title: MRI-guided single fraction ablative radiotherapy for early-stage breast cancer: a brachytherapy versus volumetric modulated arc therapy dosimetry study.
abstract: OBJECTIVE
  A radiosurgical treatment approach for early-stage breast cancer has the potential to minimize the patient's treatment burden. The dosimetric feasibility for single fraction ablative radiotherapy was evaluated by comparing volumetric modulated arc therapy (VMAT) with an interstitial multicatheter brachytherapy (IMB) approach.
  
  
  METHODS
  The tumors of 20 patients with early-stage breast cancer were delineated on a preoperative contrast-enhanced planning CT-scan, co-registered with a contrast-enhanced magnetic resonance imaging (MRI), both in radiotherapy supine position. A dose of 15 Gy was prescribed to the planned target volume of the clinical target volume (PTVCTV), and 20 Gy integrated boost to the PTV of the gross tumor volume (PTVGTV). Treatment plans for IMB and VMAT were optimized for adequate target volume coverage and minimal organs at risk (OAR) dose.
  
  
  RESULTS
  The median PTVGTV/CTV receiving at least 95% of the prescribed dose was ⩾99% with both techniques. The median PTVCTV unintentionally receiving 95% of the prescribed PTVGTV dose was 65.4% and 4.3% with IMB and VMAT, respectively. OAR doses were comparable with both techniques.
  
  
  CONCLUSIONS
  MRI-guided single fraction radiotherapy with an integrated ablative boost to the GTV is dosimetrically feasible with both techniques. We perceive IMB less suitable for clinical implementation due to PTVCTV overdosage. Future studies have to confirm the clinical feasibility of the single fraction ablative approach.
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands. Electronic address: r.charaghvandi@umcutrecht.nl.
authors.forename: Ramona K
authors.initials: RK
authors.lastname: Charaghvandi
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Mariska D
authors.initials: MD
authors.lastname: den Hartogh
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Anne-Mar L N
authors.initials: AM
authors.lastname: van Ommen
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Wilfred J H
authors.initials: WJ
authors.lastname: de Vries
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Vincent
authors.initials: V
authors.lastname: Scholten
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Marinus A
authors.initials: MA
authors.lastname: Moerland
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Mariëlle E P
authors.initials: ME
authors.lastname: Philippens
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Rogier I
authors.initials: RI
authors.lastname: Schokker
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Marco
authors.initials: M
authors.lastname: van Vulpen
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Bram
authors.initials: B
authors.lastname: van Asselen
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands.
authors.forename: Desirée H J G
authors.initials: DH
authors.lastname: van den Bongard
mesh_terms: D000368:Aged; D001918:Brachytherapy; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D009367:Neoplasm Staging; D058958:Organs at Risk; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*
keywords: Ablative; Breast cancer; Interstitial multicatheter brachytherapy; MRI-guidance; Single fraction; VMAT