JPH0649084B2 - Intraluminal source irradiation conduit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an auxiliary tool for an intracavitary radiation irradiation apparatus, and more specifically, it is convenient for guiding (inserting / holding) an intracavity irradiation source. A conduit made of a high water content gel (high water content rubber) is provided.

<Conventional Technology and Problems> The intracavitary irradiation for esophageal cancer, that is, the method of irradiating a lesion by temporarily installing a radiation source in a living body cavity is increasingly used. This intracavity irradiation method that enhances the therapeutic effect by installing a radiation source near the lesion (avoid exposure to healthy tissue as much as possible and selectively irradiates the lesion) is It is expected to be useful.

As a method of mounting the radiation source in the cavity in this case, a method of inserting a flexible tube (capillary) to a desired depth in the cavity and then inserting and filling a radiation source (radioisotope) is adopted. That is, a simulated radiation source filling tube is inserted into the cavity in advance, and after confirming that the simulated radiation source filling site of this tube matches the lesion site by X-ray photography or the like, the main radiation source is inserted to a predetermined depth ( The accuracy of the insertion position (radiation source mounting position) is ensured by means of afterloading. However, even if the insertion depth is specified in this way, it is often difficult to stably maintain the position of the radiation source (for example, the tip of a thin tube).
The distance between radiation source lesions is often unstable, making it impossible to select an appropriate irradiation time.

In order to avoid this difficulty, a method of making the outer diameter of the radiation source filling tube substantially coincide with the inner diameter of the living body cavity can be considered. In this case, regardless of whether a known flexible material such as polyvinyl chloride, natural rubber, or synthetic rubber is used as the tube material, the friction resistance during insertion into the cavity is large, and jelly or potassium hyaluronate is attached to the outer wall of the tube. It is necessary to apply a lubricant such as an aqueous solution, an aqueous dextran solution or an aqueous sodium alginate solution, and the material itself lacks flexibility, which is not preferable from the viewpoint of foreign body sensation to living tissue.

Teflon is well known as a low-friction material, but such a hard material should not be used because of fear of damage to living tissue.

<Purpose of the Invention> The present invention provides a thin tube that does not damage the mucous membrane in a living body and does not stimulate it (excellent in biocompatibility), can be easily inserted into the living body, and is filled with a radiation source. Provided is a living body intracavity source irradiation conduit which can be held at a desired position in the lumen.

<Means for Solving Problems> According to the present invention, a polyvinyl alcohol having a saponification degree of 95 mol% or more and an average polymerization degree of 700 or more is contained, and the concentration of the polyvinyl alcohol exceeds 5 _wt % and 40 _wt %.
% Or less of an aqueous solution is frozen at a temperature of -10 ° C or lower, and then a series of freezing and thawing operations of thawing is repeated, and the cumulative number of freezing is 2 to
By using the method of No. 8, an intraluminal source irradiation conduit made of a highly hydrous gel can be obtained.

Hereinafter, the present invention will be described in more detail.

The polyvinyl alcohol used in the present invention has a saponification degree of 95 mol% or more, preferably 98 mol% or more. Further, the degree of polymerization of polyvinyl alcohol used in the present invention needs to be 700 or more. In the present invention, for example, polyvinyl alcohol having a degree of polymerization of about 800 to 3,300 can be used, but it is best to use a commercially available product having a high degree of polymerization (degree of polymerization of 1,000 to 2,600).

In the present invention, first, an aqueous solution containing the above-mentioned polyvinyl alcohol is prepared. The concentration of polyvinyl alcohol is more than 5 _wt % and 40 _wt % or less, preferably 20 _wt % or less.
˜35 _wt %. Polyvinyl alcohol concentration 5 _wt
If it is less than%, the resulting highly water-containing elastic body (highly water-containing rubber) is too soft to be inserted into the cavity, while the concentration is 40%.
_{When the} content is more than _wt %, the elasticity of the obtained high water content rubber is insufficient (harder than the soft tissue in the living body), and the same kind of defects as in the case of using conventional rubber, plastic or the like occurs.

In the present invention, the above polyvinyl alcohol aqueous solution is injected into a conduit mold for intracavity insertion. The shape of the conduit for intracavity insertion corresponds to the inner diameter of the living body cavity to be treated,
After being inserted to a desired depth, there is no particular limitation other than that it can be held and fixed, and that the inside of the conduit (hollow part) can be filled with a radiation source (or an arbitrary container filled with a radiation source). It can be selected according to the size, shape and desired insertion depth of the cavity. Gypsum, glass, polyvinyl chloride, silicone rubber and the like are also useful as a mold material for obtaining such a molded product, but stainless steel can be used for the purpose of long-term repeated use.

The above-mentioned polyvinyl alcohol aqueous solution was poured into this mold, and after cooling this to -10 ° C or lower (freezing the aqueous solution), a series of operations for thawing this were repeated, and the cumulative number of freezing was 2 to
By setting the number to 8, a radiation source holding hollow container made of a highly hydrous rubber that can be used in the present invention can be obtained. In this case, the cumulative freezing number is increased and the hardness of the obtained high water content rubber is improved, but after the cumulative freezing number 9, the effect is almost disappeared (Masabu Nanbu, Polymer Processing, 22 , 523 (1983)).
Therefore, the above 2 to 8 are economical.

After such treatment, the mold is opened and the molded product is taken out.

In the present invention, the molded article thus obtained, chlorhexidine (Hibitane), Osvan (Osvan, benzalkonium chloride), fingers, sclera conjunctiva of the eyeball, cornea,
After being immersed in a urethral disinfectant, it can be washed with water for practical use, or the γ-ray irradiation sterilization method can be used.

In addition, in the present invention, the disinfectant solution may be added to the polyvinyl alcohol aqueous solution in advance, and then the solution may be frozen / thawed (gelation operation). Also in this case, it can be put to practical use after being washed with water as described above.

In the present invention, in addition to the above disinfectant solution, a component harmless to living tissue can be embedded in the molding material within a range that does not inhibit gelation of the polyvinyl alcohol aqueous solution, for example, potassium hyaluronate of 0.2 %, Or 10% of dextran 40 (molecular weight of about 40,000) is mixed, it is possible to further reduce the frictional resistance when the molded product is inserted. Similarly, the iodine compound powder is 1 to 2%.
By mixing them, it is possible to facilitate the case of checking the insertion status in the cavity by fluoroscopy.

In the present invention, not to mention the above-mentioned esophagus, if necessary, it is also possible to obtain an irradiation conduit that can be inserted into a living body cavity such as cervix, rectum, biliary tract, and maxilla, for example, when targeting the oral cavity. , It is possible to insert it between the upper and lower arches of the open state, and the semi-open state of the dorsum of the tongue, hard palate, soft palate,
After filling the semi-folded ellipsoidal highly water-containing gel in close contact with any of the palate tongue and the like into the oral cavity, the radiation source can be embedded in the hollow portion provided inside the oral cavity in advance.

In the present invention, a highly water-containing rubber (gel) is arbitrarily molded according to the size and shape of the target cavity in this way, but the target is the esophagus, biliary tract, rectum, cervix, cervix, vagina, etc. In the case of, if necessary, a fastener such as a collar or a ring is attached to the outer wall surface of the insertion exposed portion, and the fastener and the body surface or any fixing point outside the body are tied with a string or a bandage, It is possible to suppress excessive insertion of the molded product or discharge / movement after insertion. As a method of attaching the collar or the ring-shaped fastener, a method of adhering the fastener to a desired portion of the molded product, a method of similarly sewing, or the like can be adopted.

<Effects of the Invention> The radiation source conduit (holding tool) of the present invention is made of a highly water-containing rubber having a high water content similar to that of biological soft tissue, and does not use any harmful chemical reagents as gelling agents. In addition to having excellent properties (biocompatibility), the molded product can be easily elastically deformed and can be inserted into the cavity while appropriately deforming it.

In the present invention, a molded product made of a hydrogel having a water content of 60 to 95 _wt % can be easily obtained. Despite being a rubber-like elastic body with excellent mechanical strength, this gel behaves just like water with respect to living tissues due to its high water content (Nambu Masao; JETI, 33 , (9 ) 45 (1985), Y. Hond
a, M. Nambu et al., Am. J. Ophthalmology, 100 , 328 (1984), 9
9 , 492 (1985), Tamura Koichi, Nanbu Masao; Artificial Organs, 13 , 1197
(1984)), there is almost no damage to living tissue. In the present invention, in the process of gelling the polyvinyl alcohol aqueous solution, acid, alkali, peroxide, sulfur compound,
No chemical reagents such as nitrogen compounds and organic solvents are used, and no plasticizer or stabilizer is required.
The main cause of many conventional medical materials to damage biological tissues is chemical reagents remaining in the materials, organic solvents or plasticizers added to the materials, stabilizers, but hydrogels that do not require them at all The molded article of the present invention used is far superior to conventional materials.

The molding material of the present invention has a large amount (60 to 95 _wt %) of water as a constituent component, and its surface always exhibits a wet feeling.
Highly water-containing materials include agar (water content: about 98%), gelatin (water content: about 70%), konjac (water content: about 98%) and the like, and it is well known that they are all excellent in wettability. This reduction in friction due to wetting is also seen in walking during snowfall, and it is considered that the abnormal low friction property of living articular cartilage (water content: 65 to 85%) is also due to its high water content. Of course, the molded article of the present invention also has excellent wettability, and is more excellent than the case where conventional materials (polyvinyl chloride, silicone rubber, polyethylene, polypropylene, natural rubber) gelatin, dextran aqueous solution, potassium hyaluronate aqueous solution, etc. are applied. , And can be inserted into the cavity more easily.

Example 1 A 15 _wt % aqueous solution of polyvinyl alcohol having a saponification degree of 98 mol% and an average degree of polymerization of 1400 was poured into a round-bottomed cylindrical molding mold, and left standing at -30 ° C for 2 hours to freeze the aqueous solution. Then, it was thawed. After repeating this freezing and thawing operation 5 times, the mold is disassembled and the molded product 1
0 (Fig. 1) was obtained. Then, from the round bottom of the molded product, 1
At a position of 60 mm, a Teflon ring 11 having an outer diameter of 23 mm and an inner diameter of 20 mm was sewn with a nylon suture as the above-mentioned fastener. Add this to a 0.2% Hibitene aqueous solution for 12
After soaking for a time, it was washed with a large amount of tap water for 4 hours.

The dynamic modulus of elasticity of this molded product 10 was measured to be 3.5 ×
10 ⁵ Nm ⁻² (37 ° C.) was obtained. That is, the molding material of the present invention is harder than the small intestinal smooth muscle (2 × 10 ⁴ ), but is vulcanized natural rubber (1.5 × 10 ⁶ ), nitrile rubber (1.2 × 10 ⁴ ).
10 ⁶ ), tendon (10 ⁸ ), collagen fiber (10 ⁸ ), hair (10 ⁹ ), bone (10 ⁸ to 10 ¹⁰ ) and more flexible, and vascular smooth muscle (10 ⁵ · J.Krufka; Am.J. Physiol., 156 , 445 (1961),
T. Tanaka et al .; J. Biomechanice, 7 , 357 (1974), Masamitsu Hasegawa et al .; Journal of the Rheological Society of Japan, 9 , 8 (1981)), cartilage (5.8 × 10 ^{5 to} 160 × 10 ⁵ JCBray) et a
l .; J. Biomed. Mater. Res., 7 , 431 (1973), DMGore et a
l .; Phys. Med. Biol., 28 , 233 (1983)).

After performing intracavitary anesthesia as usual in patients with thoracic esophageal cancer,
The molded product was inserted into the esophagus from the round bottom (tip) through the patient's oral cavity.

This molded product is more flexible (easily elastically deformable) than any material such as silicone rubber, polyvinyl chloride, natural rubber, etc., and has a peculiar odor found in conventional natural rubber, synthetic rubber, etc. Since no taste was shown and the lubricity was excellent, the patient did not feel a sense of discomfort, and could be inserted into the chest esophagus at a predetermined position with relative ease.
Next, while using the Teflon ring of the exposed insertion portion as a slip stopper, a bandage was wrapped around this and further wrapped around the cheek to the nape to fix it. Then, separately insert a stainless steel capsule ( ⁶⁰ Co) with all sides open to the tip (round bottom) of the polyethylene thin tube (outer diameter 5 mm, inner diameter 3.5 mm, total length 635 mm with round bottom), Next, the tip of this polyethylene thin tube is inserted into the hollow of the exposed part of the molded product. After confirming that the tip of the polyethylene thin tube has reached the tip (round bottom) of the molded article of the present invention, 3
Leave for 0 minutes. During this irradiation period of 30 minutes, the position of the ⁶⁰ Co capsule was observed by simple fluoroscopy, and it was confirmed that the capsule was always held in the center of the cavity as desired. That is, according to the present invention, a polyethylene thin tube filled with a radiation source is inserted and fixedly held in the holder (cylinder) of the present invention, and also the outer wall of the holder of the present invention is closely adhered to and held on the inner wall of the esophagus. It was clear that

This temporary irradiation operation was continued every other day for 3 weeks to achieve a cumulative irradiation time of 5.5 hours, but neither inflammation of the esophagus inner wall nor abnormal proliferation of endothelial cells was observed.

As described above, the radiation source holder using the highly water-containing rubber of the present invention is easy to insert into the cavity and has a high flexibility, so that the inner wall of the cavity is not damaged and the radiation source is placed at a fixed position in the cavity. It is clear that it can be retained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an intraluminal irradiation source conduit of the present invention. In the figure, 10 is a living body irradiation conduit, and 11 is a Teflon ring.

Claims (1)

[Claims] 1. A saponification degree of 95 mol% or more and an average degree of polymerization of 70.
An aqueous solution containing 0 or more polyvinyl alcohol and having a polyvinyl alcohol concentration of more than 5 _wt % and 40 _wt % or less is injected into a mold, which is cooled and solidified at a temperature of -10 ° C or less, and then, An intraluminal radiation source irradiation conduit, which is a hollow container made of a highly water-containing rubber obtained by repeating a series of freezing and thawing operations for thawing this to obtain a cumulative freezing number of 2 to 8.