Beneficial Uses of Radiation

Chances are you've probably had at least one x-ray in your lifetime. But x-rays aren't the only way that ionizing radiation is used to diagnose and treat illnesses. Nuclear medicine and radiology procedures are among the best and most effective life-saving tools available, and they are helpful to a broad span of medical specialties, from pediatrics to cardiology to psychiatry.

What's the difference between radiology and nuclear medicine?

Both nuclear medicine and radiology are used in diagnostic procedures to examine a patient’s health and therapeutic procedures to treat illness, but they are used differently.

• In nuclear medicine, radioactive medicines and tracers are introduced into the body.
• In radiology, radiation penetrates the body from an external source, such as an x-ray machine.

Major advances in nuclear medicine diagnosis and treatment

Exploratory surgery used to be the way doctors investigated health problems. Doctors would cut, poke, and prod. But since the 1940’s, nuclear technologies have offered an increasing array of techniques that help patients avoid the pain of surgery while their physicians gain knowledge of the body’s inner workings.

• Radiotherapy for cancer treatment includes use of x-rays, gamma rays and particle sources. Patients receive a plan specifically developed for them by their oncologist. In some cases, the radiation can be delivered externally, or a radioactive source might be implanted in the body.
• Gamma radiation is now used instead of traditional surgery to treat a number of conditions of the brain. Called "Gamma Knife" radio surgery, the procedure is so precise that it delivers an intense, targeted dose of radiation to the tumor with minimal effect on surrounding, healthy tissue.
• X-rays, MRI scanners, and CT scans troubleshoot different parts of the body and diagnose conditions. Each of these is a non-invasive procedure, so patients avoid surgery.
• Nuclear imaging uses computers, detectors, and radioisotopes to give doctors even more information about a patient’s internal workings. These procedures include bone scanning, Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and Cardiovascular Imaging.
• Radioisotopes are useful because the radiation they emit can be located in the body. The isotopes can be administered by injection, inhalation, or orally. A gamma camera captures images from isotopes in the body that emit radiation. Then, computers enhance the image, allowing physicians to detect tumors and fractures, measure blood flow, or determine thyroid and pulmonary functions.

Powering space missions

Radioisotopic Thermoelectric Generators (RTGs) have been used in more than 25 space missions, providing power for Voyager 1 and 2, several Apollo missions, Galileo, Nimbus and LES. An RTG will power the next Mars mission: Mars 2020.

RTGs are generators attached to a spacecraft that supply power and heat; they use a plutonium isotope for fuel. As the isotope decays, it gives off heat, which is used to generate electricity through a thermocouple device--a process known as thermoelectric conversion. The decay heat warms one end of the thermocouple, and the cold environment of space cools the other. This produces an electric current that powers the spacecraft. Excess decay heat is also pumped through the spacecraft’s systems to warm up its instruments and subsystems, allowing it to operate in cold environments.

RTGs have enabled major scientific accomplishments including:

• the Cassini spacecraft and Huygens probe’s exploration of Saturn and Titan, one of its moons, since 2004
• the landing of the Curiosity rover on Mars in 2014
• the flyby images of Pluto from the New Horizons mission in 2015

NASA is now working on new RTG technologies capable of generating even more electricity with less fuel.

Instruments and experiments

Nuclear technology in space exploration is not limited to the use of radioactive decay heat for power.

Special instruments are used to detect radiation and determine the composition of distant stars or another planet’s rocks, atmosphere, and soil, among many other things. The data is valuable for experiments taking place back on Earth.

Life on Mars

When we have the ability to colonize distant planets, we’ll need a lot more power than an RTG can generate.

NASA and the Department of Energy’s National Nuclear Security Administration (NNSA) have successfully demonstrated a new nuclear reactor power system that could enable long-duration crewed missions to the Moon, Mars, and destinations beyond.

Known as the Kilopower Reactor Using Stirling Technology (KRUSTY, for short), it is a small, lightweight fission power system capable of providing up to 10 kilowatts of electrical power - enough to run several average households - continuously for at least 10 years. Four Kilopower units would provide enough power to establish an outpost.

Nuclear technology uses radiation to improve the productivity of the entire food chain in a substantial manner.

Learn about just a few examples

Water use and soil management

• Neutron meters improve irrigation practices that help conserve water and protect vulnerable land.
• Tagging fertilizers with radioisotopes can determine how plants are using nutrients.
• Nuclear techniques help increase crop yields and help determine which plants to grow in areas with less available water.
• Selective breeding creates disease resistant plants with greater nutritional value.

Pest control

• Sterile insect technique (SIT) uses gamma radiation to sterilize large populations of insects.

Animal health and productivity

• Radioisotope tracers are used to follow the path of the food in animals’ digestive systems and help determine the nutritional value of the feed.
• Radiation techniques can diagnose harmful pathogens in animals early so we can vaccinate them and eliminate the wide spread of diseases.

Food safety

• Irradiation kills bacteria, molds, and parasites in our food.
• Irradiated foods can be stored for an extended period without refrigeration, which increases their availability in underdeveloped countries.
• Using lower does of ionizing radiation can lengthen the refrigerated life of fresh fish and chicken for several weeks. Strawberries treated this way can last for about 30 days. Sealed, treated foods–like canned goods–can stay on your shelf at room temperature for years.

You've may have heard of carbon dating, especially if you're into dinosaurs. But there are many other uses for radiation in the arts and sciences.

Enhancing beauty

Very few people know that radiation plays a significant role in transforming the colors of gems. Gemstones can be enhanced from their natural condition by irradiation.

• Diamonds change from off-white to green or yellow
• Pearls change to blue and gray (“black” pearls)
• Topaz changes from colorless to blue, intensifies yellow and orange, or creates green

Understanding our past

Carbon-14 dating has allowed us to accurately date historical artifacts. All living beings (plant or animal) have the same ratio of carbon-14 to carbon-12. When plants or animals die, the ratio changes and this change can be used to determine the matter’s age. C-14 dating is useful for dating items up to about 50,000 – 60,000 years old, such as Neanderthals and ice age animals.

• The age of Egyptian mummies was determined to be over 2,000 years old using carbon dating.
• Charcoal from the “Marmes Man” site in southeastern Washington state allowed scientists to determine that the oldest known inhabited sites in North America are just over 10,000 years old.
• Other radioactive techniques using beryllium, aluminum, potassium, argon, and uranium have been developed to measure specimens older than 50,000 years.
• The age of Lucy, the most famous Australopithecus afarensis, was determined to be 3.2 million years old using argon-argon dating.
• The age of Earth was determined to be 4.6 billion years old using uranium-lead dating.
• The Mars Curiosity rover used the potassium-argon method to date rocks on the planet's surface at 60-100 million years old.

Preserving art; detecting forgery

• Radiation is used to restore and preserve artifacts that have been exposed to air. Irradiation kills microorganisms that can cause decay.
• By using an x-ray fluorescence technique, we can determine the chemical makeup of paint in rare paintings. This allows us to authenticate the age and place of origin of the painting and reveal a forgery.

Heart pacemakers, smoke detectors, criminal investigation, non-stick coatings, luggage and security screening, diapers – all use radiation to make our lives safer, more convenient, and more productive.

Smoke detectors

For many of us, the most familiar application of radiation is in the smoke detectors we rely on for fire safety. Here's how they work:

The smoke detector uses a tiny bit of radioactive americium-241, a source of alpha radiation. An air-filled space between two electrodes creates a chamber that permits a small, constant current to flow between the electrodes. If smoke or heat enters the chamber, the electric current between the electrodes is interrupted and the alarm is triggered. This smoke alarm is less expensive than other designs and improves the original smoke alarm by measuring more than the heat of a fire. It can detect particles of smoke too small to be visible.

There are a number of other commercial uses for radiation. Here are just a few examples:

• Medical supplies, food for patients and food for astronauts...anything that would be harmed using other methods is sterilized using radiation. Irradiation kills the bacteria and other organisms, but doesn't make the items themselves radioactive.
• The transparent plastic wrap used to package fruits and others foods depends on radiation for its strength and clinging ability.
• Radiation improves the absorbency of disposable diapers.
• Engineers use radioisotopes to gauge thicknesses of materials, fluid levels in tanks, and density of soil at construction sites.

Nuclear energy can produce hydrogen at large enough scales to meet future demand while avoiding the release of greenhouse gases, making our environmentally-friendly cars as emission-free as possible.

Per unit of fuel, hydrogen fuel cells in vehicles are about twice as efficient as combustion engines. Unlike conventional engines, fuel cells emit only water vapor and heat. Currently, sixty million tons of hydrogen are produced for global consumption per year. The goal of the U.S. Department of Energy is for hydrogen to produce 10% of our total energy demand by 2030.

Nine million tons of hydrogen could power 20-30 million cars or 5-8 million homes. If we develop the production of hydrogen fuel to its full potential, we can reduce our demand for oil by over 11 million barrels per day by the year 2040.