title: Vaginal dose assessment in image-guided brachytherapy for cervical cancer: Can we really rely on dose-point evaluation?
abstract: OBJECTIVE
  Although dose-volume parameters in image-guided brachytherapy have become a standard, the use of posterior-inferior border of the pubic symphysis (PIBS) points has been recently proposed in the reporting of vaginal doses. The aim was to evaluate their pertinence.
  
  
  METHODS
  Nineteen patients who received image-guided brachytherapy after concurrent radiochemotherapy were included. Per treatment, CT scans were performed at Days 2 and 3, with reporting of the initial dwell positions and times. Doses delivered to the PIBS points were evaluated on each plan, considering that they were representative of one-third of the treatment. The movements of the applicator according to the PIBS point were analysed.
  
  
  RESULTS
  Mean prescribed doses at PIBS -2, PIBS, PIBS +2 were, respectively, 2.23 ± 1.4, 6.39 ± 6.6, and 31.85 ± 36.06 Gy. Significant differences were observed between the 5 patients with vaginal involvement and the remaining 14 at the level of PIBS +2 and PIBS: +47.60 Gy and +7.46 Gy, respectively (p = 0.023 and 0.03). The variations between delivered and prescribed doses at PIBS points were not significant. However, at International commission on radiation units and measurements rectovaginal point, the delivered dose was decreased by 1.43 ± 2.49 Gy from the planned dose (p = 0.019). The delivered doses at the four points were strongly correlated with the prescribed doses with R(2) ranging from 0.93 to 0.95. The movements of the applicator in regard of the PIBS point assessed with the Digital Imaging and Communications in Medicine coordinates were insignificant.
  
  
  CONCLUSIONS
  The doses evaluated at PIBS points are not impacted by intrafractional movements. PIBS and PIBS +2 dose points allow distinguishing the plans of patients with vaginal infiltration. Further studies are needed to correlate these parameters with vaginal morbidity.
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France; Department of Radiotherapy, Philippine General Hospital, Manila, Philippines.
authors.forename: Elaine Johanna
authors.initials: EJ
authors.lastname: Limkin
authors.affiliation: Department of Medical Physics, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Dumas
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Eleonor
authors.initials: E
authors.lastname: Rivin Del Campo
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France; Laboratory of Molecular Radiotherapy INSERM 1030, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Chargari
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Maroun
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Annède
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Petit
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Seisen
authors.affiliation: Department of Medical Physics, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Kaya
authors.initials: K
authors.lastname: Doyeux
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Tailleur
authors.affiliation: Department of Medical Physics, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Martinetti
authors.affiliation: Department of Medical Physics, Gustave Roussy Cancer Campus, Villejuif, France; Laboratory of Molecular Radiotherapy INSERM 1030, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Lefkopoulos
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Haie-Meder
authors.affiliation: Department of Radiation Oncology, Brachytherapy Unit, Gustave Roussy Cancer Campus, Villejuif, France; Laboratory of Molecular Radiotherapy INSERM 1030, Gustave Roussy Cancer Campus, Villejuif, France. Electronic address: renaud.mazeron@gustaveroussy.fr.
authors.forename: Renaud
authors.initials: R
authors.lastname: Mazeron
mesh_terms: D001918:Brachytherapy; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D011631:Pubic Symphysis / Q000000981:diagnostic imaging; D011829:Radiation Dosage; D061089:Radiotherapy, Image-Guided; D014057:Tomography, X-Ray Computed; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*; D014621:Vagina / Q000528:radiation effects
keywords: Cervical cancer; Doses; Image-guided adaptive brachytherapy; Posterior–inferior border of the pubic symphysis (PIBS); Vagina