title: Breath-hold monitoring and visual feedback for radiotherapy using a charge-coupled device camera and a head-mounted display: system development and feasibility.
abstract: OBJECTIVE
  The aim of this study was to present the technical aspects of the breath-hold technique with respiratory monitoring and visual feedback and to evaluate the feasibility of this system in healthy volunteers.
  
  
  METHODS
  To monitor respiration, the vertical position of the fiducial marker placed on the patient's abdomen was tracked by a machine vision system with a charge-coupled device camera. A monocular head-mounted display was used to provide the patient with visual feedback about the breathing trace. Five healthy male volunteers were enrolled in this study. They held their breath at the end-inspiration and the end-expiration phases. They performed five repetitions of the same type of 15-s breath-holds with and without a head-mounted display, respectively. A standard deviation of five mean positions of the fiducial marker during a 15-s breath-hold in each breath-hold type was used as the reproducibility value of breath-hold.
  
  
  RESULTS
  All five volunteers well tolerated the breath-hold maneuver. For the inspiration breath-hold, the standard deviations with and without visual feedback were 1.74 mm and 0.84 mm, respectively (P = 0.20). For the expiration breath-hold, the standard deviations with and without visual feedback were 0.63 mm and 0.96 mm, respectively (P = 0.025).
  
  
  CONCLUSIONS
  Our newly developed system might help the patient achieve improved breath-hold reproducibility.
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan. chukichi@radiol.med.kyushu-u.ac.jp
authors.forename: Tadamasa
authors.initials: T
authors.lastname: Yoshitake
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Nakamura
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Shioyama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nomoto
authors.forename: Saiji
authors.initials: S
authors.lastname: Ohga
authors.forename: Takashi
authors.initials: T
authors.lastname: Toba
authors.forename: Takehiro
authors.initials: T
authors.lastname: Shiinoki
authors.forename: Shigeo
authors.initials: S
authors.lastname: Anai
authors.forename: Hiromi
authors.initials: H
authors.lastname: Terashima
authors.forename: Junji
authors.initials: J
authors.lastname: Kishimoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
mesh_terms: D000005:Abdomen / Q000502:physiology; D000328:Adult; D005240:Feasibility Studies; D005246:Feedback; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy; D008175:Lung Neoplasms / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D009038:Motion; D009068:Movement; D011878:Radiotherapy / Q000379:methods; D012119:Respiration; D013238:Stereotaxic Techniques; D013909:Thorax / Q000502:physiology