Evaluation of Breast Prone Position Irradiation Dose

Abstract

The prone position can be used for the planning of adjuvant radiotherapy after conservative breast surgery in order to deliver less irradiation to lung and cardiac tissue. In the present study, we compared the results of three-dimensional conformal radiotherapy planning for 15patients irradiated in the supine and prone position used compared. Tumor stage was T2N0M0 in group of patients and T2N1M0 in other .All patients had been previously submitted to conservative breast surgery. Breast size was large in 15patients and moderate in 10and small in 5. Planning in the prone position was performed using an immobilization foam pad with a hole cut into it to accommodate the breast so that it would hang down away from the chest wall. Dose-volume histograms showed that mean irradiation doses reaching the ipsilateral lung were (8.3 ± 3.6) Gy with the patient in the supine position and (1.4 ± 1.0) Gy with the patient in the prone position .The values for the contra lateral lung were (1.3 ± 0.7) Gy in supine and (0.3 ± 0.1) Gy in prone and the values for cardiac tissue were (4.6 ± 1.6)in supine and (3.0 ± 1.7)Gy in prone, respectively. Thus, the dose-volume histograms demonstrated that lung tissue irradiation was lower with the patient in the prone position than in the supine position. Large-breasted women appeared to benefit most from irradiation in the prone position. Prone position breast irradiation appears to be a simple and effective alternative to the conventional supine position for patients with large breasts, since they are subjected to lower pulmonary doses which may cause less pulmonary side effects in the future.