A Comparison of Small Field Output Factors for Stereotactic Radiation Therapy
This study investigates the clinical application of newly published small-field output factors (OPFs) for the AcurosXB 15.6 (AXB) algorithm in Varian’s Eclipse treatment planning system (TPS). The primary goal is to validate the extended AXB (AXBe) model’s accuracy in calculating dose for small-field geometries, which are known to be challenging for conventional dosimetry. Measurements were conducted using the Exradin A16 Micro ion chamber, the Sun Nuclear EDGE diode, and the IBA Razor diode to evaluate the capacity of these detectors to reliably capture small field OPFs for jaw-defined and MLC-defined fields.
This thesis offers a comprehensive comparison between measured OPFs, values provided by existing literature, and the OPFs predicted by Eclipse TPS when implementing the AXBe algorithm, identifying trends and discrepancies across detectors and field sizes. Findings from this study affirm the AXBe model’s reliability while offering insight into the performance of each detector. The discussion evaluates the clinical relevance of the AXBe model, potential limitations of the methodology used, and suggestions for further research. Future recommendations include expanding this study to include different beam energies, testing additional detectors, and considering long-term clinical trials to further validate the AXBe model for use in stereotactic radiotherapy planning.