NANTeL Radiation Worker Training Practice Test

TEDE represents the total radiation dose a person receives from all sources, by adding together the dose from external radiation and the internal dose from radionuclides that have entered the body. External sources are radiation that comes from outside the body, such as gamma rays or X-rays, while internal sources come from radioactive materials taken into the body (inhaled, ingested, or absorbed) and emitting radiation from inside. The internal dose is often described as the committed effective dose, reflecting how radionuclides behave in the body over time and deposit energy in tissues. Because TEDE combines both external and internal contributions, it provides the overall picture of exposure. That’s why the correct choice is that TEDE relates to external and internal sources. If you focus only on external or only on internal sources, you’d miss part of the total dose. External-only in most cases isn’t accurate because internal contamination can be a significant or even dominant part of the dose in many settings.