Evaluation of a new relocatable head fixation system

Precision fractionated 3D conformal and intensity modulated radiotherapy is dependent on reproducibility of the position of the radiation fields with respect to the target to the maximum extent feasible. Prior experience with the daily set-up variation with the thermoplastic mask systems in current clinical use has been reported to be 2-5 mm. Thermoplastic masks also often become ill-fitting and require adjustment over the course of radiation therapy in patients receiving concurrent steroid therapy for brain tumors. To improve patient positioning reproducibility and comfort, a new relocatable head immobilization system (HeadFix) has been used for fractionated radiation therapy of children and adolescents with tumors of the brain or head and neck. This paper describes the new head immobilization system and reports on a comparison of positioning reproducibility between the new system and a standard thermoplastic mask system in 29 patients with primary brain tumors under 18 years of age