title: An analysis of intraoperative versus post-operative dosimetry with CT, CT-MRI fusion and XMR for the evaluation of permanent prostate brachytherapy implants.
abstract: OBJECTIVE
  To assess the agreement between intraoperative and post-operative dosimetry and to identify factors that influence dose calculations of prostate brachytherapy implants.
  
  
  METHODS
  Patients treated with prostate brachytherapy implants underwent post-operative CT and XMR (combined X-ray and MR) imaging. Dose-volume histograms were calculated from CT, XMR and CT-MR fusion data and compared with intraoperative values for two observers. Multiple linear regression models assessed the influences of intraoperative D90, gland oedema, gland volume, source loss and migration, and implanted activity/volume prostate on post-operative D90.
  
  
  RESULTS
  Forty-nine patients were studied. The mean D90 differences (95% confidence limits) between intraoperative and post-operative CT, XMR and CT-MR fusion assessments were: 11 Gy (-22, 45), 18 Gy (-13, 49) and 20 Gy (-17, 58) for Observer 1; and 15 Gy (-34, 63), 13 Gy (-29, 55) and 14 Gy (-27, 54) for Observer 2. Multiple linear regression modelling showed that the observed oedema and intraoperative D90 were significant independent variables for the prediction of post-operative D90 values for both observers using all modalities.
  
  
  CONCLUSIONS
  This is the first study to report Bland-Altman agreement analysis between intraoperative and post-operative dosimetry. Agreement is poor. Post-operative dosimetry is dependent on the intraoperative D90 and the subjectively outlined gland volume.
authors.affiliation: Division of Imaging Sciences, King's College London School of Medicine, London, UK. pete_acher@hotmail.com
authors.forename: Peter
authors.initials: P
authors.lastname: Acher
authors.forename: Srikanth
authors.initials: S
authors.lastname: Puttagunta
authors.forename: Kawal
authors.initials: K
authors.lastname: Rhode
authors.forename: Stephen
authors.initials: S
authors.lastname: Morris
authors.forename: Janette
authors.initials: J
authors.lastname: Kinsella
authors.forename: Andrew
authors.initials: A
authors.lastname: Gaya
authors.forename: Prokar
authors.initials: P
authors.lastname: Dasgupta
authors.forename: Charles
authors.initials: C
authors.lastname: Deehan
authors.forename: Ronald
authors.initials: R
authors.lastname: Beaney
authors.forename: Rick
authors.initials: R
authors.lastname: Popert
authors.forename: Stephen
authors.initials: S
authors.lastname: Keevil
mesh_terms: D001918:Brachytherapy / Q000592:standards; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D016343:Monitoring, Intraoperative; D011184:Postoperative Period; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D011879:Radiotherapy Dosage; D014057:Tomography, X-Ray Computed