Yet, you’ve heard the news: Earth is 4.6 billion years old. That corn cob found in an ancient Native American fire pit is 1,000 years old. Geologic age dating—assigning an age to materials—is an entire discipline of its own.
In a way this field, called geochronology, is some of the purest detective work earth scientists do.
Effective dose is not intended to apply to a specific patient.
Geologists draw on it and other basic principles ( to determine the relative ages of rocks or features such as faults.
Relative age dating also means paying attention to crosscutting relationships.
For example, the head is less sensitive than the chest.
Effective dose relates to the overall long-term risk to a person from a procedure and is useful for comparing risks from different procedures.
X-rays, unlike sunlight, can penetrate deep into the body and deposit energy in internal organs. Absorbed dose describes the intensity of the energy deposited in any small amount of tissue located anywhere in the body.
The unit of measurement for absorbed dose is the milligray (m Gy).
There are several quantities in which dose is measured (e.g., m Gy, m Sv).
There are other dose quantities that have not been discussed. You and your radiologist or medical physicist should work together to answer questions you have about radiation dose. Please contact your physician with specific medical questions or for a referral to a radiologist or other physician.
Absorbed dose and equivalent dose measurements can be used to assess short-term risk to tissues.