Noninvasive image-guided breast brachytherapy (NIBB) is a novel approach to
deliver accelerated partial breast irradiation (APBI). NIBB is noninvasive, yet maintains a high degree
of precision by using breast immobilization and image guidance. This makes NIBB an attractive
alternative to existing APBI techniques.
Forty patients were enrolled in an institutional review board approved
prospective clinical trial evaluating APBI using NIBB. The NIBB technique is described
in detail. Briefly, patients were treated with the breast compressed and immobilized sequentially in
two orthogonal axes for each fraction. Radiation was delivered using collimated emissions from a
high-dose-rate iridium-192 source via specialized applicators. The prescribed dose was 34.0 Gy in
10 fractions. Feasibility and tolerability of treatment were assessed.
All patients completed protocol treatment. The median age was 68 years. Sixty-three
percent of patients had invasive carcinoma, and 37% had ductal carcinoma in situ. All were node
negative. Ninety-three percent of patients were postmenopausal. Mean tumor size, tumor bed volume,
and breast volume were 1.1 cm, 22.4 cc, and 1591 cc, respectively. NIBB treatment was well
tolerated. Median patient-reported discomfort was 1 on a 10-point pain scale. Treatment delivery
times were reasonable. The average treatment time per axis was 14 min (5e20 min), and the
average time from start of first treatment axis to completion of orthogonal axis was 43 min
(30e63 min). Acute skin toxicity was Grade 0, 1, and 2 in 20%, 53%, and 28% of patients, respectively.
There were no Grade 3 or greater acute toxicities observed.
NIBB holds promise as an alternative method to deliver APBI. NIBB is feasible
and well tolerated by patients. Further investigation of NIBB to deliver APBI is warranted. 2014
American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
Keywords: Noninvasive image-guided breast brachytherapy; NIBB; AccuBoost; Partial breast irradiation; APBI; Breast