Fiber Optics for Thermometry in Hyperthermia Therapy

A review of electromagnetic hyperthermia ablative therapies, a temperature measurements during microwave ablation using optical fiber temperature sensors and a fiber optic temperature sensor developed for a hyperthermia laboratory are summarized in this chapter. Hyperthermia also called thermotherapy or thermal therapy is a type of cancer treatment in which body tissue is exposed to high temperatures. All methods of hyperthermia include transfer of heat into the body from an external energy source and are currently under study, including local, regional, and whole-body hyperthermia. The application of heat to treat patients with a malignant tumor is not a novel concept. The Edwin Smith papyrus explains the topical application of heated metallic implements or hot oil that were used approximately 5000 years ago to treat patients with tumors (Izzo et al., 2001). Local hyperthermia is used to heat a small area. It involves creating very high temperatures that destroy the cells that are heated. Research has shown that high temperatures can damage and kill cancer cells, usually with minimal injury to normal tissues (van der Zee, 2002). By killing cancer cells and damaging proteins and structures within cells, hyperthermia may shrink tumors (Hildebrandt et al., 2002). Numerous clinical trials have studied hyperthermia in combination with radiation therapy and/or chemotherapy. Many of these studies, have shown a significant reduction in tumor size when hyperthermia is combined with other treatments (Wust et al., 2002). Otherwise, ablation or high temperature hyperthermia, including lasers and the use of radiofrequency, microwaves, and high-intensity focused ultrasound, are gaining attention as an alternative to conventional surgical therapies (van Esser et al., 2007). Each of these techniques works differently, the objective is to heat tissue to a temperature 50°C above to destroy cells within a localized section of a malignant tumor. Frequently, temperature monitoring during thermal therapy has been achieved using interstitial thermocouples, thermistors, or fiber optics probes. Fiber optics technology should exploit one or more of electromagnetic immunity, noninvasiveness, chemical immunity, small size, or the capacity for distributed measurement. Fiber optic thermometers are used when electrical insulation and EMI immunity are necessary. The most relevant application involves tissue-heating control during microwave ablation (MWA) or radiofrequency ablation (RFA) hyperthermia therapy for cancer treatment (Mignani & Baldini, 1996).