Reproducibility and treatment planning advantages of a carbon fiber relocatable head fixation system.

Introduction: An all carbon fiber head fixation system, VBH HeadFix Arc ('HeadFix') modified to optimize conformal radiation therapy, is described and its treatment planning and delivery advantages, positional accuracy and X-ray attenuation are presented.

Material And Methods: Serial radiation field isocenter measurements were made from weekly anterior-posterior (AP) and lateral port films taken of 13 children undergoing fractionated external beam radiation therapy for primary brain tumors. Measurements were also made of radiation transmission through the components of the HeadFix system.

Results And Conclusion: The mean deviation between simulation and port films in each of the orthogonal directions was 0.8-1.2 mm and the mean 3 dimensional deviation was 1.8+/-0.6 mm. The modified HeadFix system components attenuate between 2 and 4% of the incident beam, allowing a wider range of beam directions for conformal therapy than the previously reported system.