Improved Localization of Energy Deposition in Adaptive Phased-Array Hyperthermia Treatment of Cancer

■ Elevated cell tissue temperature (hyperthermia) due to radio-frequency (RF) energy absorption is known to produce an improved response for malignant tumors in humans when applied in combination with other anticancer modalities. However, clinical studies in thermotherapy have shown the difficulty of localizing RF energy deposition in malignant tissue deep within the body without damaging surrounding healthy tissue. The study presented in this article involves a preclinical investigation of adaptive feedback and computer control of amplitude and phase from coherent RF antenna arrays to provide improved distribution of electromagnetic energy deposition in the body. Measurements in a treatment-planning phantom irradiated with an adaptive antenna-array applicator show that noninvasive adaptive nulling can reduce the RF energy absorption in nearby healthy tissue while focusing energy into a deep-seated tumor site.