RESUMO
This study aims to estimate the absorbed radiation doses to the heart during breast cancer treatment with conventional radiotherapy. The cardiac doses of eighty-three patients during breast cancer radiotherapy were estimated, with fifty-two patients having left breast cancer and thirty-one having right breast cancer. For left breast cancer patients, a Treatment Planning System (TPS) was used to estimate the percentage volume of the heart receiving 20 Gy (V20%), 25 Gy (V25%), 30 Gy V30%), and 40 Gy (V40%). The Maximum Heart Distances (MHD) within the radiation field for left breast cancer patient sand the Minimum Distance of Heart from the Posterior Border of the Radiation Field (MDHF) for right breast cancer patients were measured. Through TPS, the mean dose to the 5% and 10% heart volumes, the lowest dose (Dmin), the maximum dose (Dmax), and the average dose (Davg) of the heart for all patients with left and right breast cancer were also calculated. For patients with left breast cancer, higher mean values of V20 (%), V25 (%), V30 (%), and V40 (%) were estimated and a direct correlation between MHD and Davg was observed. The relationship between MDHF and Davg in patients with right breast cancer was observed to be linear but with a negative slope. Patients undergoing radiotherapy for left breast cancer receive higher doses and are therefore recommended for assessment of cardiac complications during follow-ups.