Radiation Measurement
The human body is constantly exposed to radiation from natural and manmade sources that are all around us. In fact, regardless of what you do on a typical day - whether you go to school, work or stay at home - you are exposed to radiation. There is no way to avoid it.
While the human body is able to cope with these normal levels of radiation exposure, when exposure levels are raised during certain advanced medical imaging tests, such as CT scans, there can be an increased risk to your health.
Radiation Doses
Absorbed radiation is measured by the millisievert (mSv). The risk for adverse health effects from radiation is relative to the amount of radiation dose that is absorbed, and absorption depends on the type and frequency of diagnostic imaging tests that cause radiation exposure.
Below is a chart that compares the dose of radiation by common medical imaging tests. It is important to note that the doses listed in the chart are estimates only. Actual doses of radiation could be 10 times larger or three times smaller than these estimates.
Radiation Dose Comparison
|
Diagnostic Test |
Typical Radiation Dose (mSv) |
Number of Chest X-Rays (PA Film) For Equivalent Dose |
|
Chest x-ray (PA film) |
0.02 |
1 |
|
Skull x-ray |
0.07 |
4 |
|
CT of the lumbar spine |
1.3 |
65 |
|
I.V. urogram |
2.5 |
125 |
|
Upper G.I. exam |
3.0 |
150 |
|
Barium enema |
7.0 |
350 |
|
CT of the head |
2.0 |
100 |
|
CT of the abdomen |
10.0 |
500 |
Source: Radiation Protection, Referral Guidelines for Imaging, European Commission Directorate-General for the Environment, 2000
The dose of radiation you receive during a diagnostic medical imaging procedure depends on several factors, such as:
- Your weight and size;
- The type of diagnostic medical imaging test; and
- How the medical imaging equipment is used for your procedure.
Every person's health situation is unique and many factors are considered when determining whether a medical imaging procedure's benefits outweigh the risks. However, it is important to remember that radiation exposure is cumulative and a dramatic increase in advanced medical imaging procedures - particularly CT scans - has raised concerns in the medical community.
The U.S. Environmental Protection Agency offers an online calculator where you can determine your radiation exposure.