chapter 2 Flashcards
an atom whose nucleus has the same number of protons but different number of neutrons
isotopes
innermost shell; binding energy is greatest in this shell; closer to nucleus
k shell
atoms that have gained or lost electrons are called ions, which are charged particles and electrically unstable; ejection of electron from an atom
ionization
the atom which an electron has been removed is
positively charged-positive ion
the electron that has been separated is
negatively charged- negative ion
the emission and movement of energy through space in the form of electromagnetic radiation(x and gamma rays) or particulate radiation(alpha and beta particles)
radiation
any radiation that produces ions is called
ionizing radiation
the process whereby certain unstable elements undergo spontaneous disintegration(decay) in an effort to attain a stable nuclear state
radioactivity
movement of wavelike energy through space as a combination of electric magnetic fields
electromagnetic radiation
all energies of electromagnetic spectrum share the following properties:
- travel at speed of light
- no electical charge
- no mass or weight
- pass through space as particles and in wavelike motion
the distance between two similar points on two successive waves
wavelength
measure of the number of waves that pass a given point per unit of time
frequency
the speed of the wave
velocity
long wavelength equals what frequency?
low frequency
x rays are believed to consist of minute bundles(or quanta) of pure electromagnetic energy called ___; known as bullets of energy
photons(no mass or weight, invisible, cannot be sensed)
properties of x rays
- invisible
- travel in straight lines
- travel at speed of light
- no mass or weight
- no charge
- interact with matter causing ionization
- can penetrate opaque tissues and structures
- affect photographic film emulsion(latent image)
- affect biological tissue
- dense- radiopaque
- less dense- radiolucent
materials that are dense will ____ x rays(amalgam, gold) and appear____
absorb- radiopaque
thin materials and less dense structures will appear_____ (pulp cavity)
radiolucent
bodies in motion are believed to have___ energy
kinetic
produced when high speed electrons are stopped or slowed down by tungsten atoms of dental x ray tube
general/brems radiation
the electron is bent off course; kinetic energy lost is converted to xray energy
brems radiation
majority of x rays are produced in this form
brems
only a small part of xrays are produced in this form
characteristic
produced when a bombarding electron from the tube filament collides with an orbiting K electron of the tungsten target; k shell electron is dislodged from the atom; another electron in an outer shell fills the void; an xray photon is emitted
characteristic radiation
what percent is no interaction
9%
what percent is coherent(thompson scattering)
8%
what percent is photoelectric
30%
what percent is compton
60%
the incoming xray gives up all of its energy to an orbital electron of the atom; x ray absorbed and vanishes; electromagnetic energy of the xray is imparted to the electron in kinetic energy and electron flies from its orbit; forming secondary ion pairs
photoelectric effect
interacts with orbital electron and ejects it. only a part of xray energy is transferred to the electron and a new, weaker xray is formed and scattered in some new direction
compton scattering
compton effect produces what
scatter
both compton and photoelectric effects involve what
ionization; occurs during interactions with a patients body tissue or other matter
scatter is what kind of radiation
secondary radiation
SI metric system
coulombs per kilogram(C/kg)
Gray(Gy)
Sievert (Sv)
the measurement of ionization in air produced by xrays or gamma rays; and what is unit of measurement?
exposure; coulombs per kilogram(C/kg) or roentgen
the amount of energy deposited in any form of matter, such as tissues of head and neck of patient, by any type of radiation; unit of measurement
absorbed dose; gray or rad
used to compare the biological effects of the various types of radiation; term for radiation protection
dose equivalent; Sv and rem
used to compare the risk of radiation exposure producing a biological response
effective dose equivalent; microsievert
ionizing radiation that is always present in our environment
background radiation
PID
position indicating device
