Reproducibility and geometric accuracy of the fixster system during hypofractionated stereotactic radiotherapy

Abstract

BackgroundHypofractionated radiotherapy has been used for the treatment of AVMs and brain metastases. Hypofractionation necessitates the use of a relocatable stereotactic frame that has to be applied on several occasions. The stereotactic frame needs to have a high degree of reproducibility, and patient positioning is crucial to achieve a high accuracy of the treatment.MethodsIn this study we have, by radiological means, evaluated the reproducibility of the isocenter in consecutive treatment sessions using the Fixster frame. Deviations in the X, Y and Z-axis were measured in 10 patients treated with hypofractionated radiotherapy.ResultsThe mean deviation in the X-axis was 0.4 mm (range -2.1 – 2.1, median 0.7 mm) and in the Y-axis -0.3 mm (range -1.4 – 0.7, median -0.2 mm). The mean deviation in the Z-axis was -0.6 (range -1.4 – 1.4, median 0.0 mm).ConclusionThere is a high degree of reproducibility of the isocenter during successive treatment sessions with HCSRT using the Fixster frame for stereotactic targeting. The high reducibility enables a safe treatment using hypofractionated stereotactic radiotherapy.