CT-targeted irradiation of the breast and internal mammary lymph nodes using a 5-field technique.
OBJECTIVE
To develop an effective and resource-efficient radiotherapy technique to treat the breast and regional nodes, including the ipsilateral internal mammary nodes.


METHODS
Eighty female patients who underwent MRI scans for a variety of indications had coronal, T1-weighted images of the chest performed to determine the position of the internal mammary chain (IMC). Based on these results, a 5-field treatment technique was developed that would include the breast, supraclavicular fossa, and ipsilateral IMC, while maintaining a low dose to the heart, lungs, and contralateral breast. This technique was implemented in a cohort of 13 patients.


RESULTS
The lateral position of the right and left IMC were measured in three cephalo-caudad positions: at the clavicular heads, upper manubrium, and midsternum (at the 2nd/3rd rib interspace). The mean lateral separation between the right and left IMC chains at each level (and 95% confidence interval) at each level were 5.8 cm (4.67-7.00), 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 and posterior supraclavicular/axillary field, and a matching anterior electron field. Three-dimensional treatment planning of a representative case confirmed adequate coverage of the planning target volume (PTV). The median dose to the whole heart was 10 Gy, and 20% of the ipsilateral lung received more than 20 Gy. Seven of the 13 patients treated experienced moist desquamation at the junction of the electron field and breast tangents, and 1 patient had persistent ulceration at 3 months' follow-up.


CONCLUSIONS
The 5-field technique described in this paper provides good coverage to the breast and regional nodes with acceptable toxicity, and without requiring three-dimensional treatment planning or intensity-modulated radiotherapy techniques.
Scrimger
R A
RA
Department of Radiation Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada. scrimger@mail.humonc.wisc.edu
Connors
S G
SG
Halls
S B
SB
Starreveld
A A
AA
D001365:Axilla; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D002968:Clavicle; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008198:Lymph Nodes; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging / Q000532:radiotherapy; D008279:Magnetic Resonance Imaging / Q000379:methods; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D014057:Tomography, X-Ray Computed