title: Implanted gold markers for position verification during irradiation of head-and-neck cancers: a feasibility study.
abstract: OBJECTIVE
  To assess the toxicity and reliability of the use of implanted gold markers for position verification during irradiation of head-and-neck cancer.
  
  
  METHODS
  Ten patients with localized head-and-neck tumors received two gold markers in the parapharyngeal region. The acute and late radiation-related toxicity were scored prospectively using the Common Toxicity Criteria. The patients were immobilized during irradiation using a five-point mask. The marker location was detected in portal images taken with an a-Si flat panel imager. The intermarker distance, as well as the interfraction motion of the markers, was determined for all patients.
  
  
  RESULTS
  No acute major complications were observed. The acute toxicity grade was not greater than normally detected. The markers were visible in all images. On average, the projected intermarker distance varied 0.8 mm (1 standard deviation). A small time trend was observed in the intermarker distance for 3 patients. For these patients, at least one marker was located in the mucosa or pharyngeal constrictor muscle. Deeper-seated gold markers did not show a time trend in the intermarker distance. The random positioning uncertainty determined using the markers was on average 1.1 and 1.4 mm (1 SD) in the craniocaudal and AP direction, respectively.
  
  
  CONCLUSIONS
  The use of implanted gold markers for position verification during radiotherapy for head-and-neck cancer patients seems safe and feasible. To avoid any chance of migration, markers should be placed in deep muscular compartments.
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Bram
authors.initials: B
authors.lastname: van Asselen
authors.forename: Homan
authors.initials: H
authors.lastname: Dehnad
authors.forename: Cornelis P J
authors.initials: CP
authors.lastname: Raaijmakers
authors.forename: Jan J W
authors.initials: JJ
authors.lastname: Lagendijk
authors.forename: Chris H J
authors.initials: CH
authors.lastname: Terhaard
mesh_terms: D005240:Feasibility Studies; D006046:Gold / Q000009:adverse effects; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D006801:Humans; D012044:Regression Analysis; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed
chemical_list: D006046:Gold