It was another hot summer evening and we had just finished consuming the remainder of a sumptous barbecue. I was just about to have a sip of my wine when one of the women at the dinner table, announced that her doctor had convinced her that mammograms cause cancer. This statement of course evoked a response which I immediately suppressed. I have learned over the years that a knee jerk reaction to statements made in a social setting does not generate long-term friendships.
I immediately thought to myself, how on earth did she come to believe this?
Consequently, I decided this was going to be the subject of today’s post.
So what are the radiation risks and what should we be aware of as women undergoing screening mammograms or any test involving xrays.
Unbeknownst to many invdivduals, we constantly receive low doses of radiation from the sun and slightly higher doses when we are flying in airplanes or live at higher altitudes.
Over the last 10 years the medical community has also come to appreciate how much more radiation exposure is incurred by certain xray imaging procedures.
Previous studies of Japanese atomic bomb survivors and nuclear power plant accident survivors suggest that cancer risk increases as a result of accumulated radiation exposure.
The American College of Radiology has determined that the lifetime radiation exposure limit should be set at 100 millisieverts (mSv): One millisievert is equivalent to the average amount of radiation a person receives in a year.
Since cancer develops very slowly after radiation damage occurs, patient age at the time of exposure is important. If you are in your 80s, you will probably outlive the danger of developing cancer. But if you are young, it is very important to reduce the amount of radiation exposure you receive every year.
The American College of Radiology now expresses the importance of having tests with as little radiation as possible.
The tests which may cause the highest amount of radiation exposure are CT scans and cardiac imaging studies such as angiograms. If an individual is being investigated for cancer, chronic illnesses or heart disease, they could be at higher risk for reaching the 100 mSv limit.
Most of the newer scanners now deliver much less radiation than the older scanners and xray equipment did.
Ask your physician if there are radiation free tests which are available which could be used instead of x-rays to investigate a particular problem. Tests such as echocardiography (ultrasound of the heart), ultrasound and MRI do not have any radiation risk.
It is also important for individuals to keep track of the amount of radiation that they are being exposed to annually. Most hospitals and imaging facilities will keep a log of the radiation exposure received from tests done at their facilities.
Here are some examples of approximate radiation dose from some common tests;
Background radiation over one year 1-3 mSv
Dental xray 0.005-0.01 mSv
Chest x-ray 0.02 mSv
Mammogram 0.7 mSv
CT calcium scoring tests 1-3 mSv
Cardiac catheterization study 7 mSv
Cardiac CT 64 slice 7-23 mSv
Cardiac CT 320 slice 10-18 mSv
Abdominal or Chest CT scan 10 mSv
Coronary CT angiography 2-23 mSv
Radionuclide sestamibi stress test 10-12 mSv
Technetium heart stress test 6-15 mSv
Thallium stress test 17 mSv
Dual Isotope cardiac stress test 16-38 mSv
Using these values, a mammogram is less likely to cause cancer than some of the other tests over the lifetime of an individual.
In general, the risk of getting cancer from a single medical test or procedure is very low. According to the National Academy of Sciences committee on the biological effects of ionizing radiation, the estimate is that for every 1000 people exposed to 10 mSv, the radiation would add one more case of cancer to the 420 “natural” cases expected as people go through life.
In conclusion, as with any test or medication, there is always an associated risk. But make sure you understand if the risk outweighs the benefit. In the case of mammography, many studies have now shown the benefits of screening mammography in the detection and prevention of breast cancer in women.
Check with a knowledgeable radiologist or physicist as to the risks versus the benefits of having certain tests when it involves radiation.