Chapter 4 Radiation biology
Conversions
-R= 2.58 X 10^-4 C/kg -1 rad = 0.1Gy -1 rem= 0.1 Sv -1 Gy= 10 rad -1 Sv = 10 rem
Conversion
-R=2.58x10^-4 C/kg -1Gy=100rad -1Sv=100rem -1 rem=rad x QF
A free radical
-an uncharged molecule -has an unpaired electron in the outer shell -is highly reactive and unstable -combines with molecules to form toxins
The sensitivity of tissues to radiation is determed by
-mitotic activity -cell differentiation -cell metabolism
The amount of radiation exposure an individual receives varies depending on
-receptor type -collimation -technique
Which factors contributed to radiation injury
-total dose -dose rate -cell sensitivity -age
A single intraoral image using a digital sensor results in an effective exposure dose of
0.2mSv
Arrange examination types using digital receptors in order of effective dose, from smallest (A) to largest (E)
26. Panoramic E-largest 27. Single periapical/rectangular collimation A-smallest 28. complete series/round collimation D-next 29. Complete series/ rectangular collimation C-next 30. Single bite-wing/ round collimation B next smallest
What is the approximate average dose of back-ground radiation received by an individual in the United States
300m rem or 3.1 mSv per year
Arrange the annual sources of radiation exposure in the United states from smallest (A) to largest (E)
31. medical procedures; D 36% 32. cosmic (space); C 5% 33. radon and thoron; E largest 37% 34. terrestrial (soil); B 3% 35. consumer products; A smallest 2%
What is the dose at which leukemia induction is most likely to occur
5000mrad (.05Gy)
An organ that, if damaged, diminishes the quality of an individual's life is termed a:
Critical organ
The latent period in radiation biology is the time between;
Exposure to x-radiation and clinical symptoms
Which relationship describes the response of tissues to radiation
Linear, nonthreshold
What is the greatest contributor to artificial radiation exposure
Medical radiation
Which radiation unit is determined by the quality factor (QF)
Rem
Only used for x-rays
Roentgen
The traditional unit for measuring x-ray exposure in air is termed
Roentgen
Which traditional unit does not have an SI equivalent
Roentgen
Dental images ____ the patient
benefit
Radiation injuries that are not seen in the person irradiated but that occur in future generations are termed:
genetic effects
Long-term effects are seen within a small amount of radiation absorbed in a
long period
Radioresistant
mature bone cells
In dental imaging, the benefit of disease detection benefits _____ the risk of damage from radiaiton
outweighs
The unit for measuring the absorption of x-rays is termed
rad (radiation absorbed dose)
Most susceptible to ionizing radiation
small lymphocyte
Biologic damage results from _____ exposure
x-ray
Indirect radiation injury occurs when
x-ray photons are absorbed and form toxins
Direct radiation injury occurs when
x-ray photons hit critical targets within a cell
