Validation of the preconfigured Varian Ethos Acuros XB Beam Model for treatment planning dose calculations: A dosimetric study

Abstract

Varian (Palo Alto, California, United States) recently released an online adaptation treatment platform, Ethos, which has introduced a new Dose Preview and Automated Plan Generation module despite sharing identical beam data with the existing Halcyon linac. The module incorporates a preconfigured beam model and the Acuros XB algorithm (Ethos AXB model) to generate final dose calculations from an initial fluence optimization. In this study, we comprehensively validated the accuracy of the Ethos AXB model by comparing it against the Halcyon AXB model, the Halcyon Anisotropic Analytical Algorithm (AAA) model, and measurements acquired on an Ethos linac. Results indicated that the Ethos AXB model demonstrated a comparable if not superior dosimetric accuracy to the Halcyon AXB model in basic and complex calculations, and at the same time its dosimetric accuracy in modulated and heterogeneous plans was better than that of the Halcyon AAA model. Despite the fact that the same algorithm was utilized, the Ethos AXB model and the Halcyon AXB model still exhibited variations across a range of tests, although these variations were predominantly insignificant in the clinical environment. The accuracy of the Ethos AXB model has been successfully verified in this study and is considered appropriate for the current clinical scope. On the basis of this study, clinical physicists can perform a data validation instead of a full data commissioning when implementing the Ethos system, thereby adopting a more efficient approach for Ethos installation.

An in-silico assessment of the dosimetric benefits of MR-guided radiotherapy for esophageal cancer patients

“…(For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) radiotherapy for esophageal cancer patients at dedicated X-ray based systems [25,26]. Previous studies on radiation-induced toxicity after chemoradiation for esophageal cancer showed multiple correlations between an increase in lung and heart dose and pulmonary and cardiac complications and mortality.…”

“…Recently, multiple online adaptive treatment platforms have been released by various vendors which allow for online replanning and thereby potentially by-passing all interfractional anatomy geometry variations. These platforms could either be based on X-ray imaging [25,26] or MR imaging [27][28][29] and could have onboard imaging capabilities that allow for online intrafraction monitioring to allow gating [30,31] and tracking [32] to mitigate effects from intrafraction motion.…”

Dosimetric leaf gap and leaf trailing effect in a double‐stacked multileaf collimator

“…The Halcyon is delivered with the Eclipse treatment planning system (TPS) from the same manufacturer (Varian Medical Systems), which includes a fully preconfigured photon beam model based on the reference beam data. Extensive validation tests have been performed and installed systems have been found to accurately match the reference beam data preconfigured in Eclipse, including percentage depth doses, profiles, and output factors 3,5 . It has also been reported that the system complies with commissioning criteria from international guidelines 6–11 and a good agreement between measurements and calculations for clinical plans was found in patient‐specific quality assurance (QA) tests, end‐to‐end verifications and external audits 2,3,12 …”

“…Extensive validation tests have been performed and installed systems have been found to accurately match the reference beam data preconfigured in Eclipse, including percentage depth doses, profiles, and output factors. 3,5 It has also been reported that the system complies with commissioning criteria from international guidelines [6][7][8][9][10][11] and a good agreement between measurements and calculations for clinical plans was found in patient-specific quality assurance (QA) tests, end-to-end verifications and external audits. 2,3,12 RayStation (RaySearch Laboratories, Stockholm, Sweden), a TPS independent of treatment units' manufacturers, is also commercially available for the Halcyon.…”

Varian ethos online adaptive radiotherapy for prostate cancer: Early results of contouring accuracy, treatment plan quality, and treatment time

“…[18][19][20] The dosimetric accuracy of the Ethos treatment planning system has previously been comprehensively verified. 21 The workflow used on Ethos for online adaptive prostate patients involves the use of "influencer" structures that are initially auto-contoured using AI. The influencer structures are then adjusted by the user if necessary and used to create a structure-guided deformable image registration (DIR) between the planning computed tomography (CT) scan and the acquired cone beam computed tomography (CBCT) scan.…”