title: Shift in imaging modalities of the spine through 25 years and its impact on patient ionizing radiation doses.
abstract: METHODS
  Retrospective.
  
  
  OBJECTIVE
  To explore the shift in modalities when diagnosing the spine in the years 1979-2003. To see how this shift, together with a radiation protective policy, have influenced on the ionizing radiation doses.
  
  
  BACKGROUND
  The shift from CT/myelography to MR when diagnosing the spine is well known. To what extent this has changed the radiation doses has to our knowledge not yet been published.
  
  
  METHODS
  Activity reports from a department of radiology have been reviewed. Relevant radiation doses estimates have been obtained from the Norwegian Radiation Protection Authority.
  
  
  RESULTS
  MRI was introduced in 1992 and has been used increasingly since then. Conventional X-ray to the spine has been practically unchanged. Myelography and CT decreased markedly after the introduction of MRI. The total number of examinations of the spine has increased, but the radiation doses given have decreased since 1993.
  
  
  CONCLUSIONS
  The introduction of MRI together with a radiation protective policy have reduced the ionizing radiation doses given to this population, in spite of an increase in the total number of examinations of the spine.
authors.affiliation: Department of Radiology, Hospital of Buskerud, Dronning Gaten 28, Drammen, Norway. lars.borgen@sb-hf.no
authors.forename: Lars
authors.initials: L
authors.lastname: Borgen
authors.forename: Harald
authors.initials: H
authors.lastname: Østensen
authors.forename: Erling
authors.initials: E
authors.lastname: Stranden
authors.forename: Hilde Marie
authors.initials: HM
authors.lastname: Olerud
authors.forename: Tor Erik
authors.initials: TE
authors.lastname: Gudmundsen
mesh_terms: D001822:Body Burden; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data* / Q000639:trends; D009192:Myelography / Q000706:statistics & numerical data* / Q000639:trends; D009664:Norway / Q000453:epidemiology; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data / Q000639:trends; D011829:Radiation Dosage; D011835:Radiation Protection / Q000706:statistics & numerical data*; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D013116:Spinal Cord / Q000000981:diagnostic imaging* / Q000473:pathology*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data* / Q000639:trends