Critical appraisal of a non-coplanar technique for radiotherapy of breast minimising lung involvement.
OBJECTIVE
To appraise the potential benefit of a conformal technique with non-coplanar fields to minimise lung irradiation in the radiation treatment of breast.


METHODS
A comparative study was carried out at planning level for six patients selected for their inadequate sparing of healthy lung tissue with the reference tangential technique. Plans were designed for the conventional tangential technique, for an alternative conformal approach with three beams and for the newly proposed technique with two non-coplanar beams.


RESULTS
In average for the new technique compared to the reference, mean lung dose dropped from approximately 16 to 10.5 Gy, V(20 Gy) from 29.5 to 18.2% and the dose delivered to 1/3 (1/4) of the lung volume dropped from 28.5% (67.3%) to 8.7% (13.4%). For PTV, the volume receiving at least 90% of the prescribed dose resulted 97.4% for the new and 97.3% for the reference. Conformity index improved significantly from 2.58 for the reference to 1.84 for the new technique.


CONCLUSIONS
For a subgroup population of breast cancer patients, where conventional techniques failed to achieve high conformal avoidance, a treatment modality with non-coplanar beams was developed and clinically tested for six patients. It resulted dosimetrically adequate, particularly when the risk of toxicity is relevant.
Nicolini
Giorgia
G
Radiation Oncology Department, Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona, Switzerland.
Fogliata
Antonella
A
Cozzi
Luca
L
D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D008168:Lung / Q000528:radiation effects*; D011832:Radiation Injuries / Q000517:prevention & control; D018714:Radiotherapy, Adjuvant; D020266:Radiotherapy, Conformal / Q000379:methods*; D012307:Risk Factors