The efficiency of 14C detection in autoradiographs of semithin plastic sections.

Sections of uniformly labeled 14C-methylmethacrylate were used to determine the efficiency of 14C detection by Ilford L4 emulsion layers, 0.22 mu in thickness, in light microscope autoradiographs. When efficiency was expressed as a function of radiation dose (i.e., the number of decays/mu2) there was a strong dependency on radiation dose up to about 6 decays/mu2, after which detection efficiency was fairly constant. For most emulsion batches, the detection efficiency was about 5%, but it ranged from 8 to 3%.