Phantom dosimetry and evaluation of target localisation for linac based stereotactic radiation

Linear accelerators are widely used for stereotactic radiosurgery and stereotactic radiotherapy. The procedure of stereotactic irradiation involves precise localization of a small intracranial lesion and delivery of single fraction of high doses (SRS) or fractionated treatment (SRT) using multiple coplanar arcs. A phantom study was carried out to verify the dose delivered to the target and to evaluate the target positioning and localization. The dosimetry was carried out with FBX chemical Dosimeter and with Thermoluminescent dosimeter. The target position was verified by taking radiographs of a radio-opaque target. The results obtained with FBX chemical dosimeter and with TLD were within 5% of the prescribed dose. The estimated positional accuracy of the target was 2 mm