title: Monte-Carlo dosimetry for intraoperative radiotherapy using a low energy x-ray source.
abstract: Intraoperative radiotherapy (IORT) is continuously gaining ground in cancer treatment. However, there is currently no planning system associated with these devices, which precludes patient-specific dose delivery optimization. The objective of this study was the development and validation of a Monte Carlo simulation (MCS)-based dosimetry platform using the Intrabeam™ system.
  
  
  METHODS
  After surgical resection of the tumor this system delivers a single dose fraction at the surface of an applicator irradiating the tumor bed through a 50 kV x-ray beam. The GATE MCS platform was used in this study combining the phase space obtained by modeling the x-ray source and the detailed modeling of the additional parts of the Intrabeam™ system. The model was validated by comparing simulated versus experimental measurements of depth dose curves (DDC) and isotropy. A clinical validation study was also carried out using patient computed tomography images.
  
  
  RESULTS
  The mean deviation between measured and simulated DDC was 2.9% ± 4.4% and 5.9% ± 5.7% for the bare needle and the use of applicators, respectively. A good agreement with experimental measurements was also found in terms of dose isotropy with a maximum difference of 2.04% for the 40 mm diameter applicator. A patient study revealed a mean absolute deviation of 0.06 Gy between simulated and thermoluminescent dosimeters (TLD) measured skin doses.
  
  
  CONCLUSIONS
  This study shows the potential of using the GATE MCS platform to model three-dimensional dose distributions of the Intrabeam™ system for use in IORT.
authors: a Inserm UMR1101 , LaTIM, Brest , France.|b Department of Radiotherapy , CHRU Brest , France.
authors: Dounia
authors: D
authors: Bouzid
authors: a Inserm UMR1101 , LaTIM, Brest , France.
authors: Julien
authors: J
authors: Bert
authors: c Department of Gynecology and Surgery , CHRU Brest , France.
authors: Pierre-Francois
authors: PF
authors: Dupre
authors: a Inserm UMR1101 , LaTIM, Brest , France.
authors: Saadia
authors: S
authors: Benhalouche
authors: a Inserm UMR1101 , LaTIM, Brest , France.|b Department of Radiotherapy , CHRU Brest , France.
authors: Olivier
authors: O
authors: Pradier
authors: a Inserm UMR1101 , LaTIM, Brest , France.|b Department of Radiotherapy , CHRU Brest , France.
authors: Nicolas
authors: N
authors: Boussion
authors: a Inserm UMR1101 , LaTIM, Brest , France.
authors: Dimitris
authors: D
authors: Visvikis
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000601:surgery*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007430:Intraoperative Care; D015412:Mastectomy, Segmental; D008962:Models, Theoretical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011878:Radiotherapy / Q000295:instrumentation; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted; D012867:Skin; D013819:Thermoluminescent Dosimetry; D014057:Tomography, X-Ray Computed