A dosimetric comparison of three-dimensional conformal, intensity-modulated radiation therapy, and MammoSite partial-breast irradiation

Abstract 

Purpose

Limited information is available comparing target volume and normal tissue dosimetry with the different techniques of partial breast irradiation (PBI). We present results of a dosimetric comparison of single catheter, balloon-based brachytherapy using the MammoSite catheter (BRT), 3D conformal radiation therapy (3DCRT), and intensity-modulated radiation therapy (IMRT).

Methods and materials

Fifteen patients were treated using the BRT device. With the use of CT scans with balloons in inflated and deflated states, plans were developed for each patient using each of the methods of PBI, for a total of 45 plans. The plans were then compared using the below dosimetric parameters.

Results

The mean V₁₀₀ was 95%, 92%, and 94% for the BRT, 3DCRT, and IMRT techniques, respectively. The mean ipsilateral breast V₅₀ was 29%, 56%, and 46% (p<0.0001) and the mean ipsilateral lung V₃₀ was 5%, 7%, and 2% (p<0.001 for IMRT vs. others) for the BRT, 3DCRT, and IMRT methods, respectively. For the 10 patients with left-sided breast tumors, the mean heart V₅ was 12%, 4%, and 1% for the BRT, 3DCRT, and IMRT methods, respectively (p<0.01).

Conclusions

With increasing interest in PBI, our data may help clinicians individualize patient treatment decisions.

Keywords: Breast cancer, MammoSite, Partial-breast irradiation, IMRT, 3DCRT