Radiology Flashcards
Discovered the X-ray in 1895 while experimenting with a cathode Ray tube.
Wilhelm Roentgen
Production of ions.
Ionization
Radiation capable of producing ions by removing or adding an electron to an atom; X-rays produce ionization.
Ionizing radiation
Propagation of wave-like energy (without mass; without particles) through space or matter. X-rays is an example
Electromagnetic radiation
Speed of a wave
Velocity
Wavelength
Distance between crest of one wave to the crest of the next wave
Number of wavelengths that pass a point in a certain amount of time
Frequency
Very short wavelength resulting from the bombardment of tungsten by highly accelerated electrons in a vacuum.
X-Ray
What are X-rays absorbed by?
Matter
How do X-rays travel?
In straight lines and cannot be focused to a point.
High vacuum glass tube surrounded by refined oil with high insulating powers; the oil helps to absorb excess heat.
Protective leaded glass housing
Made of tungsten filament and molybdenum sup; negative charge, supplies the electrons necessary to generate X-rays, thermionic emission.
Cathode
Made of copper arm and focal spot; positive charge, focal spot is made of tungsten (target=tungsten)
Anode
This happens inside the X-ray tube.
Electron stream travels from negative cathode to positive anode, 99% of the energy is lost as heat.
Electrical pressure or potential difference between two electrical charges.
Voltage
Determines the quality of the X-ray beam (quality refers to the penetrating power of the beam) regulates electrons from cathode to anode.
Kilovoltage Peak (kVp)
Overall darkness or blackness of an image.
Density
KVp is increased, what will the image exhibit?
Increased density and appears darker
kVp is decreased, what will the image exhibit?
Decreased density and appears lighter
How sharply dark and light areas are separated on an image
Contrast
What results from a Low kVp (65 tp 70)?
High contrast image, short-scale of contrast, consider for viewing dental caries, density is low (lighter) resultant image is black and white.
What results from a high kVp ( 90)?
Low contrast image, long-scale of contrast, consider for viewing periodontal disease. Density is high (darker) and resultant image is many grays.
What affects contrast?
Only kVp and filtration
What affects quality?
Only kVp and filtration
Ampere is the unit of quantity of electric current. Controls the temp of the tungsten filament.
Milliamperage
An increase in mA will result in?
Increased density and a darker image (mA does not affect image contrast)
What does mA also control?
The temp of the tungsten filament (the hotter the filament, the greater number of X-rays produced)
Intensity of radiation is inversely proportional to the square of the distance from the source of radiation.
Inverse square law
If cone length is changed from 8 to 16 inches, how does this affect the intensity of the beam?
Intensity will decrease, 1/4 as intense.
If cone length is changed from 16 to 8 inches, how does this affect the intensity of the beam?
Intensity will increase, 4x as intense.
If a person standing 3 feet from an X-ray source receives 4 rads of exposure, how much would they receive at 6 feet?
1 RAD
Time that elapses between exposure to radiation and appearance of observable clinical signs.
Latent period
Follows latent period, cell death, changes in cell function and abnormal mitotic activity may result.
Period of injury
Cells repair the damage in this phase.
Recovery period
Caused by repeated radiation exposure leading to health problems that accumulates in the tissues and is unrepaired.
Cumulative effects
What dose is the Panoramic dose equivalent to?
4 bitewings
First sign of overexposure to x-radiation?
Erythema
Seen in the person irradiated; not transmitted to future generations.
Somatic effects
Not seen in the person irradiated but are passed to future generations
Genetic effects
Cells that divide frequently and more sensitive to radiation.
Mitotic activity
Cells that are immature and more sensitive to radiation.
Cell differentiation
Cells that have higher metabolism and more sensitive to radiation.
Cell metabolism
Highest cell sensitivity to radiation.
Reproductive tissue, lymphoid sx, bone marrow, intestines, and mucous membranes
Lowest cell sensitivity to radiation.
Nerve tissue-nosey radioresistant, skeletal muscle, heart, optic lens and mature bone
Allows the more penetrating X-rays pass through by absorbing long wave radiation and removes the “soft” radiation.
Filtration
Reduces the surface area exposed by the use of a lead diaphragm and reduction in size of beam of radiation.
Collimation
What is the beam size at the patient’s face?
Can be no larger than 2.75 inches
How much does the rectangular collimation reduce the skin surface area by?
60%
Less volume of tissue is irradiated if a long cone is used; less scatter produced with a long cone
Position indicating device (PID, cone)
This protects the reproductive and blood-forming tissues and absorbs 90% of the scatter radiation, lead equivalent is usually 0.25 mm.
Lead apron
Most effective method of radiation protection; E-speed film is twice as fast as D-speed and needs half the exposure time.
Fast Film
Reduce exposure time and reduce the amount of radiation needed to properly expose a film, therefore reducing the amount of radiation the patient receives
Intensifying screens
What must the operator remember when performing X-rays?
Stand at least 6 feet away from X-ray tubehead, stand behind barrier or wall, be positioned at a 90-135 angle to the beam.
What is the MPD for occupational use?
5 REM/year (5000 mrem) or 0.05 Sv/year (50mSv)
What is the MPD for non-occupational use?
0.1 REM/year (100 mrem) or 0.001 Sv/year (1 mSv)
What is ALARA?
As low as reasonably achievable
The smaller the focal spot size increases this, composition of film emulsion influences this, the smaller the silver halide crystals the sharper the image appears, a loss of this occurs when the patient moves during exposure.
Sharpness
Refers to an image that appears larger than the actual size of the object it represents.
Magnification
What results in less image magnification and decrease in magnification?
Less image magnification-longer PID And target to film distance
Decrease in magnification-decrease in object to film distance
How do you minimize distortion?
Object and film must be parallel to each other and the X-ray beam must be directed perpendicular to the tooth and film
Manual film processing basics
Developer/wash/fixer/wash/dry
Turns energized silver halide crystals into black metallic silver
Developer
The 2 ingredients in developer that soften the film emulsion
Hydroquinone and Elon
What’s the optimum time/temperature for developer?
5 mins at 68 degrees
What does the rinsing step do?
Removes the developer from the film and stops the development process and usually takes 30 seconds
Removes the unexposed, Unenergized silver halide crystals from the film emulsion. Removes ALL UNEXPOSED CRYSTALS; clears the film
Fixer solution
2 main ingredients in fixer that harden the film emulsion
Sodium thiosulfate and ammonium thiosulfate
How long does it take for fixer?
10 mins (twice the development time)
Thermometer in which solution?
Developer
Automatic film processing basics
Developer/fixer/wash/dry. Designed to work at higher temperatures and no rinse step exists between developer and fixer.
Provides sufficient illumination in the darkroom, low wattage bulb (7 1/2 or 15 Watts) placed a minimum of 4 feet away from the film and working area, GBX-2 filter can be used for extraoral and intraoral films, extraoral films have an increased sensitivity to light.
Safe lighting
What error caused a completely black film?
Film was exposed to light before processing
What error caused a completely clear film?
Film was not exposed to x-radiation
What error results in a light film?
Underdeveloped film; Inadequate or depleted developer, developer too cool
What error results in a dark film?
Overdeveloped film; excessive developing time, developer too hot, concentrated developer.
What results in dark spots?
Developer spots; developer splashed on film before processing.
What results in light spots?
Fixer spots; fixer splashed on film before processing
What results in herringbone or tire track pattern?
Backwards film; film placed backwards in the mouth
What results in diagonal black line?
Severely bent film
What results in air space seen and lack of apices?
Patient not biting on bite block
What results in overlapping of teeth contacts?
Overlapped images; incorrect horizontal angulation
What results in short teeth with blunted roots?
Foreshortened images; too much vertical angulation.
What results in long, distorted teeth?
Elongated images; too little vertical angulation.
What results in an unexposed area on film?
Cone-cut; central ray not in center of film
What may appear as dental caries and is radiolucent?
Cervical burnout; radiolucent artifact seen in areas of different densities
Same lingual; opposite buccal.
SLOB rule
How is an occlusal radiograph exposed?
Directing the central ray at a right angle (perpendicular) to the radiograph and shows the object in the buccal-lingual and anterior-posterior relationships
What’s the standard receptor size?
Size 2; anterior and posterior teeth in adults.
What’s the receptor size for occlusal?
Size 4
Small ovoid RL between the roots of the maxillary central incisors.
Incisive foremen; hole in bone at midline of anterior portion of hard palate
Thin RL line between max central incisors.
Median palatial suture; immovable joint between 2 palatine processes of maxilla.
Large RL area above max incisors.
Nasal cavity; pear shaped compartment located superior to maxilla.
Vertical RO partition that divides the nasal cavity.
Nasal septum; vertical bony wall/partition divides nasal cavity into right and left nasal fossae
V shaped RO area located at intersection of floor of the nasal cavity and the nasal septum.
Anterior nasal spine; sharp projection of maxilla located at anterior and inferior portion of nasal cavity.
RL area superior to the apices of the maxillary posterior teeth.
Maxillary sinus; paired compartments of bone located within the maxilla located above max premolar and molar teeth
Thin RO lines that surround/divide the sinus.
Floor of the maxillary sinus
RO upside down Y located superior to the max canine.
Inverted Y; intersection of max sinus and nasal cavity.
RO bulge distal to third molar region.
Maxillary tuberosity; rounded prominence of bone that extend posterior to the third molar region
RO hook like projection posterior to the maxillary tuberosity.
Hamulus
J or U shaped RO located superior to the max first molar region
Zygomatic process of maxilla; bony projection of maxilla that articulates with the zygoma.
Diffuse RO band extending posterior from the zygomatic process of the maxilla.
Zygoma; cheek bone composed of dense cortical bone
Ring-shaped RO below the apices of the mandibular incisors
Genial tubercles; tiny bumps of bone that serve as muscle attachment sites
Small RL dot surrounded by the genial tubercles.
Lingual foramen; hole in bone on internal surface of mandible near midline
Vertical RL lines.
Nutrient canals; tube-like passageways that house nerves and blood vessels.7
Thick RO band that extends from the premolars to the incisor region.
Mental ridge; linear prominence of bone.
RL area located above the mental ridge.
Mental fossa; scooped out, depressed area of bone.
Small ovoid or round RL in the apical region of the mandibular premolars.
Mental foramen; hole in bone located on external surface of mandible in the region of the mandibular premolars.
RL band outlined by RO lines and appears below the apices of mandibular molars.
Mandibular canal; tube like passageway thru bone that travels length of mandible.
RO band extending downward from the ramus; May continue on as the mylohyoid ridge. Also is the inferior land mark.
Internal oblique ridge; linear prominence of bone located on the internal surface of mandible and extends downward and forward from the ramus.
RO band extending downward from the ramus and typically ends in third molar region.
External oblique ridge; linear prominence of bone located on external surface of body of mandible.
RL area in the mandibular molar region below the mylohyoid ridge.
Submandibular fossa; scooped out, depressed area of bone on internal surface of mandible.
Triangular RO superimposed over the max tuberosity region; only mandibular landmark to appear on maxillary films.
Coronoid process; marked prominence of bone on anterior ramus of mandible.
Completely RO with irregular borders.
Amalgam; overhangs; and fragments
Completely RO; smooth borders
Gold restorations; crown, bridges, gold foil.
RO, but not as dense as amalgam, does not appear to fit the tooth well; “see through areas”
Stainless steel and chrome crowns
RL to RO
Composite restorations
Seen in endodontically treated teeth.
Post extends into the pulp canal and core resembles the prepped portion of a tooth
Slightly RO; appearance similar to enamel.
Porcelain restorations
Metal component is completely RO and porcelain component is slightly RO
Porcelain fused to metal crown
Slightly RO to RL; endodontic materials.
Gutta percha
RO endodontic material
Silver points
RO posts places within the bone to support restorations for missing teeth.
Dental implants
Used to ensure strength and stability with a larger restoration; generally appear RO.
Retention pins
Fixed bridge in which the Pontic is supported only on one side
Cantilevered bridge
Seen on panoramic, between the palate and tongue horizontal RL band.
Palatoglossal air space
Seen on panoramic, refers to portion of pharynx posterior to the nasal cavity, diagonal RL
Nasopharyngeal air space
Seen on panoramic, refers to portion of pharynx posterior to the tongue, vertical RL band.
Glossopharyngeal air space
Seen on panoramic, passes through the floor of the orbit and the external auditory meatus.
Frankfort plane
Seen on panoramic, divides the body into right and left sides
Midsagittal plane
Seen on panoramic, 3D curved zone in which structures are clearly demonstrated on a panoramic radiograph.
Focal trough
Maxillary incisors appear blurred and magnified; reverse smile line; hard palate superimposed over the maxillary apices.
Frankfort plane upwards (chin up)
Mandibular incisors blurred; exaggerated smile line; condyles may not be visible.
Frankfort plane down (chin down)
Anterior teeth appear skinny and out of focus.
Teeth anterior to focal trough.
Anterior teeth appear fat and out of focus.
Teeth posterior to focal trough
Unequal magnification; posterior teeth are larger on one side than the other.
Midsagittal plane not centered (head turned)
Cervical spine appears as a RO in the center of the image.
Position of the spine (pt. Slumped or slouched, ex. Scoliosis).
A dark RL shadow obscures the apices of the max teeth; cannot see maxillary teeth well.
Position of the tongue (tongue not against hard palate)
RO cone-shaped artifact obscuring the mandible; no thyroid collars with panoramic X-rays
Lead apron placed too high.
