Screening methods radioisotope

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.

There are two methods that can be used to make activity-weighted size distribution measurements screen diffusion batteries (Hopke et al., 1992 Cheng et al., 1994) and all-type cascade impactors. Although screen diffusion batteries have been widely used, the activity size distribution cannot be easily obtained with them due to technical and calculation complexities. Even when conventional equipment and the impactor method are used it is difficult to obtain a result that is not affected by the decay of the radioisotopes. 

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