ESTRO 2025 - Abstract Book

S2823

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2025

2591

Digital Poster Free-Breathing VMAT versus Deep Inspiration Breath-Hold 3D-CRT Techniques for Left-Breast Cancer: A Feasible Approach in Developing Countries Md. Jobairul Islam, Sadia Afrin Sarah, Md. Abdul Mannan, Ahammad Al Mamun Sweet, AFM Kamal Uddin, Ehteshamul Hoque, Mostafa Aziz Sumon, Md. Yousuf Ali, Qazi Mushtaq Hussain, Parvin Akhter Banu Department of Radiation Oncology, Labaid Cancer and Super Speciality Centre, Dhaka, Bangladesh Purpose/Objective: Radiotherapy for left-sided breast cancer can induce cardiac injury. Deep Inspiration Breath Hold (DIBH) is a technique that minimizes cardiac exposure during treatment. This study compares dosimetric outcomes between DIBH using 3DCRT and Free-Breathing (FB) using VMAT for left-sided breast cancer. Material/Methods: A retrospective study was conducted with 25 patients who underwent breast-conserving surgery or mastectomy. Each patient received CT simulation scans in both FB and DIBH positions using the Varian RGSC system. Treatment plans were generated using Eclipse TPS with the AAA algorithm. Patients were planned either with 3DCRT using DIBH or Free-Breath with VMAT. All patients received 40 Gy in 15 fractions. DVH analysis evaluated clinical target volume (CTV) and organs at risk (OARs). Results: Both techniques achieved adequate target coverage per RTOG-1005. PTV V 95% was 96.58±0.95% for DIBH-3DCRT and 99.23±0.45% for FB-VMAT, with VMAT-FB providing more uniform coverage. The average heart dose was significantly lower with DIBH (2.67 Gy) compared to FB plans (3.90 Gy, p = 0.000). Lung V 20Gy was higher in 3DCRT-DIBH (18.03% vs. 12.51% in FB-VMAT), but DIBH reduced V 8Gy (34.8% to 25.42%) and V 4Gy (71.61% to 38.6%). DIBH-3DCRT also delivered lower doses to the contralateral lung and breast compared to VMAT-FB. Conclusion: DIBH-3DCRT is a feasible alternative to FB-VMAT for left-sided breast cancer, particularly in developing countries, offering effective target coverage while minimizing radiation exposure to critical organs. FB-VMAT is suitable for elderly patients or those unable to perform DIBH. Careful patient selection is crucial to optimize outcomes. References: Sung H., Ferlay J., Siegel R.L., Laversanne M., Soerjomataram I., Jemal A., Bray F. Global cancer statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. Cancer J. Clin. 2021;71:209–249. Begum SA, Mahmud T, Rahman T, Zannat J, Khatun F, Nahar K, Towhida M, Joarder M, Harun A, Sharmin F. Knowledge, Attitude and Practice of Bangladeshi Women towards Breast Cancer: A Cross-Sectional Study. Mymensingh Med J. 2019 Jan;28(1):96-104. Darby, S.; Ewertz, M.; McGale, P.; Bennet, A.; Blom-Goldman, U.; Brønnum, D.; Correa, C.; Cutter, D.; Gagliardi, G.; Gigante, B.; et al. Risk of Ischemic Heart Disease in Women after Radiotherapy for Breast Cancer. New Engl. J. Med. 2013, 368, 987–998. Keywords: DIBH, VMAT, Treatment Planning