Biological Effects of Radiation Flashcards
7 cards from real CHP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Biological Effects of Radiation flashcards as text
Which of the following describes the Petkau effect in radiation biology?
Answer: Observation that low-dose-rate chronic irradiation can be more effective per unit dose in producing certain endpoints such as membrane damage
The Petkau effect describes the phenomenon where low-dose-rate, chronic radiation exposures can produce greater membrane damage per unit dose than acute high-dose irradiation, attributed to free radical chain reactions.
The microdosimetric quantity 'lineal energy' (y) is defined as:
Answer: The energy imparted by a single energy-deposition event divided by the mean chord length of the target volume
Lineal energy (y) is the energy imparted in a single event divided by the mean chord length of the sensitive volume, used in microdosimetry to characterize radiation quality at the cellular level.
Hereditary risk estimates for radiation are based primarily on:
Answer: Extrapolation from animal (primarily mouse) genetic studies using the doubling dose method
Because no statistically significant increase in hereditary disease has been detected in atomic bomb survivors' offspring, hereditary risk estimates rely on mouse genetic experiments and the doubling dose method.
Which of the following is the most direct evidence that radiation exposure causes leukemia in humans?
Answer: Excess leukemia cases in Japanese atomic bomb survivors showing a dose-response relationship
The Life Span Study of atomic bomb survivors provides the most direct human evidence, showing a clear dose-dependent excess of leukemia with a minimum latency of approximately 2–5 years.
The repair of DNA double-strand breaks (DSBs) via homologous recombination (HR) requires:
Answer: A homologous DNA template, typically the sister chromatid, and is most active in S and G2 phases
HR requires an intact homologous template (sister chromatid) and is therefore restricted to late S and G2 phases when the replicated chromosome is available, providing high-fidelity repair.
The nominal probability coefficient for fatal cancer from ICRP Publication 103 for the whole population is approximately:
Answer: 5% per Sv (0.05 Sv⁻¹)
ICRP 103 gives a nominal fatal cancer probability coefficient of approximately 5.5% per Sv for the whole population, often rounded to 5% per Sv for radiation protection calculations.
Which type of radiation produces the LOWEST oxygen enhancement ratio (OER)?
Answer: High-LET neutrons or alpha particles
High-LET radiations (neutrons, alpha particles) produce dense ionization tracks that cause clustered DNA damage independent of oxygen, resulting in an OER approaching 1.0.