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 in the development of the current sheet applicator. As a result, the effectiveness of the GBM is investigated in single and dual array applications of the lucite cone applicator (LCA). The LCA is a modified water-filled waveguide applicator with an improved effective field size (EFS > 64 cm2, aperture 10 cm x 10 cm). The GB-source parameters were calculated from the emanating E-field of a single LCA. The SAR distribution from a single LCA was measured by E-field scanning and thermographic (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 as intermedium between LCAs and phantom, a maximum SAR difference of 27% was calculated. In the absence of water as intermedium, this difference increased to 44%. These large deviations were only found in areas where the measured SAR distribution was disturbed due to antenna interactions. The average SAR differences with and without water as intermedium were 7% respectively 11%, indicating that the GBM can provide good qualitative information about the SAR distribution of dual LCA-arrays.
University Hospital Rotterdam/Daniel den Hoed Cancer Center, Department of Radiation Oncology, The Netherlands.
P J
PJ
Rietveld
M L
ML
Lumori
J W
JW
Hand
M V
MV
Prior
J
J
Van der Zee
G C
GC
Van Rhoon
D004574:Electromagnetic Fields; D006979:Hyperthermia, Induced / Q000295:instrumentation*; D008962:Models, Theoretical; D019904:Polymethyl Methacrylate; D013329:Structure-Activity Relationship
D019904:Polymethyl Methacrylate