title: A comparative dosimetric study for treating left-sided breast cancer for small breast size using five different radiotherapy techniques: conventional tangential field, filed-in-filed, tangential-IMRT, multi-beam IMRT and VMAT.
abstract: OBJECTIVE
  To compare the dosimetry for the left-sided breast cancer treatment using five different radiotherapy techniques.
  
  
  METHODS
  Twenty patients with left sided breast cancer were treated with conservative surgery followed by radiotherapy. They were planned using five different radiotherapy techniques, including: 1) conventional tangential wedge-based fields (TW); 2) field-in-field (FIF) technique; 3) tangential inverse planning intensity-modulated radiation therapy (T-IMRT); 4) multi-field IMRT (M-IMRT); and 5) volumetric modulated arc therapy (VMAT). The CTV, PTV and OARs including the heart, the regions of coronary artery (CA), the contralateral breast, the left and right lung were delineated. The PTV dose was prescribed 50Gy and V47.5≥95%. Same dose constraint was used for all five plans. The planned volumetric dose of PTV and PRV-OARs were compared and analyzed.
  
  
  RESULTS
  Except VMAT (Average V47.5 was 94.72%±1.2%), all the other four plans were able to meet the V95% (V47.5) requirement. T-IMRT plan improved the PTV dose homogeneity index (HI) by 0.02 and 0.03 when compared to TW plan and VMAT plan, and decreased the V5, V10 and V20 of all PRV-OARs. However, the high dose volume (≥ 30Gy) of the PRV-OARs in T-IMRT plan had no statistically significant difference compared with the other two inverse plans. In all five plans, the dose volume of coronary artery area showed a strong correlation to the dose volume of the heart (the correlation coefficients were 0.993, 0.996, 1.000, 0.995 and 0.986 respectively).
  
  
  CONCLUSIONS
  Compared to other techniques, the T-IMRT technology reduced radiation dose exposure to normal tissues and maintained reasonable target homogeneity, VMAT is not recommended for left-sided breast cancer treatment. In five techniques, the dose-volume histogram (DVH) of the heart can be used to predict the dose-volume histogram (DVH) of the coronary artery.
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Guang-Hua
authors.initials: GH
authors.lastname: Jin
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Chen
authors.forename: Xiao-Wu
authors.initials: XW
authors.lastname: Deng
authors.forename: Xiao-Wei
authors.initials: XW
authors.lastname: Liu
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Xiao-Bo
authors.initials: XB
authors.lastname: Huang
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D011874:Radiometry; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*