This page was created by Chase Richard Carlile.
Visualizing the Inside of the Human Body: Machines
X-rays were discovered in 1895 by Wilhelm Conrad Roentgen (1845-1923) who was a Professor at Wuerzburg University in Germany. Working with a cathode-ray tube in his laboratory, Roentgen observed a fluorescent glow of crystals on a table near his tube. The tube that Roentgen was working with consisted of a glass envelope (bulb) with positive and negative electrodes encapsulated in it. The air in the tube was evacuated, and when a high voltage was applied, the tube produced a fluorescent glow. Roentgen shielded the tube with heavy black paper and discovered a green colored fluorescent light generated by a material located a few feet away from the tube. He concluded that a new type of ray was being emitted from the tube. This ray was capable of passing through the heavy paper covering and exciting the phosphorescent materials in the room. He found that the new ray could pass through most substances casting shadows of solid objects. Roentgen also discovered that the ray could pass through the tissue of humans, but not bones and metal objects. One of Roentgen's first experiments late in 1895 was a film of the hand of his wife, Bertha. It is interesting that the first use of X-rays was for an industrial (not medical) application, as Roentgen produced a radiograph of a set of weights in a box to show his colleagues. Roentgen's discovery was a scientific bombshell and was received with extraordinary interest by both scientist and laymen. Scientists everywhere could duplicate his experiment because the cathode tube was very well known during this period. Many scientists dropped other lines of research to pursue the mysterious rays. Newspapers and magazines of the day provided the public with numerous stories, some true, others fanciful, about the properties of the newly discovered rays. Public fancy was caught by this invisible ray with the ability to pass through solid matter, and, in conjunction with a photographic plate, provide a picture of bones and interior body parts. The demonstration of a wavelength captured scientific fancy shorter than light. These generated new possibilities in physics, and for investigating the structure of matter. Much enthusiasm was generated about potential applications of rays as an aid in medicine and surgery. Within a month after the announcement of the discovery, several medical radiographs had been made in Europe and the United States, which were used by surgeons to guide them in their work. In June 1896, only 6 months after Roentgen announced his discovery, battlefield physicians were using X-rays to locate bullets in wounded soldiers.
Ultrasound imaging involves bouncing "ultrasonic" sound waves — above the audible range of human hearing — at body structures or tissues and detecting the echoes that bounce back. Obstetric ultrasonography is used to image a human fetus inside its mother's womb. It's used to confirm a pregnancy, to identify the sex and number of fetuses and to detect fetal abnormalities such as microcephaly (an abnormally small head), absence of kidneys, and spinal problems. During a scan, ultrasound waves are aimed at a pregnant women's abdomen. Based on the angle of the beam, and the time it takes for echoes to return, an image of body structures inside the fetus can be generated. Early in the use of fetal ultrasound, clinicians could only detect the baby's head, Nicolson said. "But gradually, with developing expertise, they could discern fine structures in the fetus," he said.
Magnetic Resonance Imaging (MRI), as with all medical imaging techniques, is a relatively recent technology with its foundations beginning during the year of 1946. Felix Bloch and Edward Purcell independently discovered the magnetic resonance phenomena during this year and were later awarded the Nobel Prize in 1952. Up until the 1970s MRI was being used for chemical and physical analysis. Then in 1971 Raymond Damadian showed that nuclear magnetic relaxation times of tissues and tumors differed motivating scientists to use MRI to study disease. With the advent of computed tomography (using computer techniques to develop images from MRI information) in 1973 by Hounsfield, and echo-planar imaging (a rapid imaging technique) in 1977 by Mansfield, many scientists over the next 20 years developed MRI into the technology that we now know today. Perhaps one of the most exciting developments of these was the advent of superconductors. These superconductors make the strong magnetic fields used in MRIs possible. Due to all of these technologies required, the first human being MRI examination did not occur until 1977. Since then, faster computing has made the MRI process much faster. The most significant advancement in MRIs occurred in 2003, when the Nobel Prize was won by Paul C. Lauterbur and Peter Mansfield for their discoveries of using MRIs as a diagnostic tool.
