1
What is the primary goal of radiobiology?
To understand radiation dose-response relationships.
Which law states that radiosensitivity depends primarily on a cell's maturity and metabolic activity?
The Law of Bergonie and Tribondeau
The SI unit of absorbed radiation dose is the:
Gray
What does linear energy transfer (LET) describe?
Energy deposited per unit distance
What does relative biologic effectiveness (RBE) compare?
Doses of different radiations producing the same effect
In pediatric imaging, which principle reinforces dose management?
ALARA
Which cells are the most radiosensitive?
Stem cells
Radiation dose is best defined as...
LET is measured in units of:
keV/μm
The standard radiation used for determining RBE is:
Diagnostic x-rays (200-250 kVp)
Which factor explains why the same dose causes less damage when delivered over time?
Protraction
Why are fetuses and children more radiosensitive than adults?
Their tissues have higher cell division rates
Why does tissue response vary when being exposed to the same radiation dose?
Physical and biological factors
As LET increases, the likelihood of biologic damage...
Increases
The RBE of diagnostic x-rays is
1
What is protraction?
Delivering radiation continuously at a low dose rate
When is human radiosensitivity the highest?
Before birth
Increased radiosensitivity when tissue is oxygenated is which concept?
The oxygen effect
Diagnostic x-rays have which LET value?
Low LET
Approximately 3 keV/μm
How would the body recover from sublethal radiation damage?
How does fractionation reduce radiation damage?
It allows cellular repair between exposures
What is the radiation hormesis hypothesis?
That low doses of radiation may have beneficial effects
What is the oxygen enhancement ratio (OER)?
The ratio of dose required under anoxic conditions compared to oxygenated conditions
The oxygen effect is strongest with which type of radiation?
Low LET radiation
What is repopulation?
Replacement of damaged cells by surviving cells