title: Does hormone therapy modify the position of the gold markers in the prostate during irradiation? A daily evaluation with kV-images.
abstract: OBJECTIVE
  Gold markers are frequently used for a better daily repositioning of the prostate before irradiation. The purpose of this work was to analyze if the combination of an androgen deprivation with the external irradiation could modify the position of the gold markers in the prostate.
  
  
  METHODS
  Ten patients have been treated for a prostate cancer, using three implanted gold markers. The variations of the intermarker distances in the prostate were measured and collected on daily OBI(®) kilovoltage images acquired at 0° and 90°. Five patients had a 6-month androgen deprivation started before the external irradiation (H group) and five did not (NH group).
  
  
  RESULTS
  A total number of 1062 distances were calculated. No distance variation greater than 3.7mm was seen between two markers, in any of the two groups. The median standard deviations of the daily intermarker distance differences were 0.7mm (range 0.3-1.2mm) for the H group and 0.6mm (range 0.2-1.2mm) for the NH group. The intermarker distances variations were noted as greater than -2mm, between -2mm and 2mm and greater than 2mm in 16.4, 83.4 and 0.2% for the H group and 1.3, 98.5 and 0.2% for the NH group, respectively.
  
  
  CONCLUSIONS
  The distance variations remained less than 4mm in both groups and for all the measurements. In the NH group, the variation of the distance between two markers remained below 2mm in 98.5%. In the H group, the presence of a reduction of distance above 2mm in 16.4% of measurements could indicate the shrinkage of the prostate volume.
authors.affiliation: Department of radiation oncology, centre hospitalier Lyon-Sud, hospices civils de Lyon, 165, chemin du Grand-Revoyet, 69495 Pierre-Bénite, France.
authors.forename: C
authors.initials: C
authors.lastname: Udrescu
authors.forename: B
authors.initials: B
authors.lastname: De Bari
authors.forename: O
authors.initials: O
authors.lastname: Rouvière
authors.forename: A
authors.initials: A
authors.lastname: Ruffion
authors.forename: G
authors.initials: G
authors.lastname: Michel-Amadry
authors.forename: P
authors.initials: P
authors.lastname: Jalade
authors.forename: M
authors.initials: M
authors.lastname: Devonec
authors.forename: M
authors.initials: M
authors.lastname: Colombel
authors.forename: O
authors.initials: O
authors.lastname: Chapet
mesh_terms: D000726:Androgen Antagonists / Q000627:therapeutic use*; D057918:Fiducial Markers; D006046:Gold; D006801:Humans; D008297:Male; D011467:Prostate / Q000000981:diagnostic imaging*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed
chemical_list: D000726:Androgen Antagonists; D006046:Gold