title: In vivo dosimetry using Gafchromic films during pelvic intraoperative electron radiation therapy (IOERT).
abstract: OBJECTIVE
  To characterize in vivo dose distributions during pelvic intraoperative electron radiation therapy (IOERT) for rectal cancer and to assess the alterations introduced by irregular irradiation surfaces in the presence of bevelled applicators.
  
  
  METHODS
  In vivo measurements were performed with Gafchromic films during 32 IOERT procedures. 1 film per procedure was used for the first 20 procedures. The methodology was then optimized for the remaining 12 procedures by using a set of 3 films. Both the average dose and two-dimensional dose distributions for each film were determined. Phantom measurements were performed for comparison.
  
  
  RESULTS
  For flat and concave surfaces, the doses measured in vivo agree with expected values. For concave surfaces with step-like irregularities, measured doses tend to be higher than expected doses. Results obtained with three films per procedure show a large variability along the irradiated surface, with important differences from expected profiles. These results are consistent with the presence of surface hotspots, such as those observed in phantoms in the presence of step-like irregularities, as well as fluid build-up.
  
  
  CONCLUSIONS
  Clinical dose distributions in the IOERT of rectal cancer are often different from the references used for prescription. Further studies are necessary to assess the impact of these differences on treatment outcomes. In vivo measurements are important, but need to be accompanied by accurate imaging of positioning and irradiated surfaces.
  
  
  CONCLUSIONS
  These results confirm that surface irregularities occur frequently in rectal cancer IOERT and have a measurable effect on the dose distribution.
authors.affiliation: 1 Medical Physics, Radiobiology and Radiation Protection Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Filipa
authors.initials: F
authors.lastname: Costa
authors.affiliation: 1 Medical Physics, Radiobiology and Radiation Protection Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.|2 Medical Physics Department, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Sandra
authors.initials: S
authors.lastname: Sarmento
authors.affiliation: 3 Radiation Oncology Department, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Dora
authors.initials: D
authors.lastname: Gomes
authors.affiliation: 3 Radiation Oncology Department, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Helena
authors.initials: H
authors.lastname: Magalhães
authors.affiliation: 3 Radiation Oncology Department, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Rosário
authors.initials: R
authors.lastname: Arrais
authors.affiliation: 4 UCA, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Graciete
authors.initials: G
authors.lastname: Moreira
authors.affiliation: 4 UCA, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Maria Fátima
authors.initials: MF
authors.lastname: Cruz
authors.affiliation: 5 Surgical Oncology Department, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: José Pedro
authors.initials: JP
authors.lastname: Silva
authors.affiliation: 5 Surgical Oncology Department, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.|6 Experimental Pathology and Therapeutics Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Lúcio
authors.initials: L
authors.lastname: Santos
authors.affiliation: 3 Radiation Oncology Department, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
authors.forename: Olga
authors.initials: O
authors.lastname: Sousa
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D004583:Electrons; D005373:Film Dosimetry / Q000379:methods*; D006801:Humans; D000072231:In Vivo Dosimetry / Q000379:methods*; D007432:Intraoperative Period; D010388:Pelvis; D019047:Phantoms, Imaging; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000532:radiotherapy*