Evaluation of prone position tangential breast irradiation technique

The purpose of this study was to evaluate an alternative prone position tangential breast irradiation technique for women with early stage breast cancer. Nine patients who underwent CT simulation in both the supine and prone positions were included in the study. An originally designed prone breast positioning device was used for the prone setup to displace the contralateral breast away from the tangential field border. Plans were compared using dose distribution and dose volume histograms (DVH) for the target volume, ipsilateral lung, and heart. Setup reproducibility was also analyzed comparing portal images with simulator images. Significant improvements in the doses to surrounding normal structures were achieved in the prone position compared to the supine position. Dose homogeneity within the target volume was also improved using the prone position especially in the patient with huge breasts. Setup reproducibility of the prone position was as good as the supine position in patients with normal or average sized breasts. A prone position tangential breast irradiation technique may result in improved dose homogeneity within the target volume as well as sparing of surrounding normal structures compared with conventional supine position tangential breast irradiation technique. (author)