Geometric accuracy on verification of stereotactic radiotherapy with the use of a double mask versus the Leksell G frame

Patient immobilization is an important element for the geometric accuracy of stereotactic radiotherapy (SRT) techniques. However, differences in the immobilization and accuracy with the use of a G frame versus a double remain unknown. The aim of this retrospective comparative cross-sectional study was to compare the extents of geometrical shifting on verification of stereotactic techniques with the use of a G frame versus a double mask. The study cohort included patients who received RT between February and March 2016 at the Department of Radiotherapy of Cipto Mangunkusumo Hospital. The t-test was used to compare geometrical shifting values on verification with the use of a G frame versus a double mask. The mean value of geometrical shifting in patients with SRT with the use of a double mask on the laterolateral, craniocaudal, and anteroposterior axes were 0.4 ± 0.3, 0.5 ± 0.4, and 0.5 ± 0.4 mm, respectively, while values with the use of a G frame were 0.3 ± 0.2, 0.3 ± 0.4, and 0.4 ± 0.3 mm, respectively. There were no differences in the mean geometrical shifting values with the use of a double mask versus a G frame.