Dosimetric characteristics of accelerated partial breast irradiation by interstitial multicatheter brachytherapy with intraoperative free‐hand implantation in the treatment of early breast cancer

Abstract

Introduction: The aim of this study is to evaluate the characteristics of the dosimetry and the skin dose of interstitial brachytherapy by the use of the free-hand implantation technique toward the treatment of early breast cancer. Materials & Methods: Seventeen patients diagnosed with early breast cancer were selected for the study. The implantation of the catheters for postoperative interstitial brachytherapy was performed using the free-hand technique. The total tumor dose to the tumor cavity plus 2 cm margin was 3400 cGy, twice daily for 10 fractions in 5 days. The dosage to the target and the organ at risk (OAR) were recorded for analysis. The skin dose of the patient and the phantom were measured with Gafchromic film (EBT3) and the results were compared with the skin dose calculated by the brachytherapy treatment planning system. Results: The median conformal index is 94% (range 89%-99%), and the median homogeneity index is 71%. The median skin dose measured from the skin of the patients was 20.1% lower than the skin dose calculated from the treatment planning system and consistent with the phantom surface measurement experiment. There were no grade 3 or above acute toxicity recorded. Conclusions: Interstitial brachytherapy by the use of the free-hand implantation technique for early breast cancer is feasible and avoids the need for a second surgical intervention. The calculated skin dose was overestimated by at least 20%. The results of this study may help in building a modification model for the prediction of skin toxicity in any future study. K E Y W O R D S breast cancer, interstitial brachytherapy, accelerated partial breast irradiation 1 | INTRODUCTION In the era of modern medical practice, the key role of cancer therapy is to give a high cancer control probability, while minimizing the side effects on healthy organs. Conventional whole breast irradiation (WBI) has been a standard adjuvant approach for several decades with regard to early breast cancer after breast conserving surgery (BCS). 1-3 Conventional WBI offers high local control, minimal side

Preliminary outcomes of accelerated partial breast irradiation by interstitial multicatheter brachytherapy with intraoperative free-hand catheter implantation in early breast cancer

“…Only one patient with a history of psoriasis vulgaris suffered from dermatitis in our study. In our previous study, 22 the skin dose could be overestimated by around 20% using the treatment planning system calculation, which suggests a low possibility of skin overdose. For patients with autoimmune disease, the skin dose should be evaluated carefully due to a high risk of developing dermatitis.…”