JPH07222804A - Radiotherapeutic glass and its manufacture - Google Patents

Abstract

PURPOSE:To provide a glass in which radioelement ions are stably implanted by distributing element ions which can radiate beta ray by radiation of neutron near the surface of the glass body, by forming a membrane of oxide series glass around this ions, and by making on oxide nitride exist in the neighbourhood of the ions. CONSTITUTION:Charged P<+> ion particles are implanted into a silica glass on a specified condition, N<+> ions are also implanted. At this step, the ions are colloidal and a crack is created in the silica glass accompanied by the ion passing. In succession, when the silica glass is primary-heated for example at 400 deg.C in hydrogen gas, P colloid grows big in the silica glass without sublimation. Thereafter, when the silica glass is secondary-heated for example at 900 deg.C in oxigen gas, an SiO2-P2O5 series glass membrane is formed surrounding the P colloid, and as a result, the crack of the silica glass is closed. Therefore, the presence of this membrane makes P hard to elute into liquid as well as hard to sublimate.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a glass for radiotherapy and a method for producing the same. This glass for radiotherapy can be suitably used for locally treating an affected area having cancer or tumor.

[0002]

2. Description of the Related Art As a method for treating cancer or tumor, surgical treatment for excising the affected area, chemotherapy by medication, immunological therapy for enhancing immunity, hyperthermia for heating the affected area, and DNA sequence of cancer cells by radiation. Radiation therapy that causes damage has been adopted or proposed.

Of these, surgical therapy has been the mainstream in the past, but there are many organs that do not regenerate once they are excised. Therefore, it is desired to develop another therapeutic method that kills only cancer cells and promotes growth of normal cells without excision.

However, in chemotherapy, an anticancer agent effective for killing only cancer cells has not yet been developed. Moreover, in immunological therapy, a method for producing an antibody effective only against cancer cells has not been developed. Furthermore, in hyperthermia and radiation therapy, since radiation and heat treatment are performed from outside the body, it is difficult to effectively treat only cancer deep inside the body by damaging normal tissues near the body surface.

In recent years, therefore, in radiotherapy for deep cancer, etc., as shown in FIG. 4, glass G in which radioactive particles are dispersed is injected through a catheter C into a blood vessel B reaching a cancer-affected area, and a capillary near the cancer cell T is injected. Implanted in blood vessel, cancer cell T
A method of irradiating only the body with radiation was developed.

As such a glass for radiotherapy, a radioactive element (for example, Y, produced by a general melting method) is used.
It has been disclosed that a β-emitter ⁹⁰ Y, ³² P is obtained by irradiating a glass sphere having a diameter of 20 to 30 μm containing P) with neutron rays to activate only ⁸⁹ Y, ³¹ P. No. 62-501076). Unlike α rays, β rays do not activate other atoms such as carbon C in the vicinity, and unlike γ rays, because they have a short reach, they are suitable for radiotherapy because they do not damage surrounding normal cells.

[0007]

However, in the glass having the above structure, Y is selected as the radioactive particle and Y ₂ O ₃
When Al ₂ O ₃ —SiO ₂ glass is used, Y can be contained up to about 40% by weight, but its half-life is 6
Since it is as short as 4.1 hours, the radioactivity is considerably attenuated between the time it is irradiated with neutrons and the time it is injected into the body. However, when P is selected as the radioactive particle, MgO-Al ₂
O ₃ when the -SiO ₂ -P ₂ O ₅ -based glass, the half-life is 1
Although it is as long as 4.3 days, vitrification does not occur unless the content is 5% by weight or less, so the amount of radiation that can be applied to the affected area is small. Moreover, in the glass having the above structure, since the radioactive particles are uniformly dispersed in the glass, the β-rays emitted from the inside of the glass sphere are attenuated before reaching the surface of the glass sphere.

Therefore, the present inventors have proposed a glass body obtained by implanting radioactive elements as ions into the surface (Japanese Patent Laid-Open No. 5-209919). In this glass body, since the ions of the radioactive element are present only in the layer near the surface, β rays are not attenuated until reaching the glass surface. Moreover, since ions are injected into the glass once manufactured, it is not necessary to consider the vitrification range of the component composition.

However, further studies by the present inventors have revealed that even in such a glass body, P ions are easily dissolved in the body and are unstable. An object of the present invention is to solve this problem and provide a glass in which ions of a radioactive element are stably implanted.

[0010]

[Means for Solving the Problems] The means is a glass body, an ion of an element distributed near the surface of the body and capable of emitting β-rays by neutron irradiation (hereinafter referred to as “radioactive ion”), and the surroundings of this ion. Is a glass for radiotherapy consisting of an oxide-based glass film formed in the above and an oxynitride existing in the vicinity of this ion.

In this means, β is produced by neutron irradiation.
Phosphorus P is preferable as an element capable of radiating rays, SiO ₂ —P ₂ O ₅ type glass is preferable as an oxide type glass, and silicon oxynitride SiO _x is preferable as an oxynitride.
N _y .

In a preferred method for producing a glass for radiotherapy of the present invention, ions of an element capable of emitting β-rays by neutron irradiation and nitrogen N ⁺ ions are injected into the glass at approximately the same depth. After that, in a reducing atmosphere, primary heating is performed at a temperature lower than the sublimation temperature of the element, and then in an oxidizing atmosphere, secondary heating is performed at a temperature higher than the primary heating temperature and equal to or lower than the transition point of the glass. To do.

In this case, a particularly desirable method is to use phosphorus P as the element capable of emitting β rays by neutron irradiation, high-purity silica glass as the glass, and the primary heating atmosphere and temperature at a hydrogen atmosphere and 300 to 500 ° C. The atmosphere and temperature of the next heating are oxygen atmosphere and 800 to 1000 ° C. In addition to the high-purity silica, the glass body contains A
Any composition may be used as long as it is composed of non-activating components such as l and Mg.

[0014]

The operation of the present invention will be described with reference to FIG. 1 by taking an example of injecting charged P ⁺ ion particles into silica glass. First, charged P ⁺ ion particles are injected into silica glass under predetermined conditions. The implantation amount and the depth can be controlled by the current and the implantation energy. Although not shown, N ⁺ ions are similarly implanted. Either of the injection orders may come first.
At this stage, P ⁺ ions are in a colloidal state. During ion implantation, silica glass is cracked as the ions pass through.

Subsequently, when primary heating is performed in hydrogen gas at 400 ° C., since the sublimation temperature of P is 416 ° C., the P colloid grows large in the silica glass without sublimation. After that, when secondary heating is performed in oxygen gas at 900 ° C., the cracks in the silica glass close and a SiO ₂ —P ₂ O ₅ based glass film is formed around the P colloid. Therefore, the presence of this film makes it difficult for P to sublime and also makes it difficult for P to dissolve into the liquid. N ⁺ ion is S
It is believed that it reacts with i to form silicon oxynitride SiO _x N _y and stabilizes the glass film and the silica glass body.

Thus, the ions of P ⁺ or the like injected into the glass body become β-emitters by neutron irradiation. Moreover, since it is covered with an oxide film, it remains stable in the body for a long period of time. Furthermore, since silicon oxynitride SiO _x N _y is present near the surface, the chemical durability of the entire glass is improved.

[0017]

【Example】

-Example 1-High-purity silica glass (metal impurities <0.5 pp) produced by a vapor-phase axial method with a size of 10 mm x 10 mm x 1 mm
m, OH <100 ppm) on both main surfaces, 3 P ⁺ ions
Energy of 0 keV, followed by 14 ke of N ⁺ ions
With V energy, 5 × 10 ¹⁶ cm ⁻² pieces were implanted together. The ion-implanted sample exhibited a brown color, which is probably due to the phosphorus colloid.

This glass was placed in an H ₂ atmosphere at 400 ° C. for 1 hour.
Alternatively, the glass for radiotherapy was produced by heating for 2 hours and then at 900 ° C. for 1 or 2 hours in an O ₂ atmosphere. For comparison, a glass was also produced that was just ion-implanted but not heat-treated.

These three types of glass and the high-purity silica glass before ion implantation were put in a polypropylene container containing 20 ml of distilled water and placed in an oil bath at 95 ° C.
Stroke length 3 cm, 7 at speed of 120 strokes / min
Shaved for days. After that, the concentrations of P and Si dissolved in water were examined by a high frequency induction plasma (ICP) emission spectrometry. In addition, the structures around the glass surface before and after the heat treatment and before and after the elution test were examined by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared reflection spectroscopy (FT-IR) and Rutherford backscattering spectroscopy (RBS). .

According to the XPS measurement, the injected P ⁺ is
It was present as a simple substance inside the glass and as an oxide on the surface because it was oxidized by oxygen in the air. In addition, N ⁺ is Si-N
It was confirmed that it was in the form of a bond.

According to FT-IR measurement before and after the heat treatment,
Before the heat treatment, the Si—O bond was discontinuous, but after the heat treatment, it was continuous, and it was recognized that the cracks generated during the ion implantation were repaired by the two-step heat treatment.

The ICP measurement results are shown in FIG. As can be seen from FIG. 2, in the sample which was not subjected to the heat treatment after the ion implantation, the amount of P eluted from the glass was 0.27 ppm. This concentration is approximately equal to the number of implanted P ions when converted into the total amount of P dissolved in distilled water. Therefore, it can be said that almost all P is melted out. On the other hand, the samples that were subjected to the primary and secondary heat treatments for 1 hour each,
The amount of dissolved P was 0.05 ppm, which was less than 1/3. In addition, in the sample which was subjected to the heat treatment for 2 hours, P was 0.0
Only 2 ppm melted out.

According to the RBS measurement after the dissolution test, P was not found in the glass in the sample which was not heat-treated, but it was found in the sample which was heat-treated. Based on the above results, it can be said that the two-step heat treatment not only repaired the cracks at the time of implantation but also stabilized the P ⁺ ions by covering them with the oxide film.

Example 2 In this example, the implantation order of P ⁺ ions and N ⁺ ions is described in Example 1.
And the opposite. Otherwise, a glass for radiotherapy was produced under the same conditions as in Example 1, and various structures and physical properties were analyzed by the same method as in Example 1.

The results of ICP measurement are shown in FIG. Note that X
The measurement results of PS, FT-IR, and RBS were the same as in Example 1. From these results, it was found that the same effect as in Example 1 can be obtained even if the order of ion implantation is reversed.

Comparative Example A radiotherapy glass for comparison was prepared under the same conditions as those of the two-step heating sample (heat treatment for 1 hour) of Example 1 except that N ⁺ ions were not implanted. Various structures and physical properties were analyzed by the same method.

As a result, the P concentration and S dissolved in the water
i concentration is 0.122 ppm and 0.190 p, respectively
It was pm and melted out more than in the case of Example 1. Therefore, it was considered that the oxynitride formed by the nitrogen ion implantation contributed to the stabilization of the glass.

[0028]

INDUSTRIAL APPLICABILITY As described above, the glass for radiotherapy of the present invention is suitable for radiotherapy because particles capable of being irradiated with β rays are fixed in the glass having excellent chemical durability.

[Brief description of drawings]

FIG. 1 is an explanatory view of a manufacturing process of glass for radiotherapy.

FIG. 2 is a graph showing the results of an in-water dissolution test of glass injected in the order of P ⁺ ions and N ⁺ ions.

FIG. 3 is a graph showing the results of an in-water dissolution test of glass injected with N ⁺ ions and P ⁺ ions in this order.

FIG. 4 is a diagram illustrating a method of embedding a radiotherapy glass in an affected area.

Claims (6)

[Claims] 1. A glass body, ions of an element distributed near the surface of the body and capable of emitting β-rays by neutron irradiation, a film of oxide glass formed around these ions, and present in the vicinity of these ions. Radiation therapy glass made of oxynitride. 2. The glass for radiotherapy according to claim 1, wherein the element capable of emitting β-rays by neutron irradiation is phosphorus P. 3. The glass for radiotherapy according to claim 1, wherein the oxide glass is SiO ₂ —P ₂ O ₅ glass. 4. The glass for radiotherapy according to claim 1, wherein the oxynitride is silicon oxynitride SiO _x N _y . 5. An ion of an element capable of emitting β-rays by neutron irradiation and nitrogen N ⁺ ions are injected into a portion of glass at substantially the same depth, and then the sublimation temperature of the element is set in a reducing atmosphere. A method for producing a glass for radiotherapy, comprising first heating at a lower temperature and then second heating in an oxidizing atmosphere at a temperature higher than the first heating temperature and lower than or equal to the transition point of the glass. 6. The element capable of emitting β rays by neutron irradiation is phosphorus P, the glass is high-purity silica glass, and the atmosphere and temperature of primary heating are hydrogen atmosphere and 300 to 50.
At 0 ° C., the secondary heating atmosphere and temperature are oxygen atmosphere and 8
The method for producing a glass for radiotherapy according to claim 5, which has a temperature of 00 to 1000 ° C.