title: Dosimetric advantages of generalised equivalent uniform dose-based optimisation on dose-volume objectives in intensity-modulated radiotherapy planning for bilateral breast cancer.
abstract: OBJECTIVE
  We compared and evaluated the differences between two models for treating bilateral breast cancer (BBC): (i) dose-volume-based intensity-modulated radiation treatment (DV plan), and (ii) dose-volume-based intensity-modulated radiotherapy with generalised equivalent uniform dose-based optimisation (DV-gEUD plan).
  
  
  METHODS
  The quality and performance of the DV plan and DV-gEUD plan using the Pinnacle(3) system (Philips, Fitchburg, WI) were evaluated and compared in 10 patients with stage T2-T4 BBC. The plans were delivered on a Varian 21EX linear accelerator (Varian Medical Systems, Milpitas, CA) equipped with a Millennium 120 leaf multileaf collimator (Varian Medical Systems). The parameters analysed included the conformity index, homogeneity index, tumour control probability of the planning target volume (PTV), the volumes V(20 Gy) and V(30 Gy) of the organs at risk (OAR, including the heart and lungs), mean dose and the normal tissue complication probability.
  
  
  RESULTS
  Both plans met the requirements for the coverage of PTV with similar conformity and homogeneity indices. However, the DV-gEUD plan had the advantage of dose sparing for OAR: the mean doses of the heart and lungs, lung V(20) (Gy), and heart V(30) (Gy) in the DV-gEUD plan were lower than those in the DV plan (p<0.05).
  
  
  CONCLUSIONS
  A better result can be obtained by starting with a DV-generated plan and then improving it by adding gEUD-based improvements to reduce the number of iterations and to improve the optimum dose distribution. Advances to knowledge The DV-gEUD plan provided superior dosimetric results for treating BBC in terms of PTV coverage and OAR sparing than the DV plan, without sacrificing the homogeneity of dose distribution in the PTV.
authors.affiliation: Medical Physics & Informatics Laboratory of Electronics Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan. alffrequent@gmail.com
authors.forename: T-F
authors.initials: TF
authors.lastname: Lee
authors.forename: H-M
authors.initials: HM
authors.lastname: Ting
authors.forename: P-J
authors.initials: PJ
authors.lastname: Chao
authors.forename: H-Y
authors.initials: HY
authors.lastname: Wang
authors.forename: C-S
authors.initials: CS
authors.lastname: Shieh
authors.forename: M-F
authors.initials: MF
authors.lastname: Horng
authors.forename: J-M
authors.initials: JM
authors.lastname: Wu
authors.forename: S-A
authors.initials: SA
authors.lastname: Yeh
authors.forename: M-Y
authors.initials: MY
authors.lastname: Cho
authors.forename: E-Y
authors.initials: EY
authors.lastname: Huang
authors.forename: Y-J
authors.initials: YJ
authors.lastname: Huang
authors.forename: H-C
authors.initials: HC
authors.lastname: Chen
authors.forename: F-M
authors.initials: FM
authors.lastname: Fang
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011879:Radiotherapy Dosage / Q000592:standards*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D020266:Radiotherapy, Conformal / Q000379:methods / Q000592:standards