We have so far experienced 56 cases of endoscopic Nd-YAG laser therapy for cancers of digestive tracts.
We gave a conclusion to the laser therapy for cancers of digestive tracts as a positive indication. Positive laser therapy can be adopted as the therapy of first choice, while it is otherwise adopted as the second choice as a less positive indication for such cases as with very serious diseases other than cancers or the cases wherein surgical operation can not be adopted as the first choice for some reasons. Consequently, the laser therapy should be regarded as a positive therapy for cancers of digestive tracts.
The positive applications of the laser therapy can be classified into two groups. One is the group of advanced cancers which can not be resected, while the other is the group of the cancers at early stage which have no metastasis. As there are many cases of advanced cancers which can not be resected, the laser therapy can be adopted very often for this type, whereas, for the cancers at early stage without metastasis, it is not so easy to give firm diagnosis of metastasis-free cancers (3% of all the cases with cancers at early stage) and therefore the chances of laser therapy are limited. Consequently, it is of top importance in the application of laser therapy for cancers of digestive tracts to select the type of advanced cancers as the first choice of its application.
In our experiences, the laser irradiation therapy proved to be effective for the treatment of hemorrhage, stenosis and tumor reduction of cancers which could not be resected for various reasons.

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In general surgery, treatment has been undertaken with the use of laser beams. The authors have experienced 78 cancer patients (on 123 occasions) in the last five years. The present report refers to 31 patients (seen on 54 occasions) with advanced and recurrent cancer. The treatment was undertaken to improve or eliminate the symptoms and has been found effective in many of the patients. None of the patients subjected to laser treatment has shown any adverse effects as compared with irradiation.

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For highly efficient utilization of laser energy, we have developed a YAG laser system which has a portable energy control box removable from the main body with laser generator for use in an endoscopy room or an operating theater or an outpatient department.
We have performed the following YAG laser therapy in the operating theaters:
1. Serosal Isolation Technique by use of low diffused laser beam for prevention of peritoneal dissemination during cancer operation.
2. Bloodless operation of advanced cancers in the intra-pelvic organ, such as resolution of cancer strictures, reduction of cancers, and extended radical pelvic exenteration.
3. Indepth irradiation therapy for inoperable malignant tumors in the liver, in combination with superficial vaporization of cancer, for complete and radical cure with a drastic decrease of AFP of primary hepatocellular carcinoma and CEA of metastatic liver cancers.

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The purpose of endoscopic YAG laser therapy for G.I cancer is divided into three groups; 1) radical therapy for early gastric cancer or early colonic cancer, 2) symptomatic treatment for advanced cancer, 3) tumor mass reduction therapy. Symptomatic treatment for bleeding or stenosis in case of advanced cancer is useful. Tumor mass reduction therapy is useful too. 19 cases of inoperable advanced cancer were treated and no side effect was found. It will be one of the most important conservative treatment in the future, especially in the aged.

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Because YAG laser irradiation onto advanced carcinoma of the alimentary tract has a possibility to evolve carcinomatous growth, YAG laser treatment onto advanced carcinoma should be avoided except for the purpose to releasing the luminal stenosis and hemostasis. But the rectal carcinoma, considered as the type of Borrmann-I, has indicating to YAG laser treatment according to our experience. Bleeding neccesitated blood transfusion was occasionally encounterd after laser treatment. Also, abdominal distension due to assist gas jet was encounterd in gastric stomal carcinoma. The ultrasonic endoscopy is effective to differentiate from early to advanced carcinoma.

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In the advanced carcinoma of the digestive organs, the local recurrence is a major problem in surgery. We have applied a laser irradiation to the area after lymph node dissection in the surgery for the carcinoma of the GI tract and to the raw surface of the liver after hepatic resection. Experimental study demonstrated that the laser surgery have an advantage to prevent the local recurrence. Of 133 patient undergoing the laser surgery, ten patients underwent the laser irradiation and none of these developed the local recurrence so far after 4 years in the longest-term follow up. 47 patients underwent hepatic resection using a laser knife and proved to be a good prognosis. Postoperative prognosis although enough estimation can not be made is preliminarily favolable as a whole.

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HpD and laser photoradiation therapy (PDT) was performed preoperatively in 15 cases of bronchial tumors with invasion, and the effectiveness of resectionnecessary and to extend the surgical indications of surgery was valuated. PDT improved the condition of inoperable cases to the point where surgery could be performed in 4 out of 5 cases and the extent of resection was reduced from pneumonectomy to lobectomy in 7 out of 10 cases. This methodology makes it possible to reduce the extent of resection in cases with poor pulmonary function and increase the surgical indication in cases with advanced bronchial lesions.

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The purposes of this paper are to describe the results of 1.34μm lasing in rnediLas II manufactured by MBB in West Germany and coagulation properties of this line compered to conventional 1.06μm line. We obtained the output power of 19 watts in 1.34μm by replacing the laser mirrors. Anesthetized rabbit's GI tract and liver are irradiated by this power level and 50 watts of 1.06μm line.
Though these power levels in two lines brought about the nearly same coagulation, macroscopic observations show that the coagulation properties of 1. 34 gm line are characterized by the surface limited and localized action compered to 1.06μm line. Interactions between 1.34μm laser light and the tissue are discussed.

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The development for new laser scalpel using the combination of CO laser and IR glass fiber is reviewed. CO laser, 5μm of wavelength, has been selected as cutting laser substitued for CO₂ laser, in order that the use of flexible IR glass fiber as transmission line. Moreover, it will be possible to deliver CO laser and Nd: YAG laser simultaneously into a fiber made of IR glass fiber. Thus, the fiber-deliveried laser-treatment system which has variable function may be attainable. We have already demonstrated that: I) the action for biological tissue by CO laser irradiation; 2) the high-intensity power delivery of CO laser by As2S3 glass fiber; 3) the high-power and high-efficiency operation of the room-temperature CO laser.

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The efficiency of photoradiation therapy with N₂ dye laser on gastrointestinal cancer was evaluated and compared to Ar dye laser. After adoministrating HpD to 5 dogs, N₂ dye laser and Ar dye laser were irradiated for 15 and 30 minutes at their liver surface. Liver damage caused by N₂ dye laser at 45mW was almost equal to that caused by Ar dye laser at 180mW. According to the duration times, liver damage became deeper and larger with both lasers at these settings. However, when Ar dye laser was irradiated at 50mW for over15 minutes, the damage did not increase. Treatment of early cancers (6 gastric and one esophageal) with N₂ dye laser photradiation therapy was attempted. All except one disappeared completely and the N₂ dye laser succesfully treated three of these which were not succesfully treated with a Nd-YAG laser. Irradiation with N₂ dye laser at 45mW had the same effect as that of Ar dye laser at 180mW experimentally and clinically.

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To increase the benefit of photodynamic therapy, we have introduced a gold vapor laser to our department. This has the following characteristics: Wave length, 628 nm, Peak power, 5×10⁴ W, Average power, 4.5 W, Pulse energy, 0.45 mJ, Pulse length, 5×10⁸ sec, Repetition rate, 10 KHz. Experimentally transplanted tumors in nude mice were used for the evaluation of anticancer effect of photodynamic therapy using hematoporphyrin derivative and an argon-dye laser or gold vapor laser. The benefit of the latter was thought to be more than 2 times as compared with that of the former.

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Excimer laser (C-1891) used a mixture gas which are contained 0.9%Xe, 0.1%HCL, 99%He at 2atm and circulated along the laser axis in the head tube at 3200rpm. The performance of this laser at best condition obtained 30mJ/pulse and 10.9nsec duration of half peak power at the 308nm wavelength. Average output power was 0.72W at 30pps repetition rate. Excimer laser was converted dye laser at 405nm for a excitative wavelength of hematoporphyrin derivative (HpD) by the αNPO ethanol solution. Alternate light of Excimer dye laser at 405nm and Xe-white light for a illumination passed in the endoscope fiber and irradiated the tumor. HpD emission and a endoscopical image from a tumor detected with a fluorescence analyzer and a TV camera each other. Both fluorescence spectra and the image of a tumor could be displayed the same monitor scope.

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A new laser diode pain attenuater was developed. Light power out put was increased to 60mW (830nm) and resulted much more effective than the former type (15-20mW, 830nm).
Besides light weight and easy operati (6.5kg 440/350/150mm), the safety considerations were made such as skin tuch sencing switch, two kind of sound signals (pre-warning and waning), and red ligh signal (LED) for laser irradiation, etc.
A basic study to clearify the mechanism of laser effect is now underway.

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The distribution of hematoporphyrin derivative (BPD) was studied in brain tumor bearing rats as a time dependence after iv injection of 10 mg/kg of BPD and in glioma patients as a topographical distribution 48 hours after injection of 3 mg/kg of HPD.
The maximum concentration level of HPD in the rat brain tumor was obtained at 48 hours after injection and high concentration level was kept for more than 96 hours.
In glioma patients, high concentration level of HPD in active glioma tissue was obtained.

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Tissue localizing ability of protoporphyrin in mice have been described. Protoporphyrin was analized by means of Dresel' s method. The amount of protoporphyrin which localized in the transplanted tumor tissue of mice at various times following i v. injection (20mg/kg) was higher than in the skin, music or intestinal tissue but was less than in the liver or spleen tissue. These results show that tissue distribution of protoporphyrin was similar to that of Hp D. Furthermore, comparison of transmission between 514.5nm and 630nm light have been studied by PRT and spectrophotometer. The results suggested that 630nm light transmission was prior to that of 514.5nm light.

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Photodynamic effects of hematoporphyrin derivative(HpD), hematoporphyrin(Hp) and protoporphyrin (Pp) on cultured rat hepatocellular carcinoma cells (JTC-16), human hepatocellular carcinoma (HCC-1) and gastric cancer (GCA-1) serially transplanted in nude mice were studied, under the influence of a dye laser irradiation.
The cell degeneration was observed most strongly in Pp, HpD and then Hp in order. The tumor degeneration of HCC-1 was observed most strongly in Hp and then HpD in order. On the other hand, the tumor degeneration of GCA-1 was observed most strongly in HpD and then Hp in order. Photodynamic effect of Pp was not observed in both GCA-1 and HCC-1.
Therefore, it is suggested that Pp had the most powerful photodynamic effect on the cultured cells, but not on human cancer. This phenomenon would indicate that Pp has no affinity with the cancer tissue.

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By using of the method of ESR (electron spin resonance), we tried to analize the mechanism of photodynamic therapy, After this therapy we took biopsy specimens under the endoscopy with the patient of gastric cancer. ESR spectrum of specimens showed triplet signal, which we proved σ-radical (R2NO·). As the results, we considered that singlet Oxygen destroyed Hematoporphyrin under this therapy.

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Cultured cancer cells (HeLa cell) and MH-134 tumor implanted to mouse were irradiated by LED (center wavelength: 635nm) after HpD treatment. Irradiation power density of a LED was 20 u/cm².
Three hours irradiation caused cell damage in HeLa cell and 72 hours irradiation caused the tumor necrosis so far sa a depth of 2.5mm.
Though there still remain some unclear points about LEDs interaction with HpD, this experimental data will provide useful dues for future research of PDT without using the laser light

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Hematoporphyrin derivative (HpD) has an affinity for malignant tumor and cytocidal effects are obtained by exposure to light exciting the HpD in tumor tissue. The authors treated 242 patients with malignant tumors since 1980. In this study photodynamic therapy (PDT) for lung cancer was evaluated. 100 cases with lung cancer were treated by PDT. According to clinical stage, 19 cases were early stage, 16 in stage I, 11 in stage II, 38 in stage III, 16 in stage IV. This new therapy was effective in the curative treatment of early stage and in the palliative treatment of advanced lung cancer cases.

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Effects of Photoradietion theraph (PRT) on esophageal carcinoma was discussed. Five cases of superficial esophageal carcinoma underwent PRT.
All cases were followed periodically by endoscopy with bite biopsy and the results of PRT have been effective and satisfactory. We showed some tissues connected with PRY.

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Endoscopic photodynamic therapy (PDT) for 34 cases (37 lesions) of stomach and colorectal tumors was presented. The effect of PDT was histologically examined in 7 cases of early gastric carcinoma, 1 case of gastric adenoma and 2 cases of colonic tumor. Residual carcinomas were found in 2 cases of early gastric carcinoma, one in the submucosal layer at the distal part of the irradiated area, the other focally at the margin of the laser-induced ulcer. In the case of colonic carcinoma, distal part of the tumor retained. Technical difficalty in complete visualization en-face at the time of laser irradiation was thought to be a major cause of incomplete treatment.

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We have carried out and evaluated clinically photoradiation therapy (PRT) of 19 cases of early gastrointestinal cancer. Most of those have been cured completely but in a few cases recurrence or remnant of cancer cells was seen. The accurate diagnosis of lymph node metastasis and depth infiltration of carcinoma must be done carefully before irradiation for successful treatment. We have also studied experimentally on the effect of PRT with the contact type of micro laser rod. Safety and reliability of this method have been confirmed.

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Using photoradiation therapy (PRT), 16 cases of digestive tract cancer were treated with SP171-SP375 and PRT 102. In 9 of them resection surgery was carried out after PRT. Complete disappearance was confirmed in 2 cases out of 6 early gastric cancer. In the other 4 cases cancer remain ed in the sm layer and epithelium of the margin of the new induced ulcer. As side effects of PRT clear sunburn was noted and stomach ache and severe nausea were complaint. Fundamental studies were also carried out. Combination of Argon and YAG laser and the widespread irradiation by the contact type rod should be regarded as new treatment method.

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Photodynamic therapy (PDT), in which hematoporphyrin derivative is activated by an argon-dye laser, was performed on superficial bladder tumors and CIS. The effectiveness of spot PDT using a 400μm quartz fiber and cystoscope in 51 superficial tumors is limited to tumors ≤ 2cm in size and in such cases the light intensity should be 300mW/cm₂ for ≥ 5 to 10 minutes. For the CIS therapy in 18 cases, whole bladder wall PDT using a motor driven laser light scattering optic was used. The total light dose of 30J/cm₂ or more may be useful for the CIS. Problems and counter-measures PDT are discussed and gold vapor laser is recommended to increase PDT effect.

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We described a new device for the mode of laser irradiation and its problem in argon laser treatment of cutaneous lesions. We devised 3 types of laser irradiation mode, which is multispots irradiation, single spot irradiation and focused spot irradiation, using Fiber Bundle Scanner. These three laser irradiation modes are selected being based on histopathological findings, area and location of cutaneous lesions and so on.

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We have studied experimentally and clinically to evaluate the efficacy and safety of the endoscopic VAG laser therapy, and those of the contact type of optical fiber (micro-tip) for the tumors in the gastrointestinal tract. 2 cases of superficial esophageal cancer, 7 cases of early gastric cancer, 22 cases of gastric adenoma, 6 cases of advanced cancer in the esophagus, stomach and colon with stenosis and bleeding were treated with Nd-YAG laser (Medilas). The micro-tip is made of Al₂O₃ and durable, and then able to treat under half of the exposure power less than those of quartz fiber. 5 cases out of 24 cases (15.6%) treated with quartz fiber were appeared residual tumor in course of endoscopic follow-up. The contact laser treatment is possible to cure accurately than the non-contact radiation.

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Contact irradiation of Nd-YAG laser was applied to bovine liver, mouse transplantable colon 38, and human gastric adenoma by a newly developed artificial sapphire probe, which is superior to quartz fiber is its heat resistance, hardness, and mechanical strength. The laser being applied to bovine liver at variable energy and irradiation time, the relationship between energy and effectiveness was consequently found out to be determined more aculately in contact method. The differences in tissue coagulation between CO₂ and distilled water used to protect the probe were also studied and concluded that adhesion of coagulated tissue could be prevented by allowing an outflow of distilled water and the abdominal distention relieved in the clinical treatment.

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An attempt was made to treat 16 cases of early gastric cancer by endoscopic Nd-YAG laser irradiation. As a refinement of the conventionally used technique (non-contact type), we proposed a contact type method of laser irradiation which, however, failed to produce a therapeutically adequate destructive effect on tumor lesions owing to low output (5-10W) irradiation. In the present study we performed laser irradiation (30W) of the intact gastric mucosa of dogs using a contact type terminal fitted with a heat-resisting microtip (S. L. T.-JAPAN) and examined the treated tissues both macroscopically and histologically. The results indicated that the new method of laser irradiation provided a depth of energy penetration comparable to that accomplished by the conventional method of non-contact type at approximately 1/2 of energy output with the latter.

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According to our experiences of laser lithotomy for the bile duct stone, a contact irradiation effects to make deeper concavity than a distant method. In order to obtain an exact effect of lithotomy to cholesterol and pigment stone, we have carried out the following experiment by means of MBB system. Laser irradiation, 0.5-2.0 seconds duration, 25-100 Watts in power, has been made in the air, in water,or in bile. As a result,it is clinically available that an irradiation should be done in contact with surface of the stone with out any moditication of the tip of the quartz compared to 5 mm in distance. There were no differences between cholesterol and pigment stone for crashing in water or in bile, However,an irradiation in the air could be suggested more effective in the cholesterol stone than in the pigment one.

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After various basic investigations with cholesterol and calcium bilirubinate stones we have performed cholangioscopic lithotomy using Nd:YAG laser. From our experience, a repeated irradiation of 70w, 0.5sec. on calcium bilirubinate stones and 70-80w, 2 sec. on cholesterol stones are the ideal conditions to achieve a complete lithotomy. Since an irradiation of more than 2sec. is considered dangerous, specially on GB cholesterol stone because it may slip off, an improvement of this method was achieved. Ba sic investigations using contact irradiation through new ceramics attached to the tip of the fiber, raising its temperature and breaking the stones were carried out.

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Of the 175 cases undergoing nephro-ureterolithotolipsy between Dec.,1981 and Oct., 1984, Nd-YAG laser was used in 17 cases(10%). But, since the head of the quartz fiber, used for contact irradiation, was severely damaged, we experimented with a new ceramics laser probe which was connected to the quartz fiber. The structure was conic form, and 5mm in length and had a head 0.2mm in diameter. Experiments demonstrated: 1) The depth of the holes made by laser beam was deeper. 2) The damage of the new ceranic probe was not severe. 3) The head of the probe could be inserted deeply because it was very solid. On the other hand, the diameter of the hole was smaller and the head was destroyed by high power beams. We expect that this new ceramic probe will prove valuable for application.

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Laser power distributions are studied experimentally in brain tissue under interstitial irradiation. The laser beam is coupled with a quartz fiber and radiated from its output end inserted to the tissue. The power level is explored with a fiber probe inserted from the other side of the tissue. The data is analyzed as a function of the distance and the angle between the two fiber ends in the tissue and the wavelength of the incident laser beam.

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Recently, the new ceramic laser probe was invented and utilized for endoscopic therapy of the gastrointestinal lesions. This laser probe is applied to the contact method in which the probe touches or punctures the tissue. As a preclinical step, we performed the experimental studies on the influence of laser rays in dogs and rats. The results characterized this laser probe as the destruction of deep tissue.
Therefore, Therefore, this new probe can be a more reliable method of coagulation of the center of a lesion rich in vessels. On the basis of these results, we applyed this new ceramic laser probe to clinical trials. This laser probe can be used as a new promising treatment for gastrointestinal cancers.

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A special quartz fiber with the tip finished in a hemispherical shape was prepared for super-wide diffusing radiation of laser beam. Under ultrasonic imaging, cubic volume of the tumor was calculated, the quartz fiber was inserted into the tumor through a 17G Tefron catheter, and continuous 5W radiation was applied for such a period as to reach the total energy of 1000 joules per one cubic centimeter of tumor. Two cases with 3 and 5cm hepatocellular carcinomas with liver cirrhosis and 8 cases of multiple liver metastasis maximum 12cm were treated under laparotomy in most cases. Dramatic drop of AFP and CEA values was observed in a few months. Post operative courses were satisfactory without hapatic dysfunction.

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Hematoporphyrin derivative (HPD) is retained by malignant tumors and emits fluorescence with peaks of 630 and 690nm wavelength when HPD is exposed to light. It is therefore theoretically possible to make a diagnosis of malignant tumors by detecting the fluorescence of HPD. The authors developed a spectroscope system compatible with fiberoptic endoscopes to analyze the shape of the fluorescence light spectrum. We could clearly recognize the HPD-specific fluorescence in human cancer foci. This system can be applied to the measurement of the relative amount of HPD absorbed in superficial tumor tissue before the photodynamic therapy. This might suggest the extent of tumor. The clincal diagnostic applications of this system are described in this study.

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In order to find out the suitable condition to carry out vascular anastomosis by microsurgical technique with CO₂ laser, the following study was carried out.
Carotid arteries of rabbits, 1.8-2.1mm in diameter and those of guinea pigs, 0.8-1.1mm in diameter were subjected to vascular anastomosis. Following exposure of the carotid artery, it was divided between clamps. Under microscope, 3-6 stay sutures with 10-0 nylon filament were placed in end to end fashion to approximate the vascular ends. Then, CO₂ laser irradiation was carried out under the above mentioned condition. Completing the anastomosis, the blood flow was restored. Macroscopic study of the site of anastomosis about hemorrhage, rupture, thrombus, stenosis and aneurysmal dilatation were made postoperatively.
CO₂ laser irradiation should be done after firm coaptation of the vascular edges are made by stay stitches to obtain a successful vascular anastomosis. Adequate condition for laser irradiation is as follows: power 20-40 mW, power density 1.5-2.5J/mm₂. Using this method, the anastomosis can be accomplished easier and faster than that by conventional vascular anastomosis.

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Recently, Laser has been widely used in the field of medicine and its favorable results have been obtained. Since fifteen years ago, we have performed surgical treatment for ischemic heart disease. There are a few cases among them who A-C bypass could not be performed because of diffuse and multiple stenosis of the coronary arteries. For the purpose to decrease mortality rate of severe those patients we have experimentally employed high power CO₂ Laser to make transventricular puncture for improving arterial blood perfusion in the ischemic area of the myocardium, which was produced by multiple ligation of the coronary arteries. Consequently, myocardial puncture could be made by CO₂ Laser and long term patency of it was observed microscopically which led to improve the ischemic myocardium. On the other hand, vascular anastomosis for the purpose of A-C bypass was experimentally done by application of low power CO₂ Laser. Eighteen dogs were utilized for this study. Both femoral artery and its vein were exposed under general anesthesia and mostly side to side anastomoses were made by CO₂ Laser (output 20-150 mW, irradiation time 15-240 sec). Subsequently, the following conclusions were obtained.
1) Vascular anastomosis could be satisfactorily done by CO₂ Laser.
2) 20-40 mW in output and 60-120 sec in irradiation time were optimal conditions for small vessel anastomosis.
3) Good healing at the site of anastomosis was observed in micro-scopic findings, as the time after surgery went on.
4) Vascular anastomosis by CO₂ Laser was useful method which could be indicated to clinical application in near future.

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Pain relief by low power laser therapy is getting the focus of attention. Headache due to muscle contraction and stiff neck are well cured by YAG and Diode lasers. Half of the patients of vascular headache and trigeminal neuralgia are alleviated. Frozen shoulder is good indication of laser therapy. Back pain, lumbago and joint pain are to be treated by this therapy prior to other physical therapy. It was proved in the human beeing that the laser stimulation evokes the afferent impulses in microneurogram recordings. The thermographic studies during. the treatment indicated the circulatory changes are related to the therapeutic effects. Based upon those clinical and physiological data the mechanisms of pain relif by low power laser are discussed.

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The diode laser was used in treating athletic pain. Neural, muscular and periosteal pain resulting from baseball, tennis, and golf were treated with immediate effects, although the pain usually re-surfaced 3 to 7 days later. Repeated treatments are desirable. When treating athletes, their strength, the nature of the sport, competition, and the burden on their muscles and bones must be kept in mind. Irradiation time can be drastically lengthened and overall treatment time reduced due to their strength, thus making therapy the day before a meet most advantageous. Their bodily balance must also be restored.

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Using the panalas 4,000, a diode laser pain attenuator developed by the Japan Medical Laser Laboratory and Matsushita Electric Co., we proceeded to treat 670 cases of articular, muscular and neural pain in 400 patients, achieving a 95.5% effective cure rate. Effects lasted from 5 hours to I month. An average of 6.3 treatments (average irradition time 7 min.) were administered per patient. Irradiating for over 10 minutes sometimes produced drowsiness or weariness. The laser was also effective for edema, swelling, numbness and paralysis. One patient unable to walk more than 20m. before treatment was able to walk 200m. afterwards.

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The authors investigated the effectiveness of laser stimulation therapy for pain Gallium-Aluminium Arsenide Diode Laser System in 181cases with pain and other symptoms. The diode laser emits a 70mW beam of 830cm wavelength. Laser irradiation was performed at the area of the neural conduction path and Hyodo's meridian points. Among 181 cases, 102 cases (56.4%) reported significant effectiveness, 65 cases(35.9%) reported some effect and 11 cases (6.1%) showed no effect. In 3 oases (1.7%) symptoms increased. The effective rate was 92.3%. Good results were obtained especially the cases with shoulder-arm syndrome, whiplash injury and ileus. This methodology was also effective in eliminately stridor daring asthma attack and also to promote peristalsis movement. This technology is effective in freeing cancer patients from pain without using sedatives which sometimes cause complications. There here no serious side effects.

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Carrageenin solution was used as a phlogistic stimulus. The air-pouch inflammation and the inflammatory edema was selected as experimental inflammation and we studied effects of the Diode laser using inframmatory 48 donryu rats.
The inflammatory edema and cellular infiltration was increased by the irradiation of the diode laser. It seems this phenomenon was caused in consequence of the acceleration of vascular permeability. Expansion of small vessels and vascularization was observed. As for the air-pouch inflammation, the exudate and granulation was decreased by the irradiation of laser beam.
Therefore, it seems the irradiation of diode laser showing antiphlogistic effects.

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Diode laser acupuncture has been applied to chronic pain patients. For chronic pain patients, the first injury often becomes sympathetic dystrophy and induces myofascial pain syndromes with trigger points. We applied sympathetic nerve blocks to the first injury followed by sympathetic dystrophy, and laser acupuncture to the myofascial pain syndromes as a trigger point therapy. The stimulation therapy using laser acupuncture is useful for the chronic pain patients who tend to depend on analgesics.

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An extension system of argon laser light was developed by Machida and Furukawa Co. LTD., and was put first to practical use in Jichi Medical School Hospital. With the extension system, argon laser light is distributed and extended to multiple terminals through the fiber cable, X-ray, operation and endoscopic rooms, 160, 135 and 55 meters away from the central room where the main apparatus of argon laser and distributing system are located. Considering the safety for people and fire prevention in case of unexpected severance of the fiber cable by any possibility, the whole system is well provided with double or triple safety devices.With this extension system of argon laser light, the indication of laser endoscopy has widely extended with a great advantage of economical efficiency, making it possible to perform the right procedure in the right place.

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An excimer laser pumped dye laser system is used for fluorescence photoradiation or photodynamic theraphy using HpD which has an affinity for cancer. In this system high powered laser, pulse must transmit through an optical fiber to obtain good results of cancer treatment. Quartz fiber of 400μm core diameter could transmit 600kw laser pulse (λ=620nm) without damage.

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We have developed a rounded shape optical fiber for the purpose of spreading laser light over a wide field. The purpose of this study was to evaluate a illumination characteristics of the rounded shape opyical fiber, the tapered shape optical fiber and the graded index optical fiber (Selfoc). The diverging angle of the output laser light of the rounded shape fiber, the tapered shape fiber and Selfoc were 60°, 360°and 25°, respectively. Though the tapered shape had a widest beam divergence, its energy distribution was not uniform. The rounded shape has been used clinically, however its energy distribution showed a high density at centre and a down slope. Selfoc had a small diverging angle, however its energy distribution was most uniform. The uniform area of Selfoc was three times as large as the usual fiber. These results suggest that Selfoc is most useful for a wide and uniform illumination.

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We developed a ruby laser system with a handpiece utilizing a “Kaleidoscope (Trade Mark pending)”, to produce a uniform intensity distribution over a square area for the purpose of treatment of nevus. In order to increase its maneuverability, we have improved the design of this handpiece by using a small “Kaleidoscope”, through which a laser beam becomes uniform with a square cross-section and is magnified to a desired area by a lens. By utilizing this handpiece we have been able to realize the following advantages.
(1) Irradiated area is easily adjusted by changing the position of the lens.
(2) A compact “Kaleidoscope” is used to make the handpiece light and comfortable to use.
(3) The “Kaleidoscope” does not contact the patient, so its output surface cannot become contaminated.
(4) Changeable positioning collars each with an irradiation window in a transparent disc allow quick and accurate adjustment of irradiation area and location

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The power light guide system is usefull problem in the medical applications. In order that the function be must effective, enough flexibility and security of power light guide are required. As this one technique, we have developed a flexible CO₂ laser beam guide with metal and polymer hollow tube. This method is based on parallel metal guide technique. The laser beam is propagated in a space bounded with metal and polymer. Namely, beam propagation medium is the air, therefore, this guide tube is non-toxic for CO₂ laser beam propagation.
The present experimental results show that the CO₂ laser beam transmittance exceeds 80%per meter, emitted power was obtained ca. 25W at 1m guide length, and any accident were not happen under condition that the continuous transmission in an hour.

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KRS-5 (TlBr-TlI) fiber for high power transmission has been developed. The most preferable composition for the fiber has been investigated to be 43 weight % TlBr, and under this composition the fiber with 0.5 mm diameter and 1.5 m length has excellent characteristics as follows. (1) High output power of 70 watts, (2) high transmissibility of more than 90%, (3) minimum bend, radius of 10 cm.
This fiber has been put into practical use for CO₂ laser scalpel. The scalpel has almost same incision capability and excellent flexibility in comparison with mirror joint CO₂ laser scalpel.

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CO₂ gas laser has been used as a laser scalpel. There has been strong demands for development of flexible optical fiber cable to transmit CO₂ gas laser beam for medical and industrial applications. Metal halide crystal such as alkali halide, silver halide, or thallium halide seems to be the most prospective optical fiber material. This report discusses the physical and optical characteristics of silver halide optical fiber which are essential for medical use. Then the application of those fibers on flexible waveguide for CO₂ laser scalpel and thin flexible wave-guide for endoscopic use is described.

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