Today, scientists and physicians measure exposure to X-rays and gamma rays using a unit of measurement known as the Roentgen. The scientist gained further recognition posthumously when international standards bodies named a newly discovered element, number 111 on the periodic table of elements, roentgentium in his honor.
A Glimpse at the Electromagnetic Spectrum
X-rays are essentially a form of light. They are part of the electromagnetic spectrum along with visible light, radio waves, microwaves, and gamma rays. The unique ability of X-rays to penetrate human flesh and other materials is due to their very short wavelength. Visible light has a wavelength of about 6,000 angstroms. (An angstrom is one ten-billionth of a meter – but don’t worry, you won’t be tested on these details.) The wavelength of the X-ray, in contrast, is about one angstrom. In essence, the waves are short enough to pass between the atoms in soft materials.
Modern X-ray machines work very much the way Roentgen’s original experiments worked. A medical X-ray is essentially a shadow cast by bones and other hard materials when X-rays are passed through the human body. X-rays are more detailed and more sensitive today largely because of improvements in the film plates on which the images are captured. Sources of X-rays are smaller, lighter, and less expensive than Roentgen’s originals, so they can be deployed widely in dentists’ offices, hospitals, and medical centers.
New Materials, New Approaches
By the middle of the twentieth century, the Manhattan Project and other scientific research programs had shone a light on the use of radiation, both in war and for peaceful uses. Physicians noted that radioactive materials shine brightly in X-ray scans, and gave birth to the field of nuclear medicine.
In diagnostic use, the term “nuclear medicine” refers to a variety of scans in which carefully controlled amounts of radioactive material are introduced into the patient’s body. When the patient is X-rayed or subjected to other radiographic imaging procedures, the radioactive substances provide clues as to the patient’s condition.
For example, a whole body scan using ingested or injected radioactive material can help doctors identify fractures, bone lesions, infections, sources of bone pain, or the spread of cancer.
A radioactive isotype of iodine is used in the diagnosis and study of hyperthyroidism.
Other nuclear medicine scans play a role in the noninvasive evaluation of coronary artery disease, thyroid cancers, gall bladder disease, pulmonary embolisms, and many other conditions.
Benefits of Radioactive Imaging
The use of different radioactive elements is key to nuclear medicine’s success in diagnosis. With different elements, medical technicians can target different organs, structures, or systems within the body. Different elements concentrate differently in bones, in the blood, in the lungs, in the brain – and so medical professionals have fine-tuned their work to highlight exactly the parts of the body they wish to examine.
Stay tuned for Part 3 of our Brief History of Radiology.