Deterministic Radiation Effects
Deterministic radiation effects are characterized by what two features?
A threshold dose and increasing severity
The prodromal period of ARS is characterized by what symptoms?
Nausea, vomiting, and diarrhea
Which germ cells in the testes are most radiosensitive?
Spermatogonia
Stochastic radiation effects are best described as effects that:
Increase in probability with dose
According to BEIR estimates, fatal cancer risk from radiation exposure is approximately:
5 × 10⁻² Sv⁻¹
or
5 cancers per 100 people per Sv
Why have deterministic effects not been observed from diagnostic x-ray exposure?
Diagnostic doses are far below threshold levels
Why is the latent period of ARS considered misleading?
Symptoms temporarily disappear
Radiation-induced cataracts are considered deterministic because they:
Have a threshold dose
The assumed dose-response relationship for stochastic effects is:
Linear non-threshold
Radiation-induced leukemia is considered stochastic because it:
Increases in probability with dose
Acute radiation syndrome results from what type of exposure?
High-dose, whole-body irradiation
The LD₅₀/₆₀ for humans is approximately what dose?
3.5 Gy
Which blood cells are the most radiosensitive?
Lymphocytes
Relative risk is calculated by comparing what values?
Observed cases to expected cases
The latent period for radiation-induced leukemia is approximately:
4–7 years
Which acute radiation syndrome occurs at the lowest radiation doses?
Hematologic
Partial-body irradiation requires higher doses to cause injury because:
Unirradiated tissue can compensate
Which stochastic effect is the primary concern in diagnostic imaging?
Cancer induction
A relative risk of 1.0 indicates what level of risk?
No increased risk
Which cancer has the clearest association with childhood radiation exposure?
Thyroid
Erythema and desquamation are deterministic effects because they:
Require a threshold dose
Which layer of the skin is the most radiosensitive?
Basal cell layer
Why are epidemiologic studies required to study stochastic radiation effects?
Effects are rare and delayed
Attributable risk is most useful when what condition is known?
Dose is known
The doubling dose refers to the radiation dose that does what?
Doubles the natural mutation rate