Electron transmission radiography

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Description

A radiographic technique that uses secondary electrons emitted from a thin lead foil (100 to 250 ­­µm)to produce an image of the examined object on a radiographic film. Electron transmission radiography is conducted by placing a flat object in intimate contact with the emulsion side of a single coated radiographic or photographic film. A lead foil intensifying screen is then placed on the other side of the object. A radiotransparent weight or vacuum is applied to press the layers together and minimize air gaps which deteriorate the image quality. A high energy industrial X-ray generator (200-400 kV) is used to irradiate the lead foil causing it to emit low energy electrons (through photoelectric effect and/or Compton effect) which in turn pass through the object and expose the film. The film is less sensitive to the high energy X-rays that pass through the object. Inks and paints containing heavy elements may also act as a generating source of secondary electrons replacing those that the pigments blocked from the lead screen source. This technique can be used when beta radiography is not available.

Synonyms and Related Terms

electron radiography; radiographie par electrons secondaires (Fr.); Sekunderelektronenradiographie (Deut.); radiografia de electrões secundarios (Port.)

Additional Information

° D.Kushel, "Radiographic Methods Used in the Recording of Structure and Watermarks in Historic Papers" ° H.Tomimasu, D.Kim, P.Luner, M.Suk, "Comparison of Four Paper Imaging techniques: Beta Radiography, Electrography, Light Transmission and Soft X-radiography" TAPPI Journal, 74(7):165-175, 1991. ° C.Bridgman, "The Radiography of Paper" Studies in Conservation, 10(1):8-17, 1965. + D. Schnitger, "Radiographie mit Elektronen aus Metallverstärkerfolien - Darstellung der Radiographie mit Fotoelektronen aus Metallverstärkerfolien als zerstörungsfreies Prüfverfahren für dünne organische Werkstoffe. Forschungsbericht 103, BAM Berlin, ISBN 3-88314-328-6

Authority

  • External source or communication Comment: Jean-Louis Boutaine, 20/06/2007

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