Fluorography intensifying screens

Latent image formation is most stable at low temperature ( - 70°C) and methods based on light photons (fluorography intensifying screens) should be done at this temperature (difference can be five-fold). Low temperatures do not improve latent image stability for direct exposure and ionizing radiation. 

Fig. 7.1. Three types of autoradiography can be distinguished (i) direct exposure (direct contact of specimen with film, usually separated just by a Saran wrap for wet specimens) (ii) fluorography in which fluors are excited by the radiation resulting in multiple photons per -particle (iii) phosphor-intensifying screens which can absorb radiation under the emission of photons (most stable in the cold). The proper choice of method depends on the penetration level of the radioisotope and the intensity of radiation.

Intensifying screens are used for P whereas fluorography can be used for C, H. Some highly radioactive samples may require very short exposure times or slower films without screens. 

R. A. Laskey, Radioisotope Detection by Fluorography and Intensifying Screens. Review 23, Amersham Corp., Arlington Heights, 111., 1984. 

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