We encounter radiation naturally - cosmic radiation filters down through the atmosphere, terrestrial radiation comes up from the earth in rocks and building materials, and trace amounts of radiation are found in what we eat, drink, and breathe.
On average, Americans are exposed to about 3 mSv (or 300 mrem) of natural radiation in a year, though this varies from place to place. Radiation is a useful tool in research and clinical applications.
X-rays can help image structures inside the body, small amounts of radioactive material can be injected to help identify internal processes, and large amounts of radiation can treat serious conditions such as cancer.
However, significant radiation exposure can damage skin, the lens of the eye, or even increase the risk for cancer. Whenever radiation is considered, it is important to ensure that the benefits outweigh the risks and use reasonable precautions to limit unnecessary exposure.
Our goal is to keep radiation exposure risks as low as reasonably achievable. This is accomplished by using the minimum amount of radiation needed for the desired result, and by the appropriate use of:
- Time
The amount of radiation exposure is directly related to the time exposed to the radioactive source. Reduce exposure by limiting the time near radiation to only what is necessary. - Distance
Doubling the distance from a source of radiation reduces exposure by 75%. Increase distance from the radiation source whenever possible. - Shielding
Use appropriate shielding for the type of radiation. Lead protective garments or drapes can reduce exposure during x-ray imaging. Higher energy x-rays or gamma rays can be decreased by walls of thicker lead or concrete. Beta radiation can be blocked by a centimeter of Lucite. Alpha radiation is stopped by a sheet of paper or a few centimeters of air.
The majority of our CT scans have a radiation effective dose equivalent to four or five hours of high-altitude air flight, or 11 to 15 days of normal background radiation in the United States. Your doctor believes that this risk from radiation exposure is much less than the risk of inaccurate diagnosis or treatment from proceeding with the knowledge provided by a CBCT scan.