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RADIATION SAFETY EXAM #3 Q&A
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RADIATION SAFETY EXAM #3 Q&A
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RADIATION SAFETY EXAM #3 Q&AFor radiation protection, high let radiation is of greatest concern when a radionuclide
has been implanted, ingested, injected, or inhaled because - answer-the potential exists
for irreparable damage because multiple strand breaks in dna are possible
Free radicals behave as an extremely reactive single entity as a result of what presence
- answer-unpaired electrons
What is classified as high let - answer-alpha particles
A biologic reaction is produced by a 3 gy, of a test radiation. It takes 12 gy, of 250 kvp x-
radiation to produce the same biologic reaction. What is the relative biologic
effectiveness of the test radiation - answer-4
Which action of ionizing radiation is most harmful to the human body - answer-indirect
action
Which molecules in the human body are most commonly directly acted on by ionizing
radiation to produce molecular damage through an indirect action - answer-water
When does ionizing radiation cause complete chromosome breakage - answer-when
two direct hits occur in the same rung of the dna macromolecule
When significant numbers of lymphocytes are damaged by exposure from ionizing
radiation, the body - answer-loses its natural ability to combat infection
Becomes more susceptible to bacteria
Becomes more susceptible to viral antigens
With respect to the law of bergonie and tribondeau, which would best complete this
statement? "the most pronounced radiation effects occur in cells having the ___" -
answer-greatest reproductive activity, longest, mitotic phases, and least maturity
What do basal cells of the skin, intestinal crypt cells, and reproductive cells have in
common - answer-all cells are radiosensitive
Why is it necessary for persons who administer radiation to humans for medical imaging
purposes to have a basic understanding of cell structure, composition, and function as
well as the adverse effects of ionizing radiation on these entities - answer-because the
potentially harmful effects of ionizing radiation on living systems
What will an ionized atom of biologic tissue not be able to do - answer-does not bond
properly in molecules
, Why is let an important factor in assessing potential tissue and organ damage from
exposure to ionizing radiation - answer-the amount of ionization produced in an
irradiated object corresponds to the amount of energy it absorbs and because both
chemical and biologic effects in tissue coincide with the degree of ionization
experiences by the tissue
Why is high let radiation more destructive to biologic matter than low let radiation -
answer-high let types of radiation deposit more energy per unit length of biologic tissue
traversed/high let has more interactions with tissue than low let
Why is the concept of relative biologic effectiveness (rbe) not practical for specifying
radiation protection dose levels in humans - answer-used to refer to specific
experiments with specific cells of animal tissues. The cells/tissues differ in their biologic
response per unit quantity of absorbed dose
Why does the presence of oxygen in biologic tissue make the damage produced in that
tissue by free radicals permanent - answer-oxygen reacts with free radicals to produce
organic peroxide compounds, that is a non-restorable change in the target material
What consequences can occur if ionizing radiation damages germ cells - answer-males:
rad dose of 0.1 gy can depress the sperm population and possibly cause genetic
mutations in future generations
Female: gonadal dose of 0.1 gy can delay or suppress menstruation
How can ionizing radiation interact with a dna macromolecule and create a point
mutation - answer-energy transferred could rupture one of its chemical bonds and
possibly sever one of the sugar phosphate chain side rails or strands of the ladder like
molecule structure
Why is the embryo-fetus more susceptible to radiation damage than either the child or
the adult - answer-cells are more radiosensitive when they are least mature or
specialized, greatly reproductive, and have long mitotic phases
Why is ld 50/60 a more accurate way to assess lethal dose for humans than ld 50/30 -
answer-human beings recover more slowly than other organisms, thus after the 30 day
period there can still be a risk of death
Low let radiation generally causes sublethal damage to dna - answer-true
Target theory holds that the cell will die after exposure to ionizing radiation only if the
master molecule (dna) is inactivated in the process - answer-true
Because mature spermatogonia are specialized and do not divide, they are relatively
sensitive to the effects of ionizing radiation - answer-false
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