title: Fiducial markers and spacers in prostate radiotherapy: current applications.
abstract: OBJECTIVE
  To review the use of fiducial markers and spacers in prostate radiotherapy (RT).
  
  
  METHODS
  We reviewed the literature on the use of fiducial markers to improve accuracy in delivery of RT for prostate cancer. We discuss the rationale for fiducials, the types available, the procedures and complications. We also reviewed the current literature on the novel use of spacers to reduce rectal toxicity during prostate irradiation.
  
  
  RESULTS
  Prostate motion is a significant problem both during and between RT treatments. Intraprostatic fiducials allow accurate prostate localisation ensuring RT treatment accuracy. Insertion of gold fiducials are a cost-effective marker that can be easily and quickly implanted and at least three fiducials are recommended. Severe complications from fiducial implantation are uncommon and marker migration is very rarely clinically significant. Spacers are a novel method to distance the rectum from the prostate during RT, reducing acute rectal toxicity, and have no detrimental impact on health-related quality of life.
  
  
  CONCLUSIONS
  Intraprostatic fiducials are now standard of care when delivering prostate RT and early data shows benefit of spacers in reducing RT rectal toxicity.
authors.affiliation: Radiation Oncology Victoria, Melbourne, VIC, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Ng
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Brown
authors.forename: Andrew
authors.initials: A
authors.lastname: Williams
authors.forename: Michael
authors.initials: M
authors.lastname: Chao
authors.forename: Nathan
authors.initials: N
authors.lastname: Lawrentschuk
authors.forename: Raphael
authors.initials: R
authors.lastname: Chee
mesh_terms: D057918:Fiducial Markers / Q000009:adverse effects; D005548:Foreign-Body Migration / Q000517:prevention & control; D006801:Humans; D008297:Male; D009068:Movement; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D011788:Quality of Life; D011835:Radiation Protection; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D016032:Randomized Controlled Trials as Topic; D012007:Rectum / Q000473:pathology / Q000528:radiation effects*; D015203:Reproducibility of Results
keywords: cancer; fiducials; prostate; radiotherapy; spacers