ABSTRACT
Objective To investigate the potential heart sparing effects of tangential volumetric modulated arc therapy (T-VMAT) by comparing its dosimetric properties with conventional wedged tangential fields (W-TF) technique and 6-field intensity-modulated radiotherapy (6F-IMRT) in the locoregional radiotherapy of left breast cancer after conserving surgery,including internal mammary nodal irradiation.Methods Fifteen patients with left breast cancer were enrolled in this study.Three plans were generated for each patient:W-TF,6F-IMRT and T-VMAT with two arc segments of 50°.The prescription dose to planning tumor volume (PTV) was 50 Gy in 25 fractions.Dose-volume parameters and indices of conformity were calculated and compared for the PTV and organs at risk (OAR).Results Compared with W-TF,T-VMAT not only significantly decreased D D and the high dose areas (above 10 Gy) of the heart and left anterior descending branch (LAD) (P ＜ 0.05),but also had the trend of sparing the V5Gy although there was statistically significant difference (P ＞ 0.05).T-VMAT also significantly decreased Dmean V5Gy,V10Gy and V20Gy of the heart,as well as the D V5Gy and V10 Gy of LAD (P ＜ 0.05),compared to 6F-IMRT.Furthermore,T-VMAT did not result in higher V20Gy of ipsilateral lung and higher V5Gy of contralateral breast compared with W-TF (P ＞ 0.05).T-VMAT achieved distinctly better target coverage and conformity,meanwhile obviously lowered hot volume of V110 compared to W-TF (P ＜ 0.05).Conclusions T-VMAT not only significantly decreased the high dose areas,but also had the trend of sparing the low dose area for the heat and LAD.Moreover,there was no significant difference for V20Gy of ipsilateral lung and V5Gy of contralateral breast between T-VMAT and W-TF.
ABSTRACT
In this study, DNAzymes against cyclin D1 (cyclin D1-DRz) were designed according to the secondary structure of cyclin D1 mRNA which was computed with RNAdraw and Mfold. Cyclin D1-DRz were transfected into tumor cell line u251 and HeLa by oligofectamine. The expression of cyclin D1 was detected by RT-PCR. It was shown that the expression of cyclin D1 gene was suppressed obviously, and the expressions of other cell-cycle related genes such as cyclin E1, cyclin A1 and cyclin B1 were also declined. The cell cycle analysis of tumor cells tansfected with cyclin D1-DRz revealed an arrestment in the G0/G1 phase. In conclusion, the approach is effective and feasible for designing DNAzyme. Cyclin D1-DRz is useful for interfering with the cell cycle procession of tumor cells.