title: Dosimetric comparison of four different external beam partial breast irradiation techniques: three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, helical tomotherapy, and proton beam therapy.
abstract: OBJECTIVE
  As an alternative to whole breast irradiation in early breast cancer, a variety of accelerated partial breast irradiation (APBI) techniques have been investigated. The purpose of our study is to compare the dosimetry of four different external beam APBI (EB-APBI) plans: three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), helical tomotherapy (TOMO), and proton beam therapy (PBT).
  
  
  METHODS
  Thirty patients were included in the study, and plans for four techniques were developed for each patient. A total dose of 30Gy in 6Gy fractions once daily was prescribed in all treatment plans.
  
  
  RESULTS
  In the analysis of the non-PTV breast volume that was delivered 50% of the prescribed dose (PD), PBT (mean: 16.5%) was superior to TOMO (mean: 22.8%), IMRT (mean: 33.3%), and 3D-CRT (mean: 40.9%) (p<0.001). The average ipsilateral lung volume percentage receiving 20% of the PD was significantly lower in PBT (0.4%) and IMRT (2.3%) compared with 3D-CRT (6.0%) and TOMO (14.2%) (p<0.001). The average heart volume percentage receiving 20% and 10% of the PD in left-sided breast cancer (N=19) was significantly larger with TOMO (8.0%, 19.4%) compared to 3D-CRT (1.5%, 3.1%), IMRT (1.2%, 4.0%), and PBT (0%, 0%) (p<0.001).
  
  
  CONCLUSIONS
  All four EB-APBI techniques showed acceptable coverage of the PTV. However, effective non-PTV breast sparing was achieved at the cost of considerable dose exposure to the lung and heart in TOMO.
authors.affiliation: Proton Therapy Center, National Cancer Center, Gyeonggi-do, Republic of Korea.
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Moon
authors.forename: Kyung Hwan
authors.initials: KH
authors.lastname: Shin
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Kim
authors.forename: Myonggeun
authors.initials: M
authors.lastname: Yoon
authors.forename: Soah
authors.initials: S
authors.lastname: Park
authors.forename: Doo-Hyun
authors.initials: DH
authors.lastname: Lee
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Kim
authors.forename: Dae Woong
authors.initials: DW
authors.lastname: Kim
authors.forename: Sung Yong
authors.initials: SY
authors.lastname: Park
authors.forename: Kwan Ho
authors.initials: KH
authors.lastname: Cho
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D006801:Humans; D061766:Proton Therapy; D015641:Radiography, Interventional; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D011882:Radiotherapy, High-Energy / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D036542:Tomography, Spiral Computed; D016896:Treatment Outcome; D011522:Protons
chemical_list: D011522:Protons