true or false. All ionizing is harmful, and biological change from dental x-radiation is small, byt does still have biologic damage
both statements are true
Ionization of water results in the production of hydrogen and hydroxyl _____ _______
free radicals
suggests that cell damage results when ionizing radiation directly hits critical areas, or targets within the cell (DNA)
direct theory
suggests that x-ray photons are absorbed within the cell and cause the formation of toxins, which in turn damage the cell
indirect theory
When dose and damage of radiation are plotted on a graph, what type of relationship is seen?
linear, nonthreshold
true or false. there is NO safe amount of radiation, in dental radiation, damage always does occur
true
effects that occur as a direct function of dose; the probability of occurence increases with dose, but the severity of effects does not depend on the magnitude of the absorbed dose; they do not have a dose threshold
stochastic effects
cancer induction and genetic mutations are what type of effects?
stochastic
effects that have a threshold and increase in severity with increasing absorbed dose
nonstochastic
erythema, loss of hair, cataract formation, and decreased fertility are examples of what effect?
nonstochastic
Why do high dose rates cause more damage?
because the tissues don't have enough time to repair themselves
result from exposure to a nuclear accident or atomic bomb - associated with large amounts of radiation in small amounts of time
short-term effects
effects that appear after years and years, associated with small amounts of radiation absorbed repeatedly over a long period of time - linked to the induction of cancer, birth abnormalities, and genetic defects
long term effects
All cells in the body except the reproductive cells
somatic cells
reproductive cells
genetic cells
effects seen in the person irradiated and not transmitted to future generations
somatic effects
effects not seen in the person irradiated, but passed to future generations
genetic effects
What are radiosensitive cells?
blood cells
immature bone cells
young bone cells
What cell is most sensitive to radiation?
small lymphocyte (blood cells)
what are radioresistant cells?
cells of bone
muscle
nerve
What are radiosensitive organs?
lymphoid tissue
bone marrow
testes
intestines
What are radioresistant tissues?
salivary glands
kidney
liver
Critical organs in dental radiography include:
skin
thyroid gland
lens of eye
bone marrow
a way of measuring radiation exposure by the amount of ionization that occurs in air
Roentgen
The amount of energy absorbed by a tissue; how is it measured?
Dose
rad (radiation absorbed dose)
How much radiation reduction do you get from using f-speed film?
60%
A longer source to flim distance will _______ pts exposure to radiation
decrease
true or false. The Roentgen (R) measures the amount of energy that reaches the surface of an organism, and the amount of radiation absorbed
FALSE! It does NOT measure the amount of radiation absorbed!
SI unit that measures the number of electrical charges, or ion pairs in 1 kg of air
coulomb/kg
What measurement is used to compare the biological effects of different types of radiation?
dose equivalent
the product absorbed dose (in rads) and quality factor specific for the type of radiation; the traditional unit of the dose equivalent
Rem - roentgen equivalent in man
a _____ _______ or dimensionless multiplier is used to place the exposure effects of different types of radiation on a common scale
Quality factor
SI unit equivalent of the rem is __________
sievert (sv)
SI unit equivalent of the rad is ________
gray (gy)
a form of ionizing radiation that is ubiquitous in the environment, and which humans are exposed to daily
background radiation
Radiation that originates from the stars and the sun, and the higher the elevation, the more of this you recieve
cosmic radiation
radiation that is emitted from radioactive materials present in the earth and air including potassium and uranium
terrestrial radiation
What type of radiation is the single largest contributor to artificial radiation?
medical radiation
true or false. Risk estimates suggest that death is more likely to occur from common activities than from the dental radiographic procedures, and that cancer is far more likely to be unrelated to radiation exposure
true
The use of a rectangular collimator reduces absorbed radiation dose by ______ %