Comparison of different treatment plannings for whole breast irradiation with tumor bed boost after breast-conservative surgery

Abstract

Objective To explore the difference of conformity and homogeneity of dose distribution in the whole breast and tumor bed targets and dose-volume parameters of the irradiated heart,lung and contralateral breast between the different treatment plannings for whole breast irradiation with tumor bed boost after breast-conservative surgery.Methods Twelve left-side breast cancer patients received breast-conservative surgery with negative axillary lymph node and with silver slips set in the cavity were selected.The different plannings including conventional radiotherapy(CRT),forward intensity-modulated radiotherapy with no lung block segments(IMRT-F),forward intensity-modulated radiotherapy with lung block segments(IMRT-F-L)and simultaneous integrated boost intensity-modulated radiotherapy(SIB-IMRT)were completed for each patient.The difference of conformity and homogeneity of dose distribution in the whole breast and tumor bed targets,the related irradiated dose-volume parametem of the ipsilateral lung,heart and Contralateral breast were compared among the different plannings.Results There were statistical differences of the ratios of breast volume contained by the prescribed dose given to PTV1(Vdose-PTV1)to VPTV1,volume of PTV1 contained by the prescribed dose given to PTV1(VPTV1-dose)to VPTV2,conformal index of PTV1(CIPTV1)and conformal index of PTV2(CIPTV2)among the different plannings.The volume of the lung which received more than 20 Gy(V20)in CRT planning was statistically higher those that in three IMRT plannings,but there was no significant difference among three types of IMRT.The dose irradiated to the heart in the CRT planning was significantly higher than that in IMRT-F,IMRT-F-L and SIB-IMRT planning.Dmax and Dmean in the contralateral breast for CRT plan were significantly higher than those in three types of IMRT plannings,but with no significant difference of Dmax and Dmean among three types of IMRT plannings.Conclusions Comparing the different types of treatment plannings for whole breast irradiation with tumor bed boost for the patients with left breast cancer after breast-conservative surgery,IMRT-F,IMRT-F-L and SIB-IMRT plannings are all statistically superior to CRT planning.but there are no statistical differences among three types of IMRT plannings except some other parameters. Key words: Breast-conservative surgery; Conventional radiotherapy; Intensity-modulated radiotherapy; Tumor bed boost; Treatment planning