EFFECTIVENESS OF THE GAUSSIAN-BEAM MODEL IN PREDICTING SAR DISTRIBUTIONS FROM THE LUCITE CONE APPLICATOR

The Gaussian beam model (GBM) has been shown to be a successful tool i n the development of the current sheet applicator. As a result, the ef fectiveness of the GEM is investigated in single and dual array applic ations of the lucite cone applicator (LCA). The LCA is a modified wate r-filled waveguide applicator with an improved effective field size (E FS > 64 cm(2), aperture 10 cm x 10 cm). The GB-source parameters were calculated from the emanating E-field of a single LCA. The SAR distrib ution from a single LCA was measured by E-field scanning and thermogra phic (TG) imaging, and compared with the GB-predicted SAR distribution . Deviations in the principal planes were found to be less than 5%. TG -measured and GB-predicted SAR distributions from three different dual LCA configurations were compared and evaluated. When water was used a s intermedium between LCAs and phantom, a maximum SAR difference of 27 % was calculated. In the absence of water as intermedium, this differe nce increased to 44%. These large deviations were only found in areas where the measured SAR distribution was disturbed due to antenna inter actions. The average SAR differences with and without water as interme dium were 7% respectively 11%, indicating that the GEM can provide goo d qualitative information about the SAR distribution of dual LCA-array s.