Transurethral balloon laser enhanced thermotherapy in the canine prostate

BACKGROUND AND OBJECTIVE

Hyperthermia is performed for prostate cancer. We examined the selective induction of coagulonecrotic changes in the objective area of the canine prostate in enhancing the effect of hyperthermia and treating the target area with transurethral balloon laser enhanced thermotherapy (TUBAL-ET) using a light absorbent material.

STUDY DESIGN/MATERIALS AND METHODS

The heat exchange of ultrafine carbon particles after laser irradiation was observed in a phantom study using thermography. The carbon solution was injected at the right prostatic lobe in dogs and TUBAL-ET was performed.

RESULTS

The charcoal absorbed the Nd:YAG laser energy and apparently converted it into thermal energy in the phantom study by thermographic observation. TUBAL-ET induced coagulonecrotic changes only at the area at which carbon had been injected in the prostate gland. The necrotic tissue was almost absorbed at four weeks after treatment.

CONCLUSIONS

TUBAL-ET induces tissue damage at the target area in the prostate gland.

A new instrument for hemostatic vascular management in endoscopic surgery: diode laser (STATLase-SDL) and its handpiece (dual hook)

OBJECTIVE

The authors described experimental data in hemostatic vascular transection using a STATLase-SDL with a 780-865 nm GaA/As diode wavelength and its handpiece, Dual Hook (DH).

SUMMARY BACKGROUND DATA

The STATLase-SDL and DH are newly developed devices for endoscopic surgery. It seems that the device has improved hemostatic cutting ability.

METHODS

The DH was applied to the abdominal aorta (< 2 mm) of Japanese white rabbits (n = 15) under general anesthesia. Tissue temperature during laser transection and interluminal bursting pressures were measured. Histopathological examinations at the cut end were carried out by hematoxylin-eosin (H&E) and elastica Van Gleson's (EVG) stainings. To investigate short-term effects 11 days postoperatively, the cut ends of the vessels were examined histologically in the heminephrectomy group.

RESULTS

The DH hemostatistically cut through arteries up to 2 mm in diameter. Temperatures at the inner hook and in adjunct tissue were higher than 160 degrees C, while that at the outer hook was lower than 80 degrees C. The bursting pressures immediately after transection was 307.2 +/- 35.2 mm Hg at a laser power of 8 W (n = 5), and 295.6 +/- 28.7 mm Hg at 10 W (n = 5). Histological examination of the transected sites on the vessels revealed well-opposed tissue welding of the vascular wall. Absence of fragmentation in the welding of the internal elastic lamina is crucial for closure of the vessel stump. Up to 11 days postoperatively, there were no direct complications related to the use of the DH.

CONCLUSIONS

The STATLase-SDL and DH have good hemostatic cutting ability and might be suitable for endoscopic surgery.

Transurethral balloon laser thermotherapy for urinary retention in patients with benign prostatic hyperplasia who are at high surgical risk

BACKGROUND

Twelve patients with benign prostatic hyperplasia and urinary retention, who were considered to be poor candidates for prostatectomy, were treated by transurethral balloon laser thermotherapy (TUBAL-T). The mean patient age was 78.9 years (range, 66 to 93 years) and the mean duration of bladder catheterization was 11 weeks (range, 2 to 48 weeks).

METHODS

Irradiation into the prostatic tissue was done through 360 degrees with a neodymium: yttrium aluminum garnet (Nd:YAG) laser balloon placed in the prostatic urethra, with pain relief provided by using local topical anesthesia. The total laser dose was from 45,000 to 123,376 J, with an average of 73,089 J. The irradiation time was from 40 to 54 minutes, with an average of 45.2 minutes.

RESULTS

Spontaneous voiding became possible in all patients at a mean of 2.8 days (range, 1 to 7 days) after irradiation. The mean catheter-free period was 20.5 months (range, 6 to 34 months), with the longest being 34 months. The international prostatic symptom scores, quality-of-life scores, and peak uroflow rates showed substantial improvement after laser thermotherapy. To date, long-term resumption of spontaneous voiding was successfully achieved in 9 of 12 cases (75%).

CONCLUSION

TUBAL-T is safe and effective alternative for treatment of urinary retention in patients with benign prostatic hyperplasia who are considered to be at high surgical risk.

Experimental and clinical studies on balloon laserthermia using Nd: YAG laser for uterine endometrial cancer

BACKGROUND AND OBJECTIVE

No conservative therapy for endometrial cancer exists. We therefore evaluated the new balloon laserthermia for such cases.

STUDY DESIGN/MATERIAL AND METHODS

Experimental and clinical study. We examined experimentally porcine kidney and stomach, human resected uterus and clinically on 12 patients with endometrial cancer and two patients with hyperplasia.

RESULTS

Temperatures were safely kept at the balloon surface. Laser irradiation should be performed for at least 10-15 min, 65-70 degrees C to produce a suitable degeneration, experimentally. Clinically, necrosis and degeneration to a depth of 4-6 mm was histologically observed. Eight patients with carcinoma and hyperplasia for which laserthermia was effective showed that the surface of cancer was smooth and the depth of invasion was in most cases up to 1/4 of muscle layer.

CONCLUSION

Balloon laserthermia may be effective in early endometrial cancer or precancerous lesions. Its clinical usefulness should be investigated further.

Transurethral balloon laser thermotherapy: effects of a directionally shielded balloon in canine prostates

BACKGROUND

Transurethral balloon laser thermotherapy (TUBAL-T) improves objective, but not subjective, symptoms of benign prostatic hyperplasia (BPH). We studied whether or not an Nd:YAG laser beam with a shielded balloon could successfully irradiate the prostate during TUBAL-T in selective manner, to improve the subjective symptoms.

METHODS

TUBAL-T was performed on canine prostates using the balloon with a laser probe, which was shielded anteriorly at 90 degrees (from the center of the balloon) and posteriorly at 90 degrees.

RESULTS

At 20 watts laser power, the relative power density in the bilateral non-shielded areas was 17.4 and 17.8, and in the shielded area it was 1.0. Observation by thermography revealed that the temperature after laser radiation in a non-shielded area of a fish cake phantom was higher than in a shielded area. Following transurethral thermotherapy using a shielded balloon in dogs, a cavity was formed bilaterally around the urethra, and the tissues at the anteroposterior sides and the urethra were preserved.

CONCLUSIONS

TUBAL-T, which has been performed in clinical cases of benign prostatic hyperplasia, might be useful in selective irradiation of adenoma if a shielded balloon is used.

Ultrasonographic and pathologic changes in the prostate of patients with benign prostatic hyperplasia after transurethral balloon laser therapy

Twenty-seven patients with benign prostatic hyperplasia (BPH) were treated with a transurethral flexible laser balloon (PROSTALASE) under ultrasound guidance. Three months after treatment, 22 (82%) of the patients showed a 50% or greater decrease in the AUA Symptom Score. The average uroflow rate, peak uroflow rate, and postvoiding residual urine volume also showed significant improvement. Ultrasonography showed that the prostatic volume had decreased by 17% (8%-37%). Also, a circular hyperechoic zone about 3 cm in diameter was noted around the prostatic urethra. The prostatic tissue in the hyperechoic zone was sampled by transperineal needle biopsy under transrectal ultrasound guidance, and histopathologic examination showed degenerative necrosis. The necrotic tissue was gradually absorbed, resulting in prostatic shrinkage at around the third month. These results suggest that clinical improvement, both subjective and objective, is brought about by this therapy.

Healing process of vascular cutting edge using an Nd:YAG laser bipolar dissector

The wound healing process was histopathologically investigated in a rabbit femoral artery (n = 48) after transection using a laser bipolar dissector (LBD, 1064nm the Nd:YAG bipolar contact laser) with laser power of 13W in 0.5-sec pulses. The cutting edges were harvested immediately (n = 6) and at 1 (n = 6), 4 (n = 6), and 7 (n = 6) days, 2 (n = 6), 3 (n = 6), and 4 (n = 6) weeks, and 6 months (n = 6), and evaluated by light microscopy. During the postoperative period, no perforation was seen in the 48 transected sites with the LBD. The healing process after LBD transection was accomplished within 2 weeks by organization of the intraluminal thrombus and by the formation of granulation tissue outside the adventitia of vessels. Characteristic morphological changes after LBD transection were recognized in the tapering area, i.e., cartilage and bone formation. Cartilaginous foci (n = 6) were observed in the media at 4 weeks after transection, and osseous foci (n = 3) in subendothelial space at 6 months. These observations may suggest that the heterotopic cartilaginous and osseous metaplasia of a vessel wall may be a result of the biostimulative effects of the Nd:YAG laser.

Transurethral balloon laser thermotherapy for symptomatic benign prostatic hyperplasia: preliminary clinical results

Between April 1993 and May 1994, 66 patients were treated with transurethral balloon laser thermotherapy (TUBAL-T) for the relief of bladder outlet obstruction secondary to benign prostatic hyperplasia. TUBAL-T, with a urethral cooling system, employs a balloon catheter and irradiating laser through 360 degrees to produce deep coagulation and necrosis of the prostatic tissue while preserving the urethral mucosa. The procedure was implemented under local topical anesthesia. Baseline AUA Symptom Scores, peak uroflow rates, postvoiding residual urine volumes (PVR), and prostatic volumes were measured before and at 1, 3, 6, and 12 months after treatment. The mean symptom score decreased from 18.8 preoperatively to 9.8, 6.9, 7.4, and 4.8 at 1, 3, 6, and 12 months, respectively. The mean peak uroflow rate increased from 6.4 mL/sec to 9.1, 11.2, 10.1, and 10.4 mL/sec at 1, 3, 6, and 12 months, respectively. As for the mean PVR, statistically significant reductions were clearly observed at 3 and 6 months after treatment. However, at 1 and 12 months, the difference was not statistically significant. In follow-up for as long as 12 months after the procedure, 23 of 26 patients (88%) showed an improvement of 50% or more in the AUA Symptom Scores. Of 20 available patients, 12 (60%) showed an improvement of 50% or higher in the peak uroflow rates, and 10 (50%) showed an improvement of 50% or higher in PVR. The mean prostatic volume reductions at 3, 6, and 9 months were 12%, 16%, and 14%, respectively. The serum prostate specific antigen concentration increased to four times the baseline concentration on the 7th day.(ABSTRACT TRUNCATED AT 250 WORDS)

Endoscopic and ultrasonographic observation of the canine prostate after transurethral balloon laser therapy (PROSTALASE)

We investigated the healing process and changes in the canine prostate after transurethral balloon-equipped laser (PROSTALASE) prostatectomy using both endoscopy and transrectal ultrasonography (TRUS). On TRUS, the prostate volume was significantly increased (123%) just after irradiation, decreasing to 106% at 1 week. Cavity formation was observed in the prostate 1 week after irradiation, and the median volume was 1.5 cm3 at 4 weeks. A TRUS study performed immediately after irradiation revealed a 1- to 2-mm deep hyperechoic lesion around the urethra. Urethrocystoscopy disclosed red and markedly edematous mucosa of the prostatic urethra, but no hemorrhage. The hyperechoic mass was also observed in the cavity on TRUS images 1 week later. Urethrocystoscopy disclosed abundant necrotic tissue within the cavity, and reddish granulomatous sections were observed on a portion of the cavity surface. At 4 weeks, the hyperechoic mass in the cavity was no longer observed on TRUS images. The prostate parenchyma was thin but uniformly isoechoic. At urethrocystoscopy, a smooth surface without redness and with the small craters, which were histologically identified as the duct openings of the prostate gland, were observed.

Prostalase: basic clinical research and preliminary clinical results with laser thermotherapy for symptomatic benign prostatic hyperplasia

Prostalase¿ has a probe that emits a laser beam at 360 degrees . Targeted obstructive prostatic adenoma tissue was heated to above the cytotoxic threshold temperature of 45 degrees C. After successful canine prostate study, from September 1992 to April 1993, 45 patients were treated. This paper reports the 9 months results of this initial cohort of patients. Prostatic and periprostatic temperature mapping showed the mean temperature within the adenoma zone was 49 degrees C, while the periprostatic tissue remained within the safety level of less than 42.5 degrees C. The mean prostate volume reductions at 3, 6, and 9 months were 36, 33, and 38%, respectively. Those patients whose surgery was unsuccessful had prostatic tissue removed by TURP at 2 to 3 months. This tissue revealed a definite zone of coagulative necrosis. For the clinical assessment, patients were divided into urine retention (UR) and nonretention (NR) subgroups. At 9 months, 20 of the 32 UR subgroup and 10 of the 13 NR subgroup patients were available for assessment. Due to poor response or complications, 6 of the 26 UR patients (23%) required ancillary treatment. Hence, 20 of the 26 cases (77%) remained catheter free and their mean maximum uroflow +/- SE was 9.6 +/- 0.7 ml/sec. Based on a Siroky normogram only 7 of these 26 patients (27%) became unobstructed. Two of the 12 NR subgroup patients (17%) required ancillary treatment. The mean maximum uroflow +/- SE was 10.7 +/- 1.2 ml/sec.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasal anastomoses in dogs using contact neodymium:yttrium aluminum garnet (Nd:YAG) laser

The purpose of this study is to evaluate the contact Nd:YAG laser system for vasal anastomosis in the animal model. Eighteen mongrel dogs were used. In this study, two major groups--control and laser--were defined. In the control group, vas anastomoses were performed with conventional microsurgical technique in six dogs. In the laser group, we performed contact laser assisted vas anastomosis (CLAVA) in 12 dogs by means of a contact Nd:YAG laser with synthetic sapphire probe (ERP4), emitted 2.0 sec pulse duration of minimum 1 watt to maximum 10 watts power. The time needed for completion of the vasal anastomosis in CLAVA group was 2-3 min; in the control group, approximately 25 min. The patency rate did not differ in these two groups; however, microscopic sperm granuloma formation was 16.7% (2/12) in the control group but 0% (0/12) in the CLAVA group. In conclusion, CLAVA is a fast and simple technique for vasal anastomosis and there were no significant complications, sperm granuloma, or even significant swelling or hematoma in any animal in this experiment.

Prostatectomy by transurethral balloon Laserthermia (PROSTALASE) in the canine

Prostatectomy by transurethral balloon Laserthermia (PROSTALASE) was performed in a canine model. This balloon device monitored by transrectal ultrasound can cylindrically irradiate with a laser beam. The treatment was performed in 8 canines using 15 watts for 20 minutes at 60 degrees C at a 5 mm depth of the prostate from the urethral surface. Immediately following the laser therapy, an area of coagulation necrosis was observed around the urethra to a depth of 4-5 mm from the surface. After 1 week, cavitation formation was seen in 3 or 4 canines by ultrasound, and the urethral reepithelialization was shown in 1 of 2 canines. After 2 weeks, cavitation formation was observed in both canines, and the urethra was completely reepithelialized in one canine. There was no tissue damage in the bladder neck of urethral sphincter and no urinary incontinence in any animal. This system is thought to be simple and, satisfactorily performed, is an effective transurethral prostatectomy.

Clinical application of the Nd:YAG laser bipolar dissector in intra-abdominal surgery

A laser bipolar dissector (LBD) using a 1064 nm Nd:YAG laser energy source that provides hemostatic dissection using low-powered laser energy (15-25 W) has been developed. Clinical applications have included a partial hepatectomy (n = 5), a cholecystectomy (n = 4), an appendectomy, lymphnode dissection, and division of adhesions. The LBD was effective in resection of noncirrhotic liver and reduced the number of ligations required. There were no direct complications related to using the LBD. Operative time and blood loss were difficult to compare to conventional methods. The LBD may have applications for partial hepatectomies and other intra-abdominal operations.

Nd:YAG laser bipolar dissector--preliminary results

We have developed a laser bipolar dissector (LBD) which uses the 1,064 nm Nd:YAG wavelength. The laser emits from the inner surface of the distal 7 mm of each probe made of synthetic sapphire. With low laser power (15-25 W), the bipolar provides hemostatic cutting of larger blood vessels. Animal experiments were carried out using New Zealand white rabbits. The LBD hemostatically cut through veins up to 5 mm and arteries up to 2 mm in diameter. Rebleeding did not occur. Transection of parenchymal organs such as liver and lung was easily performed with complete hemostasis. In chronic experiments a partial hepatectomy with splenectomy and left nephrectomy was performed using the LBD alone without any ligation. Up to 3 weeks postoperatively there were no direct complications related to using the LBD. In conclusion the LBD could perform a hemostatic transection of large vessels and might have clinical application in the dissection of vascular parenchymal organs.

Low-power laserthermia for the treatment of small hepatocellular carcinoma

Laserthermia by a novel interstitial probe adapted to low power Nd-YAG laser machine was used to treat small hepatocellular carcinoma (HCC). The set condition was 43-45 degrees C in thermocouple with power of 2-3 W and the duration 20-30 min. In the 5 cases studied, 1 had a good result with total necrosis of the tumour without recurrence in 16 months. 1 died of liver failure 2.5 months later although death was not related to the procedure. 1 patient died of progressive disease 18 months later. The remaining 2 had recurrent tumours 5 and 12 months later, although the treated small tumours showed good response. Histological examination showed cell degeneration and necrosis. It is concluded that laserthermia is potentially useful in the treatment of the patients with small HCC.

Laserthermia for the treatment of small hepatocellular carcinoma: a preliminary study

A newly designed interstitial probe (hybrid probe) was used to treat small hepatocellular carcinoma (HCC) with laserthermia. Before the human study, testing in normal rabbit liver was done to measure the thermal map. Laserthermia was then studied in human small HCC. The set condition was 43-45 degrees C in thermocouple and the duration of laserthermia was 20 minutes. On follow-up computed tomography and liver biopsies, laserthermia had tumorcidal effect. It is concluded that laserthermia may be helpful to patients with small HCC.

Photodynamic therapy using pheophorbide a and Nd:YAG laser

The authors describe a new photodynamic therapy (PDT) method for malignant brain tumors. Pheophorbide a (Ph-a), the photosensitizer, has low toxicity, causes no skin sensitization and is activated with an acoustic Q switched neodymium yttrium-argon-garnet (Nd:YAG) laser which achieves deep tissue penetration. The Ph-a distribution in Fisher 344 (F344) rats bearing rat T9 glioma at 24 hours after intravenous injection was very low in the normal brain tissue, but significantly higher in the T9 glioma giving a tumor to normal brain tissue concentration ratio of 7.5:1. The in vitro survival rate of T9 glioma cells pretreated with Ph-a was 68.8 +/- 5.4% after laser irradiation for 20 minutes, significantly lower than in the control groups. This indicates that Ph-a was activated with the acoustic Q switched Nd:YAG laser causing the photodynamic effect. The survival rate after Ph-a pretreatment and laser irradiation in a waterbath at 44.0 degrees C was further reduced to 15.8 +/- 3.3%. In vivo PDT studies using T9 glioma cells inoculated into the dorsal region of F344 rats showed tumor eradication in four of six rats. The combination of PDT and laser hyperthermia produced tumor eradication in all six rats. The combination of PDT and hyperthermia is a promising method for tumor treatment.

Laserthermia. A new method of interstitial local hyperthermia using the contact Nd:YAG laser

Laserthermia is a new method of delivering interstitial local hyperthermia using a synthetic contact probe with a computer-controlled Nd:YAG laser to deliver both pulsed and continuous laser energy. The system allows an easily controllable increase in temperature (for example, from 42 to 43 degrees C) over a fixed period of time (for example, 20 minutes) to be delivered to tissue. A single or multiple channel system can be used depending on the volume of tissue to be treated. Tumor necrosis appears to be related to avascular infarction. Early clinical results support the beneficial therapeutic effects of Laserthermia in its oncologic applications.

In vitro inhibition of lens epithelial cell growth by continuous wave Nd:YAG laser

Bovine lens epithelial cells were suspended in MEM medium and subjected to continuous wave, low power, pulsed neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation. The temperature of each suspension was maintained at 36 degrees C. Laser applications ranged from 1 to 10 watts and from 100 to 2000 seconds, but the total dose to each of the epithelial cell suspension was 2000 J. Six to thirty-nine percent of the cells were dead immediately after irradiation. Surviving cells, cultured for 15 days, showed decreased attachment and failed to grow. These preliminary results suggest that the Nd:YAG laser may be used during cataract surgery to prevent subsequent lens epithelial cell proliferation and the resulting vision reduction and glare.

Laserthermia: a new computer-controlled contact Nd: YAG system for interstitial local hyperthermia

Contact Nd:YAG laser surgery is assuming a greater importance in endoscopic and open surgery, allowing coagulation, cutting, and vaporization with greater precision and safety. A new contact probe allows a wider angle of irradiation and diffusion of low-power laser energy (less than 5 watts), using the interstitial technique for producing local hyperthermia. Temperature sensors that monitor continuously can be placed directly into the surrounding tissue or tumor. Using a computer program interfaced with the laser and sensors, a controlled and stable temperature (e.g., 42 degrees C) can be produced in a known volume of tissue over a prolonged period of time (e.g., 20-40 min). This new laserthermia system, using a single low-power Nd:YAG laser for interstitial local hyperthermia, may offer many new advantages in the experimental treatment and clinical management of carcinoma. A multiple system is now being developed.

Laserthermia: a computer-controlled contact Nd:YAG system for interstitial local hyperthermia

Contact Nd:YAG laser surgery is assuming a role of greater importance in endoscopic and open surgery, allowing coagulation, cutting, and vaporization with greater precision and safety. A synthetic sapphire probe allows a wider angle of irradiation and diffusion of low power laser energy (less than 5 W) using an interstitial technique for producing local hyperthermia. Sensors placed directly into surrounding tissue or tumor continuously monitor temperature, and a pertinent computer program produces a controlled and stable temperature (e.g., 42 degrees C) over a period of time (e.g., 20-40 min). The Laserthermia system (Surgical Laser Technologies, Inc., Malvern, PA), using the Nd:YAG laser, offers many advantages in the experimental and clinical treatment of carcinoma by local interstitial hyperthermia.

Photoradiation therapy in early gastrointestinal cancer

Endoscopic photodynamic therapy has been used in the treatment of 19 cases of upper gastrointestinal cancer of which six were superficial esophageal and 13 were early gastric cancer. Six patients subsequently underwent surgical resection. Residual tumors were found in the resected specimens of one esophageal carcinoma and in the two early gastric carcinomas. Technical problems resulted in one failure. Follow-up ranged from 4 months to 3 years and 11 months with no tumor recurrence in either the operated or unoperated patients. Other delivery systems are currently under investigation.

The contact Nd:YAG laser system in the treatment of bladder cancer: a preliminary report in 48 patients

A synthetic contact sapphire endoprobe attached to the quartz fiber of a neodymium:yttrium aluminum garnet (Nd:YAG) laser had been used in the transurethral treatment of bladder tumors. A total of 68 operations have been carried out in 48 patients. The contact probe was placed directly into the tumor under direct vision. Using 15-20 watts of laser energy, the tumor blanched and underwent necrosis. The technique was easy to apply, and bleeding was minimal. Damage to the ureteral orifice and ureter in the bladder wall at repeat cystoscopy appeared less than with conventional electrocautery or noncontact laser treatment. The technique of contact Nd:YAG laser surgery will have an important role in the transurethral treatment of bladder tumors.

Resection of the liver with the Nd:YAG laser

Controlled studies of experimental hepatic resection have shown noncontact Nd:YAG techniques to be superior in hepatic resection when compared with conventional finger-fracture or ultrasonic aspirator, although tissue damage was extensive. The noncontact technique is compared with the contact technique of hepatic resection (25 to 30 per cent) in male Wistar rats (n equals 60) using a specially designed artificial sapphire laser scalpel attached to the optic fiber. Contact required only low power ranges (5 to 25 watts) for a rapid hepatic lobe resection associated with less bleeding and smoke. Noncontact resection at low power (10 to 20 watts) caused uncontrollable bleeding leading to death whereas in power density ranges greater than 30 watts, successful resection of a lobe of the liver could be done, but as the power increased, there was greater tissue damage. Light microscopy showed laser penetration of 0.5 to 1.0 millimeters with the contact method with evidence of healing, fibrosis and minimal necrotic material at 15 days. In the noncontact group, laser penetration was 2 to 4 millimeters in depth with accumulated necrotic material encapsulated by fibrous tissue at 15 days. Contact hepatic resection with the laser scalpel offers many new advantages than conventional noncontact Nd:YAG laser techniques.

Artificial sapphire probe for contact photocoagulation and tissue vaporization with the Nd:YAG laser

A contact artificial sapphire, developed for use with the Nd:YAG laser, allows the performance of open surgery (laser probe) and has endoscopic applications for the treatment of gastrointestinal bleeding (micro laser tip) and tumors (micro laser rod). Advantages of this contact irradiation include precision of surgical technique, minimal tissue damage, and excellent hemostatic and cutting capabilities, with low backscattering of laser energy.

Treatment of head and neck tumors by contact Nd-YAG laser surgery

The contact Nd-YAG laser system with ceramic rods which has been developed by us was applied to animal experiments and clinical practice. It was confirmed that: 1) this method can be performed at low power of 6 to 8 W in contact laser incision of soft tissue and at 3 to 4 W in localized laser hyperthermia; 2) it permits accurate and precise incision because mis-shots of laser irradiation can be eliminated in the target tissue; 3) it causes less bleeding with minimal damage to adjacent tissue; and 4) it has remarkably high controllability. The contact Nd-YAG laser systems are very useful as one of the new modalities for surgical procedures as well as localized laser hyperthermia in head and neck tumors.