[en] A procedure has been established to identify lead-toxic children who qualify for chelation therapy by using a non-invasive L-line X ray fluorescence assessment of lead in the cortical bone of the tibia. The distributions of the absorbed dose from this procedure were determined by measurements of radiation to humans and to human phantoms from each of the two L-line X ray fluorescence instruments that are now in clinical use. An L-line X ray fluorescence test delivers an effective dose equivalent (H_E) to the patient that varies with the patient's age. H_E from one test is about 6 μSv for a one year old child, about 3 μSv for older children, and slightly under 2 μSv for adults. (author)