Christine Craig, 21st Century Science & Technology - The use of radioisotopes for the diagnosis and treatment of disease is now a vital part of modern medical practice. The most vulnerable link is the production and supply lines of the medical radioisotope most in demand throughout the world, technetium-99m. The United States is left with no domestic source (2010) for an isotope that is used in more than 30 million diagnostic procedures each year worldwide, and almost 20 million procedures in the United States alone.