ESTRO 2023 - Abstract Book

S1417

Digital Posters

ESTRO 2023

Conclusion The effect of the GG voltage change on all presented beam characteristics showed a strong linear response. The observed changes are in agreement with the expected effect of the GG voltage. As a result, no iterative procedure is required and this is a valid method to adjust the beam energy for an Elekta Unity.

PO-1704 Commissioning and implementation of the commercial daily QA tool in proton pencil beam scanning

S. Ruangchan 1 , P. Khongcharoen 1 , B. Nayong 1 , M. Chitnok 1 , I. Israngkul Na Ayuthaya 1 , T. Sanghangthum 2

1 King Chulalongkorn Memorial Hospital, Her Royal Highness Princess Maha Chakri Sirindhorn Proton Center, Bangkok, Thailand; 2 Chulalongkorn University, Her Royal Highness Princess Maha Chakri Sirindhorn Proton Center, Bangkok, Thailand Purpose or Objective The goal of this work was to commission the daily QA device for proton pencil beam scanning and to evaluate the clinical usability of the daily QA procedure. Materials and Methods The QA device, named Sphinx Compact, is composed of the flat-panel imager and removable plastic modules for beam characteristic check of proton energy 100 MeV, 150 MeV and 200 MeV, and the machine output using the PPC05 IBA chamber. The spot patterns for the measurement and evaluation are shown in Figure 1. The QA device was commissioned and evaluated compared with the regular proton QA tools. The measurement parameters were varied from 0.25 pF, 0.5 pF, 1 pF, 4pF and 8F to evaluate the detector response. The proton ranges were compared with the measurement results from beam data commissioning using a large plane parallel plate measured in the water phantom. The spot and the field homogeneity were compared with EBT3 film measurements (Figure 2), as well as the Lynx IBA detector. The beam coincidence was compared to the results of the Logos system. Results were collected and monitored for three months. Tolerances and limitations were set for monitoring based on the recommendation of TG 224 reports.