title: Patient positioning in radiotherapy based on surface imaging using time of flight cameras.
abstract: OBJECTIVE
  To evaluate the patient positioning accuracy in radiotherapy using a stereo-time of flight (ToF)-camera system.
  
  
  METHODS
  A system using two ToF cameras was used to scan the surface of the patients in order to position them daily on the treatment couch. The obtained point clouds were registered to (a) detect translations applied to the table (intrafraction motion) and (b) predict the displacement to be applied in order to place the patient in its reference position (interfraction motion). The measures provided by this system were compared to the effectively applied translations. The authors analyzed 150 fractions including lung, pelvis/prostate, and head and neck cancer patients.
  
  
  RESULTS
  The authors obtained small absolute errors for displacement detection: 0.8 ± 0.7, 0.8 ± 0.7, and 0.7 ± 0.6 mm along the vertical, longitudinal, and lateral axes, respectively, and 0.8 ± 0.7 mm for the total norm displacement. Lung cancer patients presented the largest errors with a respective mean of 1.1 ± 0.9, 0.9 ± 0.9, and 0.8 ± 0.7 mm.
  
  
  CONCLUSIONS
  The proposed stereo-ToF system allows for sufficient accuracy and faster patient repositioning in radiotherapy. Its capability to track the complete patient surface in real time could allow, in the future, not only for an accurate positioning but also a real time tracking of any patient intrafraction motion (translation, involuntary, and breathing).
authors.affiliation: INSERM, UMR 1101, LaTIM, Brest 29609, France.
authors.forename: M
authors.initials: M
authors.lastname: Gilles
authors.affiliation: INSERM, UMR 1101, LaTIM, Brest 29609, France.
authors.forename: H
authors.initials: H
authors.lastname: Fayad
authors.affiliation: Academic Radiotherapy Department, CHRU Morvan, Brest 29200, France.
authors.forename: P
authors.initials: P
authors.lastname: Miglierini
authors.affiliation: INSERM, UMR 1101, LaTIM, Brest 29609, France.
authors.forename: J F
authors.initials: JF
authors.lastname: Clement
authors.affiliation: Varian Medical Systems Imaging Laboratory GmbH, Baden-Daettwil 5405, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Scheib
authors.affiliation: Radiotherapy and Radiosurgery Department, Instituto Clinico Humanitas, Rozzano 20089, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Cozzi
authors.affiliation: INSERM, UMR 1101, LaTIM, Brest 29609, France.
authors.forename: J
authors.initials: J
authors.lastname: Bert
authors.affiliation: INSERM, UMR 1101, LaTIM, Brest 29609, France and Academic Radiotherapy Department, CHRU Morvan, Brest 29200, France.
authors.forename: N
authors.initials: N
authors.lastname: Boussion
authors.affiliation: INSERM, UMR 1101, LaTIM, Brest 29609, France and Academic Radiotherapy Department, CHRU Morvan, Brest 29200, France.
authors.forename: U
authors.initials: U
authors.lastname: Schick
authors.affiliation: INSERM, UMR 1101, LaTIM, Brest 29609, France and Academic Radiotherapy Department, CHRU Morvan, Brest 29200, France.
authors.forename: O
authors.initials: O
authors.lastname: Pradier
authors.affiliation: INSERM, UMR 1101, LaTIM, Brest 29609, France.
authors.forename: D
authors.initials: D
authors.lastname: Visvikis
mesh_terms: D019583:Dose Fractionation, Radiation; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000532:radiotherapy; D056888:Patient Positioning / Q000295:instrumentation*; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation*; D013997:Time Factors