Effects of interstitial heating on the RIF-1 tumor using an Nd:YAG laser with multiple fibers
✍ Scribed by Tobin, Kathleen M.; Waldow, Stephen M.
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 712 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0196-8092
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✦ Synopsis
Background and Objective: Hyperthermia was induced in tumorbearing C3H mice using a Nd:YAG laser emitting near-infrared radiation at 1,064 nm. The efficacy of multiple implanted fiberoptics in the control of the RIF-1 tumor was investigated. Study DesignJMaterials and Metho&: RIF-1 tumors in the right hind leg were heated interstitially at 42, 44, or 46°C for 30 or 60 minutes. Two, three, or four 400-pm quartz fibers terminating in a 1.0-cm cylindrical diffusor were inserted into each tumor, as were five microthermocouples to monitor temperature during treatment. Laser Doppler Flow (LDF) was also recorded pre-and post-treatment to determine changes in red blood cell flux in overlying skin (42,44, or 46°C) and the center of the tumor (46°C). Results: These experiments indicated that interstitial heating at 42, 44, and 46°C resulted in tumor growth delay, although longterm control of tumors was not achieved. Treatment using four fibers resulted in the greatest tumor growth delay at 42 and 44"C, increasing tumor doubling time by 5 w o or greater compared to control tumors; tumor growth delay following 46°C treatments was seven times greater than that in control tumors. Significant changes (decreases) in LDF (P < .05) were seen in four treatment groups, using two fibers at 42°C for 30 minutes, four fibers at 44 and 46°C for 60 minutes on the overlying skin, and 46°C for 60 minutes in the center of the tumor. Conclusions: Initial data indicate that interstitial heating with multiple fibers increases tumor growth delay compared to previous single fiber treatments, with tumor growth delay increasing with increasing treatment temperature; however, long-term tumor control was not achieved under the conditions investigated. Follow-up studies will explore the use of higher temperatures andlor longer treatment times in order to optimize tumor response.