title: Dosimetric comparison of Acuros™ BV with AAPM TG43 dose calculation formalism in breast interstitial high-dose-rate brachytherapy with the use of metal catheters.
abstract: OBJECTIVE
  Radiotherapy for breast cancer includes different techniques and methods. The purpose of this study is to compare dosimetric calculations using TG-43 dose formalism and Varian Acuros™ BV (GBBS) dose calculation algorithm for interstitial implant of breast using metal catheters in high-dose-rate (HDR) brachytherapy, using (192)Ir.
  
  
  METHODS
  Twenty patients who were considered for breast conservative surgery (BCS), underwent lumpectomy and axillary dissection. These patients received perioperative interstitial HDR brachytherapy as upfront boost using rigid metal implants. Whole breast irradiation was delivered TG-43 after a gap of two weeks. Standard brachytherapy dose calculation was done by dosimetry. This does not take into account tissue heterogeneity, attenuation and scatter in the metal applicator, and effects of patient boundary. Acuros™ BV is a Grid Based Boltzmann Solver code (GBBS), which takes into consideration all the above, was used to compute dosimetry and the two systems were compared.
  
  
  RESULTS
  Comparison of GBBS and TG-43 formalism on interstitial metal catheters shows difference in dose prescribed to CTV and other OARs. While the estimated dose to CTV was only marginally different with the two systems, there is a significant difference in estimated doses of starting from 4 to 53% in the mean value of all parameters analyzed.
  
  
  CONCLUSIONS
  TG-43 algorithm seems to significantly overestimate the dose to various volumes of interest; GBBS based dose calculation algorithm has impact on CTV, heart, ipsilateral lung, heart, contralateral breast, skin, and ribs of the ipsilateral breast side; the prescription changes occurred due to effect of metal catheters, inhomogeneities, and scatter conditions.
authors.affiliation: Department of Radiotherapy, Regional Cancer Centre, JIPMER, Puducherry.
authors.forename: Mourougan
authors.initials: M
authors.lastname: Sinnatamby
authors.affiliation: Department of Medical Physics, Cancer Institute, Adyar, Chennai.
authors.forename: Vivekanandan
authors.initials: V
authors.lastname: Nagarajan
authors.affiliation: Regional Cancer Centre, JIPMER and Head, Oncology, Mahatma Gandhi Medical College and Research Institute, Puducherry, India.
authors.forename: Sathyanarayana
authors.initials: S
authors.lastname: Reddy K
authors.affiliation: Department of Radiotherapy, Regional Cancer Centre, JIPMER, Puducherry.
authors.forename: Gunaseelan
authors.initials: G
authors.lastname: Karunanidhi
authors.affiliation: Department of Radiotherapy, Regional Cancer Centre, JIPMER, Puducherry.
authors.forename: Vivekanandam
authors.initials: V
authors.lastname: Singhavajala
keywords: AcurosBV; GBBS; TG-43; brachytherapy; breast interstitial implant