Exam 1 Flashcards
anything that occupies space and has mass
matter
results when matter is altered
energy
substances made up of only one type of atom
elements
central nucleus + orbiting electrons
atom
core of atom, consists of protons and neutrons
- always positively charged
nucleus
positively charged particles
Protons
particles with no charge
neutrons
tiny, negatively charged particles
- Arranged around nucleus in orbits
electrons
pathway of electrons
Orbits (shells)
number of protons and neutrons in nucleus
Mass number/Atomic weight
number of protons in nucleus equals number of electrons in atom
Atomic number
Maximum number of shells per atom
7
1 KeV =
1000 eV
attraction between the positive nucleus and negative electrons
- Keeps electrons surrounding nucleus
Electrostatic force
amount of energy needed to remove electron from its orbit
Binding energy/force
two or more atoms joined together by chemical bonds
Molecules
sharing electrons in outermost shell
Covalent bonding
transfer of electrons
Ionic bonding
can exist as neutral or unbalanced
atoms
(unbalanced atom) atom that gains/loses an electron and becomes electrically unbalanced
ion
converting atoms into ions/production of ions, become positively or negatively charged
Ionization
result of an electron being removed from atom, positive ion + negative ion
Ion pair
emission and propagation of energy through space or substance in form of waves or particles
Radiation
process of unstable atoms undergoing spontaneous disintegration to become balanced
Radioactivity
high energy capable of producing ions
Ionizing radiation
tiny particles of matter traveling in straight lines at high speed, may be charged
- HAS mass
Particulate radiation
- wave like motion
- NO mass
- Can be man-made or naturally
- Arranged on electromagnetic spectrum
Electromagnetic radiation
- discrete bundles of energy
- Photons
- No mass
- Travel as in straight line
Particle concept
- waves
- Focus on wavelength, frequency, velocity
wave concept
distance between crest of waves
Wavelength
number of wavelengths in specific time period
Frequency
wave speed
velocity
o Invisible
o No mass
o No charge
o Travel in waves and straight lines
o High frequency, short wavelength
o Cannot be focused to a point
o Penetrate gases, liquid, and solids
o Absorb matter
o Interact with matter, cause ionization
o Cause certain substances to fluoresce
o Can produce image on receptor
o Causes biological change in cells
Characteristics of X-rays
what does the metal housing in the tubehead do
protect everything
what does the insulating oil in the tubehead do
dissipates heat
what does the tubehead seal do
makes sure insulating oil is contained
what does the aluminum disks do in the tubehead
filters out long wavelength or low frequency x-rays
what does the lead collimator do in the tubehead
restricts size of x-ray beam
Supply electrons necessary to generate x-rays
Cathode (negative)
- Generates electrons
- Creates electron cloud
Tungsten filament
- Focusing electrons into one line
- Electrons always floating from cathode to anode!!
Molybdenum cup
- Convert electrons into x-rays
- Tungsten target
- Copper stem
Anode
needed to generate x-rays
electricity
flow of electrons through a conductor
Electrical current
electrons flow in one direction through conductor
Direct current
electrons flow in two, opposite directions
Alternating current
converting from AC to DC
Rectification
number of electrons moving through conductor
Amperage
speed of electrons moving from cathode to anode
Voltage
path of electrical current
Circuits
- Generates source of electrons needed to produce x-rays at filament of x-ray tube
- Controlled by mA settings
Filament circuit (3-5V)
- Provides high voltage required to accelerate electrons from cathode to anode
- Controlled by kV settings
High-voltage circuit (65,000-100,000V)
device used to increase or decrease voltage in an electrical circuit
Transformer
Decreases V
Step-down transformer
Increases V
Step-up voltage
Corrects minor fluctuations in current
Autotransformer
release of electrons from tungsten filament when electrical current passes through it and heats filament
Thermionic emission
- Aka breaking or bremsstrahlung radiation
- 70% of x-rays produced at anode
- High speed down when passing tungsten atom
- Hits: all kinetic energy converts to high-energy x-ray photon
- Misses: low-energy x-ray photon
General radiation
- 30% of x-rays
- High-speed electron dislodges inner-shell electrons from tungsten atom
- Causes ionization
- Electrons rearrange, causing loss of energy and production of x-ray photons
Characteristic radiation
penetrating x-ray beam
Primary radiation
result of primary beam interacting with matter, less penetrating than primary
Secondary radiation
form of secondary, deflected x-rays after interaction with matter going in all directions; detrimental
Scatter radiation
o Passes through atom unchanged and leaves atom unchanged
o Responsible for producing densities
o Makes dental radiography possible
No interaction
o Photoelectric effect
o Photon interacts with inner shell electrons of matter
o Photon is absorbed and electron is ejected
o Ionization occurs → BAD
Absorption
o AKA modified scatter
o Compton effect
o Photon interacts with outer shell electrons of matter
o Photon loses energy but electron still ejected
o Ionization still occurs → BAD
Compton Scatter
o AKA Thompson Scatter or unmodified scatter
o Photons interact with outer shell electrons, but matter is not altered
o Photons continue to travel with no loss of energy
- Direction changes with no energy loss
o No ionization occurs
Coherent Scatter
the study of the effects of ionizing radiation on living tissue to understand the harmful effects of x-radiation
Radiation biology
- Photoelectric effect or Compton scatter
- Results in positive atom and dislodged negative electron
- Ejected electron still in motion and interacts with other atoms
Ionization
- uncharged neutral atom/molecule that exists with one single electron in its outmost shell
- Highly reactive and unstable
Free radical formation
Cell damage can occur when ionizing radiation directly hits critical areas (cell death)
Direct theory (1/3)
X-ray photons absorbed within cell and cause formation of toxins (causing direct damage)
Indirect theory (2/3)
o Probability of occurrence increases with dose
o Severity is NOT dependent on dose
o All or none
Stochastic radiation effect
o Severity of damage dependent on dose
o Occur only after exceeding threshold
o Result of severe cell damage
Nonstochastic/Deterministic radiation effect
time to exposure to clinical signs
Latent period
time in which cellular injury occurs
Period of injury
