When a radioactive substance is placed on a surface containing a photographic emulsion, the ionizing radiations affect the silver halide in the emulsion and a blackening is observed when the emulsion is developed. The result is a self-portrait, or what is known as an autoradiograph. Today, the silver halide is usually silver bromide in a gelatin matrix (Hendee, 1973a). According to Rogers (1973), the first autoradiograph was produced by Niepce de St. Victor in 1867 when he observed blackening on emulsions of silver chloride and iodide when the emulsions were exposed to uranium nitrate and tartrate. Henri Becquerel, using uranyl sulfate exposed to sunlight, observed blackening on a photographic plate. Rogers (1973) remarked that autoradiography did not become a scientific technique until 1924, when Lacassagne and associates used the process to study the distribution of polonium in biological specimens. Today, it is a widely accepted technique used to observe the location of radioactivity within physical or biological specimens.
KeywordsSilver Halide Beta Radiation Giant Clam Pitcher Plant Gelatin Matrix
Unable to display preview. Download preview PDF.