JP3972986B2 - Contrast X-ray tube, X-ray contrast apparatus and X-ray contrast method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a contrast X-ray tube used in the medical field and the like, an X-ray contrast apparatus using the same, and an X-ray contrast method .
[0002]
[Prior art]
An angiographic transmission X-ray apparatus is a medical analyzer that must be in the clinical medical field as a low-cost and highly convenient disease diagnosis apparatus. However, in recent years, with the advancement of medical technology, a high-resolution angiographic X-ray apparatus has been demanded. For example, it is necessary to observe minute arterial arteries in order to diagnose angina pectoris, and regenerative medicine research requires a high-resolution angiographic X-ray apparatus of 10 μm or less.
As explained in Non-Patent Document 1, regenerative medicine has conventionally meant artificial joints, blood transfusions, skin transplants, organ transplants, etc., but in recent years, stem cells have been differentiated into desired organs, Regenerative medicine that treats intractable diseases with this organ has attracted attention. Since the organ in this regenerative medicine is an organ regenerated from its own cells, there is no concern about rejection as in the case of conventional transplantation of another person's organ. As described above, regenerative medicine by stem cell differentiation is the most noticeable medical technology in the future together with gene therapy, and intense research and development competition is conducted all over the world.
[0003]
Regenerative medicine based on stem cell differentiation has only just begun research, and will require an enormous amount of research and development in the future in order to be utilized for treatment. In particular, the process of differentiation has not been fully elucidated, and in order to elucidate this process, it is essential to observe the growth process of minute blood vessels during the differentiation process.
[0004]
However, the conventional angiography method using transmitted X-rays uses iodine as an angiographic contrast agent from the viewpoint of biological safety. However, since the wavelength of the X-ray to be used cannot be appropriately selected, the blood vessel portion and the portion other than the blood vessel are not used. The intensity ratio of transmitted X-rays, that is, the contrast is not sufficient. In particular, the contrast of a blood vessel image in the deep part of the tissue decreases as it passes through the tissue, and the human body can obtain a resolution of about 100 μm at most. For this reason, conventionally, when it is necessary to observe a fine blood vessel image as described above, synchrotron radiation has to be used.
[0005]
However, as is well known, synchrotron radiation accelerates electrons to high energy and uses radiation light accompanying the braking of the electrons, so although X-rays with appropriate wavelengths can be selected, It requires enormous energy, is expensive and is not convenient. For example, synchrotron radiation equipment is expensive, so one equipment is shared for multiple purposes. However, the machine time allocated to one person is short, and it cannot be operated at all in the summer when power is insufficient. For this reason, research and development of regenerative medicine is a cause of delay.
[0006]
[Non-Patent Document 1]
http: // cont. trc-net. ne. jp / basics / 01_02. html 2003/05/14
[Patent Document 1]
Japanese Patent Application No. 2001-110783 [0007]
[Problems to be solved by the invention]
The present invention In view of the above problems, the contrast by transmitting X-rays can contrast with high resolution, it is an object to provide a low-cost and simple X-ray imaging method. Also necessary for this method, a low-cost, and convenience is the X-ray tube for high have imaging and other object to provide an X-ray contrast device using the same.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the contrast X-ray tube of the present invention is a contrast X-ray used for high-resolution subject imaging by sandwiching a subject doped with iodine as a contrast agent between a contrast X-ray source and an X-ray imager. A tubular carbon cold cathode, a rod-shaped counter cathode made of cerium, and a discharge gas that fills a space including the annular carbon cold cathode and the counter cathode. The cathode material is evaporated to form a plasma, a characteristic X-ray is generated from the plasma, the object is transmitted by the characteristic X-ray, and the contrast resolution of the transmitted X-ray intensity obtained at that time is less than 50 μm. It is characterized by.
According to this X-ray tube, the Kα characteristic X-ray of cerium can be easily generated at a very low cost. The photon energy of the Kα characteristic X-ray of cerium is in the vicinity of the K absorption edge energy of iodine, which is an angiographic contrast agent, and is slightly large, so it is absorbed very well by iodine. Therefore, if the X-ray tube of the present invention is used for X-ray transmission angiography using iodine as a contrast agent, extremely fine blood vessels can be imaged.
[0010]
Further, the contrast X-ray tube of the present invention requires a constant pressure gas to cause a gas discharge, but is an assembly in which a constant pressure gas is introduced into a container containing the cathode and the counter cathode. It may be a mold.
According to this X-ray tube, X-rays can be extracted in the direction opposite to the acceleration direction of electrons, so that the number of braking X-rays is reduced, X-ray pulses with high X-ray monochromaticity and extremely high intensity can be obtained.
[0011]
The present invention is also an X-ray contrast apparatus comprising a contrast X-ray tube and an X-ray imager arranged with a subject doped with iodine as a contrast agent, wherein the contrast X-ray tube is annular. It has a carbon cold cathode, a rod-like counter cathode made of cerium, and a discharge gas that fills the space including the annular carbon cold cathode and the counter cathode, and vaporizes the counter cathode material to form plasma. Then, a characteristic X-ray of cerium is generated from this plasma, and the characteristic X-ray from the contrast X-ray tube passes through the subject, and the contrast agent is doped in the subject by the contrast of the transmitted X-ray intensity. Can be imaged with a resolution of 50 μm or less.
[0012]
In the above configuration, the contrast X-ray tube is preferably an assembly type in which a vacuum vessel containing a cathode and a counter cathode is evacuated and used. The X-ray imager is preferably an X-ray photographic film.
[0013]
In addition, the X-ray contrast method of the present invention uses a contrast X-ray tube and an X-ray imager arranged with a subject doped with iodine as a contrast agent, and the contrast X-ray source is an annular carbon A cathode, a rod-like countercathode made of cerium, and a discharge gas that fills the space including the annular carbon cold cathode and the countercathode, evaporating the countercathode material by gas discharge to form plasma; A contrast agent which generates characteristic X-rays of cerium from the plasma, transmits the characteristic X-rays from the contrast X-ray tube to the subject, and is doped in the subject by contrast of transmitted X-ray intensity. Is imaged with a resolution of 50 μm or less.
[0014]
In the above configuration, the X-ray imager is preferably an X-ray photographic film.
[0015]
As described above, using the contrast X-ray tube of the present invention , an X-ray contrast apparatus using the same, and an X-ray contrast method , it is possible to contrast a fine blood vessel of 50 μm or less, and clinical or regenerative medicine. It is useful in research fields such as In particular, in the research field of regenerative medicine, since the device is low-cost and highly convenient, many researchers can proceed with research in parallel without being restricted by the machine time of the device, This can accelerate the speed of regenerative medicine research.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram schematically showing the high-resolution angiography method of the present invention. The high-resolution angiography method of the present invention is different from the conventional angiography method using transmitted X-rays only in using a cerium Kα characteristic X-ray as an X-ray source, and the others are the same. That is, as shown in the figure, in the method of the present invention, an X-ray source 2 and an X-ray imager 3 such as an X-ray photographic film are disposed with a subject 1 doped with iodine as a contrast medium in blood, and transmitted X A blood vessel is imaged using the contrast of the line intensity.
[0017]
FIG. 2 is a graph showing the X-ray photon energy dependence of the mass absorption coefficient near the K absorption edge of iodine. In general, the mass absorption coefficient of a substance consisting of a single atom rises sharply at the photon energy peculiar to the atom with respect to the increase in photon energy (called the K absorption edge when it corresponds to excitation of K-shell electrons), and thereafter Decrease exponentially. Therefore, if X-rays having energy larger than the absorption edge energy of the contrast agent and having energy as close as possible to the absorption edge of the contrast agent are used, the proportion of X-rays absorbed by the contrast agent increases, and the blood vessel portion and the blood vessel portion are increased. Since the contrast of transmitted X-rays other than the above becomes high, high-resolution angiography can be obtained.
[0018]
As shown in the figure, the cerium Kα characteristic X-ray (34.6 keV) is very close to the K absorption edge energy (33.2 keV) of iodine, and according to the method of the present invention, the contrast of the transmitted X-ray is increased. .
As shown in the figure, the conventional measuring method using tungsten as an anti-cathode material has a low contrast because the tungsten Kα characteristic X-ray (58.7 keV) is away from the K absorption edge of iodine. Conventionally, an X-ray source using molybdenum as an anti-cathode material has also been used. However, the Kα ray of molybdenum is hardly absorbed because its energy is lower than the absorption edge of iodine, and is a contrast image by braking X-rays exclusively. Since the braking X-ray is an X-ray source having a continuous wavelength, a sufficient contrast cannot be obtained.
[0019]
Next, a high-resolution angiographic X-ray tube used in the method of the present invention will be described.
FIG. 3 is a diagram showing a configuration of a main part of the X-ray tube for high resolution angiography according to the present invention. FIG. 3A shows an X-ray tube having a hot cathode and a plate-like counter-cathode made of cerium that collides with acceleration of thermoelectrons generated from the hot cathode. FIG. 3B shows an X-ray tube having an annular hot cathode and a rod-like counter cathode made of cerium that collides with thermionic electrons generated from the annular hot cathode being accelerated. FIG. 3C shows an X-ray tube having an annular carbon cold cathode, a rod-like counter cathode made of cerium, and a discharge gas, and a rod-like counter-cathode material made of cerium is removed by gas discharge. A plasma X-ray tube is shown that evaporates to form a plasma and generates characteristic X-rays from the plasma.
[0020]
In FIG. 3A, an X-ray tube 31 has a hot cathode 32 and a plate-like counter cathode 33 made of cerium that collides with the acceleration of thermoelectrons generated from the hot cathode 32, which is a filament. . The counter cathode 33 made of cerium is embedded and fixed in a metal block 34 having good conductivity and heat conductivity or a metal block 34 having a water cooling pipe. A high voltage is applied between the hot cathode 32 and the metal block 34 to accelerate the thermal electrons to an energy higher than the K absorption edge of cerium to generate cerium Kα characteristic X-rays. X-rays are extracted laterally (35) with respect to the acceleration direction of the thermal electrons. This X-ray tube 31 also generates some braking X-rays, but there is no problem in angiography if the required resolution is about 10 μm.
[0021]
In FIG. 3B, an X-ray tube 36 has an annular hot cathode 37 that is an annular filament, and a rod-like counter cathode 38 made of cerium that collides with acceleration of thermoelectrons generated from the annular hot cathode 37. is doing. A high voltage is applied between the hot cathode 32 and the metal block 34 to accelerate the thermal electrons to an energy higher than the K absorption edge of cerium to generate cerium Kα characteristic X-rays.
Since the X-ray tube 36 extracts X-rays from the direction (39) opposite to the acceleration direction of the thermal electrons, the braking X-rays are reduced and the monochromaticity is high.
[0022]
In FIG. 3C, a plasma X-ray tube 40 is used for gas discharge filled in a space including an annular carbon cold cathode 41, a rod-like counter cathode 42 made of cerium, and the carbon cold cathode 41 and the counter cathode 42. Gas. A capacitor is connected between the carbon cold cathode 41 and the counter cathode 42, electric charge is stored in the capacitor, and gas discharge is caused in the vicinity of the carbon cold cathode 41, whereby the electric charge stored in the capacitor is instantaneously discharged, and cerium. The rod-like counter cathode 42 made of is evaporated to generate weakly ionized plasma made of cerium. Electrons collide with the plasma and are braked to generate X-rays. The intensity of the Kα characteristic X-rays of cerium propagating along the long axis direction of the plasma (denoted by reference numeral 43) is increased by stimulated emission, and the braking X-rays propagating along the long axis direction of the plasma (43) Absorbed and attenuates strength. Therefore, a cerium Kα characteristic X-ray pulse having an extremely strong intensity and excellent monochromaticity is generated. This type of X-ray tube using plasma as an X-ray generating medium is called a plasma X-ray tube (see Patent Document 1).
[0023]
Next, Example 1 will be described.
Example 1 demonstrates that high-resolution angiography can be performed by the method of the present invention and the X-ray tube of the present invention.
Rabbit heart angiography was compared with angiographic agents using iodine plastic-coated microspheres or cerium plastic-coated microspheres. The X-ray source shown in FIG. 3A was used as the X-ray source.
FIG. 4 is a transmission X-ray photograph showing angiography of a rabbit heart with different angiographic agents. (A) shows the case where iodine plastic-coated microspheres are used, and (b) shows the case where cerium plastic-coated microspheres are used.
As is apparent from FIG. 4A, when iodine is used as a contrast agent, cerium Kα characteristic X-rays are well absorbed by iodine, so that a thin coronary artery can be clearly imaged. In addition, the white line at the lower left of the figure is a contrast with a tungsten wire having a diameter of 100 μm inserted into the heart in order to confirm the resolution.
On the other hand, as is apparent from FIG. 4B, when cerium is used as the contrast agent, the photon energy of the cerium Kα characteristic X-ray is lower than the absorption edge energy of cerium, and the cerium Kα characteristic X-ray is almost absorbed by cerium. As a result, the annular artery is hardly imaged.
From this example, it can be seen that when iodine is used as a contrast agent, angiography with extremely high contrast can be performed by using cerium Kα characteristic X-rays.
[0024]
Next, Example 2 will be described.
Example 2 demonstrates that the method of the present invention and the X-ray tube can clearly contrast even a deep blood vessel.
Angiography of the dog's heart was performed using plastic microspheres coated with iodine as an angiographic agent, and an acrylic plate (thickness: 50 mm) was used as a medium for simulating the absorption and scattering of X-rays in the living body. Other implementation conditions are the same as in Example 1.
FIG. 5 is a transmission X-ray photograph showing angiography of the heart of a dog simulating the depth of blood vessels in the living body. FIG. 5 (a) shows the case where the extracted dog heart is directly angiographed, and FIG. 5 (b) shows the case where an acrylic plate having a thickness of 50 mm is inserted between the extracted dog heart and the X-ray imager. Yes.
As is clear from FIG. 5A, a fine coronary artery can be clearly imaged. Further, as is clear from FIG. 5B, even when an acrylic plate is inserted, a fine coronary artery can be clearly imaged. In addition, the white line at the lower left in FIGS. 5A and 5B is a contrast image formed by a tungsten wire having a diameter of 100 μm inserted into the heart in order to confirm the resolution. The bar-like contrast in the upper right is a contrast of the support rod used for fixing the dog's heart during photographing.
It can be seen that even if an acrylic plate is inserted, that is, even if the blood vessel to be contrasted is a blood vessel in the deep part of the living body, contrast can be contrasted without attenuation of contrast. This is because the X-ray wavelength is monochromatic.
[0025]
Next, Example 3 will be described.
Example 3 demonstrates that an angiography having a diameter of several tens of μm or less is possible according to the method and the X-ray tube of the present invention.
Microvessels in the lower limbs of rabbits were imaged. Other implementation conditions are the same as in Example 1.
FIG. 6 is a transmission X-ray photograph showing a contrast of a fine blood vessel of a rabbit ear. In the figure, the white line on the upper right is a contrast of a tungsten wire having a diameter of 50 μm. It can be seen that blood vessels with a diameter of several tens of μm or less can be imaged by comparing with this tungsten wire contrast.
FIG. 7 is a transmission X-ray photograph showing the contrast of the microvessel of the lower leg of the rabbit. FIG. 7 (a) is a diagram showing an imaging of a fine blood vessel in a lower leg of a rabbit, and (b) is an enlarged view of (a). The white line slightly below the center is an image of a tungsten wire with a diameter of 100 μm. It can be seen that blood vessels with a diameter of several tens of μm or less can be imaged by comparing with this tungsten wire contrast.
[0026]
The X-ray tube used in the above embodiment is the X-ray tube having the configuration shown in FIG. 3A, but the X-ray tube having the configuration shown in FIGS. 3B and 3C is used. Furthermore, since the monochromaticity of X-rays is high, it is clear that when these X-ray tubes are used, a high-resolution contrast of 10 μm or less can be obtained.
[0027]
【The invention's effect】
As understood from the above description, according to the present invention, high-resolution angiography can be performed. Therefore, the present invention is extremely useful when used in the clinical medical field or the medical research field such as regenerative medicine that requires observation of fine blood vessels.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a high-resolution angiography method of the present invention.
FIG. 2 is a graph showing the X-ray photon energy dependence of the mass absorption coefficient near the K absorption edge of iodine.
FIG. 3 is a schematic view showing a configuration of a main part of the X-ray tube for high resolution angiography according to the present invention.
FIG. 4 is a transmission X-ray photograph showing angiography of a rabbit heart with different angiographic agents.
FIGS. 5A and 5B are transmission X-ray photographs showing angiography of a dog's heart simulating the depth of blood vessels in a living body, wherein FIG. 5A is a direct angiogram of the extracted dog's heart, and FIG. A case where an acrylic plate having a thickness of 50 mm is inserted between the heart of the dog and the X-ray imager is shown.
FIG. 6 is a transmission X-ray photograph showing a contrast of a fine blood vessel of a rabbit ear.
FIG. 7 is a transmission X-ray photograph showing an imaging of a microvessel in the lower leg of a rabbit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Subject 2 X-ray source 3 X-ray imager 31 X-ray tube 32 Hot cathode 33 Counter cathode 34 made of cerium Metal block 35 X-ray extraction direction 36 X-ray tube 37 Annular hot cathode 38 Rod-like counter cathode 39 made of cerium X-ray Extraction direction 40 X-ray tube 41 Annular carbon cold cathode 42 Bar-shaped counter cathode 43 made of cerium X-ray extraction direction

Claims (7)

A contrast X-ray tube used for high-resolution subject imaging by sandwiching a subject doped with iodine as a contrast agent between a contrast X-ray source and an X-ray imager,
An annular carbon cold cathode, a rod-like counter cathode made of cerium, and a discharge gas that fills a space including the annular carbon cold cathode and the counter cathode,
The counter-cathode material is evaporated by gas discharge to form a plasma, and characteristic X-rays are generated from the plasma.
A contrast X-ray tube, wherein the object is transmitted by the characteristic X-ray, and the contrast resolution of the transmitted X-ray intensity obtained at that time is less than 50 μm. The angiographic X-ray tube, characterized in that the is an assembly type used by introducing the gas in a space containing carbon cold cathode and the anticathode, X-ray tube for imaging of claim 1. An X-ray contrast apparatus comprising a contrast X-ray tube and an X-ray imager arranged with a subject doped with iodine as a contrast agent,
The contrast X-ray tube has an annular carbon cold cathode, a rod-like counter cathode made of cerium, and a discharge gas that fills a space including the annular carbon cold cathode and the counter cathode. The counter-cathode material is evaporated to form a plasma, and cerium characteristic X-rays are generated from the plasma.
Characteristic X-rays from the contrast X-ray tube pass through the subject,
An X-ray contrast apparatus characterized in that a contrast agent doped on the subject can be imaged with a resolution of less than 50 μm by contrast of transmitted X-ray intensity. 4. The X-ray contrast apparatus according to claim 3 , wherein the contrast X-ray tube is an assembly type in which a vacuum vessel containing a cathode and a counter cathode is evacuated and used. The X-ray imaging apparatus according to claim 3 , wherein the X-ray imager is an X-ray photographic film. An X-ray contrast method using a contrast X-ray tube and an X-ray imager arranged with an object doped with iodine as a contrast agent,
The contrast X-ray tube has an annular carbon cold cathode, a rod-like counter cathode made of cerium, and a discharge gas that fills a space including the annular carbon cold cathode and the counter cathode.
The counter-cathode material is evaporated by gas discharge to form a plasma, and cerium characteristic X-rays are generated from the plasma.
Transmit characteristic X-rays from the contrast X-ray tube to the subject,
An X-ray contrast method characterized by contrasting the contrast agent doped on the subject with a contrast of transmitted X-ray intensity with a resolution of less than 50 μm. The X-ray imaging method according to claim 6 , wherein the X-ray imager is an X-ray photographic film.

Images