Dose-volume Analysis of Heart and Lung during 3D planning of Tangential Breast Cancer Irradiation

Background: Breast cancer is becoming more frequently diagnosed at early stages with improved long term outcomes. Radiation-related heart disease and lung cancer can occur following radiotherapy for breast cancer. The aim of this study was to evaluate some dosimetric parameters of heart and lung during whole breast radiotherapy. Methods:Twenty five consecutive patients with breast cancer who underwent radiotherapy were included in this study. Plans that employed the 3D conventional radiotherapy technique (Tangential Technique) were generated for each patient. Dose-volume histograms (DVHs) were calculated and dosimetric parameters such as, mean dose/volume receiving a dose 30 Gy (V30), mean dose/ volume receiving a dose 20 Gy (V20) for heart and lung were assessed, respectively. Results:The average of mean dose of heart on left and right side irradiation was 9.68±5.10 Gy and 1.23±1.51 Gy, respectively. The average of mean dose of ipsilateral lung on left and right side irradiation was 14.49±4.07 Gy and 11.69±3.37 Gy, respectively. The percentage of heart volume that received at least 30 Gy was 16.32±9.56% for the left-sided treatment. The percentage of lung volume that received at least 20 Gy was 23.47±11.05% and 24.12±7.77% respectively on the left and right-sided breast irradiation. Conclusion: Tangential beam conventional radiotherapy of the chest wall of postmastectomy breast cancer patients provides the potential to significantly keep the DVH parameters of heart and lung as low as the QUANTEC constrains.