The results in 53 cases of lung canser endoscopically treated by HpD and argon dye laser photoradiation were examined to evaluate the effectiveness and delineate the limitations of this new method in lung cancer cases.
The Sex distribution was 48 males and 5 females. The age distribution was 38 to 78. The cases were clinically clasified as 8 early stage, 4 stage 1,9 stage II, 22 stage III and 10 stageIV. Histologically 38 were squamous cell carcinoma,7 adenocarcinoma, 4 large cell carcinoma, 3small cell carcinoma and 1 bronchial metastasis of malignant melanoma. 2.0-5.0mg/kg body weight of HpD was administered intravenously 48-72 hours prior to photoradiation. The surfase of the lesion was irradiated in cases of superficial invation and in cases of polypoid tumors intratumoral photoradiation was performed via a quartz fiber inserted through the fiberoptic bronchoscope. Therapeutic effectiveness was evaluated as follows; complete remission(CR) means no evidence of tumor by fiberoptic bronchoscopy, biopsied histology and brushing cytology, significant remission (SR) means more than 60% reduction of the lesion endoscopically, partial remition (PR) means 20-59% reduction endscopically and no remission (NR) means less than 20% reduction. CR was obtained in 7 out of 8 eary stage and lout of 4 stage 1. SR. was obtained 5 out of 41 advanced cases. Opening of bronchi obstructed by tumor was obtained in 21 out of 38 foci. From these results this therapy was shown to be effective to treat eary stage superficial lung cancer curatively.

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Endoscopic laser surgery for stenotic lesions of inferior respiratory tract has been performed in two ways. One is the carbon dioxide laser surgery under specially designed rigid bronchoscope and the other is Nd-YAG laser surgery through the flexible fiberscope. As for the easy maneuverbility and visibility of the operation's field, the Nd-YAG laser surgery is definitely superior to CO₂ laser surgery. But the extent of the exfoliated necrotic tissue for the irradiated area could be more accurately estimated in CO₂ laser than in YAG laser. Endoscopic laser surgery is the choice of treatment for the stenotic lesions of the respiratory tract. But in the case of circular cicatricial stenosis, insertion of a silicone tube using an oral approach following laser vaporization may be useful for the prevention of a recurrent. stenosis. The insertion of silicone tube using an oral approach has the following clinical merits.
1) there is no tracheal opening necessary, 2) troublesome suction of secreation is not necessary, and 3) normal speech is possible immediately after surgery.

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The use of the CO₂ laser in laryngomicrosurgery together with the self-retaining laryngoscope is an effective surgical technique for laryngeal diseases in the ENT field. This technique is suitable for the treatment of both benign and malignant tumors, and of superficial mucosal lesions by laser vaporization or laser excision.
Advantages
1. Because of the non-contact operation, it is easier to treat deeper affected areas.
2. The appropriate energy density for irradiation is selectable to vaporize any volume of tissue.
3. Bleeding and damage to normal tissues surrounding the affected area are less.
4. There are less topographic reactions (pain, edema) and cicatrization after surgery.
5. Dissemination can be prevented at the time of vaporization of malignant tumors.
Limitations
1. The use of this surgical technique is limited to the areas of the hypopharynx and glottis.
2. For the treatment of an affected area where the rectilinear laser beam cannot reach, the concurrent use of forceps is necessary.
3. Other hemostasis is necessary to prevent hemorrhage in blood vessels larger than 0.5 mm (artery) and 1.0. mm (vein).
4. For the excision of small lesions of the vocal cord free edge such as nodes and pedicled polyps, scissors are better than the laser scalpel.
5. Further studies are still required for the single laser treatment of laryngeal cancer at the primary stage.

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Active upper G-I bleeding cases were divided into 3 groups, 45 cases were treated by Nd-YAG laser, 13 cases were treated by argon laser and 41 cases as the control group were treated by nonendoscopic methods.
Bleeding was stopped for over 72 hours in 42 cases (93%) treated by Nd-YAG laser, in 10 cases (77%) by argon laser and in 26 cases (63%) by control methods.
The mean blood transfusion volume in severe cases was 1490 ml in the Nd-YAG group, 2070 ml in the argon group and 5050 ml in the control group. In moderate cases 560 ml in the Nd-YAG group, 930 ml in the argon group and 2290 ml in the control group.
In moderate cases the rate of surgical operations which were performed within a month in the Nd-YAG grout was 7%, in the argon group was 11% and the control group was 38 %.
Using argon laser, bleeding from exposed blood vessels the diameters.of which were over 1.5 mm could not be stopped.

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We treated 29 cases of G-I bleeding and in 25 cases(86.2%) bleeding stopped with YAG laser alone. But it was difficult to control bleeding from the arteries more than 2mm in diameter. Therefore, we have tried the hemostatic procedure which combined the photocoagulation with the endoscopic local injections of HS-E solution. There were 16 cases of early gastric cancer and 4 cases of ATP treated by laser. Some were followed for 4 years and 3 months at the longest, and the course was favorable after irradiation. There were no relapses. There were 4 cases of early colonic cancer treated by laser. Two cases were followed up in 3 years and 5 months, but there were no relapres and all were well. We irradiated intractable gastric ulcer with laser which resulted in fresch, active ulcer. By this we expected to facilitate the new healing process. 16 cases of intractable gastric ulcer healed well within 2.2 months. Laser endoscopy is very useful about above clinical applications.
In treatment of early gastric cancer and early colonic cancer, all patients were unable to undertake operations for some reasons except 2 cases. This 2 cases were irradiated before 'operation. We have no complication using laser treatment about many cases until today.

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The endoscopic argon laser phototherapy was very useful for the treatment of gastrointestinal tumors.
The pathological studies of resected stomach following phototherapy revealed that both mucosal layer and submucosal layer were completely vaporlized and the coagulated necrosis was found at the upper part of proper muscle layer.
The several endoscopical biopsies following phototherapy showed that a early esophageal cancer, the early gastric cancers and the lesions of moderately atypical cells could be completely burnt down by only argon laser phototherapy without any complication.
Although short cancerous stenosis could be improved by phototherapy, it was no use to reduce the mass for far advanced cancer.

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For the removal of larger stones and incarcerated stones in the biliary duct under cholangioscopy, the easier method has been required. The YAG laser irradiation seems to be most suitable for such purposes. The main advantage of the application of YAG laser is that the stone becomes fragile and easy to be crushed after many holes are made by laser irradiation on its surface.
We have experienced 15 cases of lithotomy using YAG laser under cholangioscopy by October 1982. In 11 cases stones were found in the intrahepatic biliary duct and 4 cases, in the extrahepatic duct. In 10 cases cholangioscope was inserted through a dilated fistula for PTCD, in 3 cases through a fistula for T-tube and in 2 cases through both routes.
We have noticed that large stones as well as incarcerated stones could be removed through a thin fistula in. shoter period with this method of lithotomy using YAG laser. The laser irradiation is also effective for the dilatation of strictured anastomosis of intrahepatic cholangiojejunostomy.
We believe this method including the idea such as lithotomy before surgical procedure using YAG laser will become popular for the treatment of hepatolithiasis in near future.

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Transurethral endoscopic surgery is well developed in the field of urology, because urethra and bladder can easily pass rigid endoscopes. These technics are widely applied to laser endoscopic surgery.
Three kinds of lasers, namely Carbon dioxide laser, Neodimium-YAG laser and Argon laser are used today for laser treatment. Neodimium-YAG laser and Argon laser are suitable for the endoscopic use in urology than CO₂ laser, because these two kinds of lasers are guided through fine flexible optical fibers, so no special equipment is necessary for endoscopic laser surgery when it is done using these two kinds of lasers.
I would like to show, in this symposium, the actu-al procedures of the treatment of bladder tumor, urethral stenosis anf of urinary stones. including advantages and disadvantages of these methods.

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It is well recognized that laser spectroscopy plays important roles in the research of cancer. Little work has been done in the laser spectroscopy in malignant tumor, especially in vivo. We observed the characteristic spontaneous emission and excitation spectra obtained without any injection of probing reagents.
This emission was observed in human gastric and colon cancer and will be a good indicator for the cancer detection.

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The phototoxic effects of acridine orange (AO) or hematoporphyrin derivative (HpD) with dye laser irradi-ation on Walker carcinosarcoma 256 tumors and human gastric cancer cells were studied. Observations were made by phase-contrast microscopy and electron microscopy.
Tumor-bearing rats were injected i. p. with 40mg/Kg of AO 2hr before irradiation. Then the tumors were exposed to the argon laser at 488nm at an intensity of 15mW/cm² for 20min. Irradiation caused complete or partial tumor necrosis with sparing of surrounding mucosa. No marked temperature rise was detected during irradiation.
Human gastric cancer cells were obtained by biopsy. They were incubated in serum containing 36uM of AO or 0.9mM of HpD, and were exposed to dye laser (488nm for AO or 630nm for HpD) at the same intensity as above. Cancer cells were immediately damaged by irradiation.
The difference of phototoxic degeneration process of tumor cells between AO and HpD was discussed and the formation of singlet oxygen was suggested in these systems.

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The effect of YAG laser irradiation to the cultured gastric cancer cells was investigated and following results were obtained. Survival rate of normal mucosal cells after laser irradiation was higher than that of gastric cancer cells. The effect of laser to the poorly differentiated adenocarcinoma cells was more prominent than to the tubular adenocarcinoma cells. This may be because of the different sensitivities to the laser among histological type of cancer cells.

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We had illuminated the gastric lesions with Argon laser to study the autofluorescence of various gastric lesions since. three years ago. The results, which had been reported previously, reveal that the elevated gastric lesions, such as polyp, submucosal tumor and early gastric cancer type IIa show weak autofluorescence, while strong autofluorescence is usually noted in the early cancer type IIc, especially for the signet-ring cell carcinoma. In the present study, we have studied the histological character of both the strong and weak autofluorescence area in attempt to resolve the property of autofluorescence. Based on the results, we have the following conclusions. The extent of autofluorescence of different cancerous regions are not always similar even in the same IIc field, but the strong autofluorescence area almost always correspond to the slight depressive cancerous region. When the thickness of non-cancerous region or cancerous region overlying the muscularis mucosa, especially the former, gets thinner, the autofluorescence of the corresponding area gets stronger. The glandular epithelium, regenerative epithelium, hemorrhage and inflammatory cells in the mucosal layer as well as the lack of muscularis mucosa play a role in decreasing the extent of autofluorescence of cancerous region. Based on the histological character of both the strong and weak autofluorescence regions, we supposed that autofluorescence in the slight depressive type of early gastric cancer may be attributable to the muscularis mucosa below the cancerous layer.

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Little work has been done in the fluorescence spectroscopy in GI tract cancer. We studied the emission spectrum analysis of GI tract cancer without any administration of probing reagents.
Resected fresh specimens illuminated by Argon laser showed red, orange and yellow fluorescences.
Fluorescence spectra were classified into 4 types (A-D). Type A, which showed 2 peaks located at 560nm and 600nm, was most frequently obtained from benign region and malignant region. Type B, which showed 3 peaks located at 560nm, 600nm and 660nm, was observed from the ulcer bed. Type C spectra, which showed clear peak at 630nm, was obtained from the marginal wall and the ulcer bed of cancer, and was characteristic of cancer. This spectrum was observed from not only human cancer but also animal tumor such as MH-134 in mice. Emission spectrum and excitation spectrum of 630nm emission strongly suggested that the red emission might be originated from the native porphyrin accumulated in malignant tumor. Type D spectra was characteristic of xanthoma.

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We have been observing autofluorescence of gastric cancer and hepatoma, and suceeded in taking the endoscopic picture clearly. These lesions were illuminated with Argon Laser beam at 488-514.5 nm wave length through a 520-560 nm sharp cut filter.
We could not recognize autofluorescence excited by Argon Laser bam in intestinal metaplasia, polyp, and ATP. In benigh ulcer, autofluorescence was observed indistinctly. And remarkable autofluorescence could be noted in depressed type gastric cancer, and xanthoma. This diagnostic procedure was called laserinduced fluorescence endoscopy (LIFE).
In hepatoma we could find yellow-orange autofluorescence excited by Argon laser beam in the laparoscopy. This procedure was called laser-induced fluorescence laparoscopy (LIFL).
We concluded that these procedures were useful to diagnose with early cancer and minute cancer of the digestive organs. In the future, technology of spectrum analysis, pigment fluoroscopy, holography and magnifying, observation may put into practice for the diagnostic procedure of cancer.

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Autofluorescence of hepatoma excited by argon laser was observed in the majority of cases (12/16). Autofluorescence was recognized in a part of the tumor or all over the tumor. The same phenomena were also confirmed in metastatic liver cancer (3/3). In some nodules of liver cirrhosis (2/7), however, weak autofluorescence was recognized.
In rat hepatoma, on the other hand, autofluorescence was observed not only on cancer itself, but also on the nodules of histologically severe dysplasia.
The biological mechanism of autofluorescence excited by argon laser light stimulation is not elucidated yet. These Phenomena obtained in the present study, however, would be a significant clue to the future diagnostic procedure for early detection of hepatoma.

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The aim of this study was to evaluate the efficacy and safety of endoscopic Nd: YAG laser treatment for tumors of gastrointestinal tract.
As a local curative procedure, 30 lesions of border-line lesion of the stomach, 34 lesions of early gastric carcinoma and 34 lesions of colorectal adenoma were treated. The effect of laser treatment was histologically confirmed in 9 patients whose lesion was treated preoperatively. In the remaining cases, a long-term effect was evaluated by follow-up result after complete eradication of the lesion with negative biopsy achieved. Recurrence of tumor has been observed in 8 lesions of gastric tumor, in which the difficulty in correct aiming of laser at the lesion was thought to be major cause of incomplete treatment. 4 lesions were complicated by hemorrhage from laser-induced ulcer. All lesions complicated were of IIc type of early gastric carcinoma.
As a palliative procedure for advanced gastric or colorectal carcinoma, relief of neoplastic obstruction was attempted but failed in one patient, reduction of tumor mass achieved in 3 out of 4 patients and photo-coagulation of hemorrhagic tumor was performed in 4 patients with one therapeutic failure.

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Since March 1980, we have actively applied laser endos-copy not only for the control of massive G. I. bleeding but also for non-surgical treatment of G. I. malignant tumors. The purpose of this study are as follows:
1) Effec of palliative laser endoscopy for bleeding or stenosis.
2) Possible treatment of early cancer of upper G. I. tract by laser endoscopy.
Materials and Method: 14 cases of bleeding and 13 cases of stenosis were treated palliatively by laser endoscopy. 7 cases of early gastric cancer were preoperatively photoradiated on the part of cancerous lesion and their gastrectomized specimens were studied histologically. 8 cases of early G. I. cancer who were contraindicative for surgery or refused surgery were treated with aim of radical therapy. 2 of them who died due to other disease were studied histologically with autopsy speciemens.
The laser we used is Nd-YAG laser (MEDILAS, MBB). Laser photoradiation was performed with 70 watts of radiation power and 0.5 second of exposure time. We used GIF-2T as laser endoscopy. Results: 1) Satisfactory results were obtained in cases of bleeding or stenosis.

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Hematoporphyrin derivative (HpD) is a substance that is retained longer by malignant tissue than by normal tissue. It is a fluorescent substance and also has cytocidal effects when stimulated by light. Making use of these three properties the authors applied HpD in the diagnosis and treatment of malignant tumors of the upper G. I. tract by means of an endoscopic and laser photostimulation system. Materials included 9 esophageal carcinomas and 22 gastric cancers. Fluorescence was recognized at the site of tumor in 21 out of 22 tumors. However it was impossible to recognize fluorescence at the site of bleeding or areas covered by necrotic tissue. Therapeutically, complete remission was recognized endoscopically in 8 of 16 early stage cases. Of these, 6 were later resected and pathological examination showed complete disappearance of the tumor in 4. The fact that tumor nests remained in the other 2 was thought to be due to the difficulty in providing homogenous light stimulation. Therefore this method holds promise for the curative treatment of early stage G. I. cancer provided that further development is made in the light delivery capabilities.

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Effectiveness and mechanism of argon laser photoradiation therapy was studied in cultured cells. Photosensitizing agents used in this study included acridine orange (AO), Adriacin, Cosmegen and Mithramycin. Among these drugs, AO was most effectively photosensitized to cause cell death, whereas other anti-cancer drugs had little additional effects to their own cytocidal effect by laser irradiation. Photoradiation effect was observed only when cells were irradiated after AO treatment. Irradiation of AO or cells separately did not cause cell death. Therefore interaction between AG and cell was considered indispensable in this modality. Until now AO is the most effective photosensitizer in argon laser photoradiation therapy but some disadvantages such as genotoxicity must be overcome before it is widely applied clinically.

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By May, 1982, laser surgery was performed in 123 cases (thyroid 22, breast 15, GI tract 10, liver 63 and others 13), of which surgery of the digestive system performed in 51 cases (gastric Ca 6, colonic Ca 3, pancreatic Ca 3, hepatic Ca 33 and others 6) accounting for 41.5%.
In malignant tumor of the GI tract, CO₂ laser is useful for division and excision. The defocused CO₂ laser beam and coagulation of the Nd-YAG laser is applied to the area after lymph node dissection by which lymphatic and small vascular vessels are expected to be coagulated and occluded resulting in preventing metastasis. In malignant tumor of parenchymatous organ such as the liver, the Nd-YAG laser scalpel is useful in transection of parenchyma with less homorrhage.
In application of the laser in surgery for the malignant disease of the digestive system, the laser surgery can be expected to have a merit of less insult to remaining tissue as well as application of it to other organ.
It is important that characteristic efficasy that used laser possess should be applicable in surgery.

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We have developed technology to identify and separate biological cells while they are alive and have fabricated the automated biological cell analyzing and sorting system “CS-5000”.
The CS-5000 is a new flow-system instrument for quantitative analysis and sorting of microscopic particles, particularly biological cells, based on multiple measurements of physical and biological properties.
Cells stained with fluorescent dyes in liquid suspension are jetted out through a micro-nozzle at a high speed and are illuminated by laser beam as they flow in a stream. Optical sensors measure light-scatter, single- or two-color fluorescence. Sensor signals are electronically processed in several ways for optimum cell discrimination and displayed as pulse-amplitude distribution using a pulse-hight analyzer. Sorting is accomplished by electrically charging droplets containing the cells and electrostatically deflecting them. into collecting vessels.
Use of this system in biological and biomedical reseach and clinical medicine will greatly contribute to the further development of life sciences.

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The flashlamp-excited dye laser has been developed as the most advanced laser coagulator. In this system, dye molecules are directly excited by a xenon flashlamp. This laser generates the short-pulse laser beam which is of very high power. The wavelength is tunable in the range of 450 to 800 nm, and the maximum output energy is 1J per pulse at 1 pulse per second. The laser beam is guided to the treatment spot by the quarts fiber. The spot size can be adjusted from 1 to 4 mm diameter to obtain the energy density from 0 to 60J/cm₂. This system has two dye reservoir tanks to permit a quick change of the dye. With regard to exchanging of the dye that is owing to its degradation, it should be done every 20,000-30,000 shots in case of using RHODAMINE. It means that the dye should be exchanged every 1 to 2 months.
One of the typical applications of this coagulator is the treatment of nevi. In one way, the wavelength is tuned to 577 nm that is one of the absorption peak of hemoglobin. This enables the excellent treatment of hemangioma. To the contrary, the other wavelength (e. g. 640 nm) is well fitted to the absorption of the melanin avoiding the absorption of the blood. With these methods, the best results can be expected for the treatment of the nevi depending on its chromatic characteristics.

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We have been discussed about the future design of the laser-medical-treatment-system (LMTS) using a optical fiber as a transmission line of laser energy. To adapt various clinical treatment, the laser light source which can easily alter its cutting and/or coagulating capacity for living tissue shall be necessary. And simultaneously, it shall be necessary to employ the transmission line using flexible optical fibers. Since the optical fibers affect significantly on total performance of the LMTS, the optical fibers are the key compornents in the LMTS. In this point of view, we investigated the characteristics of various infrared fiber which have been reported. Consequently, we suggested the employment of the laser light source which is consisted with CO laser for cutting and Nd-YAG laser for coagulating, based upon the discussions of the optical fibers and the infrared lasers. These laser lights may be transmit in the infrared glass optical fiber of high strength. CO laser is essentially high-power and high-efficiency laser system. However, the CO laser which can use the medical application is not reproted before. Thus, we have been developed the CO laser device for medical use.

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This paper aimed at experimental evaluation of the operational performance concerning the CO₂ laser scalpel whose types are flexible light guided way and mirror joint one.
Worker process analysis of the CO₂ scalpel operation are carried out and the evaluation resulted in that the flexible light guided way type is much better than that of mirror joint one in the vibration and reliability.

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Milhaud laser resistant tube was compared with polyvinylchloride tube from the view points of antiburning, antiperforation and heat-proof ability. Superiorities of Milhaud tube were proved in following points.
(1) Milhaud tube has high antiburning and antiperforation ability in CO₂ laser irradiation. (2) Smoke was so little in Milhaud tube that operator's view was not prevented by this smoke. (3) Milhaud tube has excellent heat conduction ability and deformity induced by the carbonization, melting was not observed. (4) Crystalization of Silica on the Milhaud tube forms effective barrier to the heat. (5) N₂-gas perfusion side-tube prevents burning of the tube.
These results indicate that Milhaud tube can decrease accidents and damages induced by the misshots of laser irradiation and application of this tube should contribute to developments of safe laser surgery.

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We developed a ruby laser system with an output section utilizing a “Kaleidoscope”, thus having uniform intensity distribution for the purpose of treatment of neves. After some test application, we have improved this system in order to increase the maneuverability of the applicator surface: (1) the laser oscillator and the “Kaleidoscope” have been interconnected by a specially designed flexible quartz optical fiber, 1.2mm in diameter and 2m in length, (2) the quartz optical fiber has been inserted into flexible metal tubing for protection in the event that the quartz fiber snaps in use, and (3) a handpiece consisting of a “Kaleidoscope” which has been made light and compact to make it easy to handle. Neves on any surface of the body can be easily irradiated with laser light through the use of the newly designed hand piece connected with a quartz optical fiber.

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In irradiation of the medical laser through a optical fiber, a beam diverges with some conical angle, which results in irradiation and degeneration of the surrounding normal tissue is addition to the aimed area. Especially this happened frequently in endoscopical use of the laser because of the difficulty of maintaining the distance between fiber end and tissue.
In order to restrict the area of irradiation and gain high power density by focusing the laser beam, a optical fiber with lens tip was developed. A diameter of the optical fiber core was 0.6mm, lens diameter was 1.7mm and focusing distance was 2mm.
In early experiments there were many thermal damages at the fiber tip. In irradiation in water, bubbles emerged at the tip of the fiber which scatter laser beam and heat up to cause thermal damage of the lens and lowering of the irradiation power.
In order to solve these problems a nozzle was adapted to water jet or gas jet, which prevented adhesion of the bubble or heat damage of the lens and the laser power was maintained.
This lens tipped fiber was applied to destroy gall stones experimentally with successful results

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We developed the new output geometries of laser fiber for the purpose of getting both small spot size and also beam enlargement. Small spot size of laser beam means high power density, which is used for the coagulation of stop bleeding of GI tract accurately and also used for the destraction of tumors or stones under the endoscopic manipulation. Requirements of the beam enlargement are brought about by photoradiation therapy and fluorescence examination studies, in vivo. We have many methods for focussing of laser beam out-put from fiber; microlens attached to fiber tip, use of graded index rod lens and waveguide grating lens, and so on. The microlens method has some problems such as lens size,power loss and heating by scattering or reflection of the laser beam on the lens surface. Fiber used in this study is commercially avairable single quartz fiber. We designed and analyzed ball-shaped, hemispheric and trapezoid tip fiber. Straight and tapered tip fiber were made just only for the purpose of comparison. Ball-shaped, hemispheric and trapezoid one showed a high power density at the focal point than straight one, however the power density is decreased rapidly due to the beam divergence. In trapezoid one, there showed something like hot spot even without lens. Tapered one is limited in low power density because light is spread out from the wide area of tip into large angles. Ball-shaped one shows the highest power density at the focal point. This means laser light can be focused into very small spot. Advantages of those rounded tip fiber-optics are summarized as follow; it is simple design and low cost. It can be reformed many times and also be applicable to any endoscopes.

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A uniform wide angle irradiation of laser into a malignant tumor is achieved by chemically processing the output end of an optical fiber to have a rough surface. The angular distribution of the scattered light is analyzed experimentally as a function of the incident angle of the laser beam into the input end of the fiber and the length of the rough portion on the cylinderical surface of the core at the output end.

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A gradient index (GRIN) rod lens has been used for clinical endoscope which has several advantages for the application of holographic techniques to the medical internal diagnosis. First of all, the phase informations of the object can be transmitted by GRIN lens, i. e., 3-D image reconstruction as well as holographic interference techniques are perfectly available. In this paper, some foundamental discussions of GRIN lens holography, experimental results on 3-D image reconstructions and time average holographic interferometry are presented.

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The thermal effect of lasers is the most applicable to the therapeutic uses of lasers, so that measuring the temperatures of lased tissue correctly is very important for laser therapies.
The temperature of the lased tissues is usually measured with a thermocouple. However, it can not be always measured true temperature of the lasing tissue in such a laser as to penetrate into the tissue because of direct detection of penetrated laser energy in addition to the heat conduction from the target of the tissue.
The authors improved the thermocouple to have high reflectance for the lasers on its surface by spattering with reflecting material as aluminum.
The true temperature of lasing tissue can be measured correctly by using the improved thermocouple.

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Bacteriocidal effect of carbon dioxide laser irradiation was quantified as a function of the laser output (P), exposure time (t), laser beam spot size (φ) and base temperature (T) of the target (culture media). An Aloka's surgical CO₂ laser was used for defocused (φ 6, 12mm) irradiations of the laser beam onto staphylococci-inoculated, modified Müller-Hinton culture plates. Samples were incubated at 37°C for 20 hours.
The size of clear, circular zones of bacterial growth inhibition was found to have a functional relationship with the dose of laser irradiation (power×exposure time) and also depend on the beam spot size as well as the temperature of the target.
The experimental data also indicated that the values of the laser power and the exposure time for threshould inhibition satisfies the following equations: P=k/√t and ΔT=KP√t, where k and K are coefficients related to the target temperature and ΔT is the maximal temperature rise at the irradiated center of the inoculated media.

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e measured the concentration of several gases in the smoke nerated by carbon dioxide laser applied to a piece of at. Gas sample was collected at several points close to an ission spot on the meat. The concentration analysis were ne dy means of Saltzman Reagent for NOx, infrared spectroopy for HCHO, and gas detector tube for CO, CO₂, CH₃COOH, I₃NH, H₂S and CH₃SH. They are responsible for unpleasant or.
onsidering the present standards of ambient air pollution, e concentrations of NOx,CO and CO₂ were low; that is, 1-0.05, 4-20 and 400ppm, respectively. Those of HCHO and I₃COOH were relatively higher; showing 0.1-6ppm, respective. And that of CH₃NH₂ was very high level of several tens m. Among sulfur compounds figures of 1-4ppm for CH₃SH and -2ppm for H₂S were observed, but sulfur dioxide was not und.
n preliminary study was made on flying micro-particle in-uding tissue fragments and tar like material by thermal gradation of meat. And the efficiency of a gas scavenging stern which we designed for laser operation was also amined.

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Since soft tissues have a low absorption coefficient ( =lcm) and comparatively high scattering coefficient (β=9cm) to YAG laser light, it can penetrate into a soft tissue widely and can be absorbed there mildly to coagulate the area. The effects of YAG laser on tissues, however, are not so simple as CO₂ laser, so that the operaters must have adequate knowledge and well-trained skill of the technique in its practical applications. This paper discusses the basic knowledge as for the tissue coagulation with YAG laser based on the experimental results. In addition to them, practically applicable techniques for tissue coagulation with YAG laser devised by the authors are reported here.

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Our clinical experience has shown that intractable gastric ulcers can be healed effectively by Nd: YAG laser phototherapy. One of the mechanisms is a destructive effect on the fibrous tissue of the ulcers by high power densities of laser radiation. The other is a specific effect on it of the wave lentgh. However, these mechanisms are still unclear. The pourpose of this study is to make clear a specificity of the wave length of Nd: YAG laser in biological effect.
Laser was radiated to the cultured canine hepatocytes in plastic culture dish at 50w of out put power, 5 second duration and 10cm of distance. Power densities were applied from 120 to 480 J/cm² in this condition. The specific effect of the wave length was evaluated by the measurement of the viability of hepatocytes, the ability of 3H-thymidine and ¹⁴C-leucine up-takes after 24 hours of radiation.
Temperature in the culture dish rose to approximately average of 44°C during radiation. Viability of hepatocytes was 94+1%before radiation and was 9511% after radiation with 480J/cm². The ability of up-take of the radioisotopes showed no remarkable changes in comparison with non radiation group.
These results suggest that the specific effect of the wave length is not essential on a healing of intractable ulcers in condition of usual clinical application of Nd: YAG laser.

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We have been suggested the use of CO laser as a cutting laser light of the laser-medical-treatment-system in future. In oreder to demonstrate the validity of the cutting characteristics of CO laser irradiation, comparative study of cutting and coagulating characteristics of CO and CO₂ laser irradiation was performed with quantitative experimental investigation. The laser irradiation experiments against dog and cow liver were carried out in vitro. In the case of cutting experiments, the focused laser beam of 1.3-2.6kW/cm² of averaged laser power intensity (P/πω²₀) was exposured on the moving sample surface. Although, the cutting capacity of CO laser irradiation was slightly less than that of CO₂ laser irradiation, it is evident that CO laser irradiation has a sufficient cutting capacity for actual use. The thickness of coagulated layer at cross-section of cutting groove by CO laser cutting was about 50% thicker than that of CO₂ laser cutting under same conditions. In the case of coagulating experiments, the laser beam of 5-45 W/cm² of averaged power intensity was exposured on the staionary sample surface. Under 2 sec laser irradication, the coagulated layer thickness by CO laser was about 0.1-0.2 mm thicker than CO₂ laser. These performances were found to be consistent with the rough estimation and the quantitative discussion based upon water absorption coefficient in infrared. In summary, it can be inferred that CO laser is possible to use as laser scalpel.

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Cornparison of the thermal effects on the brain tissue among the carbon dioxide laser, Nd-YAG laser, infrared contact coagulator and electrosurgical unit was carried out in morphological studies and temperature measurments.The usefulness of the infrared contact coagulator in covering the insufficient hemostatic capability of the carbon dioxide laser was pointed out. Three cases including a highly vascularized tuberculum sellae meningioma, hemangioblastoma and AVM were presented. Those three cases were hemostatically operated using the carbon dioxide laser in combination with the infrared contact coagulator.

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In order to study possible cytogenetic effects of argon laser irradiation, V79 Chinese hamster fibroblasts were irradiated with a defocused argon laser beam (100-400 J/cm²). Inhibition of cell growth was observed dose dependently. Flow-cytofluorometric analysis indicated the blockage of cell cycle progression at G2+M phase. Chromosomal effects were investigated by sister chromatid exchange and chromosomal aberration, both of which were elevated dose dependently. Mutation was not induced in ouabain locus. These cytological changes were not due to elevation of temperature during irradiation or experimental artifacts such as the possible phototoxic effects of Kanamycin or phenol red in the culture medium or spontaneous emission of UV light of the laser. These results indicate that the argon laser irradiation at high doses probably induces damage at the chromosomal level.

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The lethal effect of near UV laser irradiation on 3T3 cells and SV3T3 cells were investigated by testing the growth rates and the colony formation efficiencies. The survival curves of these cells treated with near UV laser exhibited an initial shoulder at low dose followed by exponential response at the higher dose, and there was little difference on the lethal effect between these two cell lines.
This lethal effect was remarkably enhanced when the cells treated with vitamin A. Compared the survival rates of two cell lines in the presence of vitamin A, SV3T3 cells were more sensitive to near UV laser than 3T3 cells. These survival curves were showed the same pattern as those of cells treated with near UV laser only, but the quasithreshold dose and the mean lethal dose were very low.

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The authors have studied on safety for combined laser therapy (C. L. T.). The method of C. L. T. is to combine some kinds of lasers together taking advantage of each different effect on human body in order to achieve more effective treatment. For the laser safety in the C. L. T. method, the unique safety systems should be required as follows;
1. The difference of the optical characteristics of the tissues to each laser must be considered.
2. Laser protective eyewear must simultaneously cut off the lasers of every wavelengths perfectly.
3. The tissues located in surrounding area of the target should be protected against accidental radiation of every lasers using in the C. L. T..
4. In using some kinds of lasers together, a hand-switch should be provided for each laser handpiece to avoid mis-shot.
5. Every laser can be distinguished easily by the each light guide.
6. The white light is applicable for every guide light in the C. L. T..

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Recent advances of Laser Medicine have been remarkable in many fields related to clinical use. Also Laser Surgery has reached the point to develop its clinical applications in a lot of surgical aspects. Laser has a very effective usefulness for some surgical treatment in suitable indications. However it has essencially some side effects to biological tissues and human body. It is extremely important to prevent such a negative factors in order to develop its clinical use also in surgical fields. Laser safety problems are related, the one to technical factor, the other to handling matters. One of the latter problems, the reflection of laser beam from the surface of surgical instrument were measured using laser calory meter and specially contrived device, as one of fundamental items. Some surgical instruments were tested with usual surface and with surface stained in black color in order to avoid the reflection. As laser surgical apparatus, CO₂-, Nd-YAG, and Argon lasers were used. The results show that (1) There are much deviations in percentage of reflection due to the condition of surgical instrument surface, i. e. curve, convex or concurve figure etc.. (2) Black stained surgical instrument has a small reflection rate, approximately 10 % of conventional instrument. This reflection rate is somewhat higher in CO₂ compared to Nd-YAG & Argon. The use of black stained surgical instrument is recommended esp. in CO₂ laser surgery.

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Endoscopic laser irradiation is clinically applied to the hemostasis of gastro-intesinal bleeding. Now, it's used for the treatment of the gastric tumor. Our purpose is to examine the efficacy and safety of laser treatment of gastric protrouding tumor. We treated 10 cases of gastric protrouding tumor. These consist of 5 cases of gastric adenoma (one case included focal cancer) and 5 cases of early gastric cancer (IIa 3 cases, IIb 2 cases). Our method is that first, we cut off the main tumor by snare ectomy method with the high frequency electric current and next, irradiate the remained tumor. Irradiation was performed under the condition (Power of 60 watt, time of 1.0 sec). In gastric adenomas, almost whole tumor disappeared and no evidence of tumor recurrence has been observed endoscopically and histologically. In early gastric cancers, 2 cases of 5 cases recurred and were tried to reirradiation. In one case, tumor located widely, so we were requirred to several times irradiation. In another case, tumor were located posterior wall of Autrum, so we couldn't irradiate enough to disappeare. After irradiation, it's difficult to see cleardy the irradiating area because of bleeding or edema. So, our opinion about technical problems are as follows: High power irradiation, Marking of the lesion and Irradiation frame margine to center is necessary.

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From November 1979, we have studied the effects of Nd-YAG laser radiation in the canine stomach that the mucosal changes were examinedb/ magnified observations with dissecting microscopy and scanning electron microscopy, and the correlation between the degree of gastric submucosal blood flow and the depth of histological changes were evaluated using H₂ gas clearance method. From August 1980, we performed clinical Nd-YAG laser irradiation endoscopically in 3 cases of early gastric cancer without the indication for radical operation because of severe complications, 6 cases of gastric adenomas (atypical epithelium) and 5 cases of active gastric bleedings. The results were as follows; 1) The depth of tissue damage by Nd-YAG laser radiation may be in proportion to its power and duration, and moreover depend on the submucosal blood flow in the canine stomach. 2) Clinical YAG laser application irradiated within 2.0 cm in the distance from the tip of the optical fiber at the power of 40 to 50 W and the duration of 0.5 seconds pulse in cases with mucosal lesions of early gastric cancers and gastric adenomas, and then at the power over 80 W and the duration of 0.5 seconds pulse in cases with active gastric bleeding. 3) We have been observed endoscopically 9 cases of post laser therapy from 2 months to 22 months, and have no local recurrence. 4) A high power YAG laser radiation was effective initially in 4 cases out of 5 cases with active bleeding. 5) Endoscopic YAG laser therapy may be safe and easily control led method compare with the other procedures.

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Recently in Japan, there has been a growing enthusiasm for photoirradiation by Nd-YAG laser against gastrointestinal tumors. for the curative treatment of depressed early gastric cancer approximately 1 cm in diameter, especially IIc or IIc+III lesions, we have tried a circular photoirradiation started along the margins of lesion in expectation of the safe and maximum effect. The effect was first confirmed in normal gastric mucosa of dogs photoirradiated under various conditions. photoirradiation was then tried on mongrel dogs with early gastric cancer due to the administration of ENNG, and the course is now being watched. Nd-YAG laser photoirradiation was also used in the treatment of human early gastric cancer, which will be descsibed with reference to cases responding to the treatment in a promising way.

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Endoscopic laser treatments using a Olympus prototyped panendoscope, model XGIF-XQ, were attempted for four early gastric carcinomata and eleven gastric borderline lesions. While laser treatments for the four depressed early gastic carcinomata were remained inconclusive yet, laser treatments for the eleven gastric borderline lesions were found to disappeare except one large lesion (65×60mm) which is still on the process of repetitive laser radiations. Because of its caliber of 9.8 mm in outer diameter of the distal end, biopsy channel of 2.8mm in diameter and excellent capability of visualizing the entire stomach, XGIF-XQ is a suitable instrument for laser endoscopy. The over-insufflation of the stomach during laser endoscopy could be prevented by attaching a gastric tube to the shaft of the endoscope by vinyle tapes. A sole disadvantage of XGIF-XQ is that the photogaphs taken by this endoscope were not so sharpe because of its filter system to prevent the damage of the operater's eye.

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Gastric carcinoma of 23 lesions in 19 cases were endoscopically photocoagulated by Nd-YAG laser or argon laser.
After the first irradiation, 7 out of 23 lesions were observed to remain cancer cells. Cancer cells disappeared in 3 out of remained 7 lesions after the re-irradiation. Two of the remained 4 cases which were failed to treat were caused by technical problems and another 2 cases were like and I like advanced gastric cancers. Now, a total of 16 successful cases has been followed up and endoscopically observed no cancer lesion.
Endoscopic laser photocoagulation of early gastric carcinoma was effective to heal the lesion and will become one of the useful treatments for inoperable gastric carcinoma by resolution in some problems.

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The purpose is to report how we have endoscopically treated gastrointestinal (GI) lesions with the aim of their radical cure in the period from May, 1981 to Sept., 1982, using a Molectron medical laser photocoagulator. Before the clinical application there had been made a histologic study on the effect of Nd-YAG laser upon the esophagus, the stomach, the colon, and the liver.
The materials comprised a case of esophageal polyp (one lesion), 2 of gastric polyp (5 lesions), 5 of gastric ATP (7), 9 of gastic cancer (15), 6 of rectal polyp (8), and one of rectal cancer (1), with a total of 24 cases or 37 lesions. It was clinically decided that the 15 cases exclusive of gastric cancer had no indication for polypectomy with a high frequency electric current. None of the gastric cancer cases were indicated for surgical operation because of either severe complications or of personal rejection of surgical treatments.
Repeated laser photoradiations through the fiberscope of an output of 60 to 80 watts with a duration of 0.5 to 0.8 seconds were given to each lesion, following an application of the Brilliant-Blue chromo-endoscopy exclusively to the upper GI lesions.
The therapy with a Nd-YAG laser was evaluated as safe and successful, though relapse was noted in 2 of the 15 gastric cancer lesions and additional photocoagulation was required.

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