III. TECHNOLOGY MILESTONES IN HEALTH AND MEDICINE III.5. Medical Testing and Disease Diagnostics Medical imaging technologies Devices such as x-ray machines and MRI (magnetic resonance imaging) scanners, revolutionary at the time of their discovery, are now a routine part of medical diagnosis and care. Wilhelm Konrad Roentgen, the German physicist who discovered x-rays in 1895, first produced an image of the bones in his wife’s hand. By 1900, every large hospital had an x-ray machine. Nuclear magnetic resonance (NMR) technology was used to determine chemical structures in the 1970s, and Magnetic Resonance Imaging scanners were approved for human use in Chemical contrasting agents and special film emulsions improve the diagnostic value of x-rays, CT scans (three-dimensional x-ray imaging, computer tomography), and MRI and ultra sound images. Medical isotopes Medical imaging has been much aided by the use of medical isotopes to determine the function of internal organs, following the pioneering work of Georg Hevesy, the Hungarian Nobel Laureate (1943). In 1935 Hevesy determined the phosphor metabolism mechanism using radioactive nuclides. Compounds are labeled with radioactive isotopes (such as technetium-99m and thallium-201) or radio-opaques (such as barium and iodine compounds). The radio-labeled compounds can then be tracked through the body by gamma-detecting cameras to provide useful images of the organs to which they are transported. The diagnostic applications of medical isotopes include tumor detection, diagnosis of liver disease, and the stress test for cardiac function. Development of chemical assays Today, we determine medical conditions by studying disease markers or drugs residues that can be chemically detected in blood, urine, feces, saliva, and perspiration. Laboratory testing, sophisticated computer-assisted analytical instruments, and at-home testing all measure fundamental chemical reactions. In the early 19th century, diagnoses was based on observing clinical symptoms; if a patient responded positively to a disease-specific treatment, then he or she must have the disease. Diagnostic testing began in 1882 when Paul Ehrlich observed that only the presence of typhoid bacillus (as identified by a certain dye) could prove a diagnosis of typhoid fever. Before, the diagnosis was based on the color of the patient’s skin. Evolution of personal monitoring Simplified at-home test kits facilitate the personal monitoring of human health. For example, diabetic patients once had to visit a laboratory to determine if sugar was present in their urine. In 1941, Miles Laboratories introduced the first convenient sugar-in-urine assay for home use. Although difficult to develop, dip-and-read urine tests were finally introduced in In the 1960s, the first portable, battery-operated blood glucose meter was introduced to work with chemical sticks to detect the glucose, considerably improving the quality of life for diabetic patients. In the 1970s and 1980s, home-use diagnostic kits for fecal occult blood, ovulation, pregnancy, and strep were introduced. The transilluminated hand of Ms.Roentgen