Diagnostic X-rays: A Source of Potential Danger?

Last week a patient of mine complaining of cold like symptoms demanded a CT scan of the sinuses. She had been caring for her preschool age grandchild who attended day care and was now experiencing her fifth upper respiratory tract infection in the last 12 months. Her nasal congestion, sore throat, minimally productive cough, aches and pains and overall malaise were typical of the common cold caused by a host of viral agents seen frequently in crowded daycare center classes.  She had no tooth, jaw or facial pain.  We discussed why she did not need an antibiotic at this point and why exposing her to ionizing x- irradiation made no sense.

“How much radiation is safe to receive?” she asked.  According to most experts, there is no safe level of radiation to receive. Different tissues take up and store different amounts of radiation and it all depends on the size of the dose, the distance from the source of radiation and the time of exposure. Most expert panels suggest that we do not receive more than 0.05 mSv per year above our normal annual exposure.  Yes we do receive about 3 mSv per year from naturally occurring sources including cosmic radiation from outer space and radon in the ground and basement of our homes.  People living at higher altitudes receive even more annual natural exposure, with those living in the plateaus of Colorado and New Mexico getting 1.5 mSv more per year than those at sea level. As our radiation exposure increases, the chance of ill effects and ultimate malignancy increase as well.

Recent research data shows that the number of diagnostic and surveillance medical x-rays including CT scans has increased dramatically in the last decade especially in the pediatric age group which is very susceptible to the cumulative radiation doses. A simple chest x-ray exposes you to 0.1 mSv of radiation which is comparable to the natural exposure we receive from 10 days of exposure in our natural surroundings.  Compare that with a chest CT scan which provides 7 mSV of exposure or the equivalent of 2 years worth of natural exposure.  A CT scan of the head, done routinely in ER visits for minor head trauma, fainting or severe headache provides 4 mSv or 16 months worth of natural radiation exposure and is considered a “ low” risk of causing fatal cancer.   The patient who shows up in the ER with lower abdominal pain and gets a CT scan of the abdomen and pelvis with and without contrast receives up to 30 mSv of radiation which is comparable to 10 years of natural exposure.  Now think of the type of exposure cancer victims are receiving routinely to monitor the effectiveness of their treatment and disease progress.

In the hands of skilled technicians and experienced radiologists, obtaining medically necessary studies remains safe.  What may be needed is a realization by all involved that the more exposure we have the more risk we experience. For this reason, I will be giving my patients a radiation exposure history tracking card for their wallets. Each time they have a medical x- ray I will be asking them to record the date and type of procedure.  This will include dental x-rays (0.005mSv or 1 day’s natural exposure level) and all other procedures so we can track annual exposure and consider alternative diagnostic options in those with large exposure numbers.

As the country considers the new health care reform proposals and opponents speak about rationing to save money and “death panels”, remember that some of the reductions proposed are designed to spare us excessive and unnecessary ionizing radiation exposure.

For more information about radiation, visit the web sites listed below.

American College of Radiology – http://www.acr.org/

Radiology Info – http://www.radiologyinfo.org/

Effective Radiation Dose / Exposure – Chart

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