ESTRO 2022 - Abstract Book

S1330

Abstract book

ESTRO 2022

Conclusion The modular QA Ruby phantom has been successfully used to check different steps of the radiotherapy process. Results for end to end of several Vmat treatments show a good performance of the whole radiotherapy procedure, with differences < 2.5 % for dose measurements and gamma passing rates > 97 % (2%, 2 mm).

PO-1548 Investigating the relevance of the MatriXX Resolution array in dosimetric verification of SBRT plans

M. Raczkowski 1 , T. Siudzi ń ski 1 , M. Janiszewska 1

1 Lower Silesian Oncology Centre in Wroclaw, Medical Physics Department, Wroclaw, Poland

Purpose or Objective The purpose of this study is to present the feasibility of using IBA's MatriXX Resolution array, for dosimetric verification of SBRT plans. Is the use of a limited resolution matrix based on ionization chambers in small field dosimetry a good idea? The portal dosimetry (PD) method based on a-Si detectors provides adequate resolution, but is it a sensitive enough method for SBRT plans. In the presented paper, both methods were compared in an attempt to prove the thesis contained in the title - the usefulness of the investigated method for the verification of SBRT plans. Materials and Methods Dosimetric verification of SBRT plans was performed for selected sites: bone metastases, spine, lung and lymph nodes. All plans were performed using the Eclipse TPS ver. 15.6 for the VMAT technique using an HD MLC collimator. Depending on the location, the dimensions of the applied fields varied from 3x3 to 7x7 cm 2 (maximum dimensions of dynamically modulated fields). The range of measured doses was 6-18 Gy per fraction. Measurements were performed on the TrueBeam accelerator ver. 2.5. Verification for PD plans was performed in Portal Dosimetry application ver. 15.6, for the tested