Characterization of the SAR-distribution of the Sigma-60 applicator for regional hyperthermia using a Schottky diode sheet.

Introduction: Characterization of the performance of an hyperthermia applicator by phantom experiments is an essential aspect of quality assurance in hyperthermia. The objective of this study was to quantitatively characterize the energy distribution of the Sigma-60 applicator of the BSD2000 phased array system operated within the normal frequency range of 70–120 MHz. Additionally, the accuracy of the flexible Schottky diode sheet to measure E-field distributions was assessed.Material and methods: The flexible Schottky diode sheet (SDS) consists of 64 diodes mounted on a flexible 125 µm thick polyester foil. The diodes are connected through high resistive wires to the electronic readout system. With the SDS E-field distributions were measured with a resolution of 2.5 × 2.5 cm in a cylindrical phantom, diameter of 26 cm and filled with saline water (2 g/l). The phantom was positioned symmetrically in the Sigma-60 applicator. RF-power was applied to the 4-channel applicator with increasing steps from 25 W t...