Evaluation of the interfractional biological effective dose (BED) variation in MammoSite high dose rate brachytherapy

The objective of this work is to evaluate the interfractional biological effective dose (BED) variation in MammoSite high dose rate (HDR) brachytherapy. Dose distributions of 19 patients who received 34 Gy in 10 fractions were evaluated. A method was employed to account for nonuniform dose distribution in the BED calculation. Furthermore, a range of α/β values was utilized for specific clinical end points: fibrosis, telangiectasia, erythema, desquamation and breast carcinoma. Two scenarios were simulated to calculate the BED value using: i) the same dose distribution of fraction 1 over fractions 2–10 (constant case, CC), and ii) the actual delivered dose distribution for each fraction 1–10 (interfraction dose variation case, IVC). Although the average BED difference (IVC – CC) was