In a previous article (“Radiation from CT Scans Linked to Cancer”), I discussed research published in a 2009 issue of Archives of Internal Medicine revealing that CT scans deliver far more radiation than previously believed and that the scans may actually be responsible for nearly 30,000 cancers each year. Today, over five years later, the situation has only gotten worse.
The use of CT scans has tripled over the past 15 years — which means the average American is exposed to twice as much radiation from medical imaging as in the mid-1990s, according to a 2012 study published in the Journal of the American Medical Association. The newly-released March 2015 issue of Consumer Reports confirmed these findings. Their investigations found not only that CT scanning definitely increases cancer risk, but also that one-third of the more than 80 million scans performed annually serve little if any medical purpose.
CT (Computed Tomography) scans, also known as Computed Axial Tomography (CAT) scans, are sophisticated X-ray procedures providing multiple images that help doctors diagnose disease by allowing them to see with precision the internal human body.
Unfortunately, these potentially life-saving tests also emit a powerful dose of radiation — in some cases equivalent to the amount most people would be exposed to from natural sources over seven years. Radiation exposure creates free radicals that alter cellular DNA, damage healthy cells, and often lead to malignancy. The more radiation people are exposed to, the greater their lifetime risk of cancer, and young bodies are particularly vulnerable to radiation damage.
Experts Express Concern
“If the scan isn’t necessary or emits the wrong dose of radiation, the risks far outweigh the benefits,” stated Stephen Swensen, MD, Medical Director at the Mayo Clinic in Rochester, Minnesota. He added, “All too often children are receiving adult-sized doses of radiation, which is many times the amount they need…. The dose directly increases the risk of leukemia or a solid tumor. ”
Explained Marvin Lipman, MD, Consumer Reports’ chief medical adviser, “No one says that you should avoid a CT scan or other imaging test if you really need it… but the effect of radiation is cumulative, and the more you’re exposed, the greater your cancer risk. So it’s essential that you always ask your doctors why they are ordering an imaging test and whether your problem could be managed without it.”
There are a number of reasons for excessive scanning, including financial incentives for doctors, fear of lawsuits, uninformed physicians, misinformed patients, and lack of regulation.
About one-third of the people in the Consumer Reports survey assumed that laws strictly limit how much radiation a person can be exposed to during a CT scan. In truth, there are no federal radiation limits for CT imaging. Nor are there any national standards for the training of the technologists who operate the imaging machines.
No Safety in Numbers
Practitioners, as well as consumers, are often unaware of the dangers of medical radiation. A Consumer Reports survey of 1,019 U.S. adults found
that people are seldom told by their doctors about the risks of CT scans. Other studies show that doctors themselves often underestimate the dangers CT
scans pose. According to CR investigators, here are some shocking statistics:
- One CT scan can expose you to as much radiation as 200 chest X-rays.
- Researchers estimate that at least 2% of all future cancers in the U.S.—approximately 29,000 cases per year—will stem from CT scans alone.
- 15,000 people are estimated to die each year because of cancers caused by the radiation in CT scans.
- One CT scan of the abdomen or pelvis delivers more radiation than most residents of Fukushima, Japan absorbed after the nuclear power plant accident in 2011.
- Almost 35% of imaging tests are ordered mainly as a defensive effort by doctors to avoid lawsuits, not because of true medical need, according to a study presented at the 2011 meeting of the American Academy of Orthopedic Surgeons.
- Cancers from medical radiation can take anywhere from five to 60 years to develop, depending on age and lifestyle.
- In a 2012 study of 67 medical providers, less than one-half of the clinicians caring for patients undergoing abdominal CT scans said they knew that the scans could cause cancer.
- In another study, only 9% of 45 emergency-room physicians said they knew that CT scans increased cancer risk.
- A 2013 Australian study comparing more than 680,000 people who had CT scans as children with 10 million who did not have a CT scan showed that the former had a 24% increased cancer risk, and each added scan boosted risk an additional 16%.
- Children who had a CT scan before the age of five had a 35% increased cancer risk.
- Researchers estimate that for every 1,000 children who have an abdominal CT scan, one will develop cancer as a result.
- A 2012 study that looked at almost 180,000 British children linked CT scans to higher rates of leukemia and brain cancer.
- Less than 10% of people surveyed said their doctor had warned them about radiation risks of medical imaging.
- Almost as many people surveyed (17%) were very concerned about magnetic resonance imaging (MRI) –which doesn’t emit any radiation — as were concerned about CT scans (19%).
- Reducing CT radiation doses could almost halve the number of future radiation-related cancers, according to a 2013 study in the journal JAMA Pediatrics.
What You Can Do
CT scans can be an extremely valuable clinical assessment tool, but caveat emptor – be wary of unnecessary and unsafe procedures. Consumer Reportsadvises – and we agree – that you do the following before you undergo any radiation-based imaging test:
- Ask why the test is necessary and whether there is a radiation-free alternative like MRI or ultrasound that could be substituted.
- Ask whether the facility is accredited by the American College of Radiology, whether the CT technologists are credentialed by the American Registry of Radiologic Technologists, and whether the person interpreting the scans is a board-certified radiologist.
- Request the right dose for your size. The smaller or thinner you are, the lower the radiation dose you need, so before you get scanned, ask the technician if that has been factored into the scan dose.
- Ask for the lowest effective dose. The strength of the radiation dose used during a CT scan can vary tremendously, even when done in the same institution and for the same medical purpose.
- Limit the frequency of recommended follow-up scans and get busy with healthy lifestyle choices.
- Avoid unnecessary repeat scans by requesting copies of your scans to show to new doctors.
- Get a second opinion if your doctor owns a CT scanner or has a financial interest in an imaging center — which would provide incentive to order lots of tests. Research shows that doctors who have invested in radiology equipment or clinics order far more scans than other physicians.
- Avoid full body CT scans. Unlike targeted CT scans for symptomatic patients, a high benefit to risk ratio has not been established for whole body “preventive” screening
- Challenge recommendations for 3D dental (cone-beam) CTs, especially for young children.