title: A real-time respiratory motion monitoring system using KINECT: proof of concept.
abstract: OBJECTIVE
  The purpose of this study is to investigate the feasibility of a low-cost respiratory motion monitoring system based on the Microsoft KINECT sensor.
  
  
  METHODS
  The authors increased KINECT's inherent depth resolution from 1 cm to 1 mm via a motion magnification system. Using the KINECT software development kit, the authors programmed the KINECT to capture depth images and determine the average depth over a thoracic region of interest, viewed almost parallel to the subject's surface. KINECT respiratory traces (average depth vs time at a rate of 30 Hz) were acquired from four volunteers and compared with those simultaneously acquired using a commercially available strain gauge respiratory gating system.
  
  
  RESULTS
  The correlation coefficient (CC) between KINECT and strain gauge traces varied from 0.958 to 0.978, with a mean CC of 0.969. This strong correlation was also demonstrated by the joint probability distribution and visual inspection.
  
  
  CONCLUSIONS
  It is feasible to use the KINECT for respiratory motion tracking. Traces are similar to those of a clinically used strain gauge system. The KINECT-based system provides a new and economical way to monitor respiratory motion.
authors.affiliation: Department of Radiation Oncology, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Junyi
authors.initials: J
authors.lastname: Xia
authors.forename: R Alfredo
authors.initials: RA
authors.lastname: Siochi
mesh_terms: D006801:Humans; D007259:Infrared Rays; D057054:Molecular Imaging / Q000295:instrumentation / Q000379:methods*; D009068:Movement; D012119:Respiration; D013997:Time Factors