Comparison of dose distributions and organs at risk doses in whole breast irradiation with 3DCRT, for-İMRT, inv-İMRT, volumetric arc therapy and helical tomotherapy

Purpose: This study compared conventional technique (three-dimensional conformal radiotherapy; 3DCRT) with forward intensity-modulated radiotherapy (for-IMRT) and invers intensity-modulated radiotherapy (inv-IMRT, Helical Tomotherapy; HT and Volumetric Arc Therapy; VMAT) intensity-modulated radiotherapy techniques for breast cancer in order to determine whether the use of intensity-modulated radiotherapy techniques would lead to improved dosimetry for the whole breast irradiation. Materials and methods: Twenty-five patients previously treated with breast cancer were selected. The clinical target volüme (CTV) included whole breast. To evaluate CTV doses, rCTV volume defined consisted of the CTV retracted 5 mm from the skin surface. The critical structures included heart, right and left lungs, LAD and contralateral breast. Conventional and a series of invers IMRT plans were generated for comparison each other. A fractionation schedule of 50 Gy in 2 Gy/fraction. All beam energies were 6 MV in order to provide a more direct comparison with the HT plan. Comparative endpoints were planning target volume (rCTV) dose homogeneity and doses to crictical structures. Results: All modalities evaluated provide adequate coverage of the intact breast. All inv-IMRT techniques improves CN compared with forward planned technique. İnv-IMRT techniques can reduce high doses to the target and normal tissues but at the same time increased contralateral critical structures doses.