dental radiography Flashcards
what are parts of the dental xray unit
central panel, control arm, tubehead
what are parts of the tubehead
metal housing - filled with insulating oil
tubehead seal - used as a filter for xray beams
xray tube - produces the xrays
transformer - alters voltage of incoming electrical current
aluminu filter - 0.5mm or 2.5mm
lead collimator - controls size and shape of xray beam
pid - aims xray beam
what are parts of the xray tub
leaded glass vacuum tube
- prevents xrays from escaping and has a window to let the xray beam out
cathode - negative eletrodes
- has a tungsten wire filament ion a cup shaped holder made of molybdenum
anode - positive electrode
- has a tungsten plate embedded in a solid copper rod
what are the types of radiaton
primary radiation
- made of xrays from the tungsten target in xray tube
secondary radiation
- xrays xreated when primary beam interacts with matter
scattered radiation
- a type of secondary radiation that is deflected from its path by interaction with matter
what types of injuries can radiation cause
tissue damage
- protons that are absorbed can cause biologic damage
ionization
- permanent damage to living cells and tissues
biologic
- can occur from repeated exposure (eyes, bone marrow, thyroid glands, salivary glands, skin, gonads)
genetic - can be passed down to future generations
somatic - affects body, cannot be passed down to future generations
what are acute and chronic exposure
acute - large dose absorbed over short period of time
chronic - small doses absorbed repeatedly over longer period of time
what are the settings of the xrays and their effects on an image
kilovoltage - controls the penetrating power of xraybeam
milliamperage - controls the numbers of electrons produced in the xray beam
exposure time - controls flow oof electricity to generate xrays
increase in each causes increase in density (low contrast)
decrease in each causes decrease in density (high contrast)
what is used for radiation safety
lead apron and thyroid collar
fast-speed film
image receptors and holding devices
exposure factors
proper technique
what are processing errors that can occur o images
time and temp
- light (underdeveloped)
- dark (overdeveloped)
- cracks (reticulation of emulsion
chemical
- dark spots (developer spots_
- light spots (fixer spots)
- yellowish brown (stains)
film handling
- straight white border (developer cutoff)
- straight black border (fixer cutoff)
- white or black areas (overlapped film)
- white spots (air bubbles)
- black crescent shape (fingernail artifact)
- black fingerprint (fingerprint artifact)
- bllack branches (static electricity)
- white lines ( scratched film)
lighting
- black (light exposure)
- gray (fogged film)
what can occur from incorrect horizontal angulation
overlapping of teeth in image
what can occur from incorrect vertical angulation
results in foreshortening and elongation
- foreshorten = pid is too vertical
- elongation = too flat
paralleling technique
- image receptor must be positioned parallel to long axis of tooth
- central ray must be directed perpendicular to image receptor and long axis of tooth
- central ray must be directed through contact areas
what are the film placements for paralleling
- anterior film is placed vertically, posterior film is placed horizontally, identification dot in slot
what is the bisecting technique
- film is placed directly against teeth, no beam alignment device
- xray beam is directed perpendicular to imaginary bisector
bitewing technique
xray beam is directed through contacts in =10 degrees vertical angulation
- image receptors are placed parallel to the crowns of teeth
