Initial commissioning measurements of respiratory gated liver VMAT stereotactic ablative body radiotherapy

A dosimetric evaluation of a respiratory gated VMAT SABR technique was performed at two different beam energies. Dynamic ion chamber, EBT3 film and Fricke-xylenol orange-gelatin (FXG) gel measurements were acquired using a motion phantom with custom inserts for each dosimeter. Ion chamber and gel dosimeter measurements show good agreement between the measured and calculated plan dose within the planning target volume (PTV). Lower agreement than expected was observed between calculated plan dose and measured film dose, particularly for the 10 MV flattening filter free beam plan, a result that warrants further investigation.