ESTRO 2022 - Abstract Book

S832

Abstract book

ESTRO 2022

Figure 2 The results of dosimetry audits for Tomotherapy machines

Conclusion In this study, independent dosimetry audits were performed on the output dose and symmetry for 27 Tomotherapy machines. As a result of performing corrective actions and repeated processes, it was confirmed that all institutions met the tolerance level. These results indicate the quality control status of Tomotherapy machines used for radiation therapy in Korea. According to the proposed the independent external quality audit procedures, we can help establish a national- level quality management system and the SSDL (Secondary Standard Dosimetry Laboratory) based independent quality audits allow Tomotherapy high-energy beam to be safely used in radiation therapy.

OC-0941 Impact of guidelines on nationwide breast cancer treatment planning practices (DBCG RT Nation study)

L. Refsgaard 1 , E.R. Skarsø 2,3 , T. Ravkilde 2 , H.D. Nissen 4 , M. Berg 4 , M. Olsen 5 , K.L. Jakobsen 6 , K. Boye 7 , C. Kamby 7 , K. Lind Laursen 8 , I. Jensen 8 , S.N. Bekke 9 , L.W. Matthiessen 9 , E. Laugaard Lorenzen 10 , L.B.J. Thorsen 1,11 , B.V. Offersen 1,3,2 , S.S. Korreman 12,2 1 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark; 2 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark; 3 Aarhus University Hospital, Danish Center for Particle Therapy, Aarhus, Denmark; 4 Vejle Hospital, University Hospital of Southern Denmark, Department of Oncology, Vejle, Denmark; 5 Zealand University Hospital, Department of Clinical Oncology and Palliative Care, Næstved, Denmark; 6 Zealand University Hospital, Department of Clinical Oncology and Palliative Care, Næstved, Denmark; 7 Copenhagen University Hospital - Rigshospitalet, Department of Oncology, Copenhagen, Denmark; 8 Aalborg University Hospital, Department of Oncology, Aalborg, Denmark; 9 Herlev and Gentofte Hospital, Department of Oncology, Herlev, Denmark; 10 Odense University Hospital, Laboratory of Radiation Physics, Odense, Denmark; 11 Department of Oncology, Aarhus University Hospital, Aarhus, Denmark; 12 Aarhus University Hospital, Danish Center for Particle Therapy, , Aarhus, Denmark Purpose or Objective The aim of this study is to show the effect of implementation of Danish Breast Cancer Group (DBCG) and ESTRO guidelines on dosimetric parameters for heart and internal mammary nodes (IMN) over time for patients treated with radiotherapy (RT) for loco-regional (LR) breast cancer (BC). This demonstrates the value of the DBCG RT Nation study cohort, of detailed treatment plans for all retrievable LR BC RT treatments in Denmark 2008-2016. Materials and Methods We conducted a national data collection based on patients identified from the DBCG database with an indication for LR RT. Images, structures and treatment plans from 9861 patients treated at seven centres are being collected (ongoing). We implemented automatic solutions to extract and quality assure DICOM files nationwide and evaluated doses, volumes and laterality using in-house developed software. The effect of three events (E) on the volume and dose of the heart and IMN was investigated. E1: Between 2010 and 2012, national workshops were organized to discuss and strengthen the DBCG delineation consensus. E2: In June 2014, the DBCG RT guidelines were modified to include the IMN in the RT target for all LR RT irrespective of laterality of the BC. E3: In 2015, the DBCG RT guideline was modified to follow the ESTRO consensus guideline for target volume delineation in BC. Results The centres could be divided into two groups. Group 1 did not treat IMN for left-sided patients (LSP) before E2, while group 2 treated IMN for all LSP in the whole period, utilising respiratory gating. Group 1 delineated the heart for all patients, and