Experimental surface or volume deposition of radionuclides in post-mortem specimens of trabecular bone

Techniques are described that have been developed to contaminate post-mortem specimens of human trabecular bone uniformly and artificially with three different radionuclides, 14C, 45Ca and 32P, so as to produce either a uniform volume deposition of radionuclide through the bone matrix or an 'infinitely' thin layer of radionuclide on the trabecular surfaces. Uniform volume depositions of 45C and 32P were produced by neutron activation and the 14C volume distribution was successfully achieved by rehydrating the bone matrix with 14C-labelled urea solution. Surface depositions of isotope were attempted by introducing a radionuclide into solution. Surface depositions of isotope were attempted by introducing a radionuclide into solution which was in equilibrium with trabecular bone and depositions approximating to an 'infinitely' thin layer of isotope were achieved for 32P and 14C using adenosine triphosphate-labelled molecules. Ionic calcium penetrates the bone matrix very rapidly and the best 45Ca surface deposition that could be produced penetrated the trabecular surface to an average depth of about 10 micrometer. The uniformity of deposition was analysed by autoradiography and the thickness of the 'surface' layer of radionuclide was estimated using microdensitometer scans across selected strands of the autoradiograph and comparing the film density profiles thus produced with calculations.