CT-targeted irradiation of the breast and internal mammary lymph nodes using a 5-field technique

Purpose: To develop an effective and resource-efficient radiotherapy techni que to treat the breast and regional nodes, including the ipsilateral inter nal mammary nodes. Methods and Materials: Eighty female patients who underwent MRI scans for a variety of indications had coronal, T1-weight images of the chest performe d to determine the position of the internal mammary chain (IMC). Based on t hese results, a 5-field treatment technique was developed that would includ e the breast, supraclavicular fossa, and ipsilateral IMC, while maintaining a low dose to the heart, lungs, and contralateral breast, This technique w as implemented in a cohort of 13 patients. Results: The lateral position of the right and left IMC mere measured in th ree cephalo-caudad positions: at the clavicular heads, upper manubrium, and midsternum (at the 2nd/3rd rib interspace). The mean lateral separation be tween the right and left IMC chains at each level (and 95% confidence inter val) at each level were 5.8 cm (3.67-7.00), 5.6 cm (4.49-6.73), and 5.9 cm (4.66-7.19), respectively, Treatment was delivered to 13 patients using a 5 -field technique, with tangential photon fields for the breast, anterior an d posterior supraclavicular/axillary field, and a matching anterior electro n field. Three-dimensional treatment planning of a representative case conf irmed adequate coverage of the planning target volume (PTV), The median dos e to the whole heart was 10 Gy, and 20% of the ipsilateral lung received mo re than 20 Gy. Seven of the 13 patients treated experienced moist desquamat ion at the junction of the electron field and breast tangents, and 1 patien t had persistent ulceration at 3 months' follow-up, Conclusion: The 5-field technique described in this paper provides good cov erage to the breast and regional nodes with acceptable toxicity, and withou t requiring three-dimensional treatment planning or intensity-modulated rad iotherapy techniques. (C) 2000 Elsevier Science Inc.