Download TCDHA RAD MIDTERM LATEST EXAM WITH COMPLETE SOLUTIONS (A+) and more Exams Advanced Education in PDF only on Docsity!
TCDHA RAD MIDTERM LATEST EXAM WITH
COMPLETE SOLUTIONS (A+)
xray benefits
- DETECT DISEASE
- minimize & prevent toothaches, surgery
- saves time & money, prevents edentulismlosing all teeth
xray use
- DETECT diseases, lesions, trauma, foreign objects
- bone levels deteriorating, evaluate growth & developement
what can be found xray
missing teeth
- may lead to occlusion problems as a result of drifting or tipping
- orthodontic treatment in the absence of teeth can prevent occlusion problems
- conditions: hereditary ectodermal dysplasia, books syndrome, riegers syndrome*
radiograph aka radiogram a picture that is, a visible photographic record on a film produced by the passage of x-rays through an object or body
- can ONLY be prescribed by DENTISTS
- should never be routine/predetermined
impacted/embedded teeth
- MOST COMMON development defects
- should be removed surgerically to prevent odontogenic cyst formation, damage of adjacent teeth and bone resorption which may lead to fractions
impacted tooth
- one tooth is PREVENTED FROM ERUPTING due being wedged up against a neighbouring tooth
- ALWAYS necessary to extract
- most common: third molars, premolars, max cuspid (canine), supernumerary
embedded tooth
- if a tooth is not breaking though the gum because of being UNDER BONE
- tooth is being blocked by the gum it may lack the force necessary to break thru the gum
dental caries
- bitewings for interproximal various lesions
- pulse of tooth dies
- if left untreated, can result in destruction of a large amount of tooth structure and pulp all necrosis
- decay may recur under the margins of existing restorations and may or may not be seen clinically
- black circular areas on xray
- rampant dental caries, recurrent decay, early root caries
rampant dental caries
periapical lesions
- the MOST COMMON radiographic appearance of a periapical lesion is the RADIOLUCENCY (dark) area at root apex
- a diagnosis of periodical cyst, granuloma or abcesses cant be made based on xray findings alone other lesions
- numerous dental anomalies, cysts, tumours & diseases affect the jaws
- lesions may persist for years before signs & symptoms develop
- xray play VITAL role in the detection
- the importance of EARLY detection & diagnosis cannot be OVERSTATED interpretation
- ablity to read whats revealed by an xray
- an EXPLANATION of what's viewed
- dental hygienist prepares a preliminary interpretation & presents the findings to dentist
- dh must be confident w the identification (normal anatomy, caries, disease, traumatic injuries, lesions.)
diagnosis
- dh is RESTRICTED by law from rendering a diagnosis
- "TO KNOW", "to DISTINGUISH"
disclosure
- the process of informing the the pt about the particulars of exposing dental xrays
- easy language,
- explain: value & purpose, the client exam: limtiation wo xray
documentation
- informed consent obtained or refused
and type of x rays exposed
Rx DDS Name rational for exposing diagnostic information obtained from the x ray interpretation film mount
- a cardboard or plastic holder that is used to arrange x-rays in anatomic order
- any trained dental professiong w knowledge of normal radiographic landmarks are qualified to mount
- label mounts in special pencil. include the following: clients name, dentists name, date, type & number of x-rays
film mount uses
- prevent fingerprints and scatches
- readily accessible for interpretation
- easy viewing, eliminate confusion of clients right and left
- dot is always convex, clients left is viewers right, dot is on occlusal surface or incisal edge on periapical films and on the mand arch on bitewing exposures
film viewing
- an illumination (view box) is necessary to accurately view xrays and assist in interpretation
- magnifying glass is useful
electrons
- small NEGATIVELY charged particles with very little mass
- electrons and neutrons are arranged in an atom much like the solar system
- electrons move around the nucleus in orbits or shells orbits/shells
- atom has a maximum of 7 shells
- designated with letters K L M N O P Q
- K is CLOSET to the nucleus and has HIGHEST energy level
- each shell has a max number of electrons max number of electrons in a shell binding energy/force
- electrostatic force or attraction between the POSITIVE NUCLEUS and the NEGATIVE ELECTRONS
- determined by the DISTANCE between the nucleus and the orbiting electron (different for each shell)
- STRONGEST = CLOSEST to nucleus (K shell) molecules
- atoms that bond together in diff ways; atoms are joined by CHEMICAL BONDS
- can be formed by the TRANSFER of ELECTRONS or by the SHARING of ELECTRONS
- tiny invisible particle, atoms and molecules are the building blocks of solids, liquids and gases
- 2-thousands of atoms
- when 1 atom of o2 bonds w 2 atoms of H, it forms a WATER molecule (H2O, simplest molecule)
ionization
- Production of ions, or the process of turning an atom INTO IONS
- production of ions, or the process of converting an atom INTO IONS
- deals only w ELECTRONS and requires energy to overcome the electrostatic force that
binds the electron to the nucleus ion an ATOM or MOLECULE which has LOST or GAINED one or more electrons, making it pos or neg charged ionizing radiation
- radiation that is capable of producing ions by removing or adding an electron to an atom
- 2 types: particulate radiation, electromagnetic radiation
particulate radiation
- small particles of matter, has mass
- travels in straight lines at high velocities
- transfers kinetic energy
- beta particles, cathode ray, alpha particles
beta particles
- high velocity electrons emitted from the nucleus
cathode ray
- LONG= LAZY (LESS ENERGY), SHORT= STRONG (MORE ENERGY)
frequency
- number of wavelengths that pass a given point in a certain amount of time
- frequency and wavelength are INVERSELY related
- HIGH FREQUENCY RADIATION= SHORT WAVELENGTH= MORE ENERGY
-SHORT FREQUENCY RADIATION= LONG WAVELENTH= LESS ENERGY
x-radiation
- high energy, ionizing electromagnetic radiation a high-energy radiation produced by the collision of a beam of electrons with a metal target in an x-ray tube
x-ray characteristics weightless bundle of energy (x-ray photon)
possess particles of waves and particles
invisible, cannot be detected by any of the senses
NO MASS, NO CHARGE
travels at the speed of light, in straight lines and can be deflected or scattered
SHORT WAVELENGTHS AND HIGH FREQ
absorbed by matter, interacts w materials they penetrate and cause ionization produce an image on photographic film cause biological transformations in living cells components of an x-ray tube head cone/positioning indication device (PID) control panel extension arm collimator, filter cone/pid projects from the tube head and is used to direct x-radiation to the clients face LEAD LINED to prevent escape of scatter radiation
- cones= SHORT OR LONG (8" OR 16", longer, RECTANGULAR is better)
- in the past pointed plastic cones were used (unsafe bc radiation goes everywhere)
control panel
- controls line switch, milliamperage (mA), kilovoltage peak (kVp). timer
- allows radiographer to regulate the x-ray beam
tungsten aka "WOLFRAM"
- metal with melting point (3370C)
- ideal use in the filament and target because it can withstand high temps
- filament coil is the main source of electrons
- high atomic #
- filament wire is embedded in the MOLYBDENUM CUP
- electric current passes thru the coil heating it to INCANDESCENCE
- this causes the release or "boiling off" of electrons from the heated tungsten filament which is known as THERMONIC EMISSION
- dr. WILLIAM COOLIDGE invented the thermionic emission tube in 1913
Grape like structure anode
- POSITIVE charge terminal
- mostly made of COPPER ROD
- copper like oil is used to DISSIPATE HEAT
- the tungsten target is attached to the copper stem
- the speeding electrons hit the tungsten target; the target measures about 1mm x 1.5mm
collimator
- lead plate with a central hole that fits directly over the opening of the metal housing where the x-ray exits
- RESTRICTS THE SIZE OF THE XRAY BEAM (7cm = 2.75")
filter is made of
- aluminium
- 1.5-2.5mm
- filters out long wavelengths w poor penetration power (we want SHORT)
line switch
- a master switch that allows electric current into the xray machine
- kVp INCREASES = penetrating power INCREASES
- ranges 50-100kVp
timer
- controls duration of time current will pass thru x-ray tube
- duration of time to expose film varies (children decrease 1/3, edentulous decrease 1/4)
- timer, like ma dial controls FILM BLACKENING (DENSITY)
- most electric time controls register a max of 60 impulses -newer models exposure dials calibrated in impulses exposure time affected by
- radiographic technique
- type of film
- tissues being radiographed -target film distance AC -the cathode and anode r connected w high voltage to move electrons a v high speed -voltage is about 1000x more than what comes out from a 110 volt wall outlet -does not flow continuously in 1 direction, changes direction 60x per seconds Hertz = Hz
- x-rays and heat can only be produced when the current is flowing from the cathode during the time that it's negative to the anode during the time that the anode is positive.
- a machine of x-ray is capable of generating radiation every 1/60 of a second. delayed transformers
- devices utilized for increasing or decreasing the voltage in a circuit
- change the voltage of the incoming electrical current and then direct the energy to the x-ray tube
- during the production of x-rays, 3 types of transformers are utilized: step down, step up, autotransformer
step down transformer
- REDUCES 110-220V to 3-5 volts required by the FILAMENT circuit
- MORE turns in PRIMARY coil than in secondary coil
- the coil that receives the AC is the PRIMARY (input) coil; the secondary coil is the output coil thepage step up transformer
- INCREASES 110-220-line voltage to 65,000-100,000 volts used by the HIGH-VOLTAGE circuit
- MORE coils in SECONDARY coil than in the primary coil autotransformer
- serves as a voltage compensator
- it corrects for minor fluctuations in the current bremstrahlung radiation production of sudden stopping or "BRAKING" of HIGH SPEED electrons as they hit the tungsten target in the anode
general radiation
- electron hits nucleus/close to nucleus of the tungsten atom
- slows down with resulting x-ray photon LOWER energy
scatter radiation
- a form of SECONDARY radiation
- a result of an x-ray photon deflected in all directions travelling to all parts of the clients body and areas of the operatory
- harmful to client and radiographer
leakage radiation happens if x-ray tubehead is not properly sealed and lead lined
energy absorption
- absorption depends on the ernergy of the xray beam, happens as a result of "photoelectric" effect
photoelectric effect
- IONIZATION occurs (X-RAY PHOTON collides w an INNER shell electron, transferring all of its energy to eject it)
- ejected electron is a PHOTOELECTRON with a NEGATIVE charge with little penetrating power
- remaining atom has a POSITIVE charge
- photoelectric effect accounts for 30% of x-ray production
compton scatter
X-RAY PHOTON collides with OUTER shell electron and gives up PART of its energy to eject it
x-ray photon loses energy travelling in a different direction at a lower energy level
the new, weaker x-ray photon interacts with other atoms until all its energy is gone
EJECTED electron is known as COMPTON or RECOIL electron possessing a NEGATIVE charge
- accounts for 62% of the scatter that occurs in radiography POSTERIOR PAs
- PREMOLARS include DISTAL of the 3, 4, 5, 6
- MOLARS: mesial lines up with 5 or midway thru 5 INHERENT FILTRATION PRIMARY beam passes thru the : GLASS window, OIL bath, tube head SEAL in the x-ray tube 0.5-1.0mm aluminum ADDED FILTRATION
- aluminium between collimator and tube head seal
- filters out LONG wavelengths
