title: Dosimetric comparison of (192)Ir high-dose-rate brachytherapy vs. 50 kV x-rays as techniques for breast intraoperative radiation therapy: conceptual development of image-guided intraoperative brachytherapy using a multilumen balloon applicator and in-room CT imaging.
abstract: OBJECTIVE
  At our institution, the availability of a shielded procedure room with in-room CT-on-rails imaging allows for the exploration of a high-dose-rate (HDR) brachytherapy approach for breast intraoperative radiation therapy (IORT). We hypothesize that HDR brachytherapy will permit a higher prescription dose without increasing toxicity. In this study, we compare the dosimetry of intraoperative HDR brachytherapy, using multilumen balloon applicator, to IORT with a 50 kV source and then select a prescription dose for a subsequent clinical trial.
  
  
  METHODS
  The CT scans of 14 patients who had previously received multilumen balloon-based breast brachytherapy were replanned to a standard prescription to the target volume. The same 14 cases were planned to the specifications of a 50 kV x-ray system. Uniform volume optimization and prescription doses were used to permit direct comparisons. All plans were evaluated for the dose homogeneity index, tumor coverage, and dose to normal tissues, including skin, ribs, and heart (for left breast plans).
  
  
  RESULTS
  The HDR brachytherapy plans were superior to 50 kV superficial photon plans for IORT in all dosimetric parameters except for the heart and rib dosimetric parameters. Prescription dose of 12.5 Gy to the planning target volume for evaluation yielded a dose to 95 percent of the balloon surface of 19.7 Gy.
  
  
  CONCLUSIONS
  Image-guided HDR intraoperative brachytherapy with a multilumen balloon applicator provides superior target volume coverage compared with 50 kV photons, while maintaining doses within tolerance limits for normal tissues. An ongoing prospective clinical trial will evaluate the safety and feasibility of this technique.
authors.affiliation: Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Jones
authors.affiliation: Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Libby
authors.affiliation: Division of Surgical Oncology, Department of Surgery, University of Virginia School of Medicine, Charlottesville, VA.
authors.forename: Shayna L
authors.initials: SL
authors.lastname: Showalter
authors.affiliation: Division of Surgical Oncology, Department of Surgery, University of Virginia School of Medicine, Charlottesville, VA.
authors.forename: David R
authors.initials: DR
authors.lastname: Brenin
authors.affiliation: Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA.
authors.forename: David D
authors.initials: DD
authors.lastname: Wilson
authors.affiliation: Division of Surgical Oncology, Department of Surgery, University of Virginia School of Medicine, Charlottesville, VA.
authors.forename: Anneke
authors.initials: A
authors.lastname: Schroen
authors.affiliation: Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA.
authors.forename: Monica
authors.initials: M
authors.lastname: Morris
authors.affiliation: Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA.
authors.forename: Kelli A
authors.initials: KA
authors.lastname: Reardon
authors.affiliation: Varian Medical Systems, Varian Brachytherapy, Charlottesville, VA.
authors.forename: John
authors.initials: J
authors.lastname: Morrison
authors.affiliation: Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA. Electronic address: tns3b@virginia.edu.
authors.forename: Timothy N
authors.initials: TN
authors.lastname: Showalter
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D007430:Intraoperative Care / Q000295:instrumentation / Q000379:methods*; D007496:Iridium Radioisotopes / Q000627:therapeutic use; D008327:Mammography / Q000379:methods*; D015641:Radiography, Interventional / Q000379:methods*; D011874:Radiometry; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D014057:Tomography, X-Ray Computed
chemical_list: D007496:Iridium Radioisotopes; D019275:Radiopharmaceuticals
keywords: Accelerated partial breast irradiation; Brachytherapy; High dose rate; Image-guided; Intraoperative radiation