Left-Sided Whole Breast Irradiation with Hybrid-IMRT and Helical Tomotherapy Dosimetric Comparison

Abstract

Purpose. Limited-tomotherapy and hybrid-IMRT treatment techniques were compared for reductions in ipsilateral and contralateral lung, heart, and contralateral breast radiation doses. Methods and Materials. Thirty consecutively treated left-sided early-stage breast cancer patients were scheduled for lTomo and hIMRT. For the hIMRT plan conventional tangential-field and four-field IMRT plans were combined with different weightings in the prescribed dose. For the lTomo plan a geometrically limited arc was designed for the beamlet entrance. A D p of 50.4 Gy in 28 fractions was used for the PTV. The dose coverage, homogeneity index, conformity index of the target, and the dose volumes of critical structures were compared. Results. Both modalities presented similar target coverage. The homogeneity and conformity were improved for lTomo with P < 0.001 and P = 0.006, respectively. In the lTomo plan a concave dose distribution was generated with significant dose reductions in both high and low dose regions for ipsilateral lung and heart (P < 0.001). Conclusions. lTomo plan can have similar dose coverage and better homogeneity and conformity to the target. By properly designing the directionally and completely blocked structure, lTomo plan was developed successfully in reducing doses to the healthy tissues for early-stage left-sided breast cancer radiotherapy.

A treatment planning comparison of contemporary photon-based radiation techniques for breast cancer

“…Overall, TD was significantly superior to all other techniques in terms of IL sparing. Compared to previous studies, IL mean values obtained from our study in G1 were 14.9 ± 5. similar for FiF [10,15,16,32], s-IMRT 2f [14][15][16]31], s-IMRT 4f [14,31,32], VMAT [10,[14][15][16] and HT [10,18,32] while for TD it was lower than those previously published [23,32]. Rotational techniques significantly increased the low dose spillage to the contra-lateral lung as highlighted in particular by the V5Gy values that still remained well below the dose constraints as well as the endpoint for radio-induced pneumonitis.…”

Dosimetric comparison of left-sided whole-breast irradiation with 3DCRT, forward-planned IMRT, inverse-planned IMRT, helical tomotherapy, and volumetric arc therapy

“…Completely blocking the majority of the contralateral side of the body drastically reduces the beam angles used for treatment and therefore, reduces the potential conformity and ipsilateral normal tissue sparing. Previous studies used these options to design their plans [16,27], but in this study we designed a geometrical virtual structure as discussed elsewhere [28]. By contouring the specific virtual structures and setting a "directional block" or "complete block," dose distributions can be limited to a local region and dose reductions to the ipsilateral organs were achieved.…”

Image-guided intensity-modulated radiotherapy for refractory bilateral breast cancer in a patient with extensive cutaneous metastasis in the chest and abdominal walls

“…Additionally, the mean doses for critical organs at risk are decreased successfully. 14 , 15 , 27 The conformity index of HT in our patient was 0.81 and the uniformity index was 1.08 ( Figure 3 ).…”