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Radiation Protection Chapter 7
Terms in this set (42)
What is Radiation biology?
A branch of biology concerned with the effects of ionizing radiation of living systems
What are the determinants of radiation energy?
What does LET stand for?
Linear Energy Transfer
What does RBE stand for?
Relative Biologic Effectiveness
What does OER stand for?
Oxygen Enhancement Ratio
What is LET?
When passing through a medium, ionizing radiation may deposit energy along it's path
What is considered low LET?
What is considered high LET?
-Ions of heavy nuclei
-Low energy neutrons
What is RBE?
Describes relative capabilities of radiation with differing LET's to produce a particular biologic reaction
What is the RBE of X-rays?
When LET increases....
What is OER?
When irradiated in an OXYGENATED or AEROBIC state, biologic tissue is more sensitive to radiation than when it is exposed to radiation under anoxic (without oxygen) or hypoxic (low-oxygen) conditions
What is the OER of X-rays?
3.0 when the dose is high
What levels can molecular damage of irradiation be seen?
What level can any visible radiation induced injuries always begin at?
What are the effects of irradiation on Somatic cells?
If sufficient, the entire body can be disrupted
What are the effects of irradiation of Genetic cells?
-Passed on to future generations
What are the 2 classifications of ionizing radiations interactions?
Direct and Indirect
When is direct action more likely?
With high LET radiation
95% of interactions with x-ray are what kind?
What is a free radical?
Uncharged solitary molecule that is very damaging; dramatically increase the amount of biologic damage
What is a Point mutation?
-A single DNA strand break
-Can be repaired
What is a double strand break?
-A break at 2 points in a DNA strand
-Not easily repaired
What happens with a double strand break in the same rung?
-Will cause complete chromosome breakage
-Can cause cell death
What is a mutation?
-A loss or change of base sequence
-Can be passed on to future generations
What is a Covalent cross link?
-Chemical unions between atoms
-Cause molecules to stick to others
What does restitution mean?
Break rejoins and no visible damage
What does deletion mean?
Part of chromosome is lost. Results in cell mutation
What is meant by Broken and rearrangement?
Dicentric ring formation- cell mutation
What does the Target theory state?
When a cell DNA is directly or indirectly inactivated by exposure to radiation the cell will die
How does damage to the cell's nucleus reveal itself?
-Apoptosis, or programmed cell death
-Mitotic, or genetic death
-Interference with function
What is the cell survival curve used in?
What is the Low LET on the survival curve?
Has a shoulder to the curve at lower doses which indicates the cells ability to repair
What is the High LET on the survival curve?
Typically has no shoulder, indicating no repair takes place
The law of Bergonie and Tribondeau states that the most pronounced radiation effects occur in cells that have what?
-Greatest reproductive activity
-Longest Mitotic phase
What is the most susceptible to radiation damage?
What has high cell radiosensitivity?
What has intermediate cell radiosensitivity?
What has low cell radiosensitivity?
What is the tissue sensitivity of epithelial tissue?
-Lines and covers the body tissue
-Since this is constantly regenerating it is very sensitive
What is the sensitivity of muscle tissue?
Highly specialized and relatively insensitive
What is the sensitivity of nerve tissue?
-Most specialized and most insensitive to radiation exposure
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