JPH07112985B2 - Microglass for radiotherapy and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microglass for radiotherapy and a method for producing the same, and more specifically, a microglass for radiotherapy for locally treating an affected area having cancer, tumor, etc. The present invention relates to a method for manufacturing fine glass.

[0002]

2. Description of the Related Art Generally, as a method for treating cancer, a method of excising an affected part of cancer by surgery, a method of administration, a method of enhancing immunity, a sequence of DNA of cancer cells by radiation is used. How to damage the
Although various methods such as a method of heating an affected area have been adopted, none of them is decisive for the manifestation of the effect at present.

In view of these points, a method of dispersing various radioactive particles in a medium and injecting them into an artery leading to a cancer affected area is being developed in radiotherapy for deep cancer. According to such a method, the radiation particles injected into the patient's body are embedded in the capillaries leading to the cancer cells, so that only the cancer cell portions can be irradiated with radiation. As the medium, fine glass is used because of its excellent ability to fix radioactive particles.

As such a technique, there is, for example, Japanese Patent Publication No. 62-501076 by Day et al. Of Missouri University, USA.
This Japanese Patent Publication No. 62-501076 discloses a Y ₂ O ₃ —Al ₂ O ₃ —SiO ₂ system having a diameter of 20 to ₃ by a general melting method for glass production.
By making 0 mm glass spheres and irradiating them with neutrons, only ⁸⁹ Y is activated to become β-ray emitter ⁹⁰ Y with a half-life of 64.1 hours, and when glass spheres are injected into liver cancer via blood vessels, It is disclosed that only cancer can be irradiated and treated.

The glass material used in this method is one in which the radioactive isotope ⁹⁰ Y is uniformly dispersed throughout the glass, and these stable isotopes ⁸⁹ Y are used in the glass manufacturing process.
This glass is produced by simultaneously melting yttria containing Y as a raw material powder, and yttrium is activated by irradiation with thermal neutrons.

This method has the following advantages. (A) Glass is not radioactive before neutron irradiation, so it is easy to handle. (B) The glass of the above diameter reaches the place of liver cancer through the hepatic artery, stays in the blood vessels around it, and does not proceed further. (C) Beta rays have a short reach, so they do not damage normal tissues around them. Since (D) ⁹⁰ Y has a short half-life, irradiation is not continued for a long time. (E) Since the glass of the above system is chemically stable,
⁹⁰ Y does not elute and migrate elsewhere.

However, in spite of the above advantages, the half-life of ⁹⁰ Y used in this method is too short, so that the radiation is attenuated between the time the glass receives neutron irradiation and the time it is injected into the body. It has the drawback of being easy to do. Moreover, it is difficult to produce a glass containing a large amount of ⁸⁹ Y by the usual melting method.

On the other hand, non-radioactive ³¹ P becomes a β-ray emitter ³² P with a half-life of 14.3 days due to neutron irradiation, and unlike ⁹⁰ Y, a very large radioactive decay occurs between neutron irradiation and injection into the body. It has the property that it is not shown, and that it does not continue irradiation for too long in the body. Therefore, in view of such a point, in the above Japanese Patent Publication No. 62-501076, the Mg
O-Al ₂ O ₃ is used as a radiation therapeutic micro glass also -SiO ₂ -P ₂ O ₅ -based glass.

However, even in the case of this glass, it was difficult to produce a glass containing a large amount of ³¹ P. In particular, the glass composition containing P ₂ O ₅ had a composition ratio of vitrification of about 5%, which was lower than that of the glass composition containing Y ₂ O ₃ .

Further, in general, glass containing P ₂ O ₅ has a new problem that it is easily dissolved in water and its stability in the body is poor.

In particular, the glass bulb for radiotherapy containing ³² P has a half-life of 14.3 days, which is practical and has a strong desire to be used for treatment. Was no longer available.

Moreover, according to the method of Japanese Patent Publication No. 62-501076, as shown in FIG. 4, since the radioactive isotope 2a is uniformly dispersed in the fine glass body 1a, the fine glass body 1a is The β-ray irradiation from the inside of the glass bulb causes attenuation in the glass layer, and ³² P and ⁹⁰ Y capable of effectively irradiating the affected area of cancer are limited.

The present invention has been made in order to solve the above problems, and has a high therapeutic effect such as effective use of β-rays, can suppress the elution of radioactive ions in the body, and can halve it. It is an object of the present invention to provide a microglass for radiotherapy having various advantages that it is unlikely to be subject to a time limitation determined by the period.

[0014]

The present invention has been made to solve such a problem, and means for solving the problem is to irradiate the surface of the fine glass body 1 with neutron rays. This is because the ion 2, which contains phosphorus that can be turned into a main component, has been implanted.

[0015]

[Function] That is, in order to inject ions having phosphorus as a main component which can be activated by neutron irradiation as described above,
When implanting ions accelerated by a predetermined voltage into the surface of the micro glass body 1, the depth of ion implantation depends on the ion species and the type of the micro glass body 1 serving as a matrix, but is several nm to several thousand nm. Can be controlled.

Therefore, when the implanted atoms are activated by irradiation with thermal neutrons, the ion-implanted radioisotopes are distributed at a depth of several nm to several thousand nm from the glass surface as described above. Therefore, the radiation is irradiated from the vicinity of the glass surface, the attenuation of the radiation in the glass is suppressed, and the affected area of the cancer can be effectively irradiated with the radiation.

[0017]

EXAMPLES Examples of the present invention will be described below. Example 1 This example is an example of a micro glass for radiotherapy as an example. As shown in FIG. 1, in the micro glass 3 for radiotherapy of the present embodiment, P ⁺ ions 2 as an example of a radioisotope are implanted into the entire surface of a spherical micro glass body 1 made of high-purity silica. It consists of a structure. In addition to the above-mentioned high-purity silica, the fine glass body 1 contains a minute amount of impurities shown in Table 1 below.

[0018]

[Table 1]

Example 2 This example is an example of a manufacturing method for manufacturing the micro glass for radiotherapy of Example 1 above.

(A) Fabrication of micro glass body The micro glass body 1 made of high-purity silica (SiO ₂ ) is
It was produced as follows. That is, a liquid of SiCl ₄ (melting point 58 ° C.) was vaporized at 80 ° C. in advance, and then was jetted together with hydrogen and oxygen using a multilayer burner to be oxidized. The silica spheres formed became spherical due to the surface tension and were solidified as they were.

According to this method, it is effective for embolization of blood vessels.
It is possible to obtain the microsphere body 1 made of silica spheres having a diameter of ˜50 μm.

The size of the sphere can also be changed by changing the flow rate of hydrogen, oxygen or SiCl ₄ . The silica spheres obtained by this method have extremely low impurities, as shown in Table 1 above.

(B) Ion Implantation Method The silica glass spheres produced as described above are spheroidized, and then P ⁺ ions are added by 10 ¹⁶ to 10 ¹⁷ using an ion implantation apparatus as shown in FIG. injected ions / g.

That is, to explain this device,
An ion generation unit 4 for generating ions, an extraction electrode 5 for extracting the generated ion beam, an electrode group 6 for accelerating the formation of the extracted ions, a mass separation device 7 for selecting and extracting only desired P ⁺ ions, It is composed of an accelerating electrode group 8 for accelerating the extracted ions with an arbitrary energy and a chamber 9 accommodating the microsphere body 1 (not shown in FIG. 2) to be injected. The ion implantation apparatus having such a configuration is maintained at a high vacuum by a vacuum exhaust device (not shown).

The operation of implanting ions with such an apparatus will be described. First, in the vacuum, P ⁺ ions are generated in the ion generator 4, and then the ions are extracted by the extraction electrode 5 to perform mass separation. Lead to device 7. Then, only the necessary P ⁺ ions are separated and taken out, and thereafter, the taken out ions are accelerated by the acceleration electrode group 8 to be guided to the chamber 9, and the microsphere body 1 housed in the chamber 9 is irradiated with the ions. By doing so, ion implantation is performed on the microsphere body 1.

In this way, the radiotherapy microspheres 3 as shown in the first embodiment can be obtained.

Embodiment 3 This embodiment is another embodiment of the micro glass for radiotherapy. In this embodiment, the fine glass body 1 is made of Y ₂ O ₃
40% by weight, Al ₂ O ₃ 20% by weight, SiO ₂ 40% by weight
It is composed of glass that contains each.

The type of ions to be implanted is the same as in the first embodiment.

Test Example A chemical durability measurement test was carried out on the radiotherapy microglasses obtained in Examples 1 and 3 and the conventional radiotherapy microglass of Japanese Patent Publication No. 62-501076. It was First, take 20 ml of pure water in a 50 ml polypropylene container with a lid, put 1 g of sample in it, and immerse in an incubator at a temperature of 95 ° C (120 strokes /
Min) and the elution amount of P ⁺ ions was measured.

The eluted ions were measured with a high frequency inductively coupled plasma light emitting device. The measurement result is shown in FIG.

As is clear from these results, in the conventional microspheres for radiotherapy, remarkable elution of phosphorus was observed over the course of 3 days, 5 days, and 7 days. With respect to the microglass for radiotherapy, almost no elution of phosphorus was observed even after 7 days.

Example 4 This example is an example in which heat treatment is performed after ion implantation. [Test method] P ⁺ ions were applied to both sides of a high-purity silica glass plate (metal impurities <0.5 ppm, OH <100 ppm) produced by the VAD method with a size of 10 × 10 × 1 mm ³ at an acceleration energy of 30 keV at 5 ×. Ten
¹⁶ cm ^{2 was} injected. The silica glass plate was heat-treated under the temperature and atmosphere shown in Table 1. Immerse these samples in 20 ml of distilled water in a polypropylene container and keep them at 95 ° C for 7 days.
Soaked at a speed of 0 strokes / minute. The elution amounts of P and Si in water were examined by a high frequency inductively coupled plasma optical emission spectrometry. Moreover, the structure near the surface of the glass before and after the heat treatment and the dissolution test was analyzed by Fourier transform infrared reflection spectroscopy (FT-I).
R) and X-ray photoelectron spectroscopy (XPS). [Test Results] According to XPS measurement, the injected P was present in the state of an oxide by being a simple substance inside the glass and oxidized by oxygen in the air on the surface. In addition, the ion-implanted sample exhibited a brown color, which is probably due to the phosphorus colloid. The results of the dissolution test are shown in Table 1. Samples that were only ion-implanted with P but not heat-treated (NO.2) and samples that were heat-treated at 400 ° C (N.
In O.3), P in the glass was completely eluted within 7 days, and the brown color disappeared. Heat treatment at 900 ℃ in air (N
O.5), P mostly escaped during the heat treatment, and coloring was lost. Sublimation point of phosphorus (416 ° C) in reducing atmosphere (H ₂ ).
Heat treatment at the following 400 ℃, then oxidizing atmosphere (O ₂ )
Samples (NO.6 and NO.7) heat-treated at 900 ℃ in
Even after 7 days, only a small amount of Si and P was eluted.
After the elution test, brown coloring was observed, and it was confirmed by XPS measurement that P was retained in the sample. F
According to the T-IR measurement, the change in the surface structure observed in the sample (NO.2) in which P was ion-implanted but was not subjected to the heat treatment was the same as that in the sample subjected to the two-step heat treatment (NO. .6
And it was restored in No.7). In the samples (NO.6 and NO.7) that had been subjected to the two-step heat treatment, the phosphorus colloid was grown in the glass by the first heat treatment, and the surface of the phosphorus colloid was oxidized by the _second heat treatment, and SiO ₂ was surrounded by SiO _2. -P forming a ₂ O ₅ based glass, is considered to have confined the phosphorus within the capsule. Therefore, according to this example, suitable for radiation therapy,
A P-containing glass having excellent chemical durability can be obtained.

[Table 1] P and Si eluted from P ⁺ ion-implanted silica glass immersed in water at 95 ° C for 7 days -: Means that elution was not observed. Other embodiments Incidentally, as the material of the fine glass body 1 in the above embodiment, a high-purity silica or _{Y 2 O 3 -Al 2 O 3} -SiO 2 system glass, the material of the micro-glass body 1 which However, other glass-based materials may be used as long as they have excellent chemical durability and do not contain an element that emits α-rays or γ-rays by neutron irradiation.

Further, the shape of the fine glass 3 is not limited to the spherical shape as in the embodiment, but may be formed in a plate shape or a rod shape.

Further, the ions to be implanted are not limited to the phosphorus ions as in the above embodiment, but for example, phosphorus ions and yttrium ions may be implanted at the same time. The point is that ions having phosphorus as a main component that can be activated by neutron irradiation may be implanted.

Further, the ion implantation method and the type of the implantation apparatus are not limited to those in the above embodiment, and the ion implantation conditions, the ion implantation amount, the implantation depth, etc. are not important.

[0036]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the surface of a fine glass body is implanted with ions containing phosphorus as a main component which can be activated by neutron irradiation. It is possible to control and distribute in the range of several nm to several thousand nm near the surface of the glass body. Therefore, since the radiation is irradiated from the vicinity of the glass surface, it is possible to suppress the radiation attenuation in conventional glass. Therefore, it is possible to effectively irradiate the affected area of the cancer.

As a result, it is possible to treat a wider area than in the conventional case, and there is a merit that the treatment can be performed according to the condition and size of the affected part.

Further, since the atom to be activated is forcibly implanted by ion implantation, it is not necessary to previously incorporate a specific component such as yttria or phosphorus pentoxide as a glass component by melting etc. as in the conventional method. Therefore, there is an advantage that it is possible to provide a minute glass suitable for this type of glass for radiotherapy, which is intended to locally irradiate only the affected area with radiation and which requires extremely high chemical durability in the body.

Further, since the method is based on ion implantation, once implanted ions do not inadvertently separate from the fine glass body, and therefore the elution-preventing effect of radioactive isotopes such as phosphorus is remarkably higher than in the conventional case. Get better

Further, the concentration of phosphorus can be arbitrarily selected as required and is excellent in stability. Therefore, it becomes possible to perform the treatment exclusively according to the condition of the patient on that day without worrying about the half-life.

Further, it is possible to prevent elution of harmful ions in the body by performing an appropriate heat treatment after the ion implantation or by additionally implanting ions such as nitrogen.

[Brief description of drawings]

FIG. 1 is a schematic enlarged explanatory view of a micro glass for radiotherapy as one embodiment of the present invention.

FIG. 2 is a schematic explanatory view of an ion implantation apparatus used for ion implantation of the micro glass for radiotherapy.

FIG. 3 is a graph showing the chemical durability of the present invention and conventional microglasses for radiotherapy.

FIG. 4 is a schematic enlarged explanatory view of a conventional micro glass for radiotherapy.

[Explanation of symbols]

 1 ... Glass body 2 ... Ion 3 ... Micro glass for radiotherapy

Claims (2)

[Claims] 1. A micro glass for radiotherapy, characterized in that the surface of a micro glass body (1) is implanted with ions (2) containing phosphorus as a main component which can be activated by neutron irradiation. 2. A radiotherapy characterized by producing a microglass for radiotherapy by injecting into the surface of the microglass body 1 ions 2 containing phosphorus as a main component which can be activated by neutron irradiation. For manufacturing fine glass for automobiles.