In radiology, we use X-rays for diagnostic purposes. They are a form of electromagnetic radiation, just like light, and are sent through the organ or tissue to be examined. They are then captured on a digital plate and processed using a computer.
At low doses, X-ray exposure has no immediate effects on your health; it is only at high doses, either after very frequent or very intense exposures (in the range of 2000 mSv or more at once) that it can cause immediate symptoms such as tissue inflammation. mSv (abbreviation for millisievert) is the measuring unit when assessing radiation.
Not many people know this, but as humans, we are exposed daily to different sources of natural radiation, including cosmic radiation (i.e. rays from the sun and from different stars), but also from certain rocks and radioactive elements buried in the ground. Depending on where you live, you may receive up to 3 mSv of natural radiation per year.
The radiation dose received during various radiology examinations can be compared to this so-called "natural" dose. In the table below, several examinations are compared with their natural radiation dose equivalent. For example, a chest x-ray is equivalent to 10 days of natural radiation. It should be noted that these doses are typical for an average adult; the actual dose can vary substantially depending on the patient’s weight, as well as the technology used.
Approximate radiation dose (mSv)
Comparable natural radiation dose
Small bowel follow-through
COMPUTERIZED AXIAL TOMOGRAPHY (SCAN)
Head - no contrast agent
Abdomen and pelvis
Flight from New York to Los Angeles
Radiological science has evolved considerably over the past two decades, and the advent of digital technology has resulted in significantly lower doses of transmitted radiation compared to the days of analog film. Furthermore, the technologists and radiologists are all professionals trained to maintain the lowest dose of transmitted radiation as possible, while still allowing them to obtain a quality scan (ALARA: As Low As Reasonably Achievable). Your health care professional is also able to judge the risks associated with conducting a radiological examination in comparison to the benefits you may get from it.
In closing, it should be pointed out that several examinations, including ultrasound and magnetic resonance, do not transmit any radiation.