title: Clinical use of a novel in vivo 4D monitoring system for simultaneous patient motion and dose measurements.
abstract: OBJECTIVE
  A new 4D in vivo dosimetry tool, RADPOS, has been used on lung cancer patients to evaluate the feasibility of using the detectors to characterize variations in patient breathing patterns as well as to monitor daily variations in dose.
  
  
  METHODS
  The RADPOS system combines a MOSFET dosimeter with an electromagnetic positioning sensor for simultaneous measurement of real-time dose and spatial coordinates. Three RADPOS sensors were placed on patients' chest and abdomen during a 4DCT and daily treatments. A fourth detector was also placed on the couch as reference. Position data were collected in real-time and total dose was read at the end of each fraction.
  
  
  RESULTS
  Significant deviations in surface motion have been found between the day of 4DCT and treatment fractions in 9 of 10 patients. Variations in daily dose ranged from 2.5 to 13.7 cGy (2.8-14.0%) and results agreed with treatment plan values for all but three points.
  
  
  CONCLUSIONS
  Changes in breathing motion have been found that emphasize a need for continued position monitoring. RADPOS measurements can be used to monitor such variations as well as to measure surface dose without any disruption to the treatment schedule or discomfort to patients.
authors.affiliation: The Ottawa Hospital Cancer Centre, Ontario, Canada. acherpak@ottawahospital.on.ca
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Cherpak
authors.forename: Joanna E
authors.initials: JE
authors.lastname: Cygler
authors.forename: Steve
authors.initials: S
authors.lastname: Andrusyk
authors.forename: Jason
authors.initials: J
authors.lastname: Pantarotto
authors.forename: Robert
authors.initials: R
authors.lastname: MacRae
authors.forename: Gad
authors.initials: G
authors.lastname: Perry
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D055590:Electromagnetic Phenomena; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009038:Motion; D019047:Phantoms, Imaging; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome