title: [A Quality Assurance (QA) System with a Web Camera for High-dose-rate Brachytherapy].
abstract: OBJECTIVE
  The quality assurance (QA) system that simultaneously quantifies the position and duration of an (192)Ir source (dwell position and time) was developed and the performance of this system was evaluated in high-dose-rate brachytherapy.
  
  
  METHODS
  This QA system has two functions to verify and quantify dwell position and time by using a web camera. The web camera records 30 images per second in a range from 1,425 mm to 1,505 mm. A user verifies the source position from the web camera at real time. The source position and duration were quantified with the movie using in-house software which was applied with a template-matching technique.
  
  
  RESULTS
  This QA system allowed verification of the absolute position in real time and quantification of dwell position and time simultaneously. It was evident from the verification of the system that the mean of step size errors was 0.31±0.1 mm and that of dwell time errors 0.1±0.0 s. Absolute position errors can be determined with an accuracy of 1.0 mm at all dwell points in three step sizes and dwell time errors with an accuracy of 0.1% in more than 10.0 s of the planned time.
  
  
  CONCLUSIONS
  This system is to provide quick verification and quantification of the dwell position and time with high accuracy at various dwell positions without depending on the step size.
authors.affiliation: Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases.
authors.forename: Asako
authors.initials: A
authors.lastname: Hirose
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ueda
authors.forename: Shingo
authors.initials: S
authors.lastname: Oohira
authors.forename: Masaru
authors.initials: M
authors.lastname: Isono
authors.forename: Katsutomo
authors.initials: K
authors.lastname: Tsujii
authors.forename: Shouki
authors.initials: S
authors.lastname: Inui
authors.forename: Akira
authors.initials: A
authors.lastname: Masaoka
authors.forename: Makoto
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Teruki
authors.initials: T
authors.lastname: Teshima
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D011785:Quality Assurance, Health Care / Q000379:methods*; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided / Q000295:instrumentation* / Q000379:methods