Migration from full-head mask to "open-face" mask for immobilization of patients with head and neck cancer

Guang Li, D. Michael Lovelock, James Mechalakos, Shyam Rao, Cesar Della-Biancia, Howard Amols, Nancy Lee

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

To provide an alternative device for immobilization of the head while easing claustrophobia and improving comfort, an "open-face" thermoplastic mask was evaluated using video-based optical surface imaging (OSI) and kilovoltage (kV) X-ray radiography. A three-point thermoplastic head mask with a precut opening and reinforced strips was developed. After molding, it provided sufficient visible facial area as the region of interest for OSI. Using real-time OSI, the head motion of ten volunteers in the new mask was evaluated during mask locking and 15minutes lying on the treatment couch. Using a nose mark with reference to room lasers, forced head movement in open-face and full-head masks (with a nose hole) was compared. Five patients with claustrophobia were immobilized with open-face masks, set up using OSI and kV, and treated in 121 fractions, in which 61 fractions were monitored during treatment using real-time OSI. With the open-face mask, head motion was found to be 1.0 ± 0.6 mm and 0.4° ± 0.2° in volunteers during the experiment, and 0.8 ± 0.3 mm and 0.4° ± 0.2° in patients during treatment. These agree with patient motion calculated from pre-/post-treatment OSI and kV data using different anatomical landmarks. In volunteers, the head shift induced by mask-locking was 2.3 ± 1.7 mm and 1.8° ± 0.6°, and the range of forced movements in the open-face and full-head masks were found to be similar. Most (80%) of the volunteers preferred the open-face mask to the full-head mask, while claustrophobic patients could only tolerate the open-face mask. The open-face mask is characterized for its immobilization capability and can immobilize patients sufficiently (< 2 mm) during radiotherapy. It provides a clinical solution to the immobilization of patients with head and neck (HN) cancer undergoing radiotherapy, and is particularly beneficial for claustrophobic patients. This new open-face mask is readily adopted in radiotherapy clinic as a superior alternative to the standard full-head mask.

Original languageEnglish (US)
Pages (from-to)243-254
Number of pages12
JournalJournal of Applied Clinical Medical Physics
Volume14
Issue number5
DOIs
StatePublished - Jan 1 2013
Externally publishedYes

Keywords

  • Image-guided radiotherapy
  • Motion uncertainty
  • Optical surface imaging
  • Patient setup and immobilization
  • Thermoplastic head mask

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Radiology Nuclear Medicine and imaging

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