title: Quantitative MRI assessment of a novel direction modulated brachytherapy tandem applicator for cervical cancer at 1.5T.
abstract: The purpose of this work is to quantitatively investigate the artifacts and image distortions induced in the MR images by a recently proposed direction modulated brachytherapy (DMBT) tandem applicator prototype. This new MRI-compatible applicator allows better sparing of organs-at-risk (OAR) for cervical cancer patients, while providing conformal dose distributions to target volumes.
  
  
  
  Specific phantom and tools were designed and manufactured for this study. The phantom was filled with a tissue-like solution and MR images were acquired with clinical protocols as per GEC-ESTRO recommendations. Images were obtained at 6 different orientations that mimic possible clinical settings and full-width-at-half-maximum (FWHM) was recorded at multiple locations/angles. The accuracy of detecting the centerline of the tandem was assessed using a novel radial-fiducials mount.
  
  
  
  FWHM from all line profiles at all angles and all orientations was 6.14±0.7mm (compared to 6mm of the actual DMBT tandem diameter). The in-plane spatial-shift observed at para-axial and para-sagittal views was less than 0.5mm.
  
  
  
  This work demonstrated that the novel DMBT tandem applicator prototype has minimal artifact in T2-weighted images employed in clinical practice, suggesting the applicator might be a good candidate for MRI-guided adaptive brachytherapy.
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Canada.
authors.forename: Abraam S
authors.initials: AS
authors.lastname: Soliman
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada.
authors.forename: Alyaa
authors.initials: A
authors.lastname: Elzibak
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada.
authors.forename: Harry
authors.initials: H
authors.lastname: Easton
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Canada.
authors.forename: James Y
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of California San Francisco, California, United States.
authors.forename: Dae Yup
authors.initials: DY
authors.lastname: Han
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Canada.
authors.forename: Habib
authors.initials: H
authors.lastname: Safigholi
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada.
authors.forename: Shahram
authors.initials: S
authors.lastname: Mashouf
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada.
authors.forename: Amir
authors.initials: A
authors.lastname: Owrangi
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada.
authors.forename: Ananth
authors.initials: A
authors.lastname: Ravi
authors.affiliation: Department of Medical Physics, Sunnybrook Health Sciences Centre, Toronto, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Canada. Electronic address: william.song@sunnybrook.ca.
authors.forename: William Y
authors.initials: WY
authors.lastname: Song
mesh_terms: D016477:Artifacts; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D059351:Organ Sparing Treatments / Q000295:instrumentation / Q000379:methods; D058958:Organs at Risk; D019047:Phantoms, Imaging; D061089:Radiotherapy, Image-Guided / Q000295:instrumentation* / Q000379:methods; D002583:Uterine Cervical Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*
keywords: Brachytherapy; Cervical cancer; DMBT; MRI; Tandem applicator