Describe the general differences between external and internal dosimetry.

Describe the general differences between external and internal dosimetry.

• A. External dosimetry measures dose from sources outside the body; internal dosimetry measures dose from radioactive material ingested or inhaled and tracked via bioassay and intake assessments
• B. External dosimetry measures dose from inside the body; internal measures from outside the body
• C. External dosimetry uses bioassay; internal uses external dosimeters
• D. External dosimetry is theoretical; internal is actual measurement

Answer: (A)

Think of dosimetry in terms of where the radioactive source is relative to the body. External dosimetry measures the dose from sources located outside the body, typically using wearable dosimeters to monitor radiation penetrating from the workplace environment. Internal dosimetry, however, accounts for radiation dose from radioactive material that has entered the body—by inhalation, ingestion, or wound contamination—and is assessed with bioassays (like urine or feces testing) and intake assessments to estimate how much radionuclide is inside the body and which organs receive dose. This internal monitoring often uses biokinetic models to translate the body burden into organ dose. The key distinction is external versus internal source location and the corresponding method of dose assessment: direct external measurements for sources outside the body, versus measurements and calculations for material inside the body.

Think of dosimetry in terms of where the radioactive source is relative to the body. External dosimetry measures the dose from sources located outside the body, typically using wearable dosimeters to monitor radiation penetrating from the workplace environment. Internal dosimetry, however, accounts for radiation dose from radioactive material that has entered the body—by inhalation, ingestion, or wound contamination—and is assessed with bioassays (like urine or feces testing) and intake assessments to estimate how much radionuclide is inside the body and which organs receive dose. This internal monitoring often uses biokinetic models to translate the body burden into organ dose. The key distinction is external versus internal source location and the corresponding method of dose assessment: direct external measurements for sources outside the body, versus measurements and calculations for material inside the body.