title: Long-term in-vitro precision of direct digital X-ray radiogrammetry.
abstract: OBJECTIVE
  Digital X-ray radiogrammetry (DXR) calculates peripheral bone mineral density (BMD) from hand radiographs. The short-term precision for direct DXR has been reported to be highly satisfactory. However, long-term precision for this method has not been examined. Thus, the aim of this study was to examine the long-term in-vitro precision for the new direct digital version of DXR.
  
  
  METHODS
  The in-vitro precision for direct DXR was tested with cadaver phantoms on four different X-ray systems at baseline, 3 months, 6 months, and in one machine also at 12 months. At each time point, 31 measurements were performed.
  
  
  RESULTS
  The in-vitro longitudinal precision for the four radiographic systems ranged from 0.22 to 0.43% expressed as coefficient of variation (CV%). The smallest detectable difference (SDD) ranged from 0.0034 to 0.0054 g/cm(2).
  
  
  CONCLUSIONS
  The in vitro long-term precision for direct DXR was comparable to the previous reported short-term in-vitro precision for all tested X-ray systems. These data show that DXR is a stable method for detecting small changes in bone density during 6-12 months of follow-up.
authors.affiliation: INM, Rheumatology, Norwegian University of Science and Technology, MTS, 7489 Trondheim, Norway. alvilde.dhainaut@ntnu.no
authors.forename: Alvilde
authors.initials: A
authors.lastname: Dhainaut
authors.forename: Mari
authors.initials: M
authors.lastname: Hoff
authors.forename: Johan
authors.initials: J
authors.lastname: Kälvesten
authors.forename: Stian
authors.initials: S
authors.lastname: Lydersen
authors.forename: Kristina
authors.initials: K
authors.lastname: Forslind
authors.forename: Glenn
authors.initials: G
authors.lastname: Haugeberg
mesh_terms: D015519:Bone Density; D002102:Cadaver; D006225:Hand / Q000000981:diagnostic imaging*; D006801:Humans; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement; D015203:Reproducibility of Results; D013997:Time Factors