ABSTRACT
PURPOSE: To compare ultrasonographic (US) with computerized tomographic (CT) images in order to choose electron energy for radiotherapy (RT) boost field in patients with breast conserving surgery (BCS). METHODS: Thirty-seven consecutive patients with breast cancer treated by BCS and RT in our department were evaluated. Median age was 49 years (range 32-82). According to the Dokuz Eylul Breast Tumor Group Protocol (DEBTG), in patients with BCS, RT (5000 cGy to the whole breast ± lymphatic area) and boost with electron energy to the primary tumor bed (1000 cGy if surgical margin negative, or 1600 cGy if surgical margin positive was delivered. Before January 2003, the distances between skin-the deepest point of tumor bed (STD), skin-clips (SCD), and skin-fascia (SFD) were measured with US to choose electron energy in boost field. Since then, CT simulation images were used to this purpose. These two imaging systems were compared in this study. Electron energy was selected after measurement of the deepest metallic clips in CT simulation images (90%) or measurement of the STD if no clips were present (10%). RESULTS: Median measurements with US and CT were as follows: STD: US 12 mm (range 4-35), CT 28 mm (range 2-54); SFD: US 25 mm (range 6-57), CT 31 mm (range 2-93); SCD: US 14 mm (range 7-26), CT 29 mm (range 2-68). The median electron energy was 9 MeV é (range 6-12) for US and 12 MeV é (range 6-21) for CT. Concordance in US and CT measurements was 27%. CONCLUSION: This preliminary study reveals that CT-based SCD measurements are deeper than US measurements, and selected electron energy with CT is 3 MeV higher than US. These two factors can affect local control and side effects. We noticed only one local recurrence in 37 patients. We did not evaluate side effects in this study. These could be a subject of a future study.
