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Intraoral Radiology
BWX, Periapicals, Occlusals
| Question | Answer |
|---|---|
| occlusal plane parallel to floor | patient position |
| perpendicular to floor | midsagital line |
| size, speed, amount of time, # of films in packet | selection of film packet |
| what you want to be visible on the film | Film positioning |
| XCP, Snap-A-Ray, Stabe, Bitewing tabs/loops | Film Holding devices |
| round piece coming off machine where radiation comes out | PID |
| 18",12",16"(round, rectangular) | Length/Shape of PID |
| mA, kVp, time, | Control panel settings |
| how image on film gets there | Shadow casting |
| source of x-ray photons | focal spot on target of x-ray tube |
| records the image | function of the film |
| Goal of radiography | best density, contrast, sharpness, clarity using least amount of radiation |
| smallest possible source of radiation | sharper the image |
| Object and film as close as possible | reduced magnification |
| object and film parallel | decreased distortion |
| radiation must strike object and film at right angles(perpendicular) | decreased distortion |
| Ideal conditions | smallest possible source of radiation, boject far from source, object/film close as possible, object/film parallel, radiation must strike object/film at right angle |
| object/film are not parallel; radiation does not strike at right angle | Bisecting Technique |
| object to film distance is greater | Paralleling technique |
| long axis of tooth /plane of film form angle; x-ray beam directed at right angle to imaginary bisector | Bisecting Technique |
| used when parallel placement is impossible(small mouth, children, low palate, cleft palate, tori) | Bisecting |
| dimensional distortion and unequal magnification occurs in | Bisecting |
| steeper vertical angle causes shadow of zygomatic process to | superimpose roots of maxillary molars |
| film parallel to long axis of teeth | Paralleling |
| x-ray beam directed at right angle to teeth/film | Paralleling |
| Increased target to film distance to compensate for | Increased object to film distance |
| Minimal distortion, easy to learn, less time | Paralleling advantages |
| sometimes difficult to place films/patient discomfort | Paralleling disadvantages |
| patient seated upright; occlusal plane parallel to floor; midsagital plane perpendicular to floor | Patient positioning |
| Ala-Tragus line | Maxillary Point of Entry |
| 1/2 inch above mandible | Mandibular Point of Entry |
| Commissure of lips-tragus line | Bitewing Point of Entry |
| Side to side, central ray pass through interproximal space | Horizontal PID angulation |
| occurs when horizontal angulation is not correct | Overlapping |
| up/down; PID angle is zero when parallel to floor | Vertical Angulation |
| Tip of PID tilted toward floor | Positive vertical angulation |
| Tip of PID tilted toward ceiling | Negative vertical angulation |
| Views crowns and alveolar bone of Max. and Mand. teeth on 1 film | Bitewings |
| Most common dental film; included in FMX or taken alone at check-ups | BMX |
| Detect interproximal dental caries in posterior teeth(incipient lesions); Examine crestal bone of periodontal patients(vertical/horizontal) | Purpose of BMX |
| can be placed close to teeth and still be parallel to teeth of both arches | Advantages of BWX |
| doesn't show apices | Disadvantages of BWX |
| films with tabs attached, loops/adhesive tabs, XCP instruments | Bitewing holders |
| Central ray directed through contact area | Horizontal BW |
| +10 degrees | Vertical Angulation BW |
| level of occlusal plane | BW Point of entry |
| If not lined up correctly, area where no radiation hits film causes clear spot | Cone cut |
| Peri means | Around |
| Apex means | highest point |
| view the entire tooth(including root) and surrounding structures | Periapical series FMX |
| FMX film size depends on | patient age,size of mouth,shape of arches, anatomical limitations,film holder, patient's ability to tolerate film |
| Use___film patient can accomodate | largest |
| number of films in FMX | 18 including BWX |
| Film placement anterior periapicals | Vertical |
| Film placement posterior periapicals | Horizontal |
| Identification dot | towards biteblock |
| Wilhem Conrad Roentgen | 1895 discovered x-ray |
| Dr. Otto Walkoff | took 1st x-ray (Germany) |
| Dr. William aherbert Rollins | warned about dangers of radiation; also claimed to take dental x-ray 1st |
| Dr. William James Morton | Claimed to take 1st dental x-ray |
| Dr. C. Edmund Kells | also claimed to take 1st dental x-ray |
| William David Coolidge | Invented X-ray hot cathode tube |
| Howard Riley Raper | wrote 1st dental x-ray text book; introduced bitewing x-ray |
| Radiography | making of radiographs |
| X-ray/Roentgen ray | unknown ray(interchangeble terms) |
| Roentgenograph/radiograph | Image produced on the film |
| Cone-PID | end of x-ray tube |
| Panoramic radiology | Film gets entire mouth (ear-ear) on one film |
| Weston A. Price | suggested looking into bisecting/parallel teechnique(didn't receive credit) |
| A. Cieszynski | Applied rule of issemetry to bisecting technique |
| Franklin W. Mc Cormack | developed paralleling technique |
| G. M. Fitzgerald | Used longer PID with paralleling technique to compensate for distance(less magnification) |
| Tomography | Used in most Panoramic units-radiographs a single plane @ a time |
| Magnetic resonance Imaging(MRI) | method to take crossectional images produced on computer(no radiation) magnetic field |
| Computed Tomography(CT) | instead of film it uses computer to display |
| Digital Imaging | digital receptor captures images then transfers to computer |
| elements | simple substance made up of atoms |
| Atom | smallest particle of an element. Made up of subatomic particles |
| subatomic particles | Electrons, Protons, Neutrons |
| Electrons | little mass or weight and negatively charged |
| Protons | weigh more than electrons and are (+) charged (atomic #) |
| Neutrons | weigh almost the same as protons, no charge |
| Molecule | smallest particle of a substance |
| Isotopes | Atoms of an element that have the same number of protons but different number of neutrons |
| Energy levels | Electron shells |
| Ions | Atoms that have gained or lost electrons and have become electrically unstable(charged particle) |
| Positive ion | Atom that lost an electron |
| Negative ion | The free electron that was separated from the atom |
| Ion pair | the positive and negative ions |
| ionization | formation of ion pairs |
| cause of ionization | x-ray photons hitting atoms |
| electromagnetic radiation | x-rays,gamma rays,cosmic rays |
| Particulate radiation | alpha,beta particles |
| Ionizing radiation | Any radiation that produces ions |
| 2 forms of radiation | Electromagnetic, particulate |
| Radioactivity | process that occurs when unstable elemnets are trying to return to a stable nuclear state |
| Decay | The release of energy by unstable isotopes in an attempt to regain stability |
| 2 forms of radiation released by decay | Particulate, Electromagnetic(Gamma) |
| Electromagnetic Radiation | The movement of wave-like energy through space as a como of electric and magnetic fields |
| Electromagnetic spectrum | Electromagnetic radiation placed in order according to their energy |
| Travel at speed of light, no electrical charge, no mass/weight, pass through space as particles in wave-like motion, give off electrical field at right angles/magnetic field at right angles, energies measureable and different | qualities of electromagnetic radiation |
| Particles in electromagnetic radiation | photons |
| photons of particles are | bundles of energy that travel through space at speed of light |
| Wave of electromagnetic radiation | wavelength,frequency, velocity |
| Wavelength | measured from crest to crest |
| Frequency | # of wavelengths that pass in a given time |
| Velocity | speed at which waves travel |
| Wavelength and Frequency are related how? | Inversely |
| The shorter the wavelength | The higher the frequency |
| X-radiation(x-rays) | don't all have same wavelength |
| Soft radiation | long wavelength with limited penetrating power |
| Hard radiation | wavelength 0.1-0.5A with great penetrating power |
| Properties of X-rays | Invisible,travel in straight line at speed of light,no mass/weight/charge,interact with mater causing ionization,photographic film emulsion,penetrate opaque tissue, effect living tissue |
| Where are x-rays produced? | In an x-ray tube inside tube head |
| When are x-rays produced? | when high speed electrons(kinetic energy) are abruptly stopped converting to bremsstrahlung and characteristic radiation |
| Bremsstrahlung Radiation | majority of x-rays produced |
| Bremsstrahlung radiation is produced when? | high speed electron collides with nucleous of an ataom in target metal and all kinetic energy is transferred into a single x-ray photon;high speed e- is slowed down/bent off course and kinetic energy is lost turns into x-ray |
| Characteristic radiation | only produced when kVp is 70 or higher |
| only make up a portion of x-rays produced | Characteristic radiation |
| Characteristic radiation is produced by | high speed electron powerful enough to collide with and dislodge an e- from the k-shell of a tungsten target atom |
| No ionization occurs when | X-ray passes through an atom unchanged (9%) |
| Coherent scattering occurs when | x-ray is scattered unchanged(8%) |
| Photoelectric effect occurs when | x-ray gives all energy to orbital e- of an atom; original x-ray vanishes and e- with kinetic energy flies from orbit forming an ion pair. photoelectron knocks another e- from its orbit forming a secondary ion pair. keeps going until all energy used(30%) |
| Compton effect occurs when | x-ray gives some energy to orbital e- and rest forms a weaker x-ray that scatters in a different direction. The new x-ray may undergo a new comton or photoelectric (62%) |
| 2 forms of ionizing radiation | Photoelectric and Compton effect |
| forms of non-ionizing radition | no interaction, scatter |
| Exposure | measurement of ionizations in air produced by x-rays |
| Coulombs per kilogram (C/kg) | Exposure |
| Absorbed dose | amount of energy deposited in the tissue |
| Gray(Gy) | Absorbed dose |
| Dose Equivalent | Absorbed dose X biological effect mod. factor |
| Dose Equivalent= | Absorbed dose |
| Sievert (Sv) | Dose equivalent |
| (C/kg)= | Roentgen(R) |
| (Gy)= | rad |
| (Sv)= | rem |
| Line switch,mA selector,kVp selector,Timer(60 impulse a second) | Control Panel |
| Suspend tube head, allows positioning of PID, Passage of electrical current | Functions of the extension arm |
| Metal housing contains | X-ray tube,insulating oil,step-up/step-down transformer |
| protects x-ray tube,increases safety,precents over heating, absorbs any x-rays produced except for the primary beam | Functions of the metal housing |
| Conditions required for x-ray production | free source of electrons,High voltage to give speed to electrons,Target capable of stopping electrons |
| positive electrode (+) | anode |
| negative electrode(-) | cathode |
| minimizes resistance to electrons | vacuum |
| Tube location in metal housing | located behind transformers(Richards) |
| To provide free electrons needed for x-ray production | Cathode |
| Components of cathode | Filament wire and Focusing cup |
| Filament wire made of | Tungsten |
| Tungsten wire heated to | Incondecence |
| Filament wire produces | Thermionic emission(electron cloud) |
| Composed of molybdenum | Focusing cup |
| Focusing cup dose what | directs electrons towards target |
| Stops high speed electrons converting them to X-rays | Anode |
| Copper stem and Tungsten target | Components of Anode |
| Carries headt produced to the radiator | Copper stem |
| imbedded in coper stem at 20degree angle;contains focal spot; converts electrons to x-rays | Tungsten target |
| Larger target but rays come off in smaller area; looks like a square,but is really a rectangle | Line Focus Principle |
| 1st steps in x-ray tube operation | turn on unit,set control panel |
| once exposure button is pressed | Low voltage(5V) to step-down transformer to supply filament wire with electricity to form electron cloud |
| supplies the anode-cathode with high-voltage to force free electrons across tube to the target | Step-up transformer |
| Percentage of heat and x-rays produced | 99% heat, 1% x-rays |
| removes heat | copper stem in anode |
| once x-rays are produced they | scatter in all directions |
| Most x-rays absorbed by | glass envelope, oil/air, transformers, and tube head |
| x-rays going in direction of PID | exit the window of the tube(thin glass area) |
| glass window is aligned with | the port(opening in tube housing |
| x-rays exiting PID make up | Primary Beam |
| After the port x-rays go through | collimator(lead) |
| restricts size of primary beam | Lead collimator |
| Center of the primary beam | Central Ray |
| weaker x-rays(soft) absorbed by | Aluminum filter |
| controlled by mA, kVp, exposure time,distance | Intensity |
| Intensity is a combination of | # of x-rays and energy of x-rays |
| # of x-rays in a beam | quantity(mA) |
| energy or penetrating power of x-ray beam | quality(kVp) |
| thickness of a given material(aluminum) to reduce intensity of x-ray beam in half | Half-value Layer |
| Amperage measures | # of electrons(quantity) |
| An increase in amperage | increases amount of electrons available to travel across tube(produces more x-rays) |
| Amperage range for dental machines | 7mA-15mA |
| measure of electromotive force; electric potential | Voltage(quality) |
| Voltage measures | electrical pressure between two electrical charges |
| Increase in kVp | increases the speed of electrons traveling across tube; increase penetrating power |
| Voltage range for dental machine | 70kVp-90kVp |
| changes direction between (+) and (-) current | Alternating current |
| 3-8 Volts we use 5V | Filament circuit |
| High voltage circuit | 60kVp-90kVp |
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