Uncertainty in treatment of head-and-neck tumors by use of intraoral mouthpiece and embedded fiducials

Masataka Oita, Keiichi Ohmori, Kenichi Obinata, Rumiko Kinoshita, Rikiya Onimaru, Kazuhiko Tsuchiya, Keishirou Suzuki, Takeshi Nishioka, Hiroyasu Ohsaka, Katsuhisa Fujita, Teppei Shimamura, Hiroki Shirato, Kazuo Miyasaka

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Purpose: To reduce setup error and intrafractional movement in head-and-neck treatment, a real-time tumor tracking radiotherapy (RTRT) system was used with the aid of gold markers implanted in a mouthpiece. Methods and Materials: Three 2-mm gold markers were implanted into a mouthpiece that had been custom made for each patient before the treatment planning process. Setup errors in the conventional immobilization system using the shell (manual setup) and in the RTRT system (RTRT setup) were compared. Eight patients with pharyngeal tumors were enrolled. Results: The systematic setup errors were 1.8, 1.6, and 1.1 mm in the manual setup and 0.2, 0.3, and 0.3 mm in the RTRT setup in right-left, craniocaudal, and AP directions, respectively. Statistically significant differences were observed with respect to the variances in setup error (p <0.001). The systematic and random intrafractional errors were maintained within the ranges of 0.2-0.6 mm and 1.0-2.0 mm, respectively. The rotational systematic and random intrafractional errors were estimated to be 2.2-3.2°and 1.5-1.6°, respectively. Conclusions: The setup error and planning target volume margin can be significantly reduced using an RTRT system with a mouthpiece and three gold markers.

Original languageEnglish
Pages (from-to)1581-1588
Number of pages8
JournalInternational Journal of Radiation Oncology Biology Physics
Issue number5
Publication statusPublished - Apr 1 2006
Externally publishedYes


  • Head and neck
  • Intensity-modulated radiotherapy
  • Radiotherapy
  • Setup error

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research


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