Breast irradiation with three conformal photon fields for patients with high lung involvement.
Since 2001, 50 breast cancer patients, for whom extensive lung/heart involvement was expected from the use of conventional tangential 2-field technique (2F) owing to complex anatomies, were irradiated using a 3-field conformal technique (3F). Dose plans were designed for both 3F and 2F and a dose volume histogram analysis on ipsilateral lung, heart, and target was conducted. The 3F technique allowed a significant reduction in ipsilateral lung irradiation: mean dose dropped from 16.0+/-3.8 (2F) to 12.0+/-2.7 Gy (3F) and V(45Gy) from 20.7+/-6.8 (2F) to 3.2+/-2.9% (3F). Similarly, in patients irradiated to the left breast, heart mean dose was reduced from 8.1 Gy (2F) to 6.8 Gy (3F) and D(15%) from 19.0 Gy to 14.0 Gy. All differences reached a high degree of significance. The target coverage was not clinically compromised since the slight reduction using 3F compared with 2F is limited to V(95%) while V(90%) difference, even if statistically significant, is small: 98.2+/-1.8% (3F) and 98.8+/-1.6 (2F). A preliminary report on clinical follow up is also included; with a mean follow up of 15.8 months, no pulmonary or cardiac complications were observed.
Cozzi
Luca
L
Medical Physics Unit, Department of Physics Oncology, Institute of Southern Switzerland, University of Milan, Bellinzona, Switzerland. lucozzi@iosi.ch
Fogliata
Antonella
A
Nicolini
Giorgia
G
Rancati
Tiziana
T
Bernier
Jacques
J
D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy* / Q000556:secondary*; D008297:Male; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011832:Radiation Injuries / Q000517:prevention & control; D018714:Radiotherapy, Adjuvant; D020266:Radiotherapy, Conformal / Q000379:methods*; D012307:Risk Factors