DENT 1050 Chapter 4 Flashcards
The latent period in radiation biology is the time between:
a. exposure of film and development
b. subsequent doses of radiation
c. cell rest and cell mitosis
d. exposure to x-radiation and clinical symptoms
e. none of the above
d. exposure to x-radiation and clinical symptoms
A free radical:
a. is an uncharged molecule
b. has an unpaired electron in the outer shell
c. is highly reactive and unstable
d. combines with molecules to form toxins
e. all of the above
e. all of the above
Direct radiation injury occurs when:
a. x-ray photons hit critical targets within a cell
b. x-ray photons pass through the ell
c. x-ray photons are absorbed and form toxins
d. free radicals combine to form toxins
e. none of the above
a. x-ray photons hit critical targets within a cell
Indirect radiation injury occurs when:
a. x-ray photons hit critical targets within a cell
b. x-ray photons pass through the cell
c. x-ray photons are absorbed and form toxins
d. x-ray photons hit the DNA of a cell
e. none of the above
c. x-ray photons are absorbed and form toxins
Which of the following relationships describes the response of tissues to radiation?
a. linear
b. linear, threshold
c. linear, nonthreshold
d. nonlinear, nonthreshold
e. none of the above
c. linear, nonthreshold
Which of the following factors contributes to radiation injury?
a. total dose
b. dose rate
c. cell sensitivity
d. age
e. all of the above
e. all of the above
Which of the following statements is correct?
a. Short-term effects are seen with small amounts of radiation absorbed in a short period.
b. Short-term effects are seen with small amounts of radiation absorbed in a long period.
c. Long-term effects are seen with small amounts of radiation absorbed in a short period.
d. Long-term effects are seen with small amounts of radiation absorbed in a long period.
e. None of the above
d. Long-term effects are seen with small amounts of radiation absorbed in a long period.
Radiation injuries that are not seen in the person irradiated but that occur in future generations are termed:
a. somatic effects
b. genetic effects
c. cumulative effects
d. short-term effects
e. long-term effects
b. genetic effects
Which of the following is most susceptible to ionizing radiation?
a. bone tissue
b. small lymphocyte
c. muscle tissue
d. nerve tissue
e. epithelial tissue
b. small lymphocyte
The sensitivity of tissues to radiation is determined by:
a. mitotic activity
b. cell differentiation
c. cell metabolism
d. all of the above
e. none of the above
d. all of the above
Which of the following is considered radioresistant?
a. immature reproductive cells
b. young bone cells
c. mature bone cells
d. none of the above
c. mature bone cells
An organ that, if damaged, diminishes the quality of an individual’s life is termed a:
a. critical organ
b. somatic organ
c. cumulative organ
d. radioresistant organ
e. none of the above
a. critical organ
The traditional unit for measuring x-ray exposure in air is termed:
a. the gray
b. coulombs per kilogram
c. the rem
d. the rad
e. the roentgen
e. the roentgen
Which of the following radiation units is determined by the quality factor (QF)?
a. the roentgen
b. the rad
c. the rem
d. the gray
e. coulombs per kilogram
c. the rem
The unit for measuring the absorption of x-rays is termed:
a. the roentgen
b. the rad
c. the rem
d. quality factor
e. the sievert
b. the rad
Which of the following conversions is correct?
a. 1 R = 2.58 x 10^-4 C/kg
b. 1 rad = 0.1 Gy
c. 1 rem = 0.1 Sv
d. 1 Gy = 10 rads
e. 1 Sv = 10 rems
a. 1 R = 2.58 x 10^-4 C/kg
Which of the following traditional units does not have an SI equivalent?
a. the roentgen
b. the rad
c. the rem
d. quality factor
e. none of the above
a. the roentgen
Which of the following is used only for x-rays?
a. the sievert
b. the gray
c. the rem
d. the rad
e. the roentgen
e. the roentgen
Which of the following conversions is correct?
a. 1 R = 2.58 x 10^-4 C/kg
b. 1 Gy = 100 rads
c. 1 Sv = 100 rems
d. 1 rem = rads x QF
e. all of the above
e. all of the above
What is the average dose of background radiation received by an individual in the United States?
a. 0-100 mrads (0-0.001 Gy)
b. 50-100 mrads (0.0005-0.001 Gy)
c. 150-300 mrads ((0.0015-0.003 Gy)
d. 200-500 mrads (0.002-0.005 Gy)
e. 500-1000 mrads (0.005-0.01 Gy)
c. 150-300 mrads ((0.0015-0.003 Gy)
What is the greatest contributor to artificial radiation exposure?
a. radioactive materials
b. medical radiation
c. consumer products
d. weapons production
e. nuclear fuel cycle
b. medical radiation
The amount of radiation exposure an individual receives varies depending on:
a. film speed
b. collimation
c. technique
d. exposure factors
e. all of the above
e. all of the above
A single intraoral radiograph (D-speed film, 70 kVp, long PID) results in a mean surface exposure of:
a. 50 mR
b. 250 mR
c. 500 mR
d. 1 R
e. 5 R
a. 50 mR
What is the dose at which leukemia induction is most likely to occur?
a. 500 mrads (0.005 Gy)
b. 1000 mrads (0.01 Gy)
c. 2000 mrads (0.02 Gy)
d. 5000 mrads (0.05 Gy)
e. none of the above
d. 5000 mrads (0.05 Gy)
Which of the following statements is incorrect?
a. X-radiation is not harmful to living tissues.
b. Dental radiographs benefit the patient.
c. In dental radiography, the benefit of disease detection outweighs the risk of damage from radiation.
d. Radiography should be prescribed only when the benefit outweighs the risk.
e. Biologic damage results from x-ray exposure.
a. X-radiation is not harmful to living tissues.
Radiation biology
the study of the effects of ionizing radiation on living tissue
Ionization
produced through the photoelectric effect or Compton scatter and results in the formation of a positive atom and a dislodged negative electron.
Free radical with no charge
denoted by a dot following the chemical symbol
Free radical
an uncharged (neutral) atom or molecule that exists with a single, unpaired electron in its outermost shell; highly reactive and unstable
Direct theory
suggests that cell damage results when ionizing radiation directly hits critical areas, or targets, within the cell
Indirect theory
suggests that x-ray photons are absorbed within the cell and cause the formation of toxins, which, in turn, damage the cell
Dose-response curve
can be used to correlate the “response,” or damage, of tissues with the “dose,” or amount, of radiation received
Stochastic effects
occur as a direct function of dose
Nonstochastic effects
(deterministic effects) somatic effects that have a threshold and that increase in severity with increasing absorbed dose
Latent period
the time that elapses between exposure to ionizing radiation and the appearance of observable clinical signs
Length of latent period
the more radiation received and the faster the dose rate, the shorter the latent period
Period of injury
comes after latent period; includes: cell death, changes in cell function, breaking or clumping of chromosomes, formation of giant cells, cessation of mitotic activity, and abnormal mitotic activity
Recovery period
last event in radiation injury; depending on a number of factors, cells can repair the damage caused by radiation
Cumulative effects
effects of radiation are additive and if unrepaired damage accumulates in tissues; can lead to cancer, cataract formation, birth defects, etc.
Total dose
quantity of radiation received, or the total amount of radiation energy absorbed
Dose rate
rate at which exposure to radiation occurs and absorption takes place (dose rate = dose/time)
