title: Contrast-enhanced radiography by differential absorption, using a laser-produced x-ray source.
abstract: OBJECTIVE
  The authors evaluate the feasibility of differential imaging of contrast media, with division of individual pixel values obtained from digital images generated by characteristic radiation from a laser-produced plasma, bridging the K-absorption edge of the contrast agent.
  
  
  METHODS
  Laser pulses from an ultrashort-pulse terawatt laser system were focused onto gadolinium and tantalum targets, creating a plasma from which characteristic radiation and Bremsstrahlung was emitted. The elements of the target were selected so the characteristic emission lines of one of the elements were below the K edge of the contrast agent and the emission lines of the other element above. A phantom with gadolinium and other elements in various concentrations was examined. One radiographic exposure was made using a gadolinium target source and a subsequent exposure using a tantalum source. Both images were recorded digitally and the transmission ratios calculated by division of the individual pixel values.
  
  
  RESULTS
  When viewed separately, the two images of the test phantom appeared similar. In the differential image, only the gadolinium solutions were bright, reflecting a difference in attenuation between the two exposures.
  
  
  CONCLUSIONS
  Element-specific radiographs can be obtained by differential imaging. When fully explored, the technique may allow for contrast-enhanced radiography with increased sensitivity and decreased contrast dose.
authors.affiliation: Department of Radiology, University Hospital, Lund, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Herrlin
authors.forename: C
authors.initials: C
authors.lastname: Tillman
authors.forename: M
authors.initials: M
authors.lastname: Grätz
authors.forename: C
authors.initials: C
authors.lastname: Olsson
authors.forename: H
authors.initials: H
authors.lastname: Pettersson
authors.forename: G
authors.initials: G
authors.lastname: Svahn
authors.forename: C G
authors.initials: CG
authors.lastname: Wahlström
authors.forename: S
authors.initials: S
authors.lastname: Svanberg
mesh_terms: D000818:Animals; D002563:Cerium; D003287:Contrast Media; D005682:Gadolinium; D007834:Lasers; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement; D011859:Radiography; D051381:Rats; D011920:Rats, Inbred WF
chemical_list: D003287:Contrast Media; D002563:Cerium; D005682:Gadolinium