Term
|
Definition
| lack density and permit passage of x-ray beam with little or no resistance |
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Term
|
Definition
| dense and resist the passage of the x-ray beam |
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Term
|
Definition
| overall darkness or blackness of a film |
|
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Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| low kilovoltage peak settings are used. many black areas and many white areas |
|
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Term
|
Definition
| high kvp settings. many shades of gray instead of black and white. |
|
|
Term
| milliamperage is increased = |
|
Definition
| exposure time is decreased |
|
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Term
|
Definition
| two densities visible; black and white |
|
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Term
|
Definition
| many densities or shades of gray |
|
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Term
|
Definition
|
|
Term
|
Definition
| quality and quantity together |
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Term
|
Definition
|
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Term
|
Definition
| how distance affects the intensity of the x-ray beam |
|
|
Term
| when the PID length is changed from 8 to 16 inches, the source to film distance is |
|
Definition
|
|
Term
| when the PID length is changed from 16 to 8 inches, the source to film distance is |
|
Definition
|
|
Term
| what are the factors that influence sharpness? |
|
Definition
focal spot size - 0.6 to 1mm squared
film composition
movement |
|
|
Term
| what are the factors that influence magnification? |
|
Definition
target film distance
object-film distance |
|
|
Term
| closer the tooth is to the film |
|
Definition
| the less magnification there will be |
|
|
Term
| what are the factors that influence distortion? |
|
Definition
object-fillm alignment
x-ray beam angulation |
|
|
Term
| how does mA relate to dental radiography? |
|
Definition
regulates the temp. of cathode filament
7-15 mA used in dental radiography
|
|
|
Term
|
Definition
|
|
Term
|
Definition
the mean energy and penetrating power of the beam
controlled by kilovoltage |
|
|
Term
|
Definition
related to mA
increased mA = increase electrons = increased density |
|
|
Term
| what are some geometric characteristics? |
|
Definition
sharpness
magnification
distortion |
|
|
Term
|
Definition
when increasing kvp by 15, exposure time must be decreased by 1/2
when kvp is decreased by 15, exposure time should be doubled |
|
|
Term
| what are the three types of intraoral radiographic exams? |
|
Definition
1. periapical
2. interproximal
3. occlusal |
|
|
Term
|
Definition
| complete mouth radiographic series |
|
|
Term
| what is the paralleling technique? |
|
Definition
one of two techniques for completing CMRS
extension of cone paralleling
right angle technique
long cone technique |
|
|
Term
| what are the principles of paralleling? |
|
Definition
tooth and film are parallel
centray ray is perpendicular to tooth and film
requires a film holder
film must be placed away from the tooth to achieve parallelism
increased object film distance
increases magnification
target (anode) film distance but be increased
requires a long PID |
|
|
Term
| what is the purpose of a film holder? |
|
Definition
| eliminate the need for patients to stabilize the film |
|
|
Term
| When beginning a CMRS, always start |
|
Definition
|
|
Term
| film size for anteriors are normally |
|
Definition
smaller and easier to tolerate; size 1 film
|
|
|
Term
| on anteriors, you should work |
|
Definition
right to left on maxilla, left to right on mandible
begin with max. right canine, end with mand. right canine |
|
|
Term
| what are the advantages of paralleling? |
|
Definition
low dimensional distortion -- accuracy
simplicity -- easy to learn and use
duplication -- films tend to be consistent |
|
|
Term
| what are the disadvantages of paralleling? |
|
Definition
film placement is often compromised bc of patient discomfort
not usable in all situations |
|
|
Term
| how does radiation injure people? |
|
Definition
high energy radiation breaks chemical bonds
creates free radicals which can change chemicals
|
|
|
Term
| what is direct theory of injury? |
|
Definition
x-rays directly hit critical cell areas
happens infrequently |
|
|
Term
| what is indirect theory of injury? (most common) |
|
Definition
photon absorption causes toxin formation
cell death |
|
|
Term
| what is the importance of free radical formation in tissue injury? |
|
Definition
ionizing radiation causes ionization of patient tissues
photoelectric effect or compton scatter
short lifetime |
|
|
Term
| what is the major toxin involved in free radical formation? |
|
Definition
| H202 -- hydrogen peroxide |
|
|
Term
| how do free radicals achieve stability? |
|
Definition
1. recombine w/o changing the molecule
2. combine with other free radicals and cause changes
3. combine with ordinary molecules to form a toxin H202 |
|
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Term
|
Definition
| dose related, cancer, genetic alterations, no dose threshold |
|
|
Term
|
Definition
| somatic effects increase with dose/absorption, hair loss, cataracts, redness of skin, decrease fertility, definite dose threshold |
|
|
Term
|
Definition
| radiation injuries that produce changes in somatic cells produce poor health in the inradiated person |
|
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Term
|
Definition
| not sen in the person radiated but are passed on to future generations. Affect the health of the offspring |
|
|
Term
|
Definition
large amounts of radiation absorbed in short time.
ARS - acute radiation system - short term effect which includes nausea, vomitting, diarrhea, hair loss and hemorrhage |
|
|
Term
|
Definition
associated with small amounts of radiation absorbed repeated over a long period
CNS syndrome, GI syndrome, birth defects, cancer, lethal dose |
|
|
Term
| what is the risk benefit of radiation exposure? |
|
Definition
all radiation is harmful to living tissues
dental films should be prescribed only when benefit of disease detection outweighs risk of biological damage
all films are prescribed on as "as needed" basis for that patient at that time |
|
|
Term
| Define units of measurement used in radiation exposure |
|
Definition
Roentgen - amount of radiation in the air
1R = 2 billion ion pairs in a cubic centimeter of air
rad - radiation absorbed dose
rem - roentgen equivalent in man
SI - metric
Gray - Gy = rad
Sievert - Sv = rem
milli = 1/1000 |
|
|
Term
| Radiation is much better at killing cells than |
|
Definition
|
|
Term
| which cells are the most radiosensitive? |
|
Definition
| reproductive cells, blood cells, bone marrow |
|
|
Term
| which age group is most susceptible to radiation? |
|
Definition
|
|
Term
| why is it so difficult to determine if low doses of radiation cause cancer? |
|
Definition
background radiation is often higher than the level of added radiation exposure
there is a high and variable rate of cancer in the human population
there is no way to tell a radiation-induced cancer from a spontaneous cancer |
|
|
Term
| factiors determining radiation injury: |
|
Definition
total dose
dose rate
size of radiation exposure zone
cell sensitivity
age |
|
|
Term
| radiation injury sequence |
|
Definition
latent period - observable effects
injury period - cell death, dysfunction, genetic alteration
recovery period - repair or non-repair
cumulative effects - repeated exposure = health problems |
|
|
Term
| critical organs in dental radiography |
|
Definition
lens of eye
reproduction
fetus
bone marrow
thyroid gland
skin |
|
|
Term
|
Definition
older, established cells
muscle cells
nerve cells
mature bone
less harm |
|
|
Term
| patient exposure and dose |
|
Definition
film speed -- f speed
collimation
exposure factors |
|
|
Term
| Importance of dental radiography |
|
Definition
detection of disease processes
view unseen clinical conditions
basic component of comprehensive care
|
|
|
Term
|
Definition
detection (lesions, disease)
confirmation during treatment
evaluation
classify/illustrate changes
localize lesions/objects
documentation |
|
|
Term
|
Definition
Otto Walkhoff - german dentist, intraoral radiographs on himself, 25 min. exposure time
Edmund Kells - first dental radiographs on live patient
William H. Rollins - radiation safety
Howard R. Raper - 1st university course on radiation for dental students (1909) |
|
|
Term
|
Definition
-discovered x-radiation
-November 8th, 1895
-caused materials to glow, traveled several feet, first x-ray image
|
|
|
Term
| Knowledge of radiographer |
|
Definition
-background info on radiography
-rationale for procedure
-exposure factors
-manipulation of equipment
-film placement
-patient management
-methods of processing |
|
|
Term
|
Definition
-film placement, exposure, and processing
-film mounting
-patient education
-darkroom maintence
-quality control
-ordering of film and supplies |
|
|
Term
|
Definition
| form of energy carried by waves or a stream of particles |
|
|
Term
|
Definition
| high-energy radiation produced by a beam of electrons colliding with a metal target in an x-ray tube |
|
|
Term
|
Definition
| a picture on film (photographic image) produced by passage of x-rays through an object |
|
|
Term
|
Definition
| photographic image produced on film by the passage of x-rays through teeth and related structure |
|
|
Term
| Extraoral radiographic examination |
|
Definition
| inspection of large areas of the skull or jaws using film placed outside the mouth |
|
|
Term
| Intraoral radiographic examination |
|
Definition
| Inspection of the teeth and intraoral adjacent structure |
|
|
Term
| Components of x-ray machine: |
|
Definition
Extension Arm
Control Box
Tubehead - source of x-rays, heart of machine |
|
|
Term
|
Definition
| hold the film inside the mouth of the patients to get a clear picture of the tried area |
|
|
Term
|
Definition
Protons (+) positively charged
Neutrons (neutral) - no electrical charge
Nucleus contains atleast (1) proton & (1) neutron
Hydrogen is the exception...nucleus contains (1) proton |
|
|
Term
|
Definition
| something that occupies spaces and has weight |
|
|
Term
|
Definition
|
|
Term
|
Definition
| two or more atoms joined together by chemical bonds or the smallest amount of a substance that possesses its characteristic properties |
|
|
Term
|
Definition
| simple substance made up of atoms |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
attraction between the + and - electrons that maintain electrons in their orbits
role in atom is determinted by the distance between the nucleus and orbiting electron. different for each shell |
|
|
Term
|
Definition
| production of ions; process of converting atoms into ions |
|
|
Term
|
Definition
| emission and propagation of energy through space or a material in the form of waves or steam particles |
|
|
Term
|
Definition
| process by which certain unstable atoms or elements undergo spontaneous disintegration in an effort to attain a more balanced nuclear state |
|
|
Term
| Types of Ionizing Radiation: |
|
Definition
Particulate - TINY PARTICLES
Electromagnetic - wavelike energy ~ |
|
|
Term
|
Definition
|
|
Term
|
Definition
| UV rays, VISIBLE LIGHT, INFRARED LIGHT, RADAR WAVES, MICRO WAVES, RADIO WAVES |
|
|
Term
| Properties of electromagnetic radiation: |
|
Definition
No mass, no weight
No electrical charge
Speed of light (186,000 miles/per second)
Travel as both a particle and wave
Creates electric field at right angles to path of travel
Magnetic field at right angles to electric field
Different frequencies and wavelengths |
|
|
Term
|
Definition
photons are the particles
no mass, no weight
discrete bundles of energy
travel as waves at the speed of light
waves move in straight line through space
wave exhibits velocity, wavelength and frequency |
|
|
Term
|
Definition
energy required to remove an electron from its shell must exceed the energy of the electron in that shell
70 keV to remove k shell electron
12 keV to remove L shell electron
3 keV to remove M shell electron
keV = kilo-electron volt |
|
|
Term
|
Definition
| bundle of energy with no mass or weight that travels as a wave at the speed of light and moves through space in a straight line ----- |
|
|
Term
|
Definition
no mass or charge
travels at speed of light 186,000 miles/per second
invisible
particle and wave characteries
penetrating
damage living tissue through ionization |
|
|
Term
| Components of X-Ray Machine |
|
Definition
Metal housing
Insulating Oil
Tube head seal
X-ray tube
Transformer
Aluminum disks
Lead collimator
PID |
|
|
Term
|
Definition
| NEGATIVE electrode, tungsten filament, molybdenum cup |
|
|
Term
|
Definition
| POSITIVE electrode, tungsten target, copper stem |
|
|
Term
|
Definition
| produces electrons when heated |
|
|
Term
|
Definition
| focuses the electrons into a narrow beam and directs the beam across the tube toward the tungsten target of the anode |
|
|
Term
|
Definition
| supply the electrons necessary to generate x-rays |
|
|
Term
|
Definition
| convert electrons into x-ray photons |
|
|
Term
|
Definition
| plate of tungsten; serves as a focal spot and converts bombarding electrons into x-ray photons |
|
|
Term
|
Definition
| functions to dissipate the heat away from the tungsten target |
|
|
Term
|
Definition
| number of electrons that pass through a conductor; strength of electrical current |
|
|
Term
|
Definition
| intensity of the x-ray tube current used during exposure; measured in milliamperes |
|
|
Term
|
Definition
| 1,000 volts; unit of electromotive force that drives an electrical current through a circuit |
|
|
Term
|
Definition
| uses 3-5 volts, regulates flow of electrical current to the filament, controlled by mA setting |
|
|
Term
|
Definition
| uses 65k to 100k volts, accelerates electrons to the anode to produce x-rays, controlled by kVp setting |
|
|
Term
|
Definition
| used to increase or decrease voltage in a circuit |
|
|
Term
|
Definition
| increases voltage for the high voltage circuit |
|
|
Term
|
Definition
| decreases voltage from 110 to 220 down 3-5 volts |
|
|
Term
|
Definition
| voltage compensator in high voltage circuit, corrects minor fluctuations in current |
|
|
Term
|
Definition
| Braking radiation or bremsstrahlung (70% of xrays), sudden stopping or slowing of high speed electrons. Electron either hits the nucleus of tungsten atom or passes close to it. |
|
|
Term
|
Definition
| electron dislodges a k-shell electron, ionization of that atom occurs, remaining electrons rearrange to fill the space causing loss of energy |
|
|
Term
|
Definition
| radiation that exits tubehead |
|
|
Term
|
Definition
| radiation created when primary hits patient |
|
|
Term
|
Definition
| secondary radiation that is deflected from path, all directs, detrimental to patient and operator |
|
|
Term
| pass through w/o interaction GOOD |
|
Definition
| photons produce density on fil and make radiographs possible |
|
|
Term
| x-ray energy completely absorbed BAD |
|
Definition
| ionization of tissue atoms, photoelectric effect |
|
|
Term
| x-ray energy scattered BAD |
|
Definition
| self explanatory... really. |
|
|
Term
|
Definition
| x-ray photon interacts w/ orbital electron & all energy of photon is absorbed by the displaced electron in kinectic energy |
|
|
Term
|
Definition
photon collides w/ outer shell electron
photon gives up part of its energy
electron is ejected from orbit
photon continues in different direction
weaken photon interacts w/ other atoms until energy is gone
ejected electron termed "compton electron" is NEGATIVE
remaining atom is POSITIVE
62% of all scatter in diagnostic radiography |
|
|
Term
|
Definition
aka "unmodified scatter"
path of x-ray photon is altered by matter
no change in atom occurs
photon is scattered in different direction
change of direction without change in energy
8% of all interactions with matter |
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|
