A dosimetric comparison of the Contura multilumen balloon breast brachytherapy catheter vs. the single-lumen MammoSite balloon device in patients treated with accelerated partial breast irradiation at a single institution

PurposeA comparison of dosimetric findings in 33 patients treated with the Contura multilumen balloon (SenoRx Inc., Irvine, CA) (C-MLB) breast brachytherapy catheter vs. 33 patients treated with the MammoSite (Hologic Inc., Bedford, MA) (MS) at a single institution to deliver accelerated partial breast irradiation (APBI) was performed.Methods and MaterialsCT-based 3-dimensional planning with dose optimization was completed. APBI treatment of 34 Gy in 3.4 Gy fractions was delivered. Endpoints analyzed included: (1) The percentage of the prescribed dose (PD) covering the planning target volume (PTV), (2) the maximum skin dose as a percentage of the PD, (3) the maximum rib dose as a percentage of the PD, and (4) the V150 and V200.ResultsThe C-MLB was placed more frequently in patients with closer skin spacing (<7 mm) and rib spacing (<7 mm) than in MS patients (45.5% vs. 12.1%, p = 0.0057 and 57.6 vs. 33.3, p = 0.0131, respectively). Despite closer skin spacing, the overall median skin dose was significantly lower in C-MLB patients (112% of the PD vs. 134%, p = 0.0282). No statistically significant differences in the V150 or V200 were observed. In patients with very limited rib spacing (<4 mm), the C-MLB delivered significantly lower rib doses than the MS (144% of the PD vs. 191%, p = 0.0107). In all clinical scenarios, coverage of the PTV with the C-MLB was either equal to or significantly better than with the MS (p = 0.0024).ConclusionThe C-MLB catheter produced clinically significant improvements in dosimetric endpoints (e.g., reduced skin and rib doses and improved PTV coverage) in most clinical scenarios.