Internal Dosimetry and Bioassay Flashcards

Which bioassay method is preferred for monitoring workers potentially exposed to pure alpha emitters such as plutonium?

Answer: Urine bioassay (indirect)

Plutonium alpha emissions do not penetrate the body, so urinalysis (indirect bioassay) is required to detect systemic uptake.

What is the significance of the ICRP publication 66 Human Respiratory Tract Model for internal dosimetry?

Answer: It describes particle deposition and clearance in each respiratory region

ICRP 66 provides a detailed anatomical and physiological model for calculating deposition fractions and clearance rates in nasal, trachea-bronchial, and alveolar regions.

A worker's urine bioassay result exceeds the investigation level for Cs-137. What is the correct next step?

Answer: Perform a dose assessment to estimate the committed effective dose

Exceeding an investigation level triggers a formal internal dose assessment to quantify the CEDE before any regulatory reporting decision.

Which radiation type is NOT detectable by in-vivo bioassay techniques?

Answer: Pure alpha emitters

Pure alpha emitters deposit all energy within centimeters of the source in tissue, so no radiation escapes for external detection.

What does the term 'dose conversion factor' (DCF) represent in internal dosimetry?

Answer: The committed effective dose per unit activity intake (Sv/Bq or rem/µCi)

A DCF converts a measured or estimated intake quantity directly into a committed effective dose, typically expressed as Sv/Bq or rem/µCi.

Under 10 CFR Part 20, what must a licensee do if a worker's total effective dose equivalent exceeds 5 rem in a year?

Answer: Investigate and report to the NRC within 30 days if required thresholds are met

Exceeding the annual TEDE limit requires investigation and NRC reporting per 20.2203 if the overexposure meets notification thresholds.