Effects of tumor-treating field arrays on the radiation position and dose of glioblastoma / 中华放射医学与防护杂志

ABSTRACT

Objective:To preliminarily investigate the effects of tumor treating field (TTF) arrays on the positioning accuracy of radiotherapy setup in the treatment of glioblastoma.Methods:The kilovolt cone-beam CT (CBCT) and an X-ray volumetric imaging (XVI) system were used to verify the radiotherapy setup of 29 patients treated with conventional radiotherapy and 12 patients treated with TTF concurrent radiotherapy, respectively. The errors of radiotherapy position isocenter and treatment plan isocenter were evaluated in six directions, namely lateral (Lat), head pin (Lng), dorsoventral (Vrt), roll, pitch, and rotation (Rtn). Then, the plan isocenter was redetermined according to the setup error data. Moreover, the dose distribution was recalculated without changing the radiation field parameters. Finally, the V40, Dmean, D98% and D2% of both PTV and CTV and the Dmean, D20 cm 3, and D30 cm 3 of scalp tissue were evaluated. Results:When patients were treated with TTF concurrent radiotherapy wearing TTF arrays, the setup errors increased by 2 mm and 1.3 mm on average (maximum 3.5 mm and 2.7 mm) toward the foot and dorsal directions, respectively. In addition, the setup errors in both Roll and Rtn directions increased by about 1.1° toward one side. The V40 and D98% of PTV decreased by up to 4.78% and 6%, respectively. The Dmean, D20 cm 3, and D30 cm 3 to scalp tissue increased by up to 2.6%, 3.2%, and 3.5%, respectively. The errors of other dose parameters for both CTV and PTV were within 2%. Conclusions:TTF arrays have significant effects on the setup errors of patients in the Lng and Vrt directions and increase the setup difficulty in the Roll and Rtn directions, while there is no significant error in the Lat and Pitch directions. Moreover, too large setup errors can significantly reduce the dose to PTV.