DEVICE FOR IRRADIATING LASER BEAMS

Abstract: This invention relates to a device for irradiating laser beams to be used when applying laser beams to an animal, human, for example, tissue to perform incision, transpiration, or thermotherapy on the tissue, or when expanding a constricted part caused by cholesterol in a narrow passage in an organic tissue, for example, a blood vessel of a human body. A plurality of optical fibers to transmit laser beams emitted from the laser beam generator and at least tips of said fibers are exposed as cores and each core part is integrally covered with a cladding material which is used as a laser beam emitting body.

Description: The instant invention relates to a laser light irradiation apparatus comprising at least four optical fibers transmitting laser light fed from a laser light generator and through an impinging lense and a laser light emitter, i) at least the fore end portions of said optical fibers being exposed to be cores repectively ; and ii) said exposed cores being surrounded by a clad-material serving as said common laser light emitter. Medical treatments such as incisions of living tissues of animal organisms by laser light irradiation are conspicuous due to its ability of hemostasis in these days. It had been the conventional method that the laser light was irradiated from the fore end of an optical fiber which is brought out of contact with the living tissues. But this method causes severe damage to members of the optical fiber. Therefore, a method which has been utilized lately is as follows; First, laser light is transmitted into an optical fiber, whose fore end portion locates adjacent to treated living tissues. Next, the laser light is fed into an emitting probe from the optical fiber. This emitting probe is brought into or out of contact with the living tissues. Then, the laser light is emitted from the surface of the probe for irradiating against the living tissues. (hereafter "living tissue" is sometimes expressed by "tissue" only). The inventor developed many kinds of contact probes which are utilized for various purposes. When the contact probe of this type was used in the prior art, the fore end of an optical fiber was located so as to be apart from the back end face, that is an impinging face, of the probe. In this case, a physiological salt solution or pure air was passed through a gap formed between the optical fiber and a holder supporting the optical fiber, and through a space formed between the impinging face of the probe and the fore end of the optical fiber. Then, although the laser light having high power level is impinged on this impinging face of the probe, this face could be cooled due to passing of this fluid matter, thus, the damage of this face was prevented. Further, the reverse of the pieces of living organism, a blood flow and the like, which might have been occurred by a medical operation, could be also prevented due to the passing of this fluid matter. On the other hand, the inventor proposed, in Japanese Patent Application No. 63-171688, a laser light medical treatment equipment for burning off a stricture part caused by cholesterol formed on the inner wall of a blood vessel. Before this application, for the treatment of the stricture part, a heat wire probe was inserted into the stricture part. Then, since the heat wire probe was heated as a whole, a normal blood vessel other than the stricture part was possibly damaged. Therefore, in order to prevent the normal blood vessel from being damaged, the laser light medical treatment equipment was proposed. According to this equipment, while a laser light emitting probe is progressed through the blood vessel to locate before the stricture part formed in the blood vessel, the laser light is emitted so as to be irradiated against only the stricture part, which is beyond the probe. Further, lately, a localized thermal therapy is drawing special attention as a carcinostatic therapy. According to this method, cancer tissues are destroyed by keeping the cancer tissues at a temperature of about 42-44°C for 10-25 minutes by laser light irradiation. The effectiveness of this method has been reported by the inventors in the bulletin of Japan Society of Laser Medicine, vol. 6, No. 3 (January 1986), pp. 71-76 & 347-350. On the other hand, considerable attention has been paid to laser-chemical therapies including the method reported in 1987 by Dougherty et al of the United States. According to this method, 48 hours after an intravenous injection of a hematoporphyrin derivative (HpD), weak laser-light such as argon laser or argon pigment laser is irradiated against a target area of the treatment. Whereupon oxygen of the primary term which has a strong carcinostatic action is produced by HpD. Since then, there have been published various reports in this regard, including the one in the bulletin of Japan Society of Laser Medicine, vol. 6, No. 3 (January 1986), pp 113-116. In this connection, it has also been known in the art to use "pheophobide a" as a photo-reactant. Further, recently, YAG laser has been put into use as a laser-light source. In the above mentioned medical treatment, it is important that the laser light is irradiated uniformly for the cancer tissues and, in case of the thermal therapy, it is particularly important that the cancer tissues are heated uniformly. Further, for heating the tissues uniformly, the inventor disclosed in Japanese Patent Application Laid-Open No. 63-216579, that apparatus has plural number of laser light emitters and an equipment for adjusting the power level of the laser light impinging into the emitters. In case that the laser light is irradiated against the tissues from an optical fiber directly or through the intermediary of a contact probe, the power level of the laser light irradiated against the tissues is the largest at a center position of an irradiated area on the surface of the tissues. The center position is contacted by the center of the optical fiber or that of the contact probe, then, the power level is lowered as a position on the surface of the tissues parts away from the above mentioned center position. Therefore, it is difficult to irradiate the laser light uniformly, and particularly more difficult to irradiate the laser light uniformly against the tissues having broad area. Accordingly, within the limit of the predetermined power level of the laser light, laser light irradiation against each small part of the tissues should be repeated many times in order to carry out the irradiation against the all of the treated tissues having the broad area. As a result, a medical operation can not be carried out quickly. Under these circumstances as described before, the inventor proposed in Japanese Patent Application Laid-Open No. 63-216579 that the plural number of probes as the laser light emitters are provided and the laser light is irradiated from each probe simultaneously. Although the laser light can be irradiated against the tissues having a broad area to some degree by provision of the plural number of laser light emitting probes, the necessity of the probes causes a following problem. For forming the uniform temperature distribution on the irradiated tissues, the probes should be located at precise positions respectively so as to be contacted with the tissues uniformly. Therefore, the medical operation can not be carried out quickly due to troublesome in precisely locating the probes. On the other hand, since each optical fiber should correspond to each probe, the size of apparatus is large. Accordingly, this apparatus can not be used for a medical treatment in a narrow path in the tissues such as a catheter in a blood vessel. Disclosure of the Invention The laser light irradiation apparatus of the present invention is characterized by the characterizing portion of claim 1. According to the present invention, the plural number of optical fibers are provided so that their fore end portions are buried in the material of the laser light emitter, that is the clad-material. Therefore, in each power level distribution of the laser light irradiation from the emitting face of the laser light emitter, there is a peak at each axis of each optical fiber. That is to say, as shown in Fig. 1, a whole energy distribution, which is produced by combining each energy distribution, slows a uniform and broad energy distribution. Even if the laser light is fed into each optical fiber with each distribution, which is similar to a normal distribution, the power level distribution of the laser light irradiation from the laser light emitter shows, as a whole, a flat distribution. On the other hand, for the angio-plasty in the conventional art, only the center part of a blood vessel was mainly burnt off. However, by the present invention, the laser light is emitted also from the circumferential part of the fore end face of the emitter. Therefore, the inner wall of the blood vessel as well as the center part can be burnt off surely. Due to this complete burning, laser light emission with high power level is not required. Further, even if the blood vessel is bent, thereby, the normal part of the inner wall of the blood vessel is set to be faced the center position of the emitting face of the emitter, since the power level of the laser light irradiation is not so high, there is no fear of perforation at the normal part. In case of a thermal therapy, since the tissues having a broad area are heated uniformly, this therapy can be performed quickly and there is no fear that the tissues at a center position of the irradiated area is damaged seriously. US-A-4 669 467 teaches the preamble portion of claim 1. Handbook of Optics : theory and application ; ed. H.F. Wolf; publiched 1979; pp. 430-433 teaches the homogeonizing effect of the randomized fibers in a fiber bundle. However, in US-A-4 669 467, use is made of a coherent fiber-optic bundle, which is a bundle of optical fibers with both ends bonded so as to hold the optical fibers in identical or well defined spatial arrays. Brief Description of the Drawings Fig. 1 is a longitudinal sectional view of laser light irradiation apparatus in a first embodiment related to the present invention; Fig. 2 is an expanded sectional view of an important part of Fig. 1; Fig. 3 is a sectional view taken on line III-III of Fig. 2; Fig. 4 is an elevational view showing the producing operation of laser light irradiation apparatus of Fig. 1 in a preparation stage; Fig. 5 is a longitudinal sectional view of a laser light transmitting part of laser light irradiation apparatus; Figs. 6 and 7 are longitudinal sectional views of important parts of laser light emitters respectively related to the present invention; Fig. 8 is a sectional view taken on line VIII-VIII of Fig. 7; Fig. 9 is a longitudinal sectional view of an important part of another laser light emitter; Figs. 10, 11, 12 and 13 are side views respectively taken on the four lines of Fig. 9; Fig. 14 is a longitudinal sectional view of an important part of a laser light emitter having a claw-shape; Figs. 15, 16 and 17 are sectional views having several shapes respectively taken on line C-C of Fig. 14; Fig. 18 is a plan view of the fore end portion of a laser light emitter having a chisel-shape; Fig. 19 is a sectional view taken on line XIX-XIX of Fig. 18; Fig. 20 is an elevational view of Fig. 18; Fig. 21 is a side view of Fig. 18. The Best Mode to Carry Out the Invention Now, the present invention is described more particularly with several kinds of embodiments. Figs. 1, 2 and 3 show a first embodiment of laser light emitting apparatus connected to an endoscope. Plural number of, preferably four or more than four, more preferably ten or more than ten optical fibers compose a base portion X as a laser light transmitting part and a fore end portion Y as a laser light emitting part, although a boundary between these two portions X and Y can not be shown in this figure. For explaining the composition of this apparatus clearly, the producing method of this apparatus will be explained first. First, as shown in Fig. 4, original optical fibers 1, 1 are prepared. Each original optical fiber 1 has a core 1A and a clad 1B surrounding the core 1A. Then, while at the base portion X, the fibers 1, 1 are twisted in an irregular manner, the twisted original optical fibers 1, 1 at the base portion X are heated to a temperature, which is substantially the same temperature as or higher temperature than the melting point of the clad 1B and which is lower temperature than the melting point of the core 1A. Then, at the base portion X, the clads 1B, 1B of original optical fibers 1, 1 are moulded to be one clad 10B, which includes the twisted cores 1A, 1A as shown in Fig. 5. On the other hand, at the fore end portion Y, the original optical fibers 1, 1 are not twisted but arranged in parallel separately. A clad-material 10A is heated to be melted. Then, the optical fibers 1, 1 arranged in parallel are dipped in the melted clad-material 10A to a predetermined depth, at which the laser light can be penetrated. Thus, since the clad-material 10A is heated, the clads 1B, 1B can be melted to be mixed into the clad-material 10A. In this case, the temperature, to which the clad-material is heated, is the same as or higher than the melting point of the clad 1B and which is lower than the melting point of the core 1A. Further, the clad 1B and the clad-material 10A are fabricated from materials, which have similar compositions so that they can be moulded to be one substance easily. For example, these materials are same quartz or two kinds of quartz which differs in only melting point. Further, the core 1A is preferably fabricated from a material, which is also similar to the material of the clad 1B and the clad-material 10A. Therefore, in this embodiment, quartz can be used as a suitable material of the core 1A. As a result, a laser light emitter 20 composing the resulting clad-material 10A and the number of cores 1A, 1A, which are arranged in parallel and which are included in the clad-material 10A. The clad-material 10A includes also the melted clads 1B, 1B. However, since the boundary between the clad-material 10A and each clad 1B is not clear, the clads are not shown in this figure. The shape of the laser light emitter 20 depends on the shape of a container including the clad-material 10A. For example, as shown in Fig. 1, if the container has a constriction at the back end of the emitter 20, the shape of the laser light emitter 20 should be provided with an open having an inner diameter corresponding to the diameter of the constriction. The laser light irradiation apparatus of this type described above is used as follows. First, laser light fed from a laser light generator 2 goes through an impinging lense 3. Next, the laser light from the lense 3 is impinged from the back end face of each twisted core 1A. Then, the impinged laser light is transmitted in each core 1A to be emitted from the fore end face of each core 1A. Further, the emitted laser light goes through the clad-material 10A to be emitted from the fore end of the laser light emitter 20. Finally, the emitted laser light is irradiated against treated tissues M. In this case, when the laser light is impinged from the back end of each twisted core 1A, the power level distribution of the impinged laser light shows a distribution, which is similar to a normal distribution. However, the arrangement of the cores 1A, 1A is randomized due to this twisting of the cores 1A, 1A, for example, the core 1A locating at the center part is twisted so as to locate at the circumferential part and another core 1A locating at the circumferential part is twisted so as to locate at the center part. Accordingly, as shown in Fig. 1, the power level distribution of laser light emission from the emitter 20 shows a uniform distribution. In Fig. 1, the emitting face of the emitter is not covered by anything. However, as shown by an imaginary line in Fig. 2, a surface layer 21 or a scattering layer, which will be explained after, can be formed on the emitting face of the fore end portion of the emitter 20. The emitter, whose emitting face is not covered by anything, is used for mainly coagulation and heating of the tissues. On the other hand, the emitter, whose emitting face is covered with the surface layer 21, is used for mainly vaporization of the tissues. The above mentioned base portion X as the laser light transmitting part can be coated with a protection tube 4 fabricated from a synthetic resin material and the like. In the present invention, the emitter having several kinds of shapes can be applied. There are, for example, a cylindrical-shaped emitter 20A having a flat emitting face as shown in Fig. 6, a knife-shaped flat emitter 20B as shown in Figs. 7 and 8, a hook-shaped flat emitter 20C as shown in Fig. 9, claw-shaped emitters 20D as shown in Figs. 14, 15, 16 and 17, a sickle-shaped emitter 20E as shown in Figs. 18, 19, 20 and 21. The emitter 20A of Fig. 6 is used for the coagulation, the heating and the vaporization of the tissues like the emitter 20 of Fig. 1. In the emitter 20B of Figs. 7 and 8, the cores 1A, 1A of the optical fibers are gathered to be a substantial straight line. Then, tile emitter 20B is used surgically for the incision and the vaporization of tissues. The above mentioned surface layer can be formed on the knife-shaped face, that is the tapered face, of the emitter 20B. A handle 5 is attached to its back end portion. The emitter 20C of Fig. 9 is also used for mainly in a surgical treatment for the incision and the vaporization of tissues. In the emitter 20D of Fig. 14, a pair of emitting parts are provided to be faced each other. The emitter 20D is located so that the two emitting parts pinch the tumor of tissues. The emitter 20D whose emitting face is flat and covered by nothing as shown in Fig. 15 is used mainly for coagulation. On the other hand, the emitter 20D, whose emitting face is rounded off and covered with the surface layer explained hereinafter as shown in Fig. 16, is used mainly for vaporization. Further, the emitter 20D, whose emitting face is tapered and covered with the surface layer as shown in Fig. 17, is used mainly for incision respectively. A grip handle 5C is provided at the back portion of the emitter 20D and can be operated with a restoring force. The sickle-shaped emitter 20E of Figs. 18, 19, 20 and 21 is used for mainly removing a tumor formed in a narrow path of organisms. In this case, the emitter 20E is inserted to be progressed in the direction of its axis.

Claims: Laser light irradiation apparatus comprising at least four optical fibers (1) transmitting laser light fed from a laser light generator (2) and through an impinging lense (3) and a laser light emitter (20), i) at least the fore end portions (1A) of said optical fibers (1) being exposed to be cores repectively; and ii) said exposed cores (1A) being surrounded by a clad-material (10A) serving as said common laser light emitter : characterized in that iii) said optical fibers (1) are randomly twisted at their base portions (X) thus being different from the arrangement of said optical fibers at their fore end portions (Y). Laser light irradiation apparatus according to claim 1, wherein a flat surface is provided on at least around an emitting face or the emitting line of said laser light emitter (20A, 20B, 20C, 20D, 20E). Laser light irradiation apparatus according to claim 2, wherein said laser light emitter (20A) has a cylindral shape. Laser light irradiation apparatus according to claim 2, wherein said laser light emitter (20B) is a knife-shaped flat emitter. Laser light irradiation apparatus according to claim 2, wherein said laser light emitter (20C) is a hook-shaped flat emitter. Laser light irradiation apparatus according to claim 2, wherein a pair of laser light emitters (20D) including said optical fibers are arranged so that the emitting faces or the emitting lines of said emitters are faced each other. Laser light irradiation apparatus according to claim 6, wherein said laser light emitters (20D) are claw-shaped emitters. Laser light irradiation apparatus according to claim 2, wherein said laser light emitter (20E) is a sickle-shaped emitter.

Inventors: DAIKUZONO NORIO, DAIKUZONO, NORIO, DAIKUZONO, NORIO 381, KOFUDAI 4-CHOME
Applicants: SLT JAPAN KK, S.L.T. JAPAN CO, LTD.
Application year: 1990
Main classification: A61N5
IPC codes: A61B18, A61N5