Internal Dosimetry and Bioassay Flashcards

Which analytical technique is commonly used for indirect bioassay of uranium in urine samples?

Answer: Fluorometric analysis or ICP-MS

Uranium is detected in urine via fluorometric analysis or inductively coupled plasma mass spectrometry (ICP-MS) because natural uranium emits very weak radiation.

What ICRP lung model parameter describes how quickly an inhaled material is cleared from the respiratory tract?

Answer: Absorption type (F, M, or S)

The ICRP Human Respiratory Tract Model classifies inhaled materials as Fast (F), Moderate (M), or Slow (S) based on their rate of absorption into blood.

A whole-body counter (WBC) is most sensitive for detecting which type of emitter inside the body?

Answer: Gamma emitters

WBCs detect gamma photons penetrating the body using NaI or HPGe detectors, making them most useful for gamma-emitting radionuclides.

Which organ is the critical organ for dosimetry purposes when a worker inhales tritium (H-3) as HTO?

Answer: Whole body (uniform distribution)

Tritiated water (HTO) rapidly distributes uniformly throughout body water, so the whole body is used as the reference tissue for dose calculations.

What is the effective half-life (T_eff) of a radionuclide in the body?

Answer: The combined half-life accounting for both physical decay and biological elimination

T_eff = (T_physical × T_biological) / (T_physical + T_biological), combining radioactive decay with the body's elimination rate.

What trigger level typically initiates a formal internal dosimetry investigation under NRC guidance?

Answer: Intake exceeding 10% of the ALI

NRC and most internal dosimetry programs initiate formal dose assessment investigations when estimated intake exceeds 10% of the ALI.