Sonographic guidance for electron boost planning after breast-conserving surgery

Purpose This study was conducted to determine the feasibility of using sonography for electron boost planning in breast cancer treatment and to define the factors that influence the accuracy and reproducibility of this technique. Patients and Methods Seventy‐seven patients underwent 102 sonographic examinations after breast‐conserving surgery and before and after radiotherapy. The size of the electron boost field was defined by measuring the postoperative cavity. Reproducibility of the sonographic findings was investigated in 25 of the patients who were examined before and after radiotherapy (at a total dose of 46–50.4 Gy). Depth (distance from the skin surface to the posterior aspect of the postoperative cavity) was measured, and sonographic appearance of the postoperative cavity was evaluated. Type of surgical procedure, time elapsed since surgery, use of systemic therapy, menopausal status, breast size, and radiation dose were investigated for their influence on sonographic appearance and visualization of the postoperative cavity. Results The postoperative cavity was well visualized in 78% of patients and visualized with some difficulty in 22%. In all but 5 patients, it was hypoechoic and inhomogeneous. The mean depth of the postoperative cavity after radiotherapy was 27 ± 4 mm. Smaller breast (p < 0.001) and younger age (p < 0.05) were associated with decreased visibility of the postoperative cavity. Sonographic appearance was the same before and after radiotherapy, but the mean difference in postoperative cavity depth between the 2 measurements was 2 mm (range, 0–4 mm). In 43/77 (56%) of the patients, changes in electron energy or in field size were required after sonographic measurement. Conclusion Sonography is a useful and reproducible means of electron boost planning, helping to avoid underdosage of the postoperative cavity and overdosage of normal tissue. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:333–337, 2004