Formation of the latent Image

• When film is exposed to x-rays and light from intensifying screens the silver halide crystals are affected forming theLatent image.
• The latent image is not visible since, although the reduction of silver halide to metallic silver has begun there is not enough of this to appear black.
• The silver halide in the emulsion is in the form of a crystal lattice containing (negative) bromide ions and (positive) silver ions.
• Some of these ions are free to move within the crystal lattice.
• Around the crystal lattice is a "barrier" of electrons.
• During manufacture a defect is introduced into the crystal ’sensitivity speck .
• When the film is exposed to ionising radiation:
  • Some of the bromide ions in the lattice emit electrons.
  • These electrons travel rapidly to the sensitivity speck which acts as anelectron trap.
  • The electron trap builds up a negative charge.
  • Silver ions are attracted to the negative charge.
  • The positive charge of the silver ions is neutralized by the electrons in the trap (reduction) and silver atoms are produced.
  • The presence of metallic silver in the crystal lattice makes a break in the electron barrier which surrounded it and it is therefore susceptible to the action of developer.

Development

Rinsing

Fixing

Washing

Drying

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.