A proposal has been made to measure the compressed fuel areal density, ρR, in inertial confinement fusion targets by detecting the radionuclides produced by the absorption of fusion charged particles in the target shell material. Calculations were performed for a deuterium-tritium pellet surrounded by a shell of either Li2SiO3 or B2O3, and the ratio of the number of proton reaction products in 7Li, 10B, or 11B to the number of deuterium-deuterium neutrons was obtained as a function of pellet ρR. The results show a strong dependence of this ratio on ρR for ρR values between 0.01 and 2.0 g/cm2. Methods for independently determining fuel ion temperature and shell ρR are also discussed.