Operation and calibration of the novel PTW 1600SRS detector for the verification of single isocenter stereotactic radiosurgery treatments of multiple small brain metastases

Abstract

Objectives: The aim of this work was to evaluate the agreement scores for cut-off values 50%, 80%, 95%, of operation of the 1600SRS detector and to develop a 98.6 ± 1.7%, 96.5 ± 4.6%, 97.3 ± 4.4% for the 6MV plans calibration procedure for verifying the dose delivered by respectively, and 98.6 ± 1.5%, 96.6 ± 4.0% 96.4 ± 6.3%, a single isocenter stereotactic radiosurgery (SRS) treat-for the 6MV flattening filter free (FFF) plans respecment of small multiple brain metastases (BM). tively. Using the default calibration procedure instead of Methods: 14 clinical treatment cases were selected with the plan specific calibration could lead to a combined the number of BM ranging from 2 to 11. The dosimetric systematic dose offset of 4.1% for our treatment plans. agreement was investigated between the calculated Conclusion: The 1600SRS detector array with the 4D and the measured dose by an OCTAVIUS 1600SRS array phantom offers an accurate solution to perform routine detector in an OCTAVIUS 4D phantom equipped with quality assurance measurements of single isocenter SRS dedicated SRS top. The cross-calibration procedure treatments of multiple BM. This work points out the deviated from the manufacturer’s as it applied field sizes necessity of an adapted cross-calibration procedure. and dose rates corresponding to the volumetric moduAdvances in knowledge: A dedicated calibration procelated arc therapy segments in each plan. dure enables accurate dosimetry with the 1600SRS Results: Measurements with a plan specific cross-detector for small field single isocenter SRS treatment calibration showed mean ± standard deviation (SD) of multiple brain metastases for a large amount of BM.