The dosimetric study of radiotherapy after modified radical mastectomy for left breast cancer using the beam’s eye view in intensity-modulated radiation therapy / 中国辐射卫生

ABSTRACT

Objective To analyze the dosimetric features of chest wall radiotherapy after modified radical mastectomy for left breast cancer using the beam’s eye view (BEV) in intensity-modulated radiation therapy (B-IMRT). Methods A total of 13 patients treated with modified radical mastectomy for left breast cancer in the Liaocheng People’s Hospital from May 2020 to November 2020 were recruited. They were treated with postoperative radiotherapy using the plans of B-IMRT or tangential fields in intensity-modulated radiation therapy (T-IMRT). The mean dose, conformity index and homogeneity index of the target field, and dose volume parameters of left lung and heart were compared between two groups. Results Compared with those of T-IMRT group, B-IMRT significantly improved the conformity and homogeneity of the target field (P < 0.05), and their mean dose of target field was similar. In addition, V5, V10, V20, V30 and Dmean of the left-side lung, and V5, V10, V30 and Dmean of the heart in B-IMRT group were significantly reduced compared with those of T-IMRT group (P < 0.05). In comparison to those of T-IMRT, B-IMRT decreases V5, V10, V20, V30 and Dmean of the left-side lung by 9.23%, 13.29%, 9.54%, 8.28% and 10.35%, respectively, which decreases V5, V10, V30 and Dmean of the heart by 27.62%, 29.72%, 21.45% and 24.88%, respectively. Conclusion Compared with T-IMRT planning, B-IMRT presents dosimetric advantages in the conformity and homogeneity of the target field in the postoperative radiotherapy of patients treated with modified radical mastectomy for left breast cancer, especially in reducing the radiation dose and volume of the heart and lungs.