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- Ivarsson, K, et al.
(författare)
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Feedback interstitial diode laser (805 nm) thermotherapy system: Ex vivo evaluation and mathematical modeling with one and four-fibers
- 1998
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Ingår i: Lasers in Surgery and Medicine. - 0196-8092. ; 22:2, s. 86-96
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Tidskriftsartikel (refereegranskat)abstract
- Background and Objective: In this study a newly developed microprocessor controlled power regulation and thermometry system integrated with a diode laser (805 nm wavelength) was evaluated with respect to temperature distribution, effectiveness of regulation, and ability to predict temperature distributions by computer simulation. Study Design/Materials and Methods: Experiments were performed in ground bovine muscle using either a single laser fiber or four-fibers. The target temperature at one (feedback) thermistor, placed 5 mm from one of the laser fibers, was set to 50 degrees C and was maintained by means of stepwise power regulation. The temperature distribution was monitored using multiple thermistor probes. A numerical model based on the bioheat equation was used to calculate the temperature distributions. Results: Temperature regulation was excellent with a tendency towards better regulation in the four-fiber than in the single-fiber experiments. Agreement between calculated and measured temperatures was good. The coagulated (>55 degrees C) and hyperthermic (>45 degrees C) volumes were 6 and 10-11 times larger, respectively, with four-fibers than with a single fiber. Conclusion: It is concluded that the stepwise power regulation system was efficient in maintaining a stable target temperature. The results indicate that the system can produce lesion volumes adequate for treating a relatively large tumor in a single session and that computer simulation may be useful for predicting temperature distribution. (C) 1998 Wiley-Liss, Inc.
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| 2. |
- Liu, D. L, et al.
(författare)
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Tumour vessel damage resulting from laser-induced hyperthermia alone and in combination with photodynamic therapy
- 1997
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Ingår i: Cancer Letters. - 1872-7980. ; 111:1-2, s. 157-165
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Tidskriftsartikel (refereegranskat)abstract
- This study examined tumour vessel injury resulting from laser-induced hyperthermia alone and in combination with photodynamic therapy (PDT) in the treatment of rat liver tumours by means of scanning electron microscopy. A total of 18 Wistar rats were divided into three groups, Group I (six animals) underwent hyperthermia for 15 min (15-min hyperthermia). Group II (six animals) underwent hyperthermia for 30 min (30-min hyperthermia). Group III (six animals) received the combined treatment of PDT and 30-min hyperthermia. For PDT, delta-amino laevulinic acid at a dose of 60 mg/kg of body weight was intravenously administered 60 min before irradiation at 635 nm. The morphological results indicated that 15-min hyperthermia gave rise to an increase in permeability of the vessels in the treated tumour. Thirty-min hyperthermia caused extreme oedema of vascular endothelial cells and restrictive openings of tumour branch vessels. The combined therapy of PDT and hyperthermia destroyed tumour vasculature. Large breaks of the inner wall of the treated tumour vessels were deeply involved in the basement membrane of the vessel. The results indicate that there may be a close link between inhibition of tumour growth and degree of damage to tumour vessels. (C) 1997 Elsevier Science Ireland Ltd.
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