title: Initial dosimetric experience using simple three-dimensional conformal external-beam accelerated partial-breast irradiation.
abstract: OBJECTIVE
  Several accelerated partial-breast irradiation (APBI) techniques are being investigated in patients with early-stage breast cancer. We present our initial experience using three-dimensional conformal radiation therapy (3D-CRT).
  
  
  METHODS
  Sixty-one patients with tumors of 2 cm or less and negative axillary nodes were treated with 3D-CRT accelerated partial-breast irradiation (APBI) between August 2003 and March 2005. The prescribed radiation dose was 32 Gy in 4-Gy fractions given twice daily. Efforts were made to minimize the number of beams required to achieve adequate planning target volume (PTV) coverage.
  
  
  RESULTS
  A combination of photons and electrons was used in 85% of patients. A three-field technique that consisted of opposed, conformal tangential photons and enface electrons was employed in 43 patients (70%). Nine patients (15%) were treated with a four-field arrangement, which consisted of three photon fields and enface electrons. Mean PTV volumes that received 100%, 95%, and 90% of the prescribed dose were 93% +/- 7%, 97% +/- 4%, and 98% +/- 2%, respectively. Dose inhomogeneity exceeded 10% in only 7 patients (11%). Mean doses to the ipsilateral lung and heart were 1.8 Gy and 0.8 Gy, respectively.
  
  
  CONCLUSIONS
  Simple 3D-CRT techniques of APBI can achieve appropriate PTV coverage while offering significant normal-tissue sparing. Therefore, this noninvasive approach may increase the availability of APBI to patients with early-stage breast cancer.
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA 02114, USA. ataghian@partners.org
authors.forename: Alphonse G
authors.initials: AG
authors.lastname: Taghian
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Kozak
authors.forename: Karen P
authors.initials: KP
authors.lastname: Doppke
authors.forename: Angela
authors.initials: A
authors.lastname: Katz
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Smith
authors.forename: Michele
authors.initials: M
authors.lastname: Gadd
authors.forename: Michelle
authors.initials: M
authors.lastname: Specht
authors.forename: Kevin
authors.initials: K
authors.lastname: Hughes
authors.forename: Kristina
authors.initials: K
authors.lastname: Braaten
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Kachnic
authors.forename: Abram
authors.initials: A
authors.lastname: Recht
authors.forename: Simon N
authors.initials: SN
authors.lastname: Powell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D004583:Electrons / Q000627:therapeutic use; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D017785:Photons / Q000627:therapeutic use; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*