Fig 3. Effect of array rotation on field intensity for anterior-posterior tumor translations, y-axis.

A. Color map of the median field intensity (V/m) in tumors at varying y-positions (-40 mm to 30 mm, ordinate) and varying rotations (θ = 0 to 180 degrees, abscissa) of a single pair of electrode arrays. X- and z-coordinates were kept constant at x = 40 mm and z = 0 mm, respectively, for all tumors, i.e. all tumors were in the center-to-center plane of the rotated array pairs. The figure shows field maxima at two separate rotations for the most tumors. The two maxima were separated by approximately 90 degrees. B. Axial section of the GM and WM surfaces and the investigated tumors (y translations, i.e. x = 40 mm, y = -40 to 30 mm, and z = 0 mm). Array rotations and tumor locations are indicated by the corresponding arrows and the axis, respectively. C. Axial section (radiological convention) of the WM, GM and tumor volume (y = -40 mm, position indicated with a solid arrow), showing an example of the topographical distribution of the field induced by TTFields (left-right array position, θ = 90 degrees). D. Color map comparable to panel A, but illustrating the mean field induced by two orthogonal array pairs. Tumor positions are indicated on the ordinate and the rotations of the posterior array on the abscissa (θ = 0 to 90 degrees). The figure shows a single maximum of the mean field intensity at varying rotations depending on the tumor of interest. The field distribution of the “optimal” layout is shown in panel F for the tumor position y = -40 mm, while the distribution of the least effective layout (θ = 0 degrees) for the same tumor is shown in panel E.