The main purpose of the effective dose (EfD) is to project the risk based on which factor?

• A. Patient age
• B. Patient gender
• C. Exposed tissue
• D. Exposure rate

Answer: (C)

The main concept being tested is how the effective dose estimates overall risk by weighting the dose to each tissue by how sensitive that tissue is to radiation. This means the specific tissues that are exposed determine the risk the EfD reflects. Different tissues have different levels of radiosensitivity, so irradiating a highly sensitive tissue contributes more to the overall effective dose, and thus to the projected risk, than irradiating a less sensitive one. Age or gender can influence individual risk somewhat, but the EfD uses standardized tissue weighting factors to compare different exposures. Exposure rate isn’t the basis for the risk projection in EfD; it’s about which tissues receive dose and how sensitive those tissues are.