X-Ray risk from overexposure to radiation, danger and safety, CT scan, MRI safety
March 15 2016 by
Ray Sahelian, M.D.


X-rays are a form of electromagnetic radiation with a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 to 30 000 PHz (1015 hertz). X-rays are primarily used for diagnostic radiography and crystallography. X-rays are a form of ionizing radiation and as such have risks and can be dangerous.

X-Ray risk, danger, caution, harm to body and brain
Since x-rays are a type of radiation, people undergoing these tests are concerned that the radiation may increase their risk of cancer. It's true that overexposure to x-rays can damage or destroy living tissue. There is a concern that excessive exposure to x-rays can raise the risk for cancer.


MRI risk, danger
MRI uses low-energy, non-ionizing radio waves. There are no major known risks, dangers or side effects. Some people report temporary fatigue or headache. MRI is not proven to be safe during pregnancy. The magnet at the center of the procedure may affect, or be affected by, any person fitted with a pacemaker, hearing aid, or other electrical device. Unlike x-rays and computed tomographic (CT) scans, which use radiation, MRI uses powerful magnets and radio waves. The magnetic field produced by an MRI is about 10 thousand times greater than the earth's.


Cat scan risk
Every year, many patients undergo unnecessary computed tomography (CT) scans that are not indicated, exposing them to more radiation than is necessary. Four million Americans a year are exposed to what is considered a high dose of radiation because of X-rays and CT scans.


Radiation from CT scans done in 2007 will cause 29,000 cancers and kill nearly 15,000 Americans according to an article published in the Archives of Internal Medicine. Americans are overexposed to radiation from diagnostic tests, especially from a specialized kind of X-ray called a computed tomography, or CT, scan. CT scans give doctors a view inside the body, often eliminating the need for exploratory surgery. But CT scans involve much higher radiation dose than conventional X-rays. A chest CT scan exposes the patient to more than 100 times the radiation dose of a chest X-ray. About 70 million CT scans were done on Americans in 2007, up from 3 million in 1980. Radiation dosage vary between different types of CT studies, from a median or midpoint of 2 millisieverts for a routine head CT scan to 31 millisieverts for a scan of the abdomen and pelvis, which often involves taking multiple images of the same organ. By comparison, the average American is exposed to about 3 millisieverts of radiation a year from ground radon or flying in an airplane -- a level not considered a risk to health. Imaging equipment makers such as GE Healthcare , Siemens , Philips and Toshiba Medical Systems are working to develop low-dose CT scanners.


Chest X-ray and Breast Cancer

Exposure to chest X-rays may increase the risk for breast cancer risk in mutation carriers. Studies have shown that young girls who receive repeated X-rays for assessment of scoliosis have an increased risk of breast cancer. Dr. David Goldgar of Case Western Reserve University in Cleveland, Ohio, and colleagues retrospectively evaluated 1601 women who were either BRCA1 or BRCA2 carriers and were exposed to routine, occasional and conventional chest X-rays for screening or diagnosis to assess risk of breast cancer. These women already have a high risk of breast cancer without the possible risk increase conveyed by chest X-rays. The IBCCS members found that any reported exposure to chest X-rays was associated with a hazard ratio (HR) of 1.54. Women 40 years old or younger had an even higher risk of breast cancer after chest X-ray exposure with an HR of 1.97. Women born after 1949 had an HR of 2.56. BRCA1/2 carriers exposed to chest X-rays before age 20 had the highest risk, with an HR of 4.64. Journal of Clinical Oncolology 2006.


Computed tomography (CT) coronary angiography raises breast cancer risk
A special type of X-ray used to diagnose heart disease may cause cancer in women and young adults. The procedure, called a computed tomography (CT) coronary angiography can see inside the heart and its arteries without invading the body. But it gives a high dose of radiation, enough to cause cancer in vulnerable people. The CT angiography is sometimes used in emergency rooms when someone comes in with chest pain and doctors need to assess quickly whether a heart attack is likely.


Patients are receiving the equivalent of 600 chest X-rays when they get CT scans for heart disease and not enough clinics are using known ways to reduce this exposure. While the potential risk of developing cancer after a cardiac CT scan is slight, at less than 1 percent, researchers in a large, international study found the radiation doses from such tests varied widely among hospitals, suggesting more can be done to minimize patients' exposure. Dr. Thomas Gerber of the Mayo Clinic in Jacksonville, Florida was a co-author in the study published in 2009.


Dental X-ray and brain tumor
Regular dental imaging increases the risk of a common brain tumor called meningioma.


Heart scans and imaging
Heart imaging procedures deliver a significant amount of radiation to patients. Nearly 1 in 10 adults under the age of 64 have a heart procedure involving radiation over a three-year period in five major healthcare markets. For many patients in the United States, there is a substantial cumulative radiation exposure from cardiac procedures. An advanced type of heart stress test called myocardial perfusion imaging, in which doctors inject a radioactive tracer in patients to test blood flow, accounts for the vast majority of radiation exposure from heart scans. Heart catheterization and stenting - procedures in which thin tubes are fished through blood vessels to open blocked arteries - are the second biggest contributor to radiation exposure. Journal of the American College of Cardiology, online July 7, 2010.

Excess radiation exposure
Younger Americans are being exposed to high amounts of radiation from medical scans that increase their risk of cancer. The cumulative risk of repeated exposure to radiation from medical scans is a public health threat that needs to be addressed. Dr. Reza Fazel of Emory University in Atlanta did a three-year study of nearly 1 million Americans aged 18 to 64. It reveals that as many as 4 million Americans a year are exposed high doses of radiation. The findings heap new pressure on imaging equipment makers such as General Electric Co, Siemens AG and Philips Electronics NV, already facing efforts in Congress to cut payments for imaging procedures as a way to find money to expand U.S. health insurance coverage. A report in March 2009 by the National Council on Radiation Protection and Measurement found that Americans are exposed to seven times more radiation from diagnostic scans than in 1980. The two biggest contributors to radiation exposure were an advanced kind of X-ray called a computed tomography or CT scan and nuclear medicine scans -- in which a small amount of radioactive material is injected into the bloodstream and read by special cameras. One of the nuclear medicine procedures, an advanced heart stress test called a myocardial perfusion scan, is the single-biggest contributor. "It was easily the procedure that accounted for the greatest proportion of the overall radiation exposure," Dr. Reza Fazel said. Most procedures were done in outpatient settings such as doctor's offices instead of a hospital. New England Journal of Medicine, August 27, 2009.


Questions received by email
I'm a flight attendant with a quick question. I routinely carry with me BHRT meds, bioidentical hormone replacement therapy, as well as vitamins which are placed through the X-ray machines at airports all over the world. Does this affect the efficacy of these pills and estrogen creams?
    I don't have any reason to believe the weak radiation would have any effect or cause any damage.


I am a Registered Dental Hygienist and work for a pediatric dentist. Due to the age of the children, I am required to stay in the room with my patient during their routine x-rays, in order to get a diagnostic view. I am always unprotected by a led vest and am exposed 5 - 20 times a day. I stand right next to the patient, holding their head while the x-ray is taken. It is basically a job requirement at this point, at this particular job. I would like to know what kind of risks I am taking. What are my risks if I were to get pregnant and not know that first 3-4 weeks?
    This is not a topic I have studied in enough detail to have a good answer but any exposure is of concern.