Not all CT scanning is created equal. There are many differences between medical CT and dental Cone Beam CT (CBCT), but some of the primary ones are found in how the devices capture information and also the amount of radiation exposure that results. Medical scans are acquired by generating fan shaped fields of radiation that capture data in slices. The device makes multiple, overlapping revolutions around the patient’s head, typically when the patient is lying down in a tunnel-like machine. A dental scan acquires data in a cone shaped beam that involves a singular rotation around the head while the patient is typically in a seated position. The dental scan is faster, less stressful (since the patient is seated in an open-air device) and emits less radiation than its medical counterpart.
The amount of radiation that tissue is exposed to is measured in units called microsieverts. We are surround by naturally occurring radiation every day. CT is a modality which also generates radiation and the level of exposure is dependent upon the device and the study being performed. The average medical CT scan of the oral and maxillofacial area can reach levels of 1200-3300 microsieverts whereas dental CBCT is typically approximately 10 times less.* The chart below compares the effective radiation dose between traditional 2-dimensional dental x-rays, medical CT and dental CBCT which is 3 dimensional. Many studies have been performed and related articles published regarding radiation exposure from dental CT compared to medical CT and traditional dental x-rays.