ESTRO 2024 - Abstract Book

S4763

Physics - Quality assurance and auditing

ESTRO 2024

For all cases deemed suitable for DDM according to guidelines, deformation was performed using Velocity (v. 4.1, Varian Medical Systems) and QA according to guidelines was carried out. QA consisted of the steps defined as ”must” and ”should” in the guidelines (Figure 1). Three different deformable registrations were performed for each patient using the Deformable, Deformable Multi Pass, or Extended Deformable Multi Pass algorithm, respectively. A new rigid registration was used for each of these. The treated ReRT plan was re-scaled to the initially intended prescription for summation with the old mapped dose. Both dose matrices were EQD2-converted prior to DDM and summation (α/β = 10 for GTVs and 3 for remaining tissue). The plan sum was shown to the physicians who made the original ReRT decision, and they were asked whether they would choose to treat with the initial prescription or not. For completeness, we also report time taken for DDM QA, which included creating control structures and additional deformable registrations, but not the actual process of creating the main deformable registration and dose mapping.