Resolution Testing in Autoradiography

THE resolution obtainable in autoradiographs has so far been estimated 1 by the sharpness obtainable when photographic emulsions are exposed in contact with biological sections in which radioactive isotopes have been deposited by biochemical processes. The distribution of the radioactive isotope will, however, vary from one specimen to another, and T. C. Evans 2 points out that even successive sections from the same specimen will not be absolutely identical. Strict comparisons of the resolution given by different techniques or photographic emulsions are thus most difficult to make.