Assessment of radiation doses for cardiac and left anterior descending coronary artery in patients undergoing Left breast radiation therapy in Palestine

Bayan Saleh Ali Suleiman
بيان صالح علي سليمان
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Al-Quds University
Purpose: To evaluate radiation doses in cardiac radiotherapy planning in left breast cancer patients using 3D conformal radiotherapy planning technique based on computed tomography (CT) dose planning. Methods: Data was retrospectively collected from archived Computed Tomography (CT) images, whole heart and left anterior descending coronary artery (LAD) radiation doses at Augusta Victoria Hospital (AVH) between 2017-2019. Data composed of 176 breast cancer radiotherapy cases; 70 chest wall irradiated mastectomies patients, and 106 breast irradiated lumpectomies patients. Individual dose volume histograms for the whole heart and for LAD were obtained, in addition to the calculated mean, median and maximum volume percentage (V10%, V25%, V30%) of these structures for the study sample which represents the percentage of heart volume receiving (x) Gy or higher, then compared to the Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) guidelines and previous studies for dose assessment of heart and LAD. Represents the percentage of an organ’s volume receiving (x) Gy or higher Results: Results showed the whole mean heart dose (MHD) and the mean dose of LAD were 2.2 Gy and 13.94 Gy, respectively. In which, 4.5% of patients received MHD ≥ 4Gy, all subjects received V25% less than 10cm expect one V25% ≥ 10. 11 % of patients received LAD maximum dose ≥ 45 Gy. In spite of the dose variations found in both MHD and LAD in this study, and the dose differences noticed when compared to studies that used other radiotherapeutic techniques such as Deep Inspiration Breath Hold technique (DIPTH), MHD and LAD dose assessments were equivalent to those of the compared previous studies and Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) guidelines. Conclusions: Dose assessments of adjuvant CT-based radiotherapy of subjects with left breast cancer demonstrated similar MHD but higher LAD doses when compared to previous studies and QUANTEC guidelines used to predict cardiac toxicities in most patients in the study sample. Since there is no worldwide standardized protocol or heart dose constrains in left breast radiotherapy, this study suggests maintaining the lowest received dose and volume of the heart or organ at risk included in the treatment plan, as well as using advanced DIPH to reduce the latent effects on radiotherapy patients, especially the heart complications that could occur.