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Should I Be Worried About Radiation Exposure with My HeartLung Scan?

Radiation from x-rays is often misunderstood. X-rays are a form of energy, just like sunlight.

The difference is that the energy from x-rays can pass through your body and some of it gets absorbed. It’s absorbed differently by bones, organs, and tissues, which is the reason it cn be used to create images that allow radiology doctors to see the internal structures.1 Thanks to x-rays, your health care providers can diagnose and treat many medical conditions.

X-rays and radiation in common tests

Because x-rays contain radiation, many people wonder if they are safe. The amount absorbed during a routine x-ray or CT (Computed Tomography) scan does add to your radiation dose. Other tests that use radiation include positron emission tomography (PET), mammography, and nuclear medicine.1 Even the annual x-rays by your dentist contribute a small dose.

Radiation is measured in a scientific unit called a milliservent (mSv), a way of determining the dose of radiation from a radioactive source.2 A milliservent unit is used for very low doses.

Every procedure that uses x-rays has an “effective dose,” carefully calculated to balance the long-term risk of radiation to the benefit of having the procedure.3 An effective dose can be compared to the everyday exposure to natural radiation.

You are exposed to radiation every day

Everyone in the world is exposed to natural “background” radiation every day…even from outer space.1 Americans receive an average of 3-3.6 mSv a year from natural radiation.7,12 Most of the radiation—about 2 mSv—comes from radon gas in the home.1 All rocks and soils contain trace levels of natural radioactivity.4 Even food and water carry radioactivity that we swallow.4

Other exposure to background radiation depends on several factors:

· Weather can determine our exposure. Rain can wash radioactive particles from the sky and snow can cover them up.4

· People living at high altitudes in the Colorado Plateau (AZ, CO, NM, UT) receive about 1.5 mSv more per year than those living near sea level.2

· Some spots in Colorado have background radiation levels of 15 mSv a year, more than Chernobyl, which ranges between 5 mSv to 11 mSv a year.10,11

· If you have porcelain crowns on your teeth, live in a brick home, or have smoke detectors and granite countertops…you are exposed to small amounts of radiation every day.4,15

· Even sleeping next to someone for 8 hours increases your exposure, because of the natural radioactivity of potassium from the other person’s body.12

Radiation levels around the world The composition of rocks and soil is another factor that can add to annual radiation levels. Some locations, such as Kerala (India), Yangjiang (China), and Guarapari (Brazil), have background radiation levels 10-20 times higher than the global average.9

People who live In Ramsar (Iran) receive annual doses of up to 260 mSv--about 100 times the world average, because hot springs there contain great quantities of naturally occurring radioactive elements.9,18 There are no substantial differences between the radiation levels and an increase in cancer risk.18 These levels are higher than the evacuation zones of the 1986 Chernobyl and 2011 Fukushima disasters. However, the residents of these areas now are healthy and don’t show signs of being affected by the high levels of radiation.9

Radon gas

Radon is a gas that comes from the breakdown of natural radioactive elements, such as uranium and thorium, that are in rocks and soil. As the elements decay, radon is produced and moves up through the soil to the surface. It can then enter homes and buildings through the foundation, cracks, or well water. It is clear, colorless, and tasteless.4

Outdoors, radon gas will easily dissipate, but indoors, it can be trapped. Brick, stone, and concrete buildings have higher levels of radiation than those made of wood.17 The U.S. Capitol Building in Washington, DC is so radioactive, because of the high uranium content in its granite walls, it could never be licensed today as a nuclear power reactor site.9,12

Radon is the second leading cause of lung cancer after cigarette smoking16 and the leading cause of lung cancer for nonsmokers.19 It accounts for about two-thirds the annual exposure to radiation.1,19

Pilots, flight attendants, passengers Anyone who takes a flight gets exposed to galactic cosmic ionizing radiation. It sounds like something from “Star Wars,” but during air travel crew members and passengers absorb this radiation from outer space.13 It’s always present, exposing pilots and flight attendants to an additional 3.07 mSv per year during their careers.13

In 2018, the National Institute for Occupational Safety and Health (NIOSH) studied the rate of cancer in female flight attendants. Previously, female flight attendants for Pan Am Airlines, which went out of business in 1991, had claimed high rates of skin, thyroid, breast, and reproductive cancers (cervical, ovarian, and uterine) due to exposure to cosmic radiation, combined with disruption of their daily (circadian) rhythm.20 The NIOSH study announced four important findings: 1. Work-related exposures to cosmic radiation and circadian disruption were not linked to skin melanoma, thyroid cancer, cervical cancer, uterine cancer, or ovarian cancer.20 2. Women in the study were not more likely to get thyroid cancer, uterine cancer, or ovarian cancer than women in the general population.20

3. The women did seem to get breast cancer at a higher rate, but the study concluded that it was because they had babies later in life and had fewer pregnancies, both known to be risk factors for breast cancer.23

4. The rate of breast cancer did not increase for women who had worked for more years as a flight attendant, showing that more exposure to cosmic radiation was not a factor.23

How we know that radiation is safe

One of the best ways to learn about the effects of radiation is to study people who were exposed during radioactive events. Scientists have been following the survivors of Hiroshima and Nagasaki since 1945. They have also been tracking the cancer rates among residents of Chernobyl (1986) and Fukushima (2011) who were exposed to radiation during these disasters.

Very high exposure to radiation (500 mSv, which is 500 times the U.S. Nuclear Regulatory Commission’s limit for the public)19 is associated with some cancers, including leukemia. However, the time between exposure and diagnosis can be many years; the National Cancer Institute states that other factors, such as smoking, alcohol, diet, and family history, may make significant contributions to the development of these cancers.19

Besides cancer, long-term low-dose radiation might lead to genetic changes, such as chromosome changes, stillbirths, or infant mortality. However, no evidence of genetic effects has been seen in the children born to Japanese atomic bomb survivors.19 The same is true 35 years after Chernobyl.21

After the Chernobyl disaster, there was a spike in thyroid cancer among children and adolescents who lived near the site. Their cancers, which were rarely fatal, were mostly caused by drinking milk that had been contaminated by radioactivity, not direct exposure.21

Except for people who are at the site of a radioactive event and receive intense, direct, full-body radiation, scientists are unable to prove that small doses of exposure are harmful.19

Comparing a HeartLung scan to other sources of radioactivity

Your HeartLung scan is a low-dose chest CT scan that uses only 20% of the radiation from a regular CT scan. It equals about six months of background radiation.5 A recent article in the medical journal Radiology states that “low-dose chest CT scans do not appear to damage human DNA” and will not lead to cancers caused by radiation.6

Source: Radiological Society of North America

How to weigh your own risk

Your risk with any medical test or procedure refers to both short-term and long-term outcomes. Most procedures that use radiation are relatively low risk. Every imaging center and hospital follows the guidelines of ALARA (As Low As Reasonably Achievable) which means they use every possible way of using the smallest possible dose to reduce your exposure to radiation.1

It’s important to remember that 4 out of 10 Americans will get some type of cancer.21 Nearly 5 out of 10 will develop heart disease.22 You may be at even greater risk if your health care providers are unable to diagnose a disease or condition while it can still be treated. It’s possible that you will benefit more from a HeartLung scan than if you choose not to be screened. If you have any questions or concerns, contact HeartLung or your health care provider.

When you decide to schedule a HeartLung scan, you receive about 1.5 mSv of radiation exposure, equal to six months of background radiation. A disease that isn’t detected or diagnosed early can require a full body Positron Emission Tomography (PET) scan, combined with a CT scan, with 22.7 mSv of radiation exposure,1 as well as a disease that might have been preventable or treatable.