ESTRO 2023 - Abstract Book

S1818

Digital Posters

ESTRO 2023

Conclusion VMAT-SBRT is able to deliver a conformal plan for treating SBRT in prostate cancer which can be an alternative option to CK-SBRT. However, image-guided radiotherapy with fiducial markers should be careful in delivering SBRT in prostate cancer, especially for VMAT-SBRT.

PO-2046 DIBH (Deep Inspiration Breath-Hold) in left breast radiotherapy -institutional experience

M. Dzhugashvili 1 , M. Montijano 1 , B. Sevilla 2 , C. Peraza 3 , J. Fernandez 4 , D. Gonsalves 2 , M. Guijarro 2 , E. Lopez 2

1 Genesiscare, Radiation oncology, Madrid, Spain; 2 Genesiscare, Radiation Oncology, Madrid, Spain; 3 Genesiscare, Radiotherapy oncology, Madrid, Spain; 4 Genesiscare , Radiation Oncology, Barcelona, Spain Purpose or Objective Radiotherapy is the most effective treatment to eradicate the residual locoregional disease after breast cancer surgery with significative survival improvements after 15 years post diagnostic. For women receiving left-breast radiotherapy (DIBH) is used to further mitigate mortality and morbidity due to late cardiac toxicity, with a demonstrated linear relationship with Mean Heart Dose (MHD). The risk increases 7.4% per Gy, starting within the first 5 years and continuing into the third decade after radiotherapy. The aim of this study was to evaluate the effect of DIBH irradiation on MHD, V16, V8, V4 and mean, maximum and D10% left anterior descending coronary artery (LADCA) dose. Materials and Methods 75 patients with LBC able to maintain voluntary DIBH ≥ 20 seconds, were irradiated with DIBH, all received a total dose of 40.05Gy/2.67Gy per fraction in breast/chest wall and 58 patients a concomitant boost of 48Gy/3.2Gy per fraction. The target volume was delineated on CT in DIBH. Tangent-based intensity modulated radiation therapy (n: 71) or VMAT (n:4) plans were developed for both datasets. Patient set-up and tracking in FB/DIBH was monitored by Surface Guided Radiation Therapy (VisionRT, London, UK), after daily validation by cone beam CT matching. Results DIBH reduces significantly MHD, V16, V8, V4 and mean, maximum and D10% LAD dose compared to FB (p = 0.001). DIBH average MHD was 1.20 Gy (0.87-1.62) and average LADCA Dmean of 4.95 Gy (2.79-9.14) with respectively in FB 3.18 Gy (2.47-4.26) and 20.20Gy (12.29.-25.40). Conclusion DIBH in LBC does lead to a significant reduction in heart and LADCA doses by increasing the distance between target and heart. These reductions could contribute to increase cardiovascular health of LBC.

These findings apply to all patients and further studies will indicate to which subgroups the benefits are more pronounced.

PO-2047 Stereotactic radiotherapy of prostate cancer patients–two techniques comparison: preliminary results