Theoretical comparison of the SAR distributions from arrays of modified current sheet applicators with that of lucite cone applicators using Gaussianbeam modelling

The technical comparison of Current Sheet Applicator (CSA) and Lucite Cone Applicator (LCA) arrays covering an area of similar to 20 x 20 cm(2) is inv estigated based on Gaussian beam (GB) predicted SAR distributions. The comp arison is made in muscle equivalent tissue at 1 cm depth (maximum SAR norma lized to 100%) and over a volume of 3 cm depth under the aperture of the an tennae. The planar SAR distribution is tested on field sizes (FSx: area cov ering x% SAR), penetration depth (PD) and homogeneity coefficient (HC = FS7 5/FS25). From the SAR volume, a SAR-Volume histogram (volume enclosing y% S AR/total volume) is calculated as well as the volumetric HC. First, the pro totype CSA (aperture 58 x 67 mm(2), FS50 = 21 cm(2)) is technically modifie d to assure clinical safety and load independence. The modified CSA, the D- CSA, has an aperture of 66 x 75 mm(2) with an FS50 = 28 cm(2) and a PD of 1 0 mm, the LCA (aperture 105 x 105 mm(2)) has an FS50 = 76 cm(2) and PD = 12 mm. The HC equals 0.21 (D-CSA), respectively 0.22 (LCA). Secondly, a 3 x 3 D-CSA array is compared with a 2 x 2 LCA array. The FS(50)s equals 72% (D- CSA), respectively 75% (LCA). The SAR-volume histograms, planar and volumet ric HC show no significant difference; however, the planar HCs for D-CSA an d LCA increase from 0.2-0.3, indicating that incoherently powered arrays fr om these antennae build SAR distributions constructively.