title: Monte Carlo evaluation of the effect of inhomogeneities on dose calculation for low energy photons intra-operative radiation therapy in pelvic area.
abstract: The aim of this study was to evaluate the effect of inhomogeneities on dose calculation for low energy photons intra-operative radiation therapy (IORT) in pelvic area. A GATE Monte Carlo model of the INTRABEAM® was adapted for the study. Simulations were performed in the CT scan of a cadaver considering a homogeneous segmentation (water) and an inhomogeneous segmentation (5 tissues from ICRU44). Measurements were performed in the cadaver using EBT3 Gafchromic® films. Impact of inhomogeneities on dose calculation in cadaver was 6% for soft tissues and greater than 300% for bone tissues. EBT3 measurements showed a better agreement with calculation for inhomogeneous media. However, dose discrepancy in soft tissues led to a sub-millimeter (0.65 mm) shift in the effective point dose in depth. Except for bone tissues, the effect of inhomogeneities on dose calculation for low energy photons intra-operative radiation therapy in pelvic area was not significant for the studied anatomy.
authors.affiliation: Medical Physics Department, Institut de Cancérologie de l'Ouest, Bld Jacques Monod, 44805 St Herblain Cedex, France. Electronic address: sophie.chiavassa@ico.unicancer.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Chiavassa
authors.affiliation: Nantes University Hospital, 1 place Alexis Ricordeau, 44000 Nantes, France.
authors.forename: François
authors.initials: F
authors.lastname: Buge
authors.affiliation: Medical Physics Department, Institut de Cancérologie de l'Ouest, Bld Jacques Monod, 44805 St Herblain Cedex, France.
authors.forename: Chloé
authors.initials: C
authors.lastname: Hervé
authors.affiliation: Medical Physics Department, Institut de Cancérologie de l'Ouest, Bld Jacques Monod, 44805 St Herblain Cedex, France.
authors.forename: Gregory
authors.initials: G
authors.lastname: Delpon
authors.affiliation: Nantes University Hospital, 1 place Alexis Ricordeau, 44000 Nantes, France.
authors.forename: Jérome
authors.initials: J
authors.lastname: Rigaud
authors.affiliation: Medical Physics Department, Institut de Cancérologie de l'Ouest, Bld Jacques Monod, 44805 St Herblain Cedex, France.
authors.forename: Albert
authors.initials: A
authors.lastname: Lisbona
authors.affiliation: Department of Radiation Oncology, Institut de Cancérologie de l'Ouest, Bld Jacques Monod, 44805 St Herblain Cedex, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Supiot
mesh_terms: D006801:Humans; D007091:Image Processing, Computer-Assisted; D007432:Intraoperative Period; D009010:Monte Carlo Method; D010388:Pelvis / Q000000981:diagnostic imaging / Q000528:radiation effects* / Q000601:surgery*; D017785:Photons / Q000627:therapeutic use*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed
keywords: Inhomogeneities; Intra-operative radiation therapy; Monte Carlo; Pelvis