FIG. 7 is a large two-dimensional detector represented by an imaging plate (IP). After shooting, it is carried to an IP reader and digitized. FIG. 7 is a half-rotation imaging apparatus, and 211, 221, 231 and 241 are parallel X-ray generators including a spectroscope. The slits 251 to 254 arranged at the opposite positions are slits for allowing only the target X-rays to pass through, and all other than the slits prevent X-ray irradiation unnecessary for the IP by the X-ray shielding material. Further, as with conventional CT apparatuses, it is necessary to use weights 261 to 264 for balancing the centrifugal force accompanying the rotational movement during imaging.

  The IP needs to be fixed to a fixed cylindrical drum 250 at the time of photographing. However, 241 approaches 251 just before the end of photographing, and 241 comes to the place of 251 at the end of photographing. It should be noted that the radius of the drum 250 that fixes the IP needs to have a sufficiently large radius so as not to contact the 241.

  The image measurement method and the image measurement apparatus of the present invention are not particularly limited, but can be used for CT imaging of various organisms including the human body. In such a case, according to the present invention, a target high-resolution X-ray image can be obtained by parallel X-ray irradiation for an extremely short time.

  In addition, since the image measurement method and image measurement apparatus of the present invention can generate monochromatic parallel X-rays, large absorption can be achieved by adjusting the wavelength of the parallel X-rays to the high energy side of the absorption edge of the contrast agent. And the amount of the contrast agent can be greatly reduced or / or the exposure dose can be further reduced. Therefore, when performing CT imaging on various organisms including the human body, the burden on the organism can be reduced. Furthermore, since imaging can be performed for a short time, it is possible to significantly reduce the respiratory stop time of living organisms and to greatly reduce the generation of noise associated with the breathing.

  Of course, the image measurement method and the image measurement apparatus of the present invention can be used not only in the medical and life science fields but also in various fields such as non-destructive inspection.

  Moreover, the detector in the image measuring device of the present invention can be constructed from a general purpose one.

  The present invention has been described in detail with specific examples. However, the present invention is not limited to the above contents, and various modifications and changes can be made without departing from the scope of the present invention.

It is a block diagram which shows an example of the parallel X-ray generator in the image measuring device of this invention. It is a block diagram which shows the other example of the parallel X-ray generator in the image measuring device of this invention. It is a block diagram which shows the other example of the parallel X-ray generator in the image measuring device of this invention. It is a block diagram which shows the other example of the parallel X-ray generator in the image measuring device of this invention, FIG. 5 is a partially enlarged view of FIG. 4. It is a top view which shows schematic structure in an example at the time of arrange | positioning the image measuring device of this invention with respect to a to-be-photographed object. It is a top view which shows schematic structure in the other example at the time of arrange | positioning the image measuring device of this invention with respect to a to-be-photographed object. It is a top view which shows schematic structure in the modification of the image measuring apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 X-ray generator main body 11 Vacuum vessel 12 Counter cathode 13 Cathode 14 Weinert 15 Grid 16 Anode 17 X-ray extraction window 20 Electron beam 21 (white and non-parallel) X-ray 22 Parallel X-ray 30 Spectrometer 31 First (X (Line surface reflection type) crystal plate 32 second (X-ray surface reflection type) crystal plate 41 first slit 42 second slit 50 spectroscope 51 first (X-ray transmission type) crystal plate 52 second ( X-ray transmission type) Crystal plate 61 Monochromatic parallel X-ray
70 Spectrometer 71 First (X-ray surface reflection type) asymmetric cut crystal plate 72 Second (X-ray surface reflection type) asymmetric cut crystal plate 81 Rotating anti-cathode 82 Anti-cathode chamber 83 Electron beam source 84 Electron beam source Chamber 85 Drive motor 86 Rotation drive part 91 Cylindrical part 91a Electron beam irradiation part 100 Electron beam 110 X-ray 200 Image measuring device 211 Parallel X-ray generator 212 Detector 200A, 200B, 200C, 200D Image measuring device 211, 221 231 and 241 X-ray generators including a spectroscope 212, 222, 232, 242 Detector 250 Imaging plate (IP)
251 252 253 254 Slit 261 262 263 264 Weight

Claims (35)

Irradiating the surface of the target with energy rays from a predetermined energy ray source and generating X-rays from the target so as to have a size corresponding to the maximum length of the subject;
Making the X-ray incident on a spectrometer, selecting a wavelength and a wavelength width from the X-ray, and generating parallel X-rays that have become parallel light;
Irradiating the parallel X-rays while rotating around the subject, and detecting an X-ray image obtained from the subject;
An image measurement method comprising the steps of:   The image measurement method according to claim 1, wherein the X-ray image is obtained by rotating the parallel X-ray around the subject with less than a half rotation.   The X-rays are converted into the parallel X-rays by passing through one slit having a width substantially the same as the width direction of the energy rays to be irradiated to the target. Item 3. The image measurement method according to Item 1 or 2.   The image measuring method according to claim 1, wherein the spectroscope includes a crystal plate.   The image measurement method according to claim 4, wherein the crystal plate is a crystal plate made of at least one material selected from the group consisting of silicon, lithium fluoride (LiF), graphite, germanium, and quartz. .   6. The image measuring method according to claim 4, wherein two or more crystal plates are used in combination.   The image measurement method according to claim 6, wherein at least one of the crystal plates functions as an X-ray surface reflection type crystal plate.   The image measurement method according to claim 6 or 7, wherein at least one of the crystal plates functions as an X-ray transmission type (Laue type) crystal plate.   The image measuring method according to claim 4, wherein the crystal plate includes an X-ray multilayer reflector.   The image measurement method according to claim 4, wherein the crystal plate includes an asymmetric cut crystal plate.   The image measurement method according to claim 1, wherein the X-ray is transmitted through an absorption plate for removing unnecessary long wavelength components before entering the spectroscope.   The image measuring method according to claim 1, further comprising a step of forming a film on the surface of the target and reducing an evaporation rate from the target surface.   The image measurement method according to claim 12, wherein the coating is made of a material selected from the group consisting of BN, carbon film, graphite, diamond, DLC, Be, and alumina.   The image measurement method according to claim 1, wherein the target is a fixed type.   14. The target according to claim 1, wherein the target constitutes a rotary anti-cathode, and the energy ray is applied to a portion existing against a centrifugal force caused by the rotation of the rotary anti-cathode. The image measuring method as described in 2.   The image measurement method according to claim 15, wherein the energy beam is applied to the target with an intensity that melts at least a part of the target irradiation unit.   The target is a plurality of targets, and the plurality of targets are irradiated with energy rays to generate a plurality of X-rays having a size corresponding to the entire length of the incident side of the subject. The image according to any one of claims 1 to 16, wherein an X-ray image is generated and detected from the subject while rotating the plurality of X-rays relatively around the subject. Measuring method. A target for generating X-rays by energy beam irradiation;
An energy ray source for generating energy rays for generating X-rays from the target so that the X-rays have a size corresponding to the maximum length of a subject;
A spectrometer for making the X-ray incident, selecting a wavelength and a wavelength width from the X-ray, and generating parallel X-rays that have become parallel light;
A rotational drive system for generating a relative rotational movement of the parallel X-rays around the subject;
A detector for detecting an X-ray image obtained by irradiating the subject with the parallel X-ray;
An image measuring device comprising:   The image measurement apparatus according to claim 18, wherein the rotation drive system is configured to rotate the parallel X-rays at least relatively half a rotation around the subject.   The image measuring apparatus according to claim 18, further comprising at least one slit for making a cross section of the X-ray straight.   21. The image measuring apparatus according to claim 18, wherein the spectroscope includes a crystal plate.   The image measuring apparatus according to claim 21, wherein the crystal plate is a crystal plate made of at least one material selected from the group consisting of silicon, lithium fluoride (LiF), graphite, germanium, and quartz. .   The image measuring apparatus according to claim 21 or 22, wherein two or more crystal plates are used in combination.   24. The image measuring apparatus according to claim 23, wherein at least one of the crystal plates functions as an X-ray surface reflection type crystal plate.   25. The image measuring apparatus according to claim 23, wherein at least one of the crystal plates functions as an X-ray transmission type (Laue type) crystal plate. 26. The image measuring apparatus according to claim 21, wherein the crystal plate includes an X-ray multilayer reflector.   The image measuring apparatus according to claim 21, wherein the crystal plate includes an asymmetric cut crystal plate.   The image measuring apparatus according to any one of claims 18 to 27, further comprising an absorption plate for removing unnecessary long wavelength components before the X-ray is incident on the spectrometer.   29. The image measuring apparatus according to claim 18, further comprising a film formed to reduce an evaporation rate from the surface of the target.   31. The image measuring apparatus according to claim 30, wherein the film is made of a material selected from the group consisting of BN, carbon film, graphite, diamond, DLC, Be, and alumina.   31. The image measuring device according to claim 18, wherein the target is a fixed type.   31. The target is configured as a rotary anti-cathode, and the energy beam is configured to irradiate a portion existing against a centrifugal force caused by the rotation of the rotary counter-cathode. The image measuring device according to any one of the above.   The image measurement apparatus according to claim 32, wherein the energy beam is configured to irradiate the target with an intensity that melts at least a part of the target irradiation unit.   The target is a plurality of targets, and the plurality of targets are irradiated with energy rays from the energy ray source, and have a size corresponding to the entire length of the incident side of the subject. X-rays are generated, an X-ray image is generated from the subject while the plurality of X-rays are rotated around the subject by the rotation drive system, and detected by the detector. 34. The image measuring device according to any one of claims 18 to 33.   35. The image measuring apparatus according to claim 18, wherein the parallel X-ray is used for medical purposes.

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