title: In vivo rectal wall measurements during HDR prostate brachytherapy with MOSkin dosimeters integrated on a trans-rectal US probe: Comparison with planned and reconstructed doses.
abstract: OBJECTIVE
  To study if MOSkin detectors coupled to a trans-rectal ultrasound (TRUS) probe may be used for in vivo dosimetry on the rectal wall surface during US-based HDR prostate brachytherapy and to quantify possible discrepancies between planned and delivered doses.
  
  
  METHODS
  MOSkins are a specific type of MOSFET dosimeter optimized to measure dose in steep dose gradients on interfaces. Two MOSkins were assembled on a TRUS probe used for on-line treatment planning. Measurements of the dose to the rectal wall were performed over 18 treatment sessions and compared to the doses calculated on the pre-treatment plan (DPRE) and reconstructed on post-treatment images (DPOST).
  
  
  RESULTS
  Averages of the absolute differences between MOSkin readings and DPRE, MOSkin readings and DPOST and DPRE and DPOST were 6.7 ± 5.1%, 3.6 ± 1.9% and 6.3 ± 4.7%, respectively. Agreement between measurements and DPOST was significantly better than between measurements and DPRE (p=0.002) and DPRE and DPOST (p=0.004). Discrepancy between DPOST and DPRE correlated with the time required for treatment planning.
  
  
  CONCLUSIONS
  MOSkin dosimeters integrated to the TRUS probe proved to be an accurate instrument for measuring the dose delivered to the rectal wall in HDR prostate brachytherapy. The delivered doses may differ significantly from those calculated in the treatment plan.
authors.affiliation: Medical Physics Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy; Prostate Cancer Program, Scientific Director's Office, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy. Electronic address: mauro.carrara@istitutotumori.mi.it.
authors.forename: Mauro
authors.initials: M
authors.lastname: Carrara
authors.affiliation: Medical Physics Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Tenconi
authors.affiliation: Medical Physics Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Rossi
authors.affiliation: Medical Physics Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy; Prostate Cancer Program, Scientific Director's Office, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Borroni
authors.affiliation: Prostate Cancer Program, Scientific Director's Office, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy; Radiation Oncology 2 Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Cerrotta
authors.affiliation: Medical Physics Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Grisotto
authors.affiliation: Medical Physics Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Cusumano
authors.affiliation: Radiation Oncology 2 Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Brigida
authors.initials: B
authors.lastname: Pappalardi
authors.affiliation: Centre for Medical Radiation Physics, University of Wollongong, Australia.
authors.forename: Dean
authors.initials: D
authors.lastname: Cutajar
authors.affiliation: Centre for Medical Radiation Physics, University of Wollongong, Australia.
authors.forename: Marco
authors.initials: M
authors.lastname: Petasecca
authors.affiliation: Centre for Medical Radiation Physics, University of Wollongong, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Lerch
authors.affiliation: National Institute of Nuclear Physics INFN, Milan, Italy.
authors.forename: Grazia
authors.initials: G
authors.lastname: Gambarini
authors.affiliation: Prostate Cancer Program, Scientific Director's Office, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy; Radiation Oncology 2 Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Fallai
authors.affiliation: Centre for Medical Radiation Physics, University of Wollongong, Australia.
authors.forename: Anatoly
authors.initials: A
authors.lastname: Rosenfeld
authors.affiliation: Medical Physics Unit, Dept. of Diagnostic Imaging and Radiotherapy, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy; Prostate Cancer Program, Scientific Director's Office, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Pignoli
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum / Q000000981:diagnostic imaging / Q000528:radiation effects*; D018084:Ultrasonography, Interventional
keywords: HDR brachytherapy; In vivo dosimetry; MOSFET; Prostate