DEVICE FOR IRRADIATING LASER BEAMS

Abstract: This invention relates to a device for irradiating laser beams such as a laser beam irradiating body used to apply laser beams to an animal, human, for example, tissue to perform incision, transpiration, or thermotherapy on the tissue, and, in particular, to an irradiating device exceedingly effective for thermotherapy on cancer, in which a laser-permeable body is brought into contact with the surface of an animal tissue directly or through a surface layer that will be described later. The device is provided with a laser-permeable body and other bodies for transmitting laser beams, for example, glass fibers to project laser beams onto this permeable body, in which said permeable body contains scattering powder to scatter laser beams and is made of laser-permeable plastic material.

Description: Technical Field This invention relates to laser light irradiation apparatus such as a laser light emitter, which irradiates laser light to living tissues of an animal such as a human body to permit an incision, vaporization of the living tissues or a thermal therapy and, more particularly, to laser light irradiation apparatus by which a thermal therapy can be carried out efficiently for cancer tissues and the like while the penetrating member of laser light irradiation apparatus is brought into contact with the surface of the living tissues directly or through the intermediary of a surface layer provided on the penetrating member. Prior Art 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. Further, lately, 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 the 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 However, it is difficult to irradiate the laser light uniformly and it is further difficult to irradiate against broad target area. Therefore, the following method should be carried out; The laser light is irradiated many times against each small part of the target area separately so that the whole target area can be irradiated. Accordingly, it takes long time to perform the medical operation. Under these circumstances, laser light irradiation apparatus having a plural number of laser light emitters or probes were studied. With apparatus of this type, each laser light emitted from each probe is irradiated simultaneously against the tissues. Such laser light irradiation apparatus was shown also by the inventor in his Japanese Patent Application No. 62-50723. It is sure that the laser light can be irradiated against the tissues uniformly to some degree with these apparatus. However, uniformity is not enough. On the other hand, the plural number of laser light conduction passages and probes, further, a controller for the passages and the probes are necessary in these apparatus. Therefore, an increase in cost is produced. It is therefore a main object of the present invention to provide inexpensive laser light irradiation apparatus by which laser light can be irradiated against living tissues uniformly. EP-A-0 411 132 (state of the art according to Article 54(3) EPC) teaches a laser light irradiation apparatus comprising a penetrating member and at least one transmitting member through which laser light goes so as to be fed into said penetrating member, said penetrating member containing laser light scattering particles and being fabricated from a laser light penetrating synthetic material. The fore end portion of the transmitting member, which is an optical fiber, is not buried in the synthetic material. JP-A-1 135 370 teaches a similar apparatus, comprising the features of the preamble of claim 1. As far as JP-A-61 181 455 is concerned, it teaches an apparatus, also of a similar nature, but in which there is a gap between the fore end portion of the transmitting member and the penetrating member, this yielding to cooling means for preventing a heat crack. Disclosure of the invention The object of the instant invention is to provide an apparatus of the above mentioned type for heating the tissues very efficiently, without any need for a high power level of laser light. The instant invention relates to an apparatus according to claim 1. In a preferred embodiment of the apparatus of the invention, a lead wire for detecting a temperature is inserted through said penetrating member so as to be projected from the external surface of the fore end portion of said penetrating member and the inserting part of which is buried in said synthetic material of said penetrating member. In such a case, the temperature at the precise position, which is adjacent to the fore end of the contacted probe and which exists inside of the tissues, can be detected. That is to say, the probe is excellent in temperature control for heating the tissues. Brief Description of the Drawings Fig. 1 is a longitudinal sectional view of an important part of laser light irradiation apparatus in a first embodiment related to the present invention; Fig. 2 is a side view taken on line II-II of Fig. 1; Fig. 3 is a perspective illustration showing an embodiment of local thermal therapy for cancer tissues with laser light irradiation apparatus of the first embodiment and the temperature distribution diagram with this apparatus; Fig. 4 is a longitudinal sectional view of an important part of laser light irradiation apparatus in a fourth embodiment The Best Mode to Carry Out the Invention Now, the present invention is described more particularly with several kinds of embodiments. Fig. 1 shows a first embodiment. An optical fiber 1, which serves as a laser light transmitting member, is surrounded by a sheath tube 2, which is fabricated from the resin of tetrafluorethylene and the like. The fore end portion of the optical fiber 1 is inserted through a nipple 3, which is fabricated from a synthetic material such as polyethylene and the like. A lead wire 4 for detecting a temperature has a thermocouple 4a at its fore end. Then, this lead wire 4 is provided along the optical fiber 1 and is also inserted through the nipple 3. A flexible protective tube 5, which is fabricated from the resin of tetrafluorethylene and the like, is connected to the back end of the nipple 3. The back end of the optical fiber 1 is optically connected to a laser light generator (not shown). The lead wire 4 for detecting the temperature is connected to a temperature measuring unit (not shown). Then, according to the result of detecting the temperature, the power level of the laser light, which is fed into the optical fiber 1 from the laser light generator, should be controlled. This control is carried out by, for example, adjusting a timer switch, which is provided between the laser light generator and the back end of the optical fiber 1. On the other hand, the fore end portion of the nipple 3 is connected to a holder 6 by means of a screw. The holder 6 at its fore end portion, holds a probe 7 as a laser light penetrating member. The holder 6 comprises a body 6A, which is tapered toward its back end, and a sleeve-like connector 6B, which has a hollow shape and which is projected from the body 6A. The screw of the nipple 3 is adapted to mate with a connecting screw hole 6C of the holder 6 for connection. The optical fiber 1 and the lead wire 4 for detecting the temperature are inserted through the body 6A. The probe 7 composes a substantial cylindrical part with a fore end circumference being rounded off and another cylindrical part at the back side of the substantial cylindrical part having a smaller radius by the thickness of the sleeve-like connector 6B. The smaller cylindrical part of the probe 7 is fitted in the sleeve-like connector 6B, further might be fixed integrally thereto by using an adhesive between the mating surfaces; a circumferential bottom face of the larger cylindrical part of the probe 7 and the top circumferential face of the sleeve-like connector 6B for high strength in fixing. A laser light reflective layer 8 is formed on the mating surfaces of the probe 7 and the holder 6, in this embodiment, the circular front face of the body 6A and the internal side face of the sleeve-like connector 6B. Although the reflective layer 8 is preferably gold plated to give high heat resistance, it might be aluminum plated and the like in view of tile material of the layer. For forming the layer, vapor-deposit as well as plating can be used. Further, the fore end portion of the optical fiber 1 is inserted to be buried in the synthetic material of the probe 7 and the fore end of the core of the optical fiber 1 is contacted with the synthetic material of the probe 7 directly without any gap. The fore end portion of the lead wire 4 for detecting the temperature is inserted through the probe 7 so as to be projected from the external surface of the fore end portion of the probe 7 and has a sharpened tip end for inserting into the tissues easily. The probe of the present invention contains laser light scattering particles and is fabricated from the laser light penetrating synthetic material. The material is synthetic resin such as silicone resin, acrylic resin (more preferably, methyl methaacrylate resin), carbonate resin, polyamide resin, polyethylene resin, urethane resin, polyester resin and the like, more preferably, thermoplastic synthetic resin. For the scattering particles, the material, which has a larger refractive index for the laser light than that of the above mentioned synthetic material of the probe, is used, for example, a natural or artificial material such as diamond, sapphire, quartz material, single crystal zirconium oxide, laser light penetrating synthetic resin having heat resistance (it is needless to say that it is different from the above mentioned synthetic resin material of the probe), laser light reflective metal (such as gold, aluminum and the like), and these particles on whose surface the above mentioned laser light reflective metal is coated to be a compound material. On the other hand, if desired, when the probe contains laser light absorbing particles such as carbon, graphite, iron oxide, manganese dioxide and the like together with the laser light scattering particles, the laser light is impinged on the absorbing particles to generate heat energy while the laser light is scattered in the probe to be emitted from the probe. The probe 7 of the present invention is made by moulding to be a desired shape from the synthetic material, which is in a molten state and into which the scattering particles are dispersed. In the present invention, the fore end portion of the optical fiber 1 is buried in the synthetic material of the probe 7 as shown in Fig. 1 and the middle part of the lead wire 4 for detecting the temperature is buried in the synthetic material of the probe 7 so as to be fixed integrally to the probe 7. Accordingly, for fabricating this apparatus, for example, the holder 6 is made easily by moulding from one mould to which the material is poured, while the optical fiber 1 and the lead wire 4 are projected from the body 6A of the holder 6. Laser light irradiation apparatus of this type is used, for example, in a following manner. This apparatus is connected to an endoscope and inserted to a treated target area in a human body. At the same time, the laser light is generated from the laser light generator. Then, the laser light from the laser light generator is fed into the back end of the optical fiber 1 and is transmitted therein to be emitted from the fore end of the optical fiber 1. Continuously, the emitted laser light is fed into the probe 7 directly and is penetrated therein to be emitted from its external surface, while the laser light is refracted on the scattering particles many times in the probe 7. Therefore, as shown in Fig. 1, the laser light, after the many refraction, is emitted from the external surface of the probe 7 uniformly against the tissues. In this case, as shown in Fig. 1, the laser light reaching at the internal surface of the holder 6 is reflected on the reflection layer 8. Therefore, the metal holder 6 is prevented from being heated and from being damaged, further, the reflected laser light is brought to go forward. Fig. 3 shows an embodiment where cancer tissues M are treated by a local thermal therapy with the probe 7 of the first embodiment. In this therapy, the external surface of the fore end of the probe 7 is brought into contact with the cancer tissues M. Then, the fore end portion of the lead wire 4 for detecting the temperature is projected from the external surface of the fore end portion of the probe 7 and is inserted into the tissues M. The temperature of the tissues M is detected with the thermocouple 4a for controlling the power level of the laser light fed into the optical fiber 1. In other words, the power level of the laser light emitted from the external surface of the probe 7 is controlled as described before. Then, the cancer tissues M are destroyed by keeping its temperature at about 42-44°C. On the other hand, the laser light is irradiated against also the lead wire 4 for detecting the temperature in the probe 7. Therefore, in order to prevent the lead wire 4 from being to be heated and from being to be damaged, the wire 4 is preferably coated with a laser light reflecting layer such as a gold plated layer and a titanium coating layer. In Fig 4 showing the second embodiment, each lead wire 4 for detecting the temperature is not projected from the external surface of the fore end portion of the probe 7. That is to say, each fore end portion of each lead wire remains to be buried in the synthetic material of the probe 7. In this case, if the relation of the temperature in the treated tissues and the temperature in the probe 7 is known, the temperature of the tissues can be controlled by detecting the temperature in the probe 7, although the degree of accuracy in this control is more or less lowered. The scattering particles contained in the scattering layer are in principle the same as the above mentioned scattering particles in the probe. However, the particles, which can not make a film when they melt, are not suitable, thus, ceramic particles are generally used for the scattering particles. Further, if desired, a surface layer might be formed on each surface of the above mentioned several kinds of probes to give a high scattering effect. This surface layer contains the light scattering particles, which have the larger refractive index than that of the material of the probe or the above mentioned synthetic material, such as sapphire, silicon dioxide, aluminum oxide and the like, the laser light absorbing particles, which can be included in the probe as described before, such as carbon and the like and a binder, which sticks the particles to each surface and forms a film on the surface as described hereinafter. The laser light is scattered with the laser light scattering particles, further, when the laser light impinges on the laser light absorbing particles, the greater part of the energy of the laser light is converted to heat energy. Therefore, as the vaporization of the tissues is accelerated, the tissues can be incised with a low energy of the laser light penetrated into the probe. Accordingly, when the tissues are incised, the probe can be moved rapidly. Further, since the required energy of the laser light penetrating into the probe is low, the medical operation can be carried in short time with a cheap and small scaled laser light generator. On the other hand, referring to the surface layer, if a dispersion containing the laser light absorbing particles and the light scattering particles is coated on the surface of the probe, after a vaporization of a dispersion medium, the contact of the probe having the surface layer with the tissues or other substances causes a damage to the surface layer, because the both kinds of particles are attached to the surface of the probe only by physical adsorptive power. Therefore, by the binder which sticks the laser light absorbing particles and the light scattering particles to the surface of the probe, an adhesion of the surface layer to the probe is enhanced. In this case, the binder is preferably made of light penetrating particles such as synthetic particles or ceramic particles such as quartz particles and the like. For forming the film, when the synthetic particles are used as the material of the binder, the particles should be melted, or when the ceramic particles having a higher melting point than that of the probe are used, the surface of the probe should be melted. Further, by forming a rough surface on the surface of the probe or by forming the above mentioned surface layer on the rough surface, the laser light can be irradiated more effectively, because, the laser light is scattered on the rough surface when the laser light is emitted. Industrial Utilization As a result, by above mentioned laser light irradiation apparatus of the present invention, the penetrating member can be fabricated to be a desired shape easily, decrease in cost for fabricating apparatus is attained and the lead wire for detecting the temperature can be placed so as to be suitable for each medical treatment, further, the laser light can be irradiated against the living tissues uniformly.

Claims: Laser light irradiation apparatus comprising a penetrating member (7) and at least one transmitting member (1) through which laser light goes so as to be fed into said penetrating member (7), said laser light transmitting member is an optical fiber (1), said penetrating member (7) containing laser light scattering particles and being fabricated from a laser light penetrating synthetic material is held by a sleeve like connector (6B), said penetrating member (7) includes a substantial cylindrical part and, at the backside thereof, another cylindrical part having a smaller radius, the apparatus being characterized in that the fore end portion of a core of said optical fiber (1) is buried in said synthetic material of said penetrating member (7), said another cylindrical part is surrounded by said sleeve like connector (6B), and a laser light reflective layer (8) is formed on the mating surfaces of the penetrating member (7) and the connector (6B). Laser light irradiation apparatus according to claim 1 wherein said reflecting layer (8) is a gold plated layer. Laser light irradiation apparatus according to one of claims 1 and 2, wherein a lead wire (4) for detecting a temperature is inserted through said penetrating member (7) so as to be projected from the external surface of the fore end portion of said penetrating member (7) and the inserting part of which is buried in said synthetic material of said penetrating member (7). Laser light irradiation apparatus according to claim 3 wherein at least said inserting part and projecting part of said lead wire (4) are coated with a laser light reflecting material. Laser light irradiation apparatus according to one of claims 1 to 4, wherein a surface layer is formed on the surface of said laser light penetrating member (7) and said surface layer contains laser light absorbing particles, light scattering particles having a larger refractive index than that of said penetrating member and a laser light penetrable material as a binder. Laser light irradiation apparatus according to one of claims 1 to 5, wherein a rough surface is formed on said laser light penetrating member (7).

Inventors: DAIKUZONO NORIO, DAIKUZONO, NORIO
Applicants: SLT JAPAN KK, S.L.T. JAPAN CO, LTD.
Application year: 1990
Main classification: A61N5
IPC codes: A61B17, A61B18, A61N5