Radiation may sound like an ominous term. After all, most of us have seen the power of nuclear radiation in the movies and in our history books in relation to manmade disasters. The term “radiation” can conjure up fears about cancer and radiation poisoning.
However, technology has advanced tremendously since scientists first began to understand radiation, and we can now harness this force of nature in marvelous ways. For example, microwave ovens harness radiation (microwaves) to safely heat food and drink. Doctors also routinely use radiation to diagnose conditions that are otherwise invisible, and radiation is used to treat diseases. So, when is radiation helpful, and under what circumstances can it be harmful?
Radiation is All Around Us
Everything in the world is subjected to environmental radiation. In fact, our lives depend on radiation, because this phenomenon allows the sun to provide warmth and light. Everyday sources of radiation include:
- Space: The sun is one of many sources of cosmic radiation. Generally, the closer you are to outer space, the greater the radiation exposure from cosmic rays. For example, a person that travels more frequently by plane experiences more cosmic radiation.
- Food and drink: A natural diet will always have a certain amount of radiation because all matter exists in a balance of stable and radioactive forms.
- Air: Even far from civilization, the air is filled with naturally occurring radiation from radon, a radioactive gas, which is released from the Earth’s soil. Radon is the most prevalent source of radiation exposure over the course of one’s life.
Radiation is energy emitted by waves or particles. You may have heard of the “electromagnetic spectrum,” which depicts electromagnetic wavelengths.
Lower energy electromagnetic waves include visible light waves and radio waves. Cellphones, WiFi, and remote controls all use lower energy electromagnetic waves, which means they all use radiation.
Higher energy electromagnetic waves are ultraviolet light, x-rays, and gamma rays. High energy electromagnetic waves can be used in low doses to get images, like dental x-rays, or in high doses to sterilize medical equipment.
Radiation from matter pertains to radioactive decay resulting in nuclear radiation. Nuclear radiation is the result of subatomic particles shooting off the nucleus of radioactive substances. Unlike electromagnetic radiation, nuclear radiation often carries mass or charge. While nuclear technology for weapons, electricity generation, or oil exploration may come to mind, nuclear technology is also used in medicine.
Non-Ionizing and Ionizing Radiation
Radiation is described as either “non-ionizing” or “ionizing,” referring to whether the radiation has enough energy to displace particles from atoms. When radiation does not have enough energy to alter the structure of molecules, it is said to be non-ionizing. Visible light waves, infrared waves, microwaves, and radio waves are all examples of non-ionizing radiation.
On the other hand, ionizing radiation has enough energy to change molecular structures. X-rays, gamma rays, and neutron radiation (created in the process of nuclear fission to generate electricity) are examples of ionizing radiation.
Exposure to ionizing radiation can be harmful, even deadly. It can cause radiation poisoning, cancer, or inherited genetic defects. However, in medicine, controlled exposures to ionizing radiation can be helpful.
So, what makes the distinction between helpful radiation and harmful radiation? It is all about the type and dose. The type determines how deeply the radiation energy can penetrate the body (for example, x-rays penetrate differently than gamma rays). The dose is the amount of energy the radiation deposits per unit of body mass.
X-Ray Machines and CT Scanners
X-ray machines have been a standard part of medical evaluations since the early 1900s. X-ray technologists and radiologists are trained to minimize the dose of radiation on patients, so that only the smallest dose necessary to obtain the image is used. Radiation shielding techniques, such as lead aprons, block unnecessary radiation exposures. Healthcare providers are also trained to only use x-ray machines or CT scanners (which also use x-ray waves) when needed to help diagnose conditions. As with many aspects of medicine, imaging is used only when the benefits outweigh the risks. For example, it is both safer and more cost-effective to have a CT scan rather than an exploratory surgery in order to find the cause of a medical problem.
In the medical setting, nuclear imaging can be done in a variety of ways, but never at a type or dose that would be harmful. We can confidently assure their safety because nuclear medicine has now been used for more than five decades. Nuclear imaging generally refers to the use of radioactive substances that have negligible effect on the body but emit enough radiation to be detected by gamma cameras. These techniques can diagnose conditions like cancer, heart disease, and hyperthyroidism among others.
Internal and external radiation can be used to treat cancers or growths (such as a vessel or nerve malformations). Traditionally, external radiation focuses a beam of high-energy x-rays at the disease. Another very precise form of external radiation uses gamma rays to target lesions, such as tumors, in the brain.
Internal radiation, also called brachytherapy, involves implanting particles of radioactive substances in the body to better target hard-to-reach tumors, such as prostate cancer or thyroid cancer. This method delivers a high intensity but short-range radiation treatment, so less of the healthy tissue around the disease is damaged. New forms of highly specific nuclear medicine-based treatments are constantly being developed and being made available to patients.
How to Minimize Your Exposure to Ionizing Radiation
You can view a personalized estimate of your exposure to radiation by visiting the Environmental Protection Agency’s Calculate Your Radiation Dose webpage. You can drastically reduce your lifetime radiation dose by using a radon-mitigation device in your home. Radon gas exposure is the second-leading cause of lung cancer in the United States. If you work around nuclear materials, you have the right to know your level of exposure and may visit the U.S. Nuclear Regulatory Commission to learn about ways to protect yourself from radiation.
To decrease any potentially unnecessary medical exposures to radiation, ask your healthcare provider if any low-radiation options would offer similar benefits. You may consider keeping a record of your imaging if you have a condition that requires frequent imaging, especially if that imaging is ordered by different clinics or hospitals. Knowing your radiation history may help your healthcare provider to determine which imaging modality is right for you.
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American Cancer Society, “Radon and Cancer,” September 23, 2015, https://www.cancer.org/cancer/cancer-causes/radiation-exposure/radon.html
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