Life
Dosimetric Validation of Ethos Online Adaptive Radiotherapy for Prostate Cancer: An End-to-End Phantom Study
By Janiszewska M and Raczkowski M.
Abstract
Background/objectives
Online adaptive radiotherapy (oART) re-optimizes treatment on the anatomy of the day, but automatically generated plans require dosimetric verification and dose-volume assessment. We performed an end-to-end validation of the Varian Ethos workflow for prostate cancer, including cross-adaptation between two phantom anatomies.
Methods
A 3 Gy × 20-fraction reference plan was generated for a RUBY phantom. Scheduled, adapted, and cross-adapted plans were evaluated in two prostate, bladder, and rectum configurations. Absolute dose was measured with a Semiflex 3D ionization chamber at the clinical target volume (CTV), rectum, and bladder and compared with Ethos and independent Mobius calculations. Plan quality was assessed from cumulative dose-volume histograms using ICRU 83-oriented descriptors.