In the early 20th century, before the harmful effects of radiation were fully understood, treatments involving X-rays and radioactive sources were haphazardly applied, often with unintended negative consequences. Today our modern understanding of the physics behind radioactivity allows it to be safely utilized for many applications in medicine, research, and industry.
Radiation Therapy & Sterilization
The potential for cellular damage by radiation can be harnessed for therapeutic use in the destruction of unwanted cells or tissue. Radiation therapy is the use of targeted ionizing radiation to kill cancerous cells by damaging their DNA molecules (Figure 11). The primary challenge in radiation therapy is to how to avoid damaging healthy cells, which often surround the target malignant cells. To accomplish this, technicians aim low-intensity beams of radiation from multiple angles so that they intersect at the location of the cancerous cells. The intersection point then absorbs a greater amount of radiation than the surrounding tissue. The deeply penetrating nature of gamma radiation makes it the most common form of radiation used for cancer treatment, although beta radiation is also used to treat skin cancer and tumors close to the surface of the body.
The potential for cellular damage by radiation can be harnessed for therapeutic use in the destruction of unwanted cells or tissue. Radiation therapy is the use of targeted ionizing radiation to kill cancerous cells by damaging their DNA molecules (Figure 11). The primary challenge in radiation therapy is to how to avoid damaging healthy cells, which often surround the target malignant cells. To accomplish this, technicians aim low-intensity beams of radiation from multiple angles so that they intersect at the location of the cancerous cells. The intersection point then absorbs a greater amount of radiation than the surrounding tissue. The deeply penetrating nature of gamma radiation makes it the most common form of radiation used for cancer treatment, although beta radiation is also used to treat skin cancer and tumors close to the surface of the body.
Radiation can also be used to sterilize foods in order to make them safer for consumption. Food irradiation, which has existed since the mid-20th century, uses small doses of gamma rays from radioactive cobalt-60 to kill insects, microbes, and parasites without negatively affecting the food. Produce such as eggs, grains, fruits, and vegetables can be treated with radiation to eliminate bacteria, prevent spoilage, and prolong shelf life. Irradiation does not cause food to become radioactive. However, it does cause slight chemical changes that can alter the flavor or nutritional content of food, much like cooking. In the United States, the U.S. Food and Drug Administration has approved food irradiation as a sterilization technique and regulates how it is used.
Radiation Treatment Interactive on BBC
Radiometric Dating
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Smoke Detectors Interactive on BBC
Smoke Detectors
Believe it or not, there is most likely a radioactive source in your own home. Many common household smoke detectors contain a tiny sample of americium-241, which undergoes alpha decay to become neptunium-237. The alpha particles emitted by the americium source ionize the air within a chamber of the detector, creating a weak but measurable current. When smoke enters the detector, it absorbs the alpha particles and decreases the current flow in the circuit, thus triggering the alarm. A typical new smoke detector contains less than 1 microgram of americium, which is not enough to pose a hazard to household occupants compared to other natural sources of radiation (Figure 13).
Believe it or not, there is most likely a radioactive source in your own home. Many common household smoke detectors contain a tiny sample of americium-241, which undergoes alpha decay to become neptunium-237. The alpha particles emitted by the americium source ionize the air within a chamber of the detector, creating a weak but measurable current. When smoke enters the detector, it absorbs the alpha particles and decreases the current flow in the circuit, thus triggering the alarm. A typical new smoke detector contains less than 1 microgram of americium, which is not enough to pose a hazard to household occupants compared to other natural sources of radiation (Figure 13).
Radioactive Tracers
Radioactive tracers also have wide applications outside of medicine. Agricultural researchers use radioactive tracers in fertilizers to examine how various nutrients are taken up by plants. This allows the researchers to determine how much fertilizer should be used and how it should be most effectively applied. Automobile engineers study the wear of pistons and other engine components by treating the cylinder walls with radioactive substances. The concentration of radioactive metal particles in the lubricating oil then provides a basis for comparing the effectiveness of various methods of lubrication.
In all of these cases, radioactive tracing provides a practical method for detecting and tracking individual atoms that would not be possible using conventional microscopy.