The frequency of gastrointestinal (GI) cancers varies in each countries in the world. Therefore, as to laser endoscopic treatment for these cancers, in Japan, radical treatment for early gastric cancer has been performed most frequently, in European countries and U.S.A., recanalization of GI stenosis caused by inoperable advanced cancer has been performed, chiefly. All reports were performed by Nd: YAG laser, with contact (Steger, Hira) or non-contact irradiation. Recanalization for esophageal stenosis was performed by prograde method (Fleischer, two steps method) and by retrograde method (Pietrafitta, Ell). In retrograde method, guide probe (Ell), boogie (Riemann) or dilator (pietrafitta) was applied before insertion of endoscope. Efficacy between contact and non-contact irradiation using Nd: YAG laser for recanalization of esophageal stenosis was compared. Opinions were divided that the latter had advantages (Ell) and the former had advantages (Radford, Ahlquist). In Japan, almost all specialists confirmed the superiority of contact method. The other methods were compared to laser therapy, as BICAP (Johnston, Fleischer), Ir¹⁹² (Bader, Hagenmuller), intubation (Ell, Buset and Cremer, Louzou and Bown) and radiotherapy (Mellow). According to literature assessment (except of Japan) from Index Medicos, as the Table, laser endoscopic treatment was performed most frequently for esophageal cancer (306 cases), and then colon cancer. In total, 407 cases of upper GI cancer and 257 cases of lower GI were reported. As to upper GI cancer, 1,019 treated cases were reported from 43 papers. Recanalization was achieved in 92.7%and functional retrieval in 83.4%, 4.2%of perforation and 1.7%(8 cases) of death by the treatment were reported.

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Photodynamic therapy (PDT) and diagnosis (PDD) is achieved by photoreaction. This concept was already known at the beginning of this century. However, the development of laser equipment and medical electronics brought recent rapid progress of these modalities. The Mayo Clinic group developed hematoporphyrin derivative (HpD) which they attempted to use for the localization of bronchogenic malignancy in 1960's. The authors have tried to examine the possibility of the localization and treatment of lung cancer by means of endoscopic laser photodynamic systems since 1978.
Excimer dye laser system was developed for these studies.
The system consists of an excimer laser, polychrometer, SIT tube, analyzer and TV-monitor and bronchoscope. As a laser beam, an XeCl excimer laser which emits a 308nm wavelength, is used. This system can be used for both diagnosis and treatment by simply changing the dye cells in order to obtain a different wavelength laser beam. For diagnosis, 405nm wavelength beam is obtained by diphenyl sulphen dye and for treatment 630nm light is obtained by rhodamin B dye pumped by the excimer laser.
PDD was effective in 19 of 20 lesions, showing this equipment to be effective to localize malignant lesions.
PDT was performed in 178 lung cancer patients with 216 lesions by argon dye laser and excimer dye Laser. In 47 early stage lung cancer cases with 56 lesions complete cure was obtained in 61.7%. Thirty three patients are alive at present and the longest survival period is 120 months.
There are still some problems concerning to incurabirity and skin photosensitibity. These modalities are effective for early stage cancer diagnosis and treatment and will be more promising modality in future by the development and/or improvement of photosensitizers and laser equipments.

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Laser endoscopy was put in practical use for photocoagulation of gastrointestinal bleeding by Frühmorgen and kiefhabar in 1975. In Japan, Endoscopic laser therapy of gastric cancer has been rapidly spread among concerned institutes Techniques of this therapy are divided into those based on coagulation by Nd-YAG laser beams, those based on photochemical by low power of Yag-laser beams, and those based on photochemical reaction of HPD by argon dye laser beam. The former is such a simple procedure that it is actively used in the gastric cancer patients who are inoperable because of cardiac and/or respiratory disease. It is expected to be a modality of curative potential, particularly against gastric mucosal cancer (II a, II c type) smaller than 1cm without ulceration, In contrast, the laser beam has not yet been put to practical use in the detection of cancer. Two approaches are now under intensive study: One determining autofluorescence of the lesion and the other determining PHD fluorescence accumulating in the lesion. We found the autofluorescence of gastric cancer by irradiation with argon laser beam at 514.5nm under a filter 0-55 in 1980. However endoscopy.
Further improvements are expected in the field of cancer detection by laser beams.

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A brief history of laser angioplasty and currently available techniques of laser angioplasty were reviewed. Percutaneous transluminal laser angioplasty (PTLA) is an alternative or adjunct treatment to reconstructive surgery for the occlusive arterial disease in selected cases, PTA has been a major adjunct to surgery in the treatment of ASO, but some cases are impossible to treat with PTA because of unsuccessful passage of the guidewire or balloon catheter through the tight stenosis or occlusion of the diseased artery. The cumulative patency rate of PTLA for 63 lesions treated in Dokkyo University Koshigaya Hospital and Hirosaki University Hospital and long-term follow-up for 6 years since 1985 are introduced, and the results seem to support the superiority of PTLA to PTA, although further studies are needed. The 5-yea cumulative patency rate was 88.4% in total cases, 88.7%in iliac artery region, 86.1% in femoro-popliteal artery region and 100% in the infra-genicular artery region.

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CO₂ Laser has been widely used for the treatment of various diseases in the head and neck area. We used CO₂ laser to fifty-four laryngeal cancer (glottis)patients and one hundred and eighteen allergic rhinitis patients.
CO₂ laser was applied via laryngomicrosurgery to laryngeal cancers. Seven cases were not cured by laser and underwent laryngectomy. The patients were followed up for 7 to 96 months (mean 48.5 months).Fifty-three cases(98%) are survived without an evidence of recurrence. From this follow-up study we concluded as follows: 1) Tla can be treated by laser alone, 2) Tlb can be treated by laser alone or by a combination of laser and radiation, 3) a careful selection of cases for laser use is required in T2.
The inferior turbinates of allergic rhinitis patients were vaporized by means of CO₂ laser. Improvement of nasal stuffiness was observed 85% of patients. Laser did not work for rhinorrhea and sneeze as effective as for stuffiness. Laser was effective to 63% of patients to control rhinorrhea and to 64% of patients to control sneeze. Laser enables a surgeon to perform the operation with minimum hemorrhage. The patients complained no pain during and after the operations. The operation can be done on out patients basis and no hospitalization is necessary.

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Recently, lasers are extensively applied in many clinical fields of medicine. In the field or dentistry, laser has not been prompted for clinical application until 1975. However, lasers are gradually utilized for clinical fields or dentistry.
The authors have demonstrated that a normal pulse Nd:YAG laser was the most suitable among the lasers to produce a resistance against acid decalcification of human teeth enamel. A combined treatment of laser irradiation and fluoride application onto the enamel obtained most remarkable acid resistance. Fluoride application after laser irradiation produced a greater fluoride uptake in the enamel than fluoride application alone. Similar results acre obtained from the in vitro and in vivo experiments on incipient dental caries with the subsurface demineralization or human enamel. The inhibitory, effect on enamel demineralization and enhancing effect on enamel remineralization of incipient caries lesion were obtained laser irradiation alone and in combination with fluoride.
The mechanism of acquired acid resistance of lased enamel was investigated. The contents of water, carbonate and organic substances were reduced in lased enamel and lased enamel showed a highly positive birefringence, suggesting the formation of 'microspaces' in enamel. It was suggested that laser irradiation might create the microspaces which could act as sites for trap of ions released by an acid attack.
These results suggest that the application normal pulse Nd:VAG laser is a practical and useful procedure for the prevention or dental caries.
Furthermore, a new method of caries removal and cavity preparation without thermal damage using a laser is under development.

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Lasers have contributed enormously to the advancement an evolution of medicine, taking another step in the march towards and improved human condition. The two most common high-powered operatingroom lasers are the Nd: YAG and CO₂. Contact surgery tips were recently developed for the YAG laser. These synthetic sapphire tips fit on the end of the quartz delivery fiber and serve as “laser scalpels”. The argon and frequency-doubled YAG-KTP lasers both produce a green wavelength of light that can be delivered through an optical fiber. This advantage, along with the fact that these beams can be transmitted through fluids, has made them preferable to some surgeons. The dye laser has been used to remove kidney stones lodged in the lower urinary tract. Researchers found that the dye laser beam, delivered through an optical fiber, can be focused on the stone. Diode lasers and He-Ne lasers have been used in biostimulation studies. In the past couple of years, excimer lasers have gained publicity because of their potential usefulness in medical application. The great advantage of these short-pulse, high-energy lasers is their ability to ablate tissue with minimum thermal damage. Initial concerns about the possible mutagenic effects of the ultraviolet wavelengths are gradually warning as research results come in. Main research areas with these precise surgical tools are angioplasty and corneal sculpting. Short-pulse dye laser (pumped by an excimer laser) is developed for corneal sculpting. The system uses extremely short pulses to ablate tissue, producing a 10μm wide incision. Some manufactures developed the medical systems based on the tunable laser crystal, titanium-doped sapphire. This medium lasers in the range 650-1000 nm. Frequency-conversion techniques, including a proprietary method of extending the range in the infrared, are expected to yield a device that tunes from 325-3000nm. This widely tunable laser may be the basis for a “universal” surgical tool that suits a variety of applications. Some researchers use the Er: YAG laser for research. Short pulses from the Er: YAG have an ablative effect with little thermal damage. And also the Er: YAG offers a superior cutting tool when longer pulses are used. Moreover, the 2.9μm output radiation can be delivered through optical fiber. The free-electron laser (FEL) may also find use in the future world of medicine. Several research efforts are underway to determine the cellular effects of the FEL beam. Whatever the possible applications of this laser may be, designers will certainly have to reduce its size and expense before it finds wider use. For these practical reasons, the FEL is probably the laser least likely to impact the medical world in the near future.

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The most popular laser therapy in ophthalmology has been photocoagulation of the retina with argon and krypton lasers. However, dye laser photocoagulation is now very promising, thanks to the selectivity of the emission wavelength in the visible range (577 nm to 630 nm). This technique is used in the treatment of retinal lesions like those of diabetic retinopathy and retinal vein occlusion. Recently, the diode laser (GaAlAs, 810 nm), which has a output range of 2 W, has been developed as a photocoagulator. It has many advantages over other unit by it's compactness, durability and inexpensiveness.
As therapy for acute glaucoma attack, laser iridotomy with the combined use of argon and Nd-YAG lasers is the method of choice, and for chronic open angle glaucoma, laser trabeculoplasty by argon laser is very effective. In addition, cyclocoagulation (photocoagulation of the ciliary body) utilizing CW-YAG and diode lasers has proved highly satisfactory in reducing ocular tension in malignant glaucoma.
The Nd-YAG laser is also used to perforate the clouded posterior lens capsule, particularly when an intraocular lens is inserted in cataract surgery.
Very recently, the excimer laser (AIF, 193 nm), which emits an ultraviolet beam, was proved an effective tool in incising corneal lesions and to ablating the corneal surface for the correction of astigmatism and myopia.

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Several kinds of laser, CO₂, Ar, Nd: YAG, Ar dye, Pulsed dye and Diode lasers have been used for the skin incision, treatment of penile carcinoma and bladder tumor, urethral stenosis, stone destruction and acupuncture. Ar dye laser has been utilized as a photodynamic therapy (PDT) with the use of photosensitized agents (HpD). Though the PDT was evaluated as the ideal treatment of CIS, there still remains the problem to be solved in terms of the hypersensitivity of the skin by HpD. After the development of extracorporeal shock wave lithotripsy (ESWL), laser surgery was attempted to the endoscopic destruction of the ureteral stone. Pulsed dye laser is now commercially available. But more powerful laser is hoped to be developed without appreciable changes to the living tissue by the laser irradiation. Nd: YAG laser is able to transmit through quartz fiber, making it feasible to perform transurethral laser surgery. Therefore, special interests were focused in the treatment of bladder tumor and urethral stenosis. Because of the limited indication of Nd: YAG laser therapy, instrumental development and technical expertise will be needed to magnify the indication of the laser therapy.

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Recent advances in laparoscopic surgery has enabled the gynecological surgeon to treat an increased number of diseases of the reproductive organ, which include endometriosis, tubal factor, ectopic pregnancy, ovarian cyst, myoma and pelvic inflammatory disease. The advantages of laparoscopic treatment include a decrease in patient morbidity, reduction in length of hospital stay and costs, as well as the opportunity to treat at the time of diagnosis, and potentially a reduction in postoperative adhesion formation with an increased pregnancy rate. Many doctors are under impression that surgical laser offers a new and improved form of treatment with a marked increase in the success rate over the other modalities such as electrocautery and endocoagulation. However, there is no evidence that surgical laser in more successful than conventional electrosurgery in affecting the pregnancy rate of tubal factor infertility and endometriosis associated infertility. The role of laser still remains to be evaluated in the laparoscopic treatment of gynecological diseases.

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Acupuncture and moxibustion remained as a folk remedy for a long time, because of hardly understandable Yin-Yang and five elements theory. But the success of surgical operation by the acupuncture anesthesia came into prominence all over the world. Soon it cleared that naloxone reduces the analgesic effect by acupuncture and then systematic studies on the acupuncture have been developed. The essentials of the acupuncture points and channels are unknown, however the acupuncture points are detectable as the low impedance points on the skin and laser irradiation to them is therapeutically effective in the following diseases; muscle contraction headache, stiff neck, frozen shoulder, back pain, lumbago, tennis elbow, sprain, vascular headache, trigeminal neuralgia, postherpetic neuralgia, sciatica, gonalgia, rheumatoid arthritis, Raynaud's phenomenon, toothache, gingivitis, tonsillitis, etc, Both inflammatory and non-inflammatory pain are relieved ha the laser acupuncture, although it is always accompanied with placebo-effect in high rate. Neural and humoral alterations by the laser biostimulation are briefly summarized and discussed based on biophysical aspects.

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To assess whether laser-induced fluorescence (LIF) spectra could discriminate atherosclerotic plaque from normal artery, two kinds of spectral analysis were studied. 1) Spectral analysis based on LIF from arterial samples after treatment of exogenous fluorescence probe, chlortetracycline hydrochloride (CTC), 2) spectral analysis based on autofluorescence from non-treated arterial samples.
The CTC-treated samples were irradiated by 308nm high power excimer laser light, and the non-treated samples by 325nm low power laser light.
A spectrum from CTC-treated normal artery had a broad emission band between 350-700nm and was characterized 2 fluorescence intensity peaks at 390 and 430nm. A new characteristic fluorescence intensity peak at 540nm for CTC-treated atheromatous tissue was observed. This peak was fluorescence emission band from CTC, which fluoresced only in the form of fluorescence chelate after binding to calcium ion and this peak was enhanced in the presence of collagen.
Autofluorescence spectra from normal artery was characterized by fluorescence intensity peak at 450nm, that from smooth plaque by that at 390nm and that from ulcerated plaque by low intensity and broad fluorescence emission band.
Both spectral analysis could differentiate atherosclerotic plaque from normal, but autofluorescence spectral analysis seems to reflect the pathological conditions of plaque.

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Measurement of organ function by the techniques of optoelectronics made it possible to diagnose non-invasively and quantitatively. Laser flowmetry is one of the application of the optoelectronics and clinically used for the in-vivo assessment of the tissue microcirculation.
We have reported the importance of mucosal blood flow in the pathogenesis of mucosal lesions using organ reflectance spectrophotometry system. In animal study, the usefulness of combined use of organ reflectance spectrophotometry and laser flowmetry was confirmed in the analysis of the microcirculatory disturbances induced by hemorrhagic shock. Laser flowmetry was applied to the evaluation of the change of gastric mucosal blood flow after endoscopic resection of gastric mucosa in human and the significant increase of mucosal blood flow at the ulcer margin was observed as a healing process of artificial ulcer.
We reported the two dimensional distribution of gastrointestinal mucosal blood volume by the image analysis using electronic endoscopy. Future advances in the functional diagnosis using laser are expected in the field such as two dimensional analysis of mucosal hemodynamics, fluorescence spectrum analysis and feedback system of diagnosis and therapy.

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A newly developed fiber-optic pulsed photo-thermal radiometry (PPTR) equipment and its application for gastric diagnosis were described. The PPTR is one of radiometry analysis which was developed by Tam in 1970s. Optical absorption and thermal diffusion characteristics of samples can be simultaneously obtained by this method. Therefore, this PPTR method can offer different information which is obtained by fluorescence spectrometry, refractive spectrometry and ultrasonic imaging, which have been utilized with endoscope.
We had developed fiber-optic PPTR equipment and we had applied it to urological and cardiovascular samples, We successfully improved this equipment using newly designed fiber-tip and lock-in amplifier. Since the detectivity and sensitivity of the equipment were remarkably improved, a thin (490μm) and long (2m) infrared fiber which is formed detection line could be employed.
Intra-gastric measurement is one of the best application of the fiber-optic PPTR method, since the air atmosphere which is necessary to attain this method was easily obtainable. In situ measurement of rabbit gastric wall suggested that fiber-optic PPTR may be applied to diagnose ulcer advance and/or prevent wall perforation by therapeutic laser ablation.

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During the past decade, photodynamic therapy (PDT) has been increasingly recognized as a viable therapeutic modality used in the treatment of malignant tumors. We have developed a new laser system which uses a pulsed excimer dye laser for PDT and also PDD. The excimer laser beam is obtained by exciting XeCl. A 405 nm beam tuned by DPS dye is used for tumor localization and a 630 nm beam obtained with rhodamine B dye is used for treatment. The equipment was supplied clinically on the basis of extensive experimental research. Effectiveness for cancer localization was examined in 21 cases including 7 cases of CIS. All cases were squamous cell carcinoma except for one case of adenocarcinoma and large cell carcinoma individually. Fluorescence was recognized in 20 cases out of 21 and the equipment was effective for localization. However, false positive was also observed in 10 cases out of 17 cases with 2 mg/kg of Photofrin II. Recently, the trial of low dose Photofrin II administration is undergoing now and the result showed its effectiveness.

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The clinical treatment with the contact Nd: YAG laser surgery was carried out on 325 cases with head and neck tumors over 6 years. Since the contact laser surgery offers precise, controlled cutting and hemostasis, the surgeon is not troubled by bleeding from small vessels during the incision of skin, muscle and mucosal wall and while dissecting subcutaneous tissue. Moreover, we were applied to a laserthermia for 21 cancer in head and neck using a ceramic probe to insert into tumor tissue and irradiate the Nd: YAG laser omnidirectionally. Four cases showed complete and 23 cases showed partial remission after combined treatment of laserthermia and radiochemotherapy, especially in oropharynx cancer. Based on these results, we believe that therapeutic effect of laser treatment for advanced cancer in head and neck was increased by combination with radiotherapy or chemotherapy.

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Seventeen patients with subglottic and tracheal stenosis have been treated with laser surgery. Six patients had airway stenosis caused by malignant tumors. Out of sixteen patients who required emergency endolaryngeal Laser surgeries, Twelve patients could achieve satisfactory result, with enough space for airation.
Five cases with airway tumors underwent Laser surgeries for creating enough airway, however, only one patient have got excellent result, and rest of five patients failed to have enough airway, or fair airway openings.
Airway obstructions caused by tumors can be controlled well enough immediately after the Laser operations, though long term follow up after the operations confirmed recurrence of tumors and this is to be overcome in clinical future follow up.

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The objectives of this study are to demonstrate 1) the effect of endoscopic Nd: YAG laser irradiation on air way dilatation and/or hemostasis, 2) the prolongation of life span and 3) the possibility predicting necessary joules for tumor vaporized volume.The materials consisted of a total of 84 malignant tumors including 56 tracheobronchial carcinomas, 18 esophageal carcinomas and 10 other malignancies.The results obtained herein are as follows;
1) The improvements were demonstrated in 72 (86%) of 84 patients and the higher improvement percentage was shown in the more central site. The type of diseases, however, had no particular relation to the effect.
2) Approximately 20 joules were necessary for 1 mm³ vaporization of tumor.
3) Median survival periods in improved and unchanged patients were 6 months and 3 months, respectively. Furthermore, 5 year survival rate in improved patients were 11% which is fairly good, in contrast,no one survived beyond 1 year in unchanged patients.The results between these 2 groups were statistically significantly different.
In conclusion, endoscopic Nd:YAG laser treatment is considered to be very effective on the air way dilatation resulting in relief of dyspnea and the prolongation of life span. Appropriate joules for necessary tumor vaporization could be predicted and the treatment not irradiating excessive joules is appeared to be inevitable in the decrease of its fatal complications.

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Since 1982, we have been using the Nb: YAG laser endoscopically to treat 104 patients with malignant stricture of gastrointestinal cancers. Those cases consisted of 21 esophagus, 42 cardia, 4 body, 14 antrum, 11 stoma, and 9 colorectum, and the functional success was seen in 78%, 72%, 33%, 57%, 62%, and 83% respectively. The length of time requiring no hospitalization (outpatient period) accounted for 4 weeks or more, or accounted for 30% or more of the remainder of patient's life after laser therapy, was seen in 56% of esophagus, 64% of cardia, and 50% of antrum.
As to the survival time, there was statistically no significance between the laser and non-curative resection groups both in cardia and in antrum. In addition to that, the median value of outpatient period was 17 weeks of the laser and 3 weeks of the chemotherapy group (p<0.05) in cardiac obstruction, and 8 weeks of the former and 0 week of the latter (p<0.01) in antral obstruction.
We conclude that Nd:YAG laser therapy for malignant gastrointestinal stricture should be applied to a patient who is unable to operate because of such factors, as high risk or distant metastasis.

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As a thoracoscopic treatment for spontaneous pneumothorax, electrocautery has been mainly used. But contact type electro-cautery has a risk of perforation of blebs. We adopted carbon monoxide laser (wave length 5.4μm) and good coagulation shrinkage or blebs could be obtained by non-contact irradiation. CO laser was delivered by As-S glass fiber and power of fiber tip was 2-4 W. Compared with Nd: YAG laser (wavelength 1.06μm) CO, laser showed lower risk of perforation of blebs. Thoracoscopic CO laser coagulation shrinkage of blebs proved to be a important method of treatment for patient of spontaneous pneumothorax.

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Recently, a percutaneous procedure for lumbar disc herniation has been developed and used clinically as an alternative to conventional surgical methods, such as laminectomy and disc removal. vertevral bone fusion or others. In the early 1980s, chemonucleolysis with chymopapain was enthusiastically tried in America and Europe. The procedure is easy and takes less operation time. However, complications, such as anaphylactic shock, paraplegia, etc., occurred. The incidence is rare but should not be ignored. Now fewer chemonucleolysis procedure are being done. Instead, a percutaneous nucleotomy (PN) with a punch, which was first proposed and established by Hijikata, or automated nucleotome has been done more commonly in the late 1980s. But the diameter of the PN cannula is more than 3 mm, so the PN procedure may cause technical problems and tissue damages.
Since 1986, Percutaneous intradiscal laser nucleotomy (PILN) has been studied in our laser laboratory. And the process of this study had been reported in ASLSM last two annual meetings. The purpose of this study is to develop PILN as an alternative to chemonucleolysis and percutaneous discectomy, which are currently applied, and to establish a safe, easy, accurate and short time therapy method for lumbar disc herniation. Using laser for nucleotomy has the following advantages; 1) as the output power can be easily controlled, it can be used safely; 2) because high energy can be transmitted into the deep tissues through 200-600 micron flexible fibers, atraumatic therapy for deep tissue is possible; 3)chemical complication are avoided; and 4) it is easy and safe to approach to the deep tissue with a small-diameter needle.

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Laparoscopic laser surgery has been performed on 24 cases of clinically defined endometriosis and 9 cases of functional dysmenorrehea, by applying the potassium-titanyl-phosphate (KTP) laser, which radiate a visible green-light laser beam at 532 run as the frequency doubled or second harmonic Eight of Nd: YAG laser of invisible 1064 nm. This laser has no need for an specific aiming beam and is easily applicable with minimum invasion of several small tapping holes into the abdominal cavity by easily delivering through flexible optic fiber of 600 micron in diameter.
Clinically, in all cases of various per involvements of endometriosis has been effectively carried out by vaporization, adhesiolysis, and ovarian cystectomy on chocolate cyst, without any apparent side effect of perforation or bladder, ureter and/or rectum. Laparoscopic uterosacral nerve ablation (LUNA) has been performed on 9 cases of so-called functional dysmenorrhea, revealing 7 cases (77.8%) of complete or symptomatic improvements, all of which have been documented as the sufficient depth of ablation, excluding the ineffective initial two cases of minimum and superficial ablations.

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Laparoscopic cholecystectomy has been popularized as a minimally invasive surgery for benign gallbladder disease. The purpose of this report is to introduce our initial experience and to clarify the efficacy of the laparoscopic cholecystectomy using Nd: YAG laser. Since October 1990, 55 cases were treated by laparoscopic cholecystectomy. The indication of this procedure was cholecystolithiasis in 52 cases and gallbladder polyp in 3 cases. Our procedures were summarized as follows: pneumoperitoneum by CO₂ gas insufflation, four-trocar-technique, keeping the laparoscope with the operator's left hand, separately clipping the cystic duct and the cystic artery, and dissection of the gallbladder from the liver bed by Nd:YAG laser. Contact laser was applied with a saphire tip connected to quartz fiber or directly from a soft touch fiber. Contact Nd: YAG laser was useful for dissecting sharply thick tissue of the gallbladder wall due to chronic cholecystitis, and also for hemostasis with coagulation. Total volume of the laser energy was averaged 2312J in 41 cases. As a minor complication injury of the gallbladder body was caused by laser scalpel in 13 cases, and bleeding from the serosa or the liver bed occurred in 12 cases. However no case has been required major laparotomy for the reason of the laser injury. We conclude that laser is an effective benefactor to challenge the minimally invasive therapeutics.

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The utility of KTP/Nd:YAG and Nd:YAG laser systems for dissection of the liver bed in laparoscopic cholecystectomy (L.C.) was compared with that of electrocautery. KIP/ Nd:YAG laser system is time-saving since KTP laser with high cutting capability and Nd:YAG laser with good hemostatic effect can be used through a single fiber. Among YAG systems, contact tip type and soft touch fiber type have good cutting capability, but their hemostatic efficacy is lower than that of free beam type and complementary use of electrocautery is necessary for coagulation.
We suggested that laser damaged less amount of tissue than electrocautery during operations on the following bases: in cases of laser application.
1) the width of degenerative zone at the cutting surface was markedly thin.
2) less liver parenchyma was attached with the resected specimens of gallbladder.
3) the incidence of perforation of the gallbladder and hemorrhage from the liver bad was low.
4) postoperative elevation of serum GOT and GPT was mild.
Laser systems without deep tissue damage are suitable for dissection of the liver bed in L.C. in which more safety is required in compared with open cholecystectomy.
Laser systems also showed sharp cutting abilities for edematous or fibrotic connective tissue in the liver bed.
Pressure elevation within the closed peritoneal cavity during L.C. should be monitored carefully in case of contact tip application which needs tip-cooling gas plume.

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In 1984 we developed a method of hyperthermia using Nd:YAG laser (laserthermia) for transmitting continuous low power energy (2W) through an artificial sapphire interstitial probe for local hyperthermia (43±0.5°C). Our experimental and clinical evidence indicated that this method is safe and effective. The process of tumor destruction induced by laserthermia is, however, poorly understood.
We performed both light microscopic and electron microscopic observations after laserthermia in vivo, and a comparative study of laserthermia, microwave hyperthermia and heating alone on the cytocidal effects in vitro, and obtained the following results; 1) At the tissue level, the initial change after laserthermia was damage of tumor feeding vessels. 2) At the cellular level, immediately after laserthermia the mitochondria in the intracellular organella were completely destroyed. 3) In in vitro studies, laserthermia demonstrated the most notable decrease in viability. In conclusion, as for the mechanism of laserthermia, it seems that the immediate of feet is cellular damage caused by both heat energy and Nd:YAG laser light followed by subsequent damage of tumor vessels.

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To investigate the mechanism of cell photostimulation by low-intensity laser irradiation, we studied the influences of different wavelength irradiations (351nm, 465nm, 514nm) of Ar laser on the mitochondrial respiration.
Isolated ginea-pig liver mitochondria and isotonic buffer (0.25M saccharose, 2mM MgCl₂, 10mM K₂HPO₄, 10mM KCl, 0.2mM EDTA, 4mM HEPES, pH 7.4) were introduced into a fixed temperature reaction chamber (37°C, 2ml). Either in respiratory condition of state 4 (addition of 4mM saccinate into the chamber) or state 3 (addition of 4mM saccinate plus 180μM ADP into the chamber), the oxygen consumption (O₂ cons.) in the chamber was measured using a oxygen electrode with or without laser irradiation.
In state 4, shorter wavelength (351nm, 465nm) laser irradiation increased the O₂ cons. In contrast, in state 3, only 514nm laser irradiation increased the O₂ cons..
These studies suggest that the Ultra-Violet laser irradiation may injure the mitochondrial inner-membrane, while the green laser irradiation may promote the ability of ATP-synthesis.

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In 1990, we began to use, instead of an argon dye laser (ADL), an excimer dye laser (EDL), which emits a pulsed laser beam, in photodynamic therapy (PDT) for superficial esophageal cancer (SEC) and early gastric cancer (EGC), and have been getting favorable results. The procedure, as shown on table 1, was as follows: 2mg of PHE (Photofrin II freeze-dried) was injected intravenously which was manufactured for Quadra Logic Technologies, Canada by Ortho Diagnostic Systems, Inc., USA and was provided by Lederle Japan. Then about 50 hours later, the entire lesion plus a 5mm width of marginal mucosa was irradiated with EDL transmitted endoscopically. The irradiation was delivered at 4mJ per pulse with 40 pps during 6 to 7 minutes per cm² for giving a total energy density more than 60J/cm². The characteristics of the EDL of a model PDT EDL-1 of Hamamatsu Photonics were shown on table 2. After PDT, the patients were kept in bed with no food and were given continuous i. v. infusion of glucose and saline solution with an H₂-blocker and antibiotics for two days. During these periods, the patients were kept in dim light, and their faces and hands were coated with antisunburn cream. These precautions were gradually reduced, and the patients returned to normal conditions after one week. Three cases of SEC and 11 cases of EGC were treated by PDT with the EDL. These patients could not be treated by operation because of high risk factors or old age. The response was evaluated by endoscopy with biopsy and cytology in the follow-up examinations. Local cure was obtained in all cases except for one case whose follow-up periods was too short to evaluate responses. The morphological type of cancer, the size and depth of lesions, the total energy density (J/cm²) and responses of these cases were shown on table 3 and 4. The rates of cure in them by PDT with EDL were far superior to those with ADL which were shown on table 5 and 6.

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The authors applied argon laser therapy for squamous cell carcinoma in gingiva convinined with chemotherapy by bleomycin(BLEO). In this photochemotherapy, the affected target was applied to argon laser beam at power density 1.3W/cm² for 30 seconds (39J/cm²) following the intervenous administration of 15mg of BLEO, and the laser treatment was repeated on overlapping spots over the affected and surrounding tissue. This therapeutic regimen was repeated at each session with twice the interval of administration of BLEO as usual in this chemotherapy regimen. In spite of the reduction of the usual dosage of BLEO by half, remarkable effect was noted from the begining of this therapeutic regimen and the tumor was reduced and improved with increase in the photochemotherapy sessions. The author designed some optical evaluation in this photochemotherapy and obtained interesting results. 1) Spectoral analysis for the reflectance of the argon laser at the target tissue during the laser therapy revealed the tumor tissue had the wave band of much lower reflectance to the argon laser. 2) The reflecting image of the argon laser beam on the tumor site was darker than that of the normal site. These result proposes that the tumor tissue had the high absorption of the laser beam. 3) Since the reflection intensity of the argon laser in the tumor tissue was evidently lower than that of the normal site, the tumor site was clearly identified as a darker pattern than the normal site.

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We made a basic study on the usefulness of photodynamic therapy of hepatoma with PH-1126 (Hamari chemicalas, Osaka, Japan) which is a new photosensitizer excreted in normal liver tissue in an early stage but localizing in tumor and report the result.
The examination to see the localization of PH-1126 in the course of time in the tumor area and normal liver tissue in the VX₂ hepatoma model in rabbits disclosed that it was highly localized in the tumor area in the quantity about 60 times that in normal liver tissue 48 hours after administration. Laser irradiation (50mw, 80J/cm²) 48 hours after PH-1126 administration caused wedgeshaped tumor degeneration and necrosis but failed to exert sufficient effect onto deep tumor.
Accordingly, we had developed a new fiber tip (Moritex Ltd., Tokyo, Japan) suitable for intratumor puncture as a device for laser irradiation for deep-seated tumor like hepatoma and performed the study of its therapeutic effect.
We expect that in the future photodynamic therapy would be available in series of intensive therapeutic approaches to hepatoma

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Pig furors are ablated in air with a KrF excimer laser(248nm) at several energy densities in ho range of 0.16-14.8J/cm²/pulse. Ablation craters are examined by means of scanning electron microscopy. Energy density threshold for ablation is ~32J/cm² pulse. Melting of the mineral components of bone is not observed at the bases of ablation craters. The shape of ablation debris is needle like when there is no plasma formation, and is spherical when there is plasma formation. These results suggest that hone is ablated at a temperature below the melting point of the mineral components(~1600°C), and that the ablated bone is thermally influenced by the formed plasma.

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This study aims at the observation by which osteosynthesis after Osteotomy by Excimer laser.
Shank bone of Rats were cut by KrF Excimer Laser (wave length 248nm, palsewidth. 15ns, frequency 30Hz, pulse energy 80mJ, focus wide 0.1 mm²) Then fixed again by wire and metal plate from the outside of the skin.
Specimen was taken at 2 weeks, 4 weeks, 6 weeks and 8 weeks after operation, and fixed in formalin for light microscopic observation, Moreover, the cutting side was observed with a scanning type electronic microscope immediately after cutting.
Result
The cutting side of the bone was smooth and no heat effect was seen immediately after Osteotomy. Also between the cutting surface, the organization of cartilage was observed four weeks after fixation.

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The ability of the combination of semiconductor laser and the laser probe with "fiber tip", which had a processed tip at the fiber, was demonstrated with animal experiment. The equipment constructed with this combination was evaluated clinically with the minor operations.
The laser unit used in this experiment was OSL-1000 (Osada electric industry co. ltd) which is composed with semiconductor laser with one watt continuous output. The fiber tip with needle shape was mainly used.
In animal experiment, skin and muscle of anesthetized rat was used. The skin could be cut with the carbonization at the surface and some coagulation under it. The muscle could be also cut with a little carbonization and some coagulation under it. The cut end of the vessels with less than almost 1mm diameter could be coagulated to make no bleeding.
In clinical, this equipment was applied in 14 cases of minor operations. It was used to stop minor bleeding or fine cutting of the tissue without any bleeding.
This equipment was found out to be useful for minor operation through these experiment.

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This study was designed to assess the relative cutting and coagulation effects of KTP laser (wavelength 532nm.) vs. Nd: YAG laser (wavelength 1064nm.) on the rat liver. Eleven-week-old male Wister rats were used in the experiment. Comparisons Were made at different energy levels applied for different time period. Both contact and noncontact (working distance 5mm) applications were performed to induce lesions. The KTP/YAG Surgical Laser System of Laserscope^(R), which has the option for accessing either the Nd: YAG or the KTP energy independently within few seconds was used. Sacrifice times were immediately after lesion induction by continuous bleeding from the abdominal aorta. Comparative evaluation consisted of morphological examination of the wounds with measurements of the widths, depths and different zones of lateral thermal damages. The results of the studyindicated a considerable differences between the two surgical lasers in their cutting and hemostatic capabilities while used in liver tissue. KTP laser showed a better and definite cutting capabilities with a reasonable hemostatic effect while YAG gave a deep coagulation effect with larger lateral thermal damage. But YAG showed a poor vaporization or cutting performance. A combination of both seemed to be highly effective in liver surgery for both cutting and hemostatic purposes.

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We experienced a patient with giant emphysematous bulla which occupied the who right thoracic cavity. Progressive dyspnea suggested that the bulla might exert pressure on the residual lung. Surgical removal usually makes prolonged air leakage. Therefore, laser coagulation shrinkage of bulla was indicated. Carbon monoxide and Nd:YAG laser were used. The collapsed lobes reexpanded and blood stream restored and pulmonary function returned to good level. We concluded CO laser therapy is useful for patient of respiratory disorder with giant bulla.

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Recently arthroscopic surgery has become popular technique for joint surgery. This method is superior to conventional open methods because of atraumatic procedure. But it is not always easy to observe and operate in the narrow space. The purpose of this study is to develop a system of double arthroscope with laser for easy and atraumatic arthroscopic laser surgery.
Sacrificed pig knee joints and human knee joint tissues. An original arthroscope was composed of hard arthroscope with a lumen for a Small diameter flexible arthroscope. A flexible arthroscope has 4 channel; image fiber, light guide, flush lumen and a lumen for laser fiber. And the top of the flexible arthroscope was able to flex one direction voluntary. With these instruments, we could observe joint space in detail with double monitor and to operate with laser. Various kinds of laser were irradiated to joint tissues. And histological changes has been studying with light microscopic observation. In this time, we will introduce results of giant pulse Nd: YAG laser and high output semiconductor laser irradiation.
Double monitoring system of our arthroscopy was useful to observe joint space in detail. Especially, the back joint space could be observed easily. However, to operate this system was need two staff now. Tissue cutting, coagulation and vaporization could be done both lasers. But the histological findings were different with each wavelength. Now, we have developing this system at the points of feasibility.

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Since 1986, we had been experimentally studying Laser Nucleotomy with Nd; YAG laser because of its superior coagulation effect for the water-rich tissue such as nucleus pulposus.
The purpose of this report is to investigate the feasibility of a newly-developed pressure transducer for measuring Intradiscal Pressure (IDP), and to recognize the decompression effect after intradiscal laser irradiation.
Materials were anesthetized dogs. IDP measurement had been done with needle type transducer before and after irradiation. Irradiation was done under 10 W power with duration of 0.3 sec. intermittened by a pause of 1.7 sec.
After laser irradiation, the stepped like decompression had been observed with correspondence to the total delivered energy.
The usefulness of this pressure transducer was recognized, and the measurement of IDP is speculated to be essential examination to decide the treatment indication and to determine the decompression effect during procedures, especially in combination with MR imaging.

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Commercially available ruby laser systems have long pulse duration of 2 msec and have produced excellent effects in the treatment of superficial pigmentated diseases, but not enough effects in patients with deep lesions. We have recently used the shorter pulse duration ruby laser, having pulse duration of 200-400 microsec, in the treatment of pigmentated diseases of the skin, and had favorable results. In the present study, histological changes in the skin taken on surgery after the short pulse ruby laser irradiation were compared with those after conventional long pulse duration irradiation at pulse duration of 2 msec. The short pulse laser irradiation produced basically similar changes in the basal cell of the epidermis to those produced after long pulse laser irradiation, but the former was more selectively effective than the latter for intradermal melanins. Especially, with short pulse duration, low-energy level (about 10J/cm²) laser irradiation, “crater-like degeneration” was observed in the area where melanins were present in the upper dermis layer, despite of little changes in basal layer of epidermis.

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A ruby laser has been clinically used for patients with pigmented cutaneous lesions to reject selectively over-deposited melanin granules (MG) in the skin. Previously using a medical ruby laser system with wave length 694 nm and pulse duration of 2 msec (Toshiba LRT-301A), we obtained excellent results in treatment on cases of nevus spitus, senile lentigo and seborrheic keratosis in which MG are present in the epidermis and dermis. On the other hand, we could not get adequate effects with this type of laser system on nevus pigmentosus and/or nevus Ota which include MG in the deep dermis. In the present study, we have applied modified Toshiba LRT-301A ruby laser system with shorter pulse duration of 200-400 microsec. on with various pigmented dermatoses. In cases of superficial pigmented diseases, such as nevus spilus, senile lentigo and seborrheic keratosis, the therapeutic effects obtained were similar to those of with ordinary type. In cases of both nevus pigmentosus and nevus Ota, however, more favorable effects could be obtained using the short pulse ruby laser system.

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We have reported that the absorption and permeance of Nd-YAG laser varied depending on the color of the irradiated substances, and that the reflection ratio of Nd-YAG laser in black was measured by use of a computerized spectrometer to be 14% whereas that in other colors very high. Therefore, we considered that the lesion of melanin pigmented and non-melanin pigmented skin diseases could absorb and/or permeate lower level of Nd-YAG laser when stained in “black” than when not stained. Clinical application of Nd-YAG laser was performed on cases of milium, acne, granuloma telangiectaticum, keratosis, verruca, etc. Since no anesthesia was necessary in most of the cases and the procedure was very simple, the method was applicable to even the infants and gravida. Little scar formation was observed and beneficial clinical effects were obtained.

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104 patients, 21 days to 67 years of age, with benign cutaneous vascular lesions other than port-wine stains were treated using the flashlamp dye laser (Candela, SPTL-1P SPTL-1), The patients whose lesions did not lighten significantly at the first treatment would receive two or more treatments at intervals of more than one month. At least three months after the final irradiation, evaluation of its effects were made as follows: Excellent; Identical to uninvolved skin, Good; Marked improvement, Fair; Slight improvement, Poor; No improvement.
The results of the 104 total patients were excellent in 53 patients (51%), good in 48 (46%), fair in 2 (2%), poor in 1 (1%), Satisfactory results (excellent or good) were achieved in 97% of total patients, 91% of the patients with hemangiomas, 100% of the patients with nevus araneus, angioma serpiginosum or rosacea erythematosa, 98% of the patients with facial telangiectasias.
Scarring was observed none of the total patients. Twelve patients developed transient hyper or hypopigmentation, which returned to normal skin color within six months.

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A fundamental and a clinical studies with KTP/YAG laser were performed. The new KTP/YAG Surgical Laser System from Laserscope provides two fiberoptic deliverable wavelength, KTP/532 and YAG/1064 nm. In fundamental study, the effect of KTP laser were examined histlogically on H. E. stained specimens of ectocervical, endocervical and endometrial areas of the resected uterus to which the laser were irradiated at the conditions of a 3mm spot size and 15-60 joules. The relation between irradiation energy (joules) and the laser penetration on every area was considered to be significant such as Y=1.8+0.3X (P<0.001) on squamous area. Twentysix with CIN, 1 with questionable early cervical cancer, were treated at an outpatient basis under local anesthesia. Each laser was irradiated in contact or in non-contact with tissue with a hand piece at output power of 10 to 20 watts.
Excellent results were obtained and side effects were minimum. In conclusion KTP/YAG laser is suggested to be a good tool for the treatment of uterine diseases.

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Laparoscopic uterosacral nerve ablation (LUNA) has been clinically performed on 9 cases of functional dysmenorrhea, which is defined as the severe dysmennorrhea showing minimum signs of endometriosis by laparoscopic examination except for the thickened and/or callous uterosacral ligaments. The potassium-titanyl-phosphate (KTP 532) laser has been applied to the laparoscopic surgery via thin flexible optic glass fiber of 600 micron in diameter, characterized by the visible green light of 532nm, showing minimum attenuation in transparent fluids of ascites or saline solution without any necessity of aim beam. KTP 532 is radiated as the doubled frequency or second harmonics of conventional Nd: YAG laser of 1064nm by adding some components of non-linear Q-switch. The ablation of uterosacral ligament has been performed as the vaporization of the posterior portion of ligament closely adjacent to uterine cervix with 1-2cm in length and about 1cm in depth.
Clinical evaluation has resulted in the 4 cases of complete remission and 3 cases of significant relief, with 2 cases of ineffective outcome, both of which has been documented as a superficial or insufficient ablation performed as the initial two cases, definitely suggesting the effective alternative treatment for this difficult and ineffective disorders by the conventional remedies.

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The homozygous Polydacyly Nagoya (Pdn/Pdn) mice exhibit 1-3 extra digits both in the fore- and hindlimbs preaxially. Female Pdn/+ mice crossed with Pdn/+ males were injected intraperitoneally with ritodorin hydrochloride, and with pentobarbital on day 13 of gestation. The uterus was exposed from the abdominal cavity by a midline abdominal incision. A small incision was made on the uterine myometrium. Thus the conceptuses were exposed out of uterus but still kept in contact via the placenta. The extra digital anlage of the left hindlimbs in Pdn/Pdn emeryo on day 13 was irradiated with the argon laser beam with 2 watts for 0.3 seconds through the yolk sac membrane after taking out from the uterine myometrium. Hislologieally, the destruction of extra digital anlage in the hindfoot plate was observed. Internal hemorrhage and coagulation necrosis surrounded by perifocal edema in the extra digital mesodermal condensations were observed. The embryos received fetal laser surgery on day 13 of gestation were recovered on day 18. The extra digit of the hindlimb was lost. I don't consider now that fetal surgery of polydactyly in the human fetus is much superior to the cutting of the extra digits after birth.
However, the combination of laser instrument with the fetoscope, and/or with the real-time ultrasound scanner, will promote the study designed to prevent congenital anomalies such as not only the limb malformations. but also teratoma, intrauterine amniotic bands, and umbilical cord of a twin in the human.

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Er: YAG lasers will soon become the most efficient medical lasers, The wave-length of this lasers is 2.94 μm and their ability of incising biotissues is much stronger than CO₂ lasers (wavelength: 10.6μm). Our experiments prove that, for example, Er:YAG lasers are able to cut into livers about two times as deep as CO₂ laser are. Furthermore, Er:YAG lasers cause much less thermal damage to biotissues than CO₂ lasers, because Er:YAG laser beams are more easily absorbed by water than CO₂ laser beams are.
For studying possibilities of applying Er:YAG lasers to endscopy. We tested fluoride glass fibers (ZrF₄), chalcogenide glass fibers (As₂S₃), and a hollow light guide all of which may be used in an Er:YAG laser delivery system. The transmittance of the fluoride glass fibers we measured was 90%, at 1m long and the average output power was about 4W at 10pps. Regarding the chalcogenide glass fibers, transmittance was 75% at 1m long, while the average output power was 1.2W at 10pps. The test shows that these fibers are applicable to Er:YAG laser endscopes, although the fibers have a fragile mechanism and some other problems yet to be solved. On the other hand, the transmittance of the A1 hollow light guide measured 64% per meter and the average output power was 1.4W at 10pps. This hollow light guide may be too large to be used for endscopy but it will be applied to surgical laser blades, because it has a rigid mechanism and is able to transmit high power laser.

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As is well known, ordinary quartz fibers can not be used for power UV beams generated with excimer lasers. We have developed a technique for producing a UV-beam hollow light guide made of a aluminum and polymer compound. The hollow light guide provides a transmittance of 35%/m (KrF) and 50%/m (XeCl) at 0.5mm height of guide aperture. To enhance laser transmittance in delivery hollow light guide, the laser radiation should be polarized linearly. Also, the transmittance of a hollow light guide is determined by the degree of damage caused to the surface of an aluminum reflector installed at the end of guide's incident part. The transmittance and allowable maximum incident peak power depend on the height size of aperture. The flexibility loss of hollow light guide is due to the height size of aperture. For example, the short height size guide has a good flexibility and low flexibility loss, although the transmittance of the short height size guide is lower than long one.
As a result of the experiments mentioned, the ultraviolet laser beam hollow light guide we propose will be able to be used in UV laser power delivery systems if its transmission power and transmittance are improved through increasing the reflectance of its aluminum surface.

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A laser delivery system is essential for medical application of lasers. The quartz fiber is available for the laser delivery in visible-ultraviolet region. The transmittance of the quartz fiber was observed to be reduced in KrF excimer laser delivery at the delivery intensity of 0.6J/cm². The absorption band was induced at 215nm in the core glass after KrF laser delivery. This absorption band originates in E' defect, the formation of which is related to the dopants in the core glass. OH dopant was shown to be effective in suppressing the formation of the laser-induced defect. The transmittance of the fiber with the gradually reduced index profile in the clad was above 60% during the 7200 pulses delivery.

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one incision by excimer laser irradiation with a layer of water on the bone surface was found to be more effective than without. In XeCL laser irradiation, the saturation of the incision depth was not observed below the intensity of 6 J/cm² for bone surface with a layer of water. In pulse irradiation with high peak power such as the excimer lasers, tissues are incised by an ablation effect. In this tissue ablation, some of the incidence laser lights are scattered or absorbed by particles ablated from the bone surface in laser pulse duration, especially at high intensity irradiation. The water layer acted to suppress the expansion of particles from the bone surface. so that the laser energy could be efficiently injected to the ablation surface.

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In the application of a laser to bone cutting, it is difficult to find when the cut is completed, because the surgery does not depend on tactile sensation. Earlier we revealed that in laser cutting, the generated acoustic waves offered information on the incision depth. In the present study, we made the experimental investigations of this acoustic technique from a clinical standpoint. The focused pulses of KrF excimer laser radiation were incident on the surface of pig femurs at various energy densities. The acoustic waves which propagated through the air were detected with a PZT sensor. The arrival time of the acoustic wave was delayed as the incision depth (D) increased. This time delay (Δt ) was measured with a time pick-off device and a personal computer system. We examined the effect on Δt of the sensor position relative to the cutting direction, the effect of laser energy density and the effect of the water sprayed over the cutting surface.
As a result, we found that the relation between Δt and D was expressed as a linear equation, D=k₁·Δt+k₂, when the sensor was set in the forward or the lateral position to the cutting direction. Here k₁ and k₂ were the functions of the energy density and the amount of sprayed water. These findings suggest that the acoustic technique is applicable to the real time monitoring of the incision depth in the bone surgery.

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We developed a laserlithotriptor by selecting a 480nm wavelength (WV) laser beam. The 480nm WV laser, when irradiated, generated larger shock wave than the 504nm WV laser since it is absorbed by urinary stones better than the 504nm WV laser which is already in clinical use.
Shock wave generated with 480nm WV laser irradiation was amplified significantly by placing the calcium oxalate stone in water colored with indigo carmine or phenolsulphonphtalein (PSP). Shock wave was amplified an average of about 1.5 times in the indigo calamine solution which was added to water in a 1 to 400 ratio compared with the shock wave resulting from irradiation in indigo-free water. When the dilution rate was 1 to 200, shock wave was amplified an average of 1.79 times. In PSP added water with a 1 to 100 ratio, shock wave amplification was enhanced an average of 1.74 times compared to that resulting from irradiation in PSP-free water.
This approach might be effective to disintegrate hard stone such as cystine stone without increasing output energy.

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