Radiology Flashcards
What type of radiation is high in energy and is capable of producing ions
ionizing radiation
What type of radiation is particulate and electromagnetic radiation?
ionizing radiation
What type of radiation involves particles that have a mass and travel in straight lines at high speeds (but not the speed of light)?
Particulate radiation
What is electromagnetic radiation?
electric and magnetic fields of energy that move through space in a wave-like motion
What are the characteristics of x-rays
invisible
travel at the speed of light
travel in waves
high frequency short waves
can penetrate objects
can cause changes in cells
can cause ionization
What is the number of electrons per second
Ampere (mA)
What is the force that moves electrons?
volt
What determines the speed at which an electron is propelled from the cathode, and determines quality
KiloVoltage peak (kVp)
What is the cathode controlled by
mA
What is in the cathode that emits electrons when heated
tungsten filament
What is the anode controlled by?
kVp
What in the cathode focuses the direction of electrons towards the anode
the molybdenum cup
What in the anode is the spot where the electron HIT to produce x-rays
Tungsten target
What is a small area on the target of the anode toward which the electrons from the focusing cup of the cathode are directed
Focal spot
Where are electrons originated
the focal spot
What dissipates excessive heat
the copper stem
What is the process of thermionic emission
at the cathode, an electron cloud is produced around the tungsten filament
What are the photons that leave the x-ray tube but have not interacted with any other matter characterized as
primary radiation
what are the majority of x-rays in dentistry produced by
bremsstrahlung (braking) radiation
How are x-rays produced from bremstrahlung
when high-energy electrons come close to the nuclei of the tungsten atom. The electrons slow down, and energy is released
What is characteristic radiation
electrons from the cathode dislodge electrons from the K/L shell of the tungsten atom, and an electron from other orbits fill the empty space.
what is created when beams of primary radiation interact with an object
secondary (scatter) radiation
What type of scatter radiation is the most common in dentistry
Compton scatter
How does compton scatter occur
a photon interacts with an outer shell electron and ejects it
can compton scatter cause ionization
yes
What type of scatter radiation occurs when a photon interacts with an inner shell electron?
photoelectric effects
can ionization occur with the photoelectric effect
yes
What type of scatter radiation occurs when a photon interacts with an outer shell electron but the matter is not altered?
coherent scatter
Does ionization occur with coherent scatter
no
What are the units used in the traditional system of measurment
Rem and Rad
What are the units used to measure the absorbed dose and dose equivalent
Rem and Rad
What is the equivalent to Rad in the SI system
the Gray
What is the direct theory
radiation damages the protein, lipid, carbohydrate, and the DNA molecule resulting in cell death
What is the indirect theory
radiation interacts with the water content of the cells and produces free radicals
time between radiation exposure and observed clinical effect
latent period
high doses of radiation to the whole body may result in what
nausea, diarrhea, fever, hair loss, and death
in the recovery period are most injuries from low-dose radiation repaired naturally?
yes
injury to the person being affected
stomatic effect
injury to the future generation
genetic effect
the probability of the occurrence increases with dose, but the severity of not dependent on the dose
ALL OR NONE
stochastic effect
severity of the damage is dependent on the dose
ex: loss of hair
non-stochastic effect
what cells are highly sensitive to radiation
immature cells, quickly dividing cells, younger people’s cells
EX: bone marrow, reproductive, intestines
highly specialized cells, mature cells, and slowly dividing cells are more or less sensitive to radiation?
less
What type of filter is built into the machine and includes glass tube, oil, and 0.5-2mm of aluminum
inherent filtration
What us the Maximum Permissible Dose (MPD) for an occupational person
5 rem/year
what is the MPD for non-occupational person
10% of worker amount, or 0.5 rem
what is the beam intensity affected by?
mA, kVp, distance, and exposure time
what is the half-value layer
thickness of aluminum filters that reduces the intensity of the beam by half.
what is the inverse square law
intensity of radiation is inversely proportional to the square of the distance from the source of radiation
what is density proportional to
amperes, kVp, and seconds
ex: if time is deacrease, mA must be increased to maintain similar density
what is contrast dependent on
kVp
what is the blurring at the edges of a structure on a radiograph
penumbra
sharpness is increased when:
tungsten target is small
object to film distance is short
tube to file distance is short
What technique requires bisection of the angles formed by the film and long axis of the tooth
bisecting technique
What technique requires the long axis of the tooth and the film are parallel to each other
paralleling technique
which technique causes less distortion
paralleling technique
What is the SLOB rule
same lingual, opposite buccal
tube head and object moved in the same direction- where is the object located?
lingual
tube head and object moved in the opposite direction- where is the object located?
buccal
what causes overlap
inappropriate horizontal angulation
what error causes foreshortening and elongation
inappropriate vertical angulation
