Preliminary results for prone-position breast irradiation.

Purpose: To evaluate an alternative prone-position technique for breast irradiation after conservative surgery.

Methods And Materials: A plexiglas platform with a circular opening for the breast and a double 30 degrees craniocaudal and 10 degrees transverse (left-right for the right breast and right-left for the left breast) slope was evaluated for positioning, the possible use of CT, and dosimetric study in 35 patients with large pendulous breasts who were likely to benefit from irradiation of the breast alone after conservative surgery.

Results: The positioning was excellent for all but 3 obese patients who could not achieve adequate prolonged immobilization. The platform height and position made it possible to obtain CT in the other 32 patients. Three-dimensional dosimetry revealed that 85 degrees and 265 degrees angles of the tangential fields for the right breast and 275 degrees and 95 degrees angles for the left breast were adequate for all patients. The use of 4 or 6 MV photon energy and a variety of wedges made it possible to treat the whole breast and the chest wall. The high-dose regions of the base and the top of the breast did not exceed 105%. No interruption was necessary during treatment, and only grade I-II acute skin reactions were observed.

Conclusion: The results of this study have demonstrated the feasibility of the technique, which has the great advantage of using a similar position for CT scanning and treatment.