Author: Versant Physics

24 Aug 2021

The Seven Most Influential Women in Radiation History

The role of women in science is often overlooked. However, the research and discoveries of these brilliant minds have drastically altered commonly held theories in particle physics, chemistry, and nuclear medicine, and contributed to our modern understanding of radiation. In this post, we highlight seven of the most influential women in radiation history and their outstanding accomplishments.

Marie Curie (1867-1934)


Madame Marie Curie was a physicist and chemist whose pioneering research in radioactivity won her two Nobel Prizes in two scientific fields. In addition to her groundbreaking work in nuclear physics and chemistry, she developed the mobile X-ray unit which was first used to diagnose injuries during World War I.

Born in Poland in 1867, Curie moved to France to study physics, chemistry, and math at the University of Paris in 1891. There she met her future husband and research partner Pierre Curie. She earned two degrees from the institution, one in 1893 and another in 1894.

In 1903, Curie and her husband received the Nobel Prize for their joint research in radioactivity alongside Henri Becquerel. They were responsible for the discovery of new elements radium and polonium which came from the radioactive mineral pitchblende, now commonly known as uraninite. She was the first woman to win the Nobel Prize.

In 1910, she was successful in producing radium as a pure metal, further proving the element’s existence, and was awarded her second Nobel Prize in Chemistry in 1911.

Curie served in World War I as the director of the Red Cross Radiology Service. She created small, mobile X-ray units called “Petite Curies” which were vehicles containing an X-ray machine and darkroom equipment. She trained over 150 women to operate the units which ultimately helped treat over one million soldiers near the battlefront.

Curie died in 1934 of aplastic anemia, likely a result of her work with radiation.  

Awards & Recognition

  • 1903 – Received the Nobel Prize in Physics (with her husband Pierre Curie and Henri Becquerel)
  • 1911 – Awarded the Nobel Prize in Chemistry
  • 1920 – Became the first female member of The Royal Danish Academy of Sciences and Letters
  • 1924 – Became an Honorary Member of the Polish Chemical Society
  • Received 4 honorary doctorates from Polish universities
  • The radioactivity unit “curie” is named in honor of Marie and Pierre Curie
  • Element 96 was named curium

Lise Meitner (1878-1968)


Dr. Lise Meitner was an Austrian-Swedish physicist who helped discover the element protactinium-231 and nuclear fission. She received her doctorate in physics—the second woman to do so—at the University of Vienna in 1906. In 1926 she became Germany’s first female professor of physics, a role she held until the rise of Nazi Germany and the Nuremberg Laws forced her to flee to Sweden to escape religious persecution.

She worked closely with Otto Hahn, a prominent chemist, throughout the years. Their work on discovering isotopes resulted in the introduction of protactinium-231.

In 1939, Dr. Meitner coined the term “fission” after discovering that uranium atoms split when bombarded with neutrons. Her role in this major discovery, which allowed for nuclear energy and nuclear bombs, was overlooked by the Nobel Prize committee, and the award was given exclusively to Otto Hahn in 1944. Because of this discovery, she was invited to work on the Manhattan Project, however, she opposed the atomic bomb and declined the offer. She was ultimately nominated for the Nobel Prize 48 times for physics and chemistry projects but never won.

She was a strong supporter of women in science and spent the last half of her life traveling and speaking to female students.

Awards & Recognition

  • 1925 – Awarded the Lieben Prize from the Austrian Academy of Sciences
  • 1944 – Named “Woman of the Year” by the Women’s National Press Club in Washington D.C.
  • 1945 – Became a foreign member of the Royal Swedish Academy of Sciences
  • 1954 – Awarded the inaugural Otto Hahn Prize of the German Chemical Society
  • 1966 – She was awarded the Enrico Fermi Award alongside chemists Otto Hahn and Fritz Strassmann for her “pioneering research in the naturally occurring radioactivities and extensive experimental studies leading to the discovery of fission”
  • 1997- The chemical element meitnerium was named in her honor

Irene Joliot-Curie (1897-1956)


Irene Joliot-Curie was a chemist and physicist known for her work on natural and artificial radioactivity, transmutation of elements, and nuclear physics.  

She was born in Paris, France in 1897 to Marie and Pierre Curie. She studied chemistry at the Radium Institute and completed her Ph.D. in chemistry from the University of Paris. Her doctoral thesis focused on radiation emitted by polonium.

During World War I, Irene worked alongside her mother on the battlefield as a nurse radiographer. For a time, she also taught doctors how to locate shrapnel in soldiers using radiological equipment.

Alongside her husband, chemical engineer Frederic Joliot, Irene studied atomic nuclei. Together they were the first to calculate the accurate mass of the neutron and discovered that radioactive elements can be artificially produced from stable elements. The pair shared the 1935 Nobel Prize in Chemistry in recognition of this discovery, which had practical applications in radiochemistry, specifically in medicine and the treatment of thyroid diseases. In addition, her research on the action of neutrons on heavy elements was an important step in the discovery of nuclear fission.

Outside of her research, Irene was the Chair of Nuclear Physics at the Sorbonne and a Professor in the Faculty of Science in Paris. Beginning in 1946 she served as the director of the Radium Institute and was instrumental in the design of the Institute of Nuclear Physics in Orsay, France. She died in 1956 of leukemia, likely a result of her work with polonium-210.

Awards & Recognition

  • 1935 – Received the Nobel Prize in Chemistry for the discovery of artificial radioactivity (with Frederic Joliot-Curie)
  • 1940 – Received the Barnard Gold Medal for Meritorious Service to Science (with Frederic Joliot-Curie)
  • Was an Officer of the Legion of Honour

Edith Quimby (1891-1982)


Edith Quimby was a pioneer in the field of radiation physics, a founder of nuclear medicine, and is considered the first female medical physicist in the United States.

She was born in 1891 in Rockford, Illinois, and earned degrees in physics and mathematics from Whitman College and the University of California, Berkeley. Much of her early work at the Memorial Hospital for Cancer and Allied Diseases in New York focused on the medical effects of radiation and limiting side effects with proper dosages. Furthermore, she was also interested in the safe application of radioactive isotopes in the treatment of thyroid disease, brain tumors, and other cancers.

Edith Quimby helped found the Radiological Research Laboratory at Columbia University, was the first female physicist president of the American Radium Society and was influential in the founding of the American Association of Physicists in Medicine. She was a professor at both Cornell University Medical College and Columbia University, and she authored several books throughout her career, including the classic Physical Foundations of Radiology (1944), and over 70 scientific papers.

Awards & Recognition

  • 1940 – Recipient of the Janeway Medal from the American Radium Society
  • 1941 – Awarded the Gold Medal of the Radiological Society of North America
  • 1963 – Awarded the Gold Medal from the American College of Radiology
  • AAPM established a lifetime achievement award in her honor

Tikvah Alper (1909-1995)


Tikvah Alper was a renowned radiobiologist and physicist whose work on identifying the infection agent in Scrapie revolutionized scientific understanding of diseases like mad cow disease and kuru.

She was born in 1909 in South Africa and graduated with a distinction in physics from the University of Cape Town in 1929. She was mentored by Lise Meitner as a doctoral student in Berlin from 1930 to 1932 where she published an award-winning paper on delta rays produced by alpha particles.

In addition to her life as a mother and homemaker, she was a physics lecturer at Witwatersrand University and researched in Britain on the irradiation of bacteriophage. She became head of the Biophysics Section in South Africa’s National Physics Laboratory; however, she was forced out of this position in 1951 due to her opposition to apartheid. Afterward, she moved to London with her family and worked her way up to director of Hammersmith Hospital’s MRC Experimental Radiopathology Research Unit in 1962.

Alper found that radiation did not kill the infective agent in Scrapie, an infectious brain disease found in sheep. Instead, by irradiating scrapie samples with different wavelengths of UV light, Alper was able to prove the infective agent was able to replicate despite its lack of nucleic acid. This work became extremely important during Britain’s Mad cow disease outbreak in the 1990s.

Chien-Shiung Wu (1912-1997)


Chien-Shiung Wu, also known as the “First Lady of Physics,” was a Chinese American particle and experimental physicist who worked on the Manhattan project and played an important role in the advancement of nuclear and particle physics.

Madame Wu was born in 1912 in Shanghai. She received a degree in physics from what is now known as Nanjing University and later enrolled at the University of California, Berkeley where she completed her Ph.D. She worked as a physics instructor at Princeton University and Smith College before joining the Manhattan Project in 1944. Her work at the Substitute Alloy Materials Lab was meant to support the gaseous diffusion program for uranium enrichment. Her research also improved Geiger counters for radiation detection.

As a leading physicist on beta decay, Madame Wu was able to confirm Enrico Fermi’s 1933 theory of beta decay. She was also responsible for disproving “the law of conservation of parity” in what is known as the Wu Experiment. In this experiment, she measured the small particles released from cobalt-60 atoms and found that they were emitted asymmetrically. This proved the theory that parity is not reserved for beta decay, vastly altering long-held beliefs in the physics community.

Awards & Recognition

  • 1958 – Became the 7th female member elected to the National Academy of Sciences
  • 1964 – Was the first woman to win the Comstock Prize in Physics from the National Academy of Sciences
  • 1975 – Became the first woman president of the American Physical Society
  • 1975 – Honored with the National Medal of Science
  • 1978 – Received the first Wolf Prize in Physics
  • 1990 – 2753 Wu Chien-Shiung asteroid was named after her
  • Held honorary degrees from Harvard University, Dickinson College, University of South Carolina, University of Albany, SUNY, Columbia University, and National Central University

Rosalind Franklin (1920-1958)


Rosalind Franklin was a chemist and X-ray crystallographer who is best known for her work on the structure of DNA, RNA, and coal. She also performed cutting-edge research on the molecular structure of viruses that cause plant and human diseases.

Franklin was born in London, England in 1920. She studied physical chemistry at Newnham Women’s College at the University of Cambridge. During World War II, Franklin researched the physical chemistry of coal and carbon under the British Coal Utilisation Research Association. By studying the porosity of coal, she concluded that substances were expelled in order of molecular size as temperature increased. This work was important for accurately classifying and predicting coal performance for fuel and wartime production and served as her Ph.D. thesis.

After the war, Franklin accepted a position as a research fellow at King’s College London. During this time, she investigated DNA samples. She took clear x-ray diffraction photos of DNA and was able to conclude that the forms had two helices. Her work–specifically her image Photo 51–was the foundation of James Watson and Francis Crick’s discovery that the structure of DNA was a double-helix polymer, for which she was not cited or credited.

Afterward, she continued working with x-ray diffraction photos of viruses at the J.D. Bernal’s crystallography laboratory at Birkbeck College and collaborated with virus researchers from around the world. She studied RNA of the tobacco mosaic virus and contributed to published works on cucumber virus 4 and turnip yellow mosaic virus.

During her career, she published 19 articles on coal and carbons, 21 on viruses, and 5 on DNA.

Versant Physics is proud to be a woman-owned company at the forefront of the medical physics and radiation safety industry. To learn more about our physicists and service offerings, visit our regulatory page.

12 Aug 2021

A Step-by-Step Guide to Implementing a Radiation Safety Program

Implementing a radiation safety program is the best way to protect radiation workers and maintain safe radiological conditions in your clinic or university. If you are a new facility starting from scratch, implementing a radiation safety program can be an overwhelming task. We have put together a step-by-step guide to help clarify areas you will need to address.

Who Regulates What?

It is important for any new radiation safety program to understand which regulations to follow. The U.S. Nuclear Regulatory Commission (NRC) is responsible for regulating radioactive materials in the United States. However, they do not regulate radioactive material in any of the 37 Agreement States. These Agreement States have signed agreements with the state’s governor and the chair of the NRC that declare they take responsibility for all radioactive material regulation within the state. Agreement States can set their own rules for how radiation is monitored, handled, and used if they are at least as strict as the NRC.

Each state regulates the use of ionizing radiation generating equipment within the state. It is very important to research your individual state regulations.

For a list of individual state radiation control programs and their specific rules and regulations, we recommend visiting the Conference of Radiation Control Program Directors (CRCPD) website.

Step 1: Identify a Radiation Safety Officer

A Radiation Safety Officer is a required element of a radiation safety program.

According to AAPM Report 160, the RSO in a radiation safety program “is responsible for the implementation, coordination, and day-to-day oversight of the radiation protection program.” An RSO enforces policies and procedures regarding radiation safety and ensures the facility’s use of ionizing radiation is compliant with regulatory requirements, whether that be state or federal. These individuals are required to meet certain education, training, and experience requirements to assume the role.

The responsibilities of the RSO are many. In addition to managing the radiation safety program, this person will:

  • Provide advice and assistance on radiological safety matters,
  • Ensure safe use of radioactive materials,
  • Ensure compliance with regulatory and license requirements,
  • Identify radiation safety problems and correct them,
  • Ensure ALARA practices are enforced,
  • Perform audits and surveys of work areas as necessary,
  • Dose monitoring,
  • Instrument calibration,
  • And more.

Step 2: Get Copies of State and Federal Regulations

Federal regulations can be found on the NRC website. As mentioned above, most states have their own regulatory body. This may also be a good time to contact your state regulator and introduce yourself.

Step 3: Set-up Administrative Documents & QA Program

You will want to lay out the various roles in your radiation safety program in an organization chart. This includes management, IT, radiation safety resources, and additional radiation modalities and departments.

It will also be helpful to create a Standard Operating Procedure Manual on radiation protection that describes emergency procedures, training policies, and credentialing all radiation workers should be familiar with.

Step 4: Establish a Radiation Safety Committee

A radiation safety committee is typically made up of:

  • The RSO,
  • An authorized user of each type of use permitted by the license,
  • A nursing representative, and
  • A representative who is neither an authorized user nor the RSO.

Many universities and larger clinics find an RSC helpful for efficient radiation safety program management. However, they are not always mandatory depending on your use of radiation. You may find a radiation safety committee is not necessary for your facility.

Step 5: X-ray Room Shielding

Radiation Worker Behind Shielding

Facilities that utilize radiation are required to have a shielding plan developed by a qualified expert, such as a medical physicist. Most states also require the shielding plan to be submitted to the state before the equipment can be used.  

When setting up a radiation safety program, it will be necessary to contact an appropriate QE to put together the shielding plan. You will work with them to implement the appropriate materials and signage throughout your facility. Afterward, integrity and regulatory surveys must be performed to ensure compliance with area dose limits.

Step 6: Registration of Radiation Machines & RAM License Application

A new facility with new X-ray equipment must register each unit with the state, typically within 30 days of acquiring the unit. The use of X-ray-producing equipment is regulated on a state-by-state basis. The appropriate forms and required supporting documentation can be found on your state’s regulatory website or by contacting your regulator.

A new facility intending to use radioactive material must apply to either their Agreement State or the NRC for approval. In preparation for submitting the application, all the previous steps should be completed. Many of the items above will be reviewed along with the license application to determine approval status.

Note that some states may require radiation-producing machines to be inspected regularly by state-approved qualified experts to maintain a registration.

Step 7: Set-up a Personnel Monitoring Program

Licensees/Registrants are required to monitor radiation exposure of radiation workers to remain in compliance with occupational dose limits.

Instadose+ Dosimeter

It is important to set up a personnel monitoring program for radiation workers who regularly work with or could encounter radiation while on the job. These programs require personnel to wear a dosimeter badge which measures their total received exposure. RSO’s periodically review the personnel exposures.

There are a variety of dosimeter options available including TLDs, ring badges, and badges that provide on-demand dose reads.

Step 8: Recordkeeping

Implementing a radiation safety program means there will not be existing inspection reports, previous audits, or correspondence with regulators on file to familiarize yourself with. However, as the RSO, you will be responsible for maintaining all records regarding personnel exposure, exposure levels to the public, surveys, calibrations, and any maintenance completed on the facility’s X-ray equipment moving forward. Consult your state regulations to determine how long individual records need to be kept.

Conclusion

While there are many moving parts to setting up a radiation safety program, it is an important aspect of a safe workplace. Following these steps will have you well on your way to leading a successful program.

Our experienced radiation safety officers, health physicists, and medical physicists can help you implement a radiation safety program. Contact sales@versantphysics.com to be connected with a physicist or visit our regulatory page for more information.

Interested in becoming a Radiation Safety Officer yourself? Versant Physics offers a 20-hour online Medical Radiation Safety Officer course that teaches how to implement a successful, compliant radiation safety program. It will help you gain a practical understanding of regulations governing the safe use of radiation-emitting machines and radioactive materials, as well as responsibilities for managing radiation safety in a medical setting.

21 Jul 2021
online radiation safety course

The Mobile Radiation Safety Software Solution for the Modern RSO

Fieldwork is an essential component of radiation safety programs. From inventorying radioactive materials, machines, and equipment, to performing audits and inspections, there exists a need to capture real-time information while on the go.

Historically, this information would be recorded on paper forms and later transcribed to an electronic record or placed in a binder. Such methods are both outdated and time-consuming. Their very nature prohibits RSOs from accessing the most up-to-date records while traveling or on-site, and keeps them from streamlining effective administrative processes within their radiation safety programs.

But with the advent of mobile-optimized radiation safety software, performing these tasks and recording the results is more efficient than ever before.

In response to the growing awareness and need for such a software solution in radiation safety, Versant Physics has developed the cloud-based software Odyssey, with mobile optimization as a core focus. Users of the software can access Odyssey on their desktop or laptop computers, tablets, and mobile phones anywhere they have an internet connection.

odyssey screenshot of sealed sources

Versant Physics’ implementation analyst, Katelyn Waters, has seen multiple Odyssey clients incorporate the software into their fieldwork.

“Clients frequently use Odyssey to perform on-site inventories of RAM, sealed sources, radioactive waste, machines, and equipment. They use tablets and cell phones to quickly pull up inventory records by location. From there, individual profiles can be viewed and edited on the go as needed.”

These inventory records are displayed as a table with a simple and searchable format convenient for reviewing information on the smaller screens of mobile devices. Tables contain links to individual profiles with buttons to easily adjust the activity of radioactive materials, update survey, inspection, or calibration due dates, or edit other profile information.

Each profile also has the option to print out a physical label for the inventory. The label can include a logo, information from the profile, free text, and a unique QR code. The QR code can be scanned to take a user directly to a profile to increase speed and accuracy during an inventory.

“The biggest benefit of the QR code system that I see is the ability to perform cradle-to-grave tracking of RAM, sealed sources, and waste containers,” says Waters. “Users can scan the QR code attached to the material throughout its lifetime to view location, activity, and ownership changes to ensure that they are always accessing accurate, up-to-date information.”

odyssey qr code

These QR codes are available to be printed for RAM, sealed sources, waste containers, machines, equipment, and laboratories in Odyssey. Utilizing the labeling tools not only helps radiation safety staff quickly access information, but also complies with FDA and NRC labeling requirements for radioactive materials, machines, and laboratory doors.

“In addition to completing inventories, we also see our clients utilize the Forms module of Odyssey for audits, inspections, and surveys,” says Waters. “Customizable forms can be created which include images like floor plans. These forms can be filled out and the images marked up using mobile devices during the inspection itself.”

odyssey customizable form screenshot

The forms utilized during these inspections are custom forms set up during the implementation process by the Versant Physics team, or by an administrator. The same form can be filled out repeatedly for consistency and to track changes in responses over time. This standardization of forms is an essential aspect of radiation safety for quality control.

Another important consideration for data capture is efficiency. Odyssey aims to accomplish efficient data collection by prefilling data from its other modules into the form where applicable. This reduces the amount of time spent filling out the form and helps minimize the potential for human error as existing data does not need to be copied over.

Utilizing cloud-based software has become increasingly relevant as radiation safety programs move from paper-based methods to electronic solutions. Performing work in the field itself on mobile devices aids in getting records more efficiently into this desired electronic format. Odyssey is engineered to assist with this transition to increase data accessibility, efficiency, and accuracy for radiation safety programs.

You can schedule a live demo with our software specialists to learn more about individual Odyssey modules, mobile features, and software usability.

24 Jun 2021
Packaged tomatos

What is Food Irradiation?

Food irradiation is a common practice that is frequently misunderstood. Not only has the process of exposing food products to ionizing radiation, including X-Rays or electron beams, been heavily researched and utilized safely for over a century, it is a process that has proven benefits for the health of human beings.

The history of food irradiation.


The process of irradiating food began as early as 1905 when patents were issued in the U.S. and Great Britain to use ionizing radiation to kill bacteria found in foods. After World War II, research was conducted by the U.S. Army to verify the safety and efficacy of the irradiation process for meat, dairy products, fruits, and vegetables. Food irradiation has been controlled by the Food and Drug Administration since 1958 and recognized by the United Nations since 1964, when the first meeting of the Joint Expert Committee on Food Irradiation took place. It was determined by this committee in 1980 that “irradiation of foods up to the dose of 10 kiloGrays introduces no special nutritional or microbiological problems,” and the use of irradiation in the U.S. food supply was expanded by the FDA in 1986. In addition to the FDA and the UN, irradiation has been endorsed by the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), and the U.S. Department of Agriculture (USDA).

Why irradiate food?


There are several important reasons to irradiate food which ultimately benefit humans.

  • Prevention of Food borne Illness – Nobody likes having food poisoning. Food irradiation eliminates bacteria and molds like Salmonella and Escherichia coli (E. coli) which can spoil food and cause serious foodborne illnesses.

  • Sterilization – Irradiated foods can be used to sterilize foods which do not require refrigeration. These can be used in hospital settings for individuals with compromised immune systems or those undergoing chemotherapy. A variety of household and consumable products are also irradiated for sterilization purposes, including Band-Aids, cotton balls, medical products like surgical gloves, and even cosmetics.

  • Preservation – Have you ever wondered why spices have such a long shelf life, or why that bag of potatoes you bought last week is still sprout free? The answer is food irradiation. Food irradiation can extend the shelf life of certain foods by destroying organisms that cause spoilage and early sprouting.

  • Pest-Control – Irradiation helps control invasive insects that live in or on imported fruits and vegetables by killing or sterilizing them to prevent new bugs from infecting U.S. crops. This method is also safer than certain pest-control practices which have the potential to harm the produce through the use of toxic chemicals.

Of course, the benefits to irradiating food do not diminish the need for safe food handling practices by growers, processors, and consumers. All food should be stored, handled, and cooked appropriately. If safe handling practices are not followed, disease-causing organisms can still contaminate food and illness can occur.

It also does not completely remove all food dangers. For example, food irradiation can slow fruits and vegetables from aging, but it does not stop them. It also does not eliminate dangerous toxins that are already in food, such as Clostridium botulinum, a common bacterium which produces a toxin that causes botulism.

What kind of foods are irradiated?


In the United States, the FDA has approved a variety of foods to undergo irradiation, including:

  • Beef and Pork
  • Poultry
  • Lobster, Shrimp, and Crab
  • Fruits and Vegetables
  • Lettuce and Spinach
  • Shell eggs
  • Shellfish
  • Spices and Seasonings
green radura symbol

The international symbol for irradiation is called the Radura. This green symbol is required to be present on food packaging of irradiated food alongside the statements “Treated with radiation” or “Treated by irradiation.” According to the FDA, bulk foods like fruits and vegetables must be individually labelled with this symbol, however it is not required for individual ingredients in multi-ingredient foods, such as spices, to be labelled. If this symbol is present, this also indicates that the food is not classified as organic no matter how it was grown or produced.

How is food irradiated?


The overall process is simple. Three different kinds of radiation are approved for use: Gamma rays, electron beams, or x-rays. Packaged or bulk food pass through a radiation beam in a radiation chamber on a conveyor belt. The ionizing radiation breaks the chemical bonds into the bacteria or mold cells, which kills or damages the pathogens enough that they cannot multiply. This process does not affect the taste or smell of the food being irradiated.

This process also does not bring food into contact with radioactive materials, nor does it make food radioactive. Irradiated food does not expose those who eat it to radiation.

Are there risks to eating irradiated food?


Eating irradiated food is not harmful and there are no radiation-related risks. In fact, irradiating foods increases the availability of healthy and nutritious food supplies on a global scale. The chemical changes to food caused by irradiation are comparable to the changes food undergoes when cooked or canned.

Safe and beneficial.


Exposing food products to ionizing radiation is a safe, heavily researched process endorsed by governing agencies around the world. It is responsible for controlling invasive insects, destroying harmful bacteria that can cause food borne illnesses, and increases the shelf-life of certain foods which allows for more widespread access to healthy, nutritious food. This process also poses no radiation-risks to the public.

Further reading:

http://hps.org/publicinformation/ate/faqs/foodirradiationqa.html

https://www.epa.gov/radtown/food-irradiation

https://ccr.ucdavis.edu/food-irradiation/history-food-irradiation

https://www.fda.gov/food/buy-store-serve-safe-food/food-irradiation-what-you-need-know

15 Jun 2021

The Truth About Background Radiation

Background radiation is all around us, and always has been. That idea can be a frightening concept at face value, but the truth is background radiation is natural, normal, and expected.

Most natural background sources of radiation fall into one of three categories:

Cosmic Radiation

Think of this as steady waves of external radiation being sent from the sun and stars in space to Earth. This type of radiation occurs naturally and introduces extremely low levels of radiation to the average person. The amount (or dose) of cosmic radiation one receives can depend on weather and atmospheric conditions, the Earth’s magnetic field, and differences in elevation. For example, people who live at higher altitudes like Denver, Colorado are exposed to slightly more cosmic radiation than people who live in lower altitudes, such as New Orleans, Louisiana or Miami, Florida. Furthermore, the farther north or south one is from the equator results in a higher dose of cosmic radiation due to the way the Earth’s magnetic field deflects cosmic radiation toward the North and South poles.

silver airplane flying above orange clouds

Air travel can also expose individuals to low levels of cosmic radiation. The received dose is similarly dependent on altitude, latitude, and the duration of the flight. A coast-to-coast flight in the United States would expose an individual to approximately 3.5 mrem. For comparison, a typical medical procedure involving radiation, such as a chest X-ray, exposes an individual to 10 mrem, and the average American receives a total radiation dose of 540 mrem each year.

In general, a person’s average dose from cosmic radiation in the United States is small, making up only 6% of their total annual dose.

Terrestrial Radiation

Terrestrial radiation is the portion of natural background radiation that is emitted by naturally occurring radioactive materials on earth, and it is responsible for approximately 3% of the average person’s annual received dose. The physical earth, including soil and sedimentary and igneous rock, contains common elements like uranium, thorium, and radium. These naturally occurring radioactive materials, which have existed as part of the earth’s crust since the earth was formed, are released into the water, vegetation, and the atmosphere as they breakdown at different rates. People are largely exposed to the resulting emitted radiation through their skin.

Radon:

diagram of radon gas infiltrating a house

Perhaps the most significant form of terrestrial radiation is that which is inhaled. When the naturally occurring radioactive element uranium (found in the earth’s crust, underwater caves, and seawater) decays it can change into a scentless, invisible gas called radon. All the air we breathe contains trace amounts of radon, and it is responsible for the largest portion of background radiation dose that the average American receives in a year. Outdoors, this radioactive gas disperses rapidly and does not pose any health risk to human beings. A build-up of radon gas indoors, however, can potentially increase the risk of lung cancer over time, which is why it is important to test homes and workplaces for radon on a regular basis. Smoking, especially near or inside the home, can amplify the risk of cancer when coupled with radon exposure.

The average person can expect to receive 42% of their annual radiation dose from radon.

Internal Radiation

Background radiation can also be received through ingestion. Some common foods contain small amounts of radioactive elements that do not pose a radiation risk to the person ingesting them. The most common example is the banana. This delicious, nutritious fruit contains naturally high levels of potassium which helps muscles contract, keeps your heartbeat regular, and offsets the harmful effects of sodium on blood pressure. A tiny portion of potassium is also naturally radioactive. A single banana emits 0.01 mrem, which is received internally by the person eating it. According to the EPA, a person would have to eat 100 bananas to receive the same amount of radiation exposure naturally received each day from the environment. (It should be noted that this naturally occurring radiation is not the same thing as food irradiation, which is a process used by humans to kill bacteria, molds, and pests to prevent foodborne illnesses and spoilage.) Overall, the levels of natural radionuclides found in our food and water are low and considered safe for human consumption by regulatory bodies.

Most surprisingly for some is the fact that other humans are also a source of exposure to one another. From birth, people have internal radiation in the form of radioactive potassium-40, lead-210, and carbon-14. These elements reside in our blood and bones. As previously noted, humans also ingest traces of naturally occurring radioactive material found in our food and water. When our bodies metabolize the non-radioactive and radioactive forms of potassium and other elements, they then contain small amounts of radiation which can act as exposures to others.

Man-Made Radiation Exposure

A more familiar source of radiation exposure to many is man-made radiation, such as procedures using X-Rays and radiation therapy to treat cancer. According to the Health Physics Society, approximately 42% of annual dose comes from man-made radiation. This percentage includes medical procedures, household products like smoke detectors, and small quantities of normal discharges from nuclear and coal power plants.

Learn more about the health effects of man-made ionizing radiation in our blog post here.

Conclusion

Natural background radiation has always been a part of life on earth, and it always will be. It is important to understand that this is not something to be feared. Low levels of ionizing radiation from naturally occurring sources such as space, the ground beneath our feet, and even some of the food we eat are not dangerous and do not pose a direct health risk to ourselves or our loved ones.

For more information, visit the Health Physics Society webpage, epa.gov, or the International Atomic Energy Agency.

Note: Visit our regulatory page to learn how Versant Physics’ board-certified Internal Dose Specialists, Medical Physicists, and Health Physicists, can assist with your radiation safety program needs.

Additional Sources:

https://www.nrc.gov/about-nrc/radiation/around-us/sources/nat-bg-sources.html

https://www.cdc.gov/nceh/radiation/air_travel.html

NCRP Report 160

NCRP Report 184

20 May 2021
Smiling pregnant worker

Occupational Radiation Workers & Declaring a Pregnancy

Employees who become pregnant and work with radiation or radioactive materials during their pregnancy are often concerned about the safety of doing so, as well as the potential effects of radiation on their unborn child. Occupationally exposed workers are not required to declare a pregnancy to their employer. However, if they decide to declare there are dose limits that should be observed and additional protective measures that can be taken to protect both mom and baby.

Declaring a Pregnancy


In the United States, pregnant employees who work with or around radiation have the option of declaring their pregnancy. This declaration is voluntary and informs the worker’s employer in writing of their pregnancy as well as the estimated date of conception. This information is confidential and shared only with the employer and radiation safety officer, however, it is valuable for reducing exposure and allowing for close monitoring of both the employee and the baby throughout the pregnancy.

pregnant radiation worker consulting with radiation safety officer

The NRC and States require licensees and registrants (i.e., the facility the employee works at) to make efforts to limit the declared pregnant worker’s received dose. This can mean that some normal job functions may not be permitted if doing those jobs would result in the fetus/embryo receiving more than 500 mrem.

Employees also have the option to discuss with their employer or radiation safety officer about potential changes to their job status prior to declaring a pregnancy if they so choose. The option to revoke a declaration of pregnancy even if the worker is still pregnant is also available at any time throughout the pregnancy.

When an employee declares a pregnancy, they should sit down with their radiation safety officer for a one-on-one counseling session. This is a great opportunity to ask questions and address any monitoring or safety concerns that may arise.

They are then issued a fetal dosimeter in addition to their regular monitoring device, which is worn at the hip or waist level. For procedures where a lead apron is worn, the dosimeter should be worn beneath it while the regular dosimeter is worn on the outside at the neck or collar. The fetal dosimeter is monitored monthly by the radiation safety officer to ensure that the regulatory fetal dose limits are not exceeded.

According to regulations, the lower dose limit for the embryo or fetus remains in effect until the worker withdraws the declaration in writing or is no longer pregnant. If it is not withdrawn, the original declaration expires after one year.

If an employee chooses not to declare their pregnancy, the employee and her baby are restricted to the standard occupational dose limits that apply to all occupationally exposed workers. The annual total effective dose equivalent (TEDE) for the whole body is 5,000 mrem. (10 CFR Part 20.)

Occupational Exposure


In most cases, the ways in which a pregnant woman may be occupationally exposed to radiation within regulatory limits are not likely to cause adverse health effects for the developing fetus.  However, most regulations are guided by the principle that any level of radiation can potentially result in negative biological effects and that the likelihood of such effects increases as the dose received increases.

The NRC requires licensees to “limit exposure to the embryo/fetus of an occupationally exposed individual to 500 mrem (5 mSv) or less during pregnancy for a declared pregnant worker who is exposed to radiation from licensed radioactive materials including radionuclides.” (10 CFR 20.1208) This lower dose limit is “based on a consideration of greater sensitivity to radiation of the embryo/fetus and the involuntary nature of the exposure.”  

Pregnant nurse on the phone with ipad

To break this down further, the regulations state that the radiation dose from occupational exposure should be limited to 500 mrem for the duration of the pregnancy and no more than 50 mrem per month. At this level, (1/10 the dose that a regular occupationally exposed worker may safely receive in a year) the risk of negative health effects is low.

Pregnant workers can speak directly with their radiation safety officer or on-site medical or health physicist to determine the safest dose limits for their individual needs, which may depend on their exposure history and the types of jobs they perform on a regular basis.

Undergoing Medical Procedures While Pregnant


Occupational limits for declared pregnant workers do not apply to individuals who undergo diagnostic or therapeutic procedures, such as X-rays, fluoroscopy, or radiation therapy.

According to Robert Brent, MD, Ph.D. for HPS.org, diagnostic procedures of different parts of the body, such as the head, teeth, legs, or arms do not directly expose the fetus. Modern medical imaging procedures focus the X-ray beam only on the body part of interest, and the amount of radiation that could reach the embryo or fetus during these diagnostic procedures is small and unlikely to increase the risk of miscarriage or birth defects. Most procedures expose the developing fetus or embryo to less than 50 mSv, if at all. At this level of exposure, there is no cause for concern.

Regardless of pregnancy status, the ALARA principle should be implemented by the individual’s care team to guide decisions made about treatment and diagnostic procedures. A radiation safety officer or medical physicist can also help provide options to minimize dose. It should also be noted that those with fetal dosimeters should not wear their dosimeter during an X-ray or nuclear medicine procedure.

Conclusion


Ultimately, the decision to declare a pregnancy is that of the pregnant radiation worker. Under the current safety guidelines, the risk for adverse health effects to an embryo or fetus posed by occupational exposure or medical procedures is low. However, employees should take advantage of the resources available such as the NRC regulations, literature provided by the Health Physics Society, and the expertise of their radiation safety officer and on-site medical or health physicist.

Visit our website to learn more about Versant Physics regulatory services, including radiation safety officer support, personnel dosimetry management for declared pregnant workers, and more.


Sources

https://www.cdc.gov/nceh/radiation/emergencies/prenatalphysician.htm

https://www.nrc.gov/reading-rm/doc-collections/cfr/part020/index.html

https://hps.org/hpspublications/articles/pregnancyandradiationexposureinfosheet.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3835582/