Quantification in macroscopic autoradiography with carbon-14--an evaluation of the method.

Macroscopic autoradiograms can generally be quantified by exposing previously calibrated standard sources together with the labeled sections and measuring the silver grain density by photometric methods. Variation in section thickness is a real problem with isotopes like 14C, with beta-particles of higher energy than those of 3H. Differences in self-absorption between tissues may be neglected at low section thickness. A simple fitting procedure for non-linear relationship between radiation dose and optical density is described. The combined effect of the examined errors for the practical evaluation of autoradiograms is discussed.