title: Dosimetric analysis of a simplified intensity modulation technique for prone breast radiotherapy.
abstract: OBJECTIVE
  Prone-position breast radiotherapy (RT) has been described as an alternative technique to improve dose homogeneity for women with large, pendulous breasts. We report the feasibility and dosimetric analysis of a simplified intensity-modulated RT (IMRT) technique, previously reported for women in the supine treatment position, to plan prone-position RT to the intact breast.
  
  
  METHODS
  Twenty patients with clinical Stage TisN0-T1bN1 breast cancer undergoing breast-conserving therapy underwent whole breast RT using a prone position technique. The treatment plans were developed using both conventional tangents and a simplified intensity-modulated tangential beam technique based on optimization of the intensity distributions across the breast. The plans were compared with regard to the dose-volume parameters.
  
  
  RESULTS
  Dose heterogeneity within the breast planning target volume was significantly greater for the conventional tangent plans. Of 20 patients, 16 (80%) received maximal doses of > or =110% using the conventional tangents vs. only 1 (5%) using the IMRT plan. The isodose level encompassing 5% of the planning target volume was reduced from an average of 110% with conventional tangents to 105% with IMRT. The maximal dose within the planning target volume was reduced from an average of 114% with conventional tangents to 107% with IMRT. The greatest improvement was seen in the patients with the most pendulous breasts.
  
  
  CONCLUSIONS
  An IMRT planning approach is feasible for prone-position breast RT and improves dose homogeneity, particularly in women with larger, pendulous breasts. Additional follow-up is necessary to determine whether the improvements in dose homogeneity impact acute toxicity and cosmetic outcome in this cohort of women who have historically suffered from poor cosmesis after breast-conserving therapy.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
authors.forename: Karyn A
authors.initials: KA
authors.lastname: Goodman
authors.forename: Linda
authors.initials: L
authors.lastname: Hong
authors.forename: Raquel
authors.initials: R
authors.lastname: Wagman
authors.forename: Margie A
authors.initials: MA
authors.lastname: Hunt
authors.forename: Beryl
authors.initials: B
authors.lastname: McCormick
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D018270:Carcinoma, Ductal, Breast / Q000473:pathology / Q000532:radiotherapy; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000473:pathology / Q000532:radiotherapy; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D011187:Posture; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*