STATE OF THE ART IN BREAST INTRAOPERATIVE ELECTRON RADIATION THERAPY AFTER INTRAOPERATIVE ULTRASOUND INTRODUCTION
STATE OF THE ART IN BREAST IOERT AFTER IOUS INTRODUCTION
Breast intraoperative electron radiation therapy (B-IOERT) requires the protection of the tissues underneath the target volume, positioning a shielding disk between the residual breast and the pectoralis fascia. The aim of this study is to evaluate the role of intraoperative ultrasound (IOUS) in improving the quality of B-IOERT.
B-IOERT was introduced in Trieste in 2012 and its technique was improved in 2014 with IOUS, Both needle and IOUS were used to measure target thickness; the latter was used even to check the correct position of the shielding disk. The effectiveness of IOUS was verified with “in vivo dosimetry”. We compare patients who underwent IOUS exam with those treated without it.
The cases treated with B-IOERT as a boost were analyzed in this study: in 38 of them both needle and IOUS were used (Group 1) and in 72 only the needle (Group 2).
The target thickness measured with the IOUS probe and with the needle were similar (mean difference of 0.1 mm (p=0.38). The percentage of patients in which the shield was perfectly aligned after IOUS introduction increased from 23% to more than 70%. moreover, patients treated after IOUS guidance had less acute toxicity (36.8% vs. 48.6%, p=0.33) from radiation therapy. Late toxicity turned out to be similar regardless of the use of IOUS guidance: 39.5% vs. 37.5% (p=0.99 ).
IOUS showed to be accurate in measuring the target depth. Furthermore, it decreased the misalignment between collimator and disk and appeared to reduce the adverse effects.