Board review dh227 RADIOLOGY Lisa Mayo, rdh, bsdh

Board review dh227 RADIOLOGY Lisa Mayo, rdh, bsdh

Radiation Discovery Wihelm Conrad Roentgen: 1985
X-ray: unknown nature Discovered when experimenting with a cathode ray tube 1st dental radiograph: 1896

Fundamental of Radiation
Emission & propagation of energy through space Particulate Radiation Tiny particle of matter that possess mass & travel in straight lines at high speeds Electrons, beta particles, cathode rays, protons, alpha particles, neutrons

Electromagnetic Radiation Propagation of wave-like energy (w/out mass) through space or matter X-rays, cosmic rays, UV rays, visible light, infrared light, radar waves, microwaves, radio waves Vary in energy Ionizing vs non-ionizing Believed to move through space as both a particle (photon) and a wave (next slide)

Light Spectrum

Fundamentals of Radiology
Left of Visible Light Longer wavelengths Lower frequencies Right of Visible Light: x-rays Shorter wavelengths: resulting from tungsten target being hit with accelerated e- in a vacuum Higher frequencies

Wave Concept Velocity: speed of a wave = speed of light Wavelength: distance between one crest of one wave and the crest of the next Determines the energy and penetrating power Shorter wavelength, higher the energy, more penetrating (harder) the beam Frequency: # wavelengths that pass a given point in a certain amt of time

Fundamentals of Radiation
Wavelength Definition: distance in a periodic wave between 2 points of corresponding phrases Frequency: # of crests that pass per unit of time

Light: wave or a stream of particles? Age old-debate Exhibits characteristics of both Particle: Isaac Newton Wave: Maxwell’s Theory of Electromagnetism Describes wave-like properties of all electromagnetic radiation

Electromagnetic Radiation Properties expressed best by: Wave Theory Quantum Theory

WAVE THEORY

Electromagnetic Radiation Wave Theory How radiation propagated in the form of waves Useful when considering radiation in bulk when millions of quanta are being examined Electric & magnetic fields orientated in planes at right angles to one another Oscillate perpendicular to the direction of motion

Electromagnetic Radiation Quantum Theory Electromagnetic energy described as bundles of energy called photons Successful in correlating experimental data Interaction of radiation with atoms Photoelectric effect Production of x-rays

Ionization Most atoms are neutral # protons = # electrons Ion: atom gains or loses an electron Atoms loses an electron, an ion pair results Proton = (+) Electron= (-) Ionizing Radiation: radiation that is capable of producing ions

Photon Elementary particle responsible for electromagnetic phenomena Carrier of electromagnetic radiation of all wavelengths (gamma, x-ray, UV, visible, infrared, microwave, radio) Differs from electron & quark in that it has zero rest mass Travels in a vacuum & at the speed of light Has both wave and particle properties

Primary Radiation X-ray beam that exists the tubehead Secondary Radiation X-radiation that is created when the primary beam interacts w/matter Scatter Radiation Form of secondary radiation X-ray that has been deflected from its path by the interaction w/matter Interaction of X-Radiation X-ray can pass through the patient X-ray can be completely absorbed by patient X-ray can be scattered X-ray can be transmitted

Light can have 4 fates when hits tissue
1. Absorbed Primary & beneficial effect of laser energy 2. Reflected Beam redirecting itself off the surface, no effect on tissue Ex: Caries-detecting laser 3. Scattered May harm surrounding structures 4. Transmitted Laser energy directly through tissues

Bremsstrahlung Radiation Produced by sudden slowing or speeding of e- towards a target Primary source of x-rays Negatively charged e- directed towards a (+) charged source → loss of velocity occurs Generate continuous spectrum of photons Characteristic Radiation Only a minor source of radiation e- from filament displaces an e- from a shell of tungsten target atom – atom ionizes

NBQ A radiograph produced from the movement of an electron from an outer shell to a vacancy in an inner shell is referred to as: a. Thomson scatter b. Bremsstrahlung radiation c. Characteristic radiation d. Particulate radiation

Properties of X-Rays Characteristics: invisible, no mass, no weight
Travel: in a straight line, at the speed of light Wavelengths Have shorter wavelengths, high frequency Hard x-rays: short, high penetration Soft x-rays: longer less penetrating, more likely to be absorbed into the tissues Penetration: pass through matter or absorbed by matter, depending on atomic structure of matter Produces: an image on photographic film Causes: ionization Distance: lose intensity with distance

Image Characteristics
Detail/Resolution/Definition Over sharpness of image Called “radiographic definition” Relates to distinct and sharp demarcation of image elements Focal spot size: smaller = sharper image Film composition: smaller silver halide crystals= sharper image Movement of film or patient during exposure= less sharp image Influenced by: BID length, type of films, use of intensifying screens

Penumbra (“fuzziness or un-sharpness”) 1. Source of radiation small Small focal spot keep penumbra small Lg focal spot ↑ penumbra 2. Source to object distance Long SFD will ↓ penumbra, short SFD will ↑ penumbra 3. Object to film distance Small object to film distance ↓ penumbra ↑ source-to-film-distance will ↑ un-sharpness 4. Object and film parallel Foreshorten or elongation 5. Source perpendicular to object and film

Sharpest image w/ least magnification Small focal spot Short object-to-film-distance Large target (source)-to-film-distance Film and tooth parallel Beam perpendicular to film

Density Overall Darkness or Lightness More photons = more density Influenced by: film type, processing, exposure time. mA settings, BID length, kVp setting, source to object distance Contrast Variations of gray and between white and black How sharply dark and light areas are separated Influenced by: patient size, film type, processing, film storage, MAINLY kVp setting

High contrast/Short Scale Few shades of gray, mostly black and whites High visual contrast Produced by low kVp settings Less than 75kVp Low contrast / Long Scale Many shades of gray Low visual contrast Produced by high kVp Settings higher than 80kVp

Factors Tubehead Film Density Film Contrast mA ↑ # photons ↑ density Exposure Time kVp ↑ penetration Long scale, many grays, low visual contrast Aluminum ↓ #photons Remove weak photons ↓ density Distance Increase ↓ # photons

Radiolucent Portion of a processed radiograph that is dark or black Things that permit the passage of x-rays Air space, soft tissue Radiopaque Portion of a processed radiograph that is light or white Structures that absorb x-rays Enamel, dentin, bone, metals

Magnification Image appears larger than the actual size of the object it represents Decrease object-film distance decrease magnification (tooth close to film) Increase target-to-film distance decrease magnification (use a longer PID or cone)

Distortion Variation in the true size and shape of the object being radiographed May be unequal magnification of different parts of the same object Results from improper film alignment or angulation of the x-ray beam To minimize distortion: Object and film must be parallel X-ray beam must be directed perpendicular to the tooth and film Can cause: Elongation & Foreshortening

Image Characteristics Principles of Shadow Casting
Geometric Characteristics Influencing Factors Effect of Influencing Factors Result Sharpness Focal spot size Film composition Movement ↓ focal spot ↓ crystal size ↓ movement ↑ sharpness Magnification Target-film distance Object-film distance ↑ target-film dist. ↓ object-film dist. ↓ magnification Distortion Object-film alignment X-ray beam alignment Object & film parallel Beam perpend. To object & film ↓ distortion

DEFINITIONS Attenuation: process where radiation loses power as it travels through matter. (Removal of x-ray photons) As the energy of radiation ↑, the # of photons passing through matter ↑ As density, atomic #, electrons per gram of the material ↑, the # of photons passing through the matter ↓ Elongation Central ray not perpendicular to object Object and film not parallel Insufficient vertical angulation Foreshortening Central ray not perpendicular to films Excessive vertical angulation

Elongation Foreshorten

NBQ Both milliampere and exposure time determine the a. Degree of film fog b. Number of x-rays produced c. Energy of the radiation produced d. Amount of scattered radiation produced

NBQ Which of the following describes a radiographic film that has many graduations of gray from totally white to totally black? a. Overexposed b. Underexposed c. Low contrast d. High contrast

NBQ Sharpness of the radiographic image is increased by
a. Using a smaller focal spot b. Decreasing the focal spot-object distance c. Decreasing the mA d. Increasing the object-film distance e. Using screen-film technique

X-RAY MACHINE Glass vacuum tube All air removed
Surrounds electrodes of x-ray tube to provide a vacuum The aperture or window: thin segment of the glass that allows maximum emission of x-rays and minimum absorption by the glass Leaded glass housing Prevents x-rays from going in all directions

X-RAY MACHINE Cathode (-)
Serves as the source of e- to be directed at anode Composed of: Filament (tungsten wire): Filament that lies in a focusing cup: heated to give off e- (thermionic emission) Focusing cup: e- from focusing cup are directed to focal spot mA control regulates Step-down transformer Heating of the filament Quantity of electrons “boiled off” during thermionic emission Because charges repel – the electron beam is directed to a small area on the anode

X-RAY MACHINE Anode (+) Composed of:
Tungsten target (high atomic #) in a Copper stem (remember tungsten & copper) that functions to conduct heat away from the target Focal spot: portion of a target bombarded by electrons Convert e- from filament into photons Kilovoltage control regulates the: Step-up transformer Voltage between the cathode and the anode Accelerating potential (speed) of electrons

X-RAY MACHINE Focal Spot Power Supply
Sharpness of radiograph ↑as size of radiation source ↓ Heat ↑ as focal spot ↓in size Power Supply Ohm’s Law: Volts = Amperes (I) x Resistance(R) (electrical potential) (rate of e- flow) Voltage = kVp. Describes the potential differences between the (-) and (+) and therefore, the speed or force of the moving e-toward the (+) charge

XRAY MACHINE Power Supply: Transformer (changes potential difference of incoming electrical energy to any desired level) Provide low-Volt current to heat filament by use of step-down transformer Operation regulated by mA switch: adjusts R and therefore current flow – regulates temp. of filament – Quality of x-rays Step-up transformer Increases the voltage sufficiently to propel electrons across the vacuum tube circuit to produce x-ray energy Generate high difference between anode/cathode Controlled by kVp dial - selects varying V – controls V between anode & cathode ↑ V = ↑ speed e- toward anode

X-RAY MACHINE PID: Position-indicating devise
An open ended, circular or rectangular “cone” that extends from the tube head toward the image receptor Fed regs: 7cm/2.75in diameter Length that ↑ focal-to-object distance creates a less divergent beam Use fastest image receptor system: “F” speed intraoral film requires the least amt of radiation to produce a diagnostic image Longer PID = produce x-ray beam that is less divergent Decrease radiation exposure Provide better image resolution

NBQ Federal guidelines limit the size of the intraoral x-ray beam at the client’s skin to: a. 1 ¾ inches b. 2 ½ inches c. 2 ¾ inches d. 3 ½ inches e. 3 ¾ inches

NBQ Which of the following position-indicating devises (cones) best minimizes the dose of radiation to the patient? a. Pointed, plastic b. Leaded, circular c. Leaded, circular d. Open-ended circular e. Leaded, rectangular

NBQ Use of which of the following causes unnecessary secondary radiation to the patient? a. Speed D films b. Plastic pointed cone c. kVp under 70 d. Aluminum filtration over 2.0mm e. Short (8”) target-to-films distance

FACTORS CONTROLLING XRAY BEAM
Exposure Time Tube Current (mA) Tube Voltage (kVp) Filtration Collimation

X-Ray Beam Quality Exposure time: duration of x-ray production (quantity) Distance: greater the distance, less x-ray reach film (quantity) mA: regulates # e- and thus amt of x-ray produced (quantity) kVp: regulates the energy or penetrating characteristics of the beam (quality)

↑ QUALITY ↑ KvP ↑Filtration ↑ Collimation ↑ Energy, speed of e-
↑Film density ↓ Contrast

X-Ray Beam Quality Kilovoltage Peak (kVp, Voltage)
Voltage is the difference between 2 electrical charges (cathode/anode) This difference determines the speed of e- when traveling from cathode to the anode kVp Determine the quality of x-ray production (penetrating power)

↑ QUANTITY ↑mA ↑ Time ↑ kVp ↓Distance ↓ Collimation ↓ Filtration

X-Ray Beam Quantity Exposure Time mA
Interval of time x-rays are produced Longer exposure = more x-ray photons Longer exposure = higher density 60 impulses/second mA The ampere if the unit of quality of electric current Regulates # e- travelling from cathode to anode Increased mA=more x-ray photons Increased mA=higher density

X-Ray Beam Quantity Millampere-seconds (mAs) Distance
Both mA & exposure time have a direct influence on # e- produces When combined, they form a factor termed milliampere-seconds mAs = mA x exposure time (sec) Distance Greater distance from source of radiation (x-ray tube) to x-ray film need more x-ray photons

X-Ray Beam Quantity Inverse Square Law
Intensity of radiation is inversely proportional to the square of the distance from the source of radiation Original intensity = New intensity____ New distance = Original distance2

X-RAY MACHINE Filtration
Process of selectively removing x-rays from the beam Filters low-energy, non-penetrating rays Federal regs: 1.5mm of aluminum-equivalent filtration for units operating below 70kVp 2.5mm for units operating above 70kVp

X-RAY MACHINE Collimation
Process of restricting the size and shape of x-ray beam Achieved by use of lead diaphragm disc w/ circular or rectangular opening through which the beam is narrowed Reduced scatter radiation Reduce film fogging

NBQ The focusing cup in an x-ray tube serves
a. To focus the electron beam b. As the source of x-rays c. As the source of electron d. To focus the x-ray beam e. Adjust the focal spot

XRAYS & BIOLOGY X-ray photons are either Dental x-rays cause
Absorbed: photons transfer energy to patient Scattered: photons change in direction Transmitted: photons pass through pt unchanged Dental x-rays cause Coherent Scattering Photoelectric Absorption Compton Scattering

XRAYS & BIOLOGY Review interactions of x-rays on humans
Effects on oral tissues Effects on Fetus Effects on Total Body: Leukemia, Cancers, Growth and Development, Gene Mutation Osteoradionecrosis Mandible Bone is destroyed (bone death) Brittleness

XRAYS & BIOLOGY Radiation Injury Ionization
Not all x-rays reach the film Many are absorbed by patient tissues Ionization Occurs when x-rays strike patient tissues May have little effect on cells if the chemical changes do not alter sensitive molecules May have a profound effect on structures of great importance to cell function (DNA)

XRAYS & BIOLOGY Free radical formation
A molecule with a single, unpaired e- in its outermost shell Results with reactive & unstable free radicals The ionization of water is the most common mechanism of damage in humans FR – combine to form- toxins such as H2O2 Dose-response curve & radiation injury What level of radiation is acceptable? No safe amt of radiation exposure Dose-response curve Correlates the damage (response) of tissues w/ amt (dose) of radiation

XRAYS & BIOLOGY Sources of radiation exposure Natural radiation
Background or environmental radiation Cosmetic, terrestrial, radon Artificial radiation Man-made Medical / dental, wristwatches, TV, smoke alarms, airport security

XRAYS & BIOLOGY Radiographs during pregnancy
ER tx can be done anytime: prefer to avoid 1st trimester 2nd trimester best Genetic dose w/out lead apron Men: 1/10,000 Women: 1/50,000 Dental vs Background Radiation FMX = 2-4 days 4BWX=8 hrs Panoramic = 8 hrs

XRAYS & BIOLOGY Radiation injury sequence, repair, accumulation
Latent period: time from exposure to radiation and appearance of clinical signs Period of injury Recovery period: cellular damage can repair to a certain extent Cumulative effects: effects of radiation exposure are additive

XRAYS & BIOLOGY Somatic & Genetic Effects Somatic cells Genetic cells
Cells in the body except the reproductive cells If effected produce poor health (cataracts, cancer, etc..) but not transmitted to future generations Genetic cells Reproductive cells (ova, sperm) Effects not seen in the person irradiated, but are passed to future generations

XRAYS & BIOLOGY Radiation effects on cells
Cells may be resistant to radiation Cells may be sensitive to radiation Determined by: Mitotic activity: cells that divide frequently more sensitive Cell differentiation: immature cells are more sensitive Cell metabolism: cells w/high metabolism are more sensitive

XRAYS & BIOLOGY High sensitivity Medium sensitivity Low sensitivity
Reproductive tissue, lymphoid system, bone marrow, intestines, mucous membranes Medium sensitivity Fine vasculature, growing cartilage/bone, salivary glands, lungs, kidneys, liver Low sensitivity Nerve tissue, skeletal muscle, heart, optic lens, mature bone

XRAYS & BIOLOGY Tissue & Radiation Effect
Hematopoietic (blood-forming) Reproductive Thyroid Skin Eyes Leukemia Mutations Carcinoma Cataracts

NBQ Arrange the following cells and tissues from MOST SENSITIVE to LEAST SENSITIVE to ionizing radiation 1. Adult bone and nerve 2. Epithelium and muscle 3. Alimentary tract and immature bone 4. Blood-forming cells and reproductive cells a. 1, 4, 2, 3 b. 4, 1, 2, 3 c. 4, 2, 3, 1 d. 4, 3, 2, 1

XRAYS & BIOLOGY Short & Long-Term Effects Short-term effects
Assoc w/ large amts radiation Nausea, vomiting, diarrhea, hair loss, hemorrhage Long-term effects Small amts radiation over long period Cancer, birth abnormalities, genetic defects

XRAYS & BIOLOGY Oral effects of radiation Short-term effects
Erythema, mucositis Ulcers, dermatitis Long-term effects Loss of taste, xerostomia Radiation caries, candidiasis Possible development of osteoradionecrosis

RADIATION PROTECTION 16in Target-to-film distance
16cm Source-2-skin distance 2.75in Collimation (beam on pt’s face) Max Permissible Dose (MPD) Occupational and non-occupational radiation exposure Old units and new – learn both! (next slide)

RADIATION PROTECTION Old MPD Occupational 5 rem/yr 400 mrem/mo
Measurement Old Units S.I. Units Exposure to air Roentgen Coulomb/Kg Absorbed dose Rad Gray (Gr) Dose equivalent in man Rem Sievert (Sv) Old MPD Occupational 5 rem/yr 400 mrem/mo 100 mrem/wk Old MPD Non-Occupational 0.5rem/yr New MPD Occupational 6.2 Sv/yr New MPD Non-Occupational Sv/yr

RADIATION PROTECTION Filtration Collimation Position Indicating Devise
Aluminum discs Filter out long wavelength, low energy x-rays, low penetrating x-rays Total filtration > 70kVp = 2.5mm of Aluminum Total filtration ≤ 70kVp = 1.5mm of Aluminum Collimation Restricts the size and shape of beam Lead plate w/ central hole Round or rectangular Federal regulations: x-ray beam < skin Position Indicating Devise 8in (short) 16in (long) < volume of tissue is irritated < scatter

RADIATION PROTECTION Thyroid collar Lead apron
Absorbs 90% of the scatter radiation that would have reached the reproduction tissues Lead equivalent = 0.25mm Fast film Film speed determines how much radiation and how much exposure time are necessary to produce an image on a film Using a fast film is the most effective method to reduce radiation exposure

RADIATION PROTECTION Films speed
Determines how much radiation and how much exposure time are necessary to produce a image on a film A speed (slowest) – F speed (fastest) Speed doubles w/ each letter B twice as fast as A C 4x as fast as A

NBQ With all other technique factors remaining constant, an increase in film speed will: a. Increase image density b. Decrease image density c. Increase image contrast d. Decrease image contrast e. Have no effects on the image

NBQ Using an “E” speed group film rather than a “D” speed group film to produce a radiograph requires a. A longer exposure time b. A shorted exposure time c. A decreased developing time d. An increased developing time

RADIATION PROTECTION Intensifying screens ALARA
Used in extraoral radiography Reduce exposure time & amt radiation a patient receives ALARA All exposure to radiation must be kept to a minimum “As low as reasonably achievable”

FILM PROCESSING Film Composition Latent Image Formation
Film base: flexible piece of plastic Adhesive layer: attaches emulsion to film base Film emulsion Gelatin: suspends silver halide crystals Silver halide crystals: sensitive to radiation Protective layer Latent Image Formation Silver halide crystals absorb x-ray and store the energy Various amts of stored energy Invisible pattern of stored energy: Latent Image

FILM PROCESSING Film sizes Size 0: BWX/PA in small children
Size 1: PA’s adult teeth, BWX in kids Size 2: PA’s adult teeth, BWX in adults Size 3: BWX’s only. Longer, narrower than size 2 (shows all post teeth) Size 4: occlusal films

FILM PROCESSING Extraoral Films Panoramic: shows wide view
Cephalometric: shows facial profile Intensifying screens Intensify the effect of x-rays on film Less radiation is required

FILM PROCESSING Manual Development Rinsing: removes developer Fixation
Washing: removes excess chemicals Drying

FILM PROCESSING Developer Fixer
Precipitate all of the silver in those silver halide crystals that contain a latent image speck Swell and soften the emulsion of the film Hydroquinone & Elon 5min at 68° Fixer Remove the undeveloped/unexposed silver halide crystals from emulsion Shrink and re-harden the emulsion of the film Sodium thiosulfate & ammonium thiosulfate 10min (2x development time)

FILM PROCESSING DEVELOPER (reduce) FIXER (clear)
Solvent: H2O (soften film emulsion) Solvent: H2O Preservative: Na-sulfite (protects from oxidation) Reducing agents: Phenidone/Elon (older version is Elon) (bring out gray) Hydroquinone (bring out contract) Clearing agent: Ammonium triosulfate Activator: alkaline pH Speeds up reducing process Acidifier: acetic acid (low pH = 4.5) Restrainer: Na, K, Br (anti-fog agents) Hardening agent: AlK-sulfate, CrK-sulfate, K alum

FILM PROCESSING Automatic Processing Development: 80° for 1.5min
Fixation: 1.5min Washed: 30sec Dried: 30sec

NBQ Radiographic images that are too dark are the result of all the following EXCEPT: a. Overdevelopment b. Film Fog c. Non-exposure to x-rays d. Hot temperature of solution e. Over active chemicals

NBQ Which of the following are purposes of the fixing solution in processing radiographs? 1. Soften emulsion 2. Harden Emulsion 3. Develop exposed silver halide salts 4. Remove undeveloped silver halide salts a. 1 and 2 b. 1 and 4 c. 2 and 3 d. 2 and 4 e. 3 and 4

NBQ A major difference between automatic and manual processing of radiographs is that automatic processing a. Is more expensive b. Provides better quality films c. Allows more latitude in exposure techniques d. Requires special solutions at higher temperatures

FILM PROCESSING Darkroom Light-tight Safelighting Low-wattage bulb
Safelight filter: removes short wavelengths in blue-green, permits red-orange light Min. of 4 feet from film & working area Can still cause film fogging w/long exposure

FILM PROCESSING Under-Developed = White Over-Developed = Dark
Under-Fixed = Cloudy, Yellow-Brown

FILM PROCESSING Underdeveloped Overdeveloped Reticulation of Emulsion
Film appears light Inadequate development time or temp Depleted / contaminated developer solution Overdeveloped Film appears dark Excess development time or temperature Concentrated developer solution Reticulation of Emulsion Film appears cracked Sudden temp change between the developer solution and the water bath

FILM PROCESSING Chemical Contamination Errors Developer spots
Dark spots on film Developer solution contacts film before processing Fixer spots White spots on the film Fixer solution contact film before processing Air bubbles White spots, air trapped on the film surface after being placed into processing solutions Yellow-brown stains Exhausted chemicals, insufficient rinsing, incomplete fixation

Air Bubbles

Yellow Brown Stains

FILM PROCESSING Film Handling Errors Overlapped films
White or black areas on film Appearance depends if happens in developer or fixer Static electricity Thin, black branching lines Occurs when a packet is opened quickly Slightly bent film Elongated roots Film may be bent to accommodate pt’s anatomy, such as in the area of the ant maxilla Severely bent film Diagonal black line Film bent too severely to accommodate patient

Static Electricity

What’s wrong with this? How did this happen?

FILM PROCESSING Film Handling Errors Fingernail artifact
Black crescent-shaped marks Emulsion damaged by fingernails Fingerprint artifact Black fingerprint Touching film Scratched film White lines on film Soft emulsion removed from the film by a sharp object Roller marks: dirty rollers

Roller Marks

FILM PROCESSING Lighting Errors Light leak Fogged film
Exposed area appears black Fogged film Film appears gray and lacks image detail and contrast Improper safelight, outdated films, improper film storage, contaminated solutions

FILM PROCESSING Operator Errors Pt not biting all way on block
Air space seen or lack of apices Tipped film Images are tipped to one side Cone-cut Unexposed area on film Central ray not in center of film Cervical burnout May appear as dental caries, radiolucent Radiolucent artifact seen in areas of different densities

TECHNIQUE Paralleling Technique
XCP technique (extension cone paralleling) RT-angle technique Long-cone technique Principles Film is placed in the mouth parallel to the long axis of the tooth Central ray of the x-ray beam directed perpendicular to the film and long axis of the tooth Film holder must be used To achieve parallelism the film should be placed away from the tooth and towards the middle of the oral cavity Object-film distance is increased To compensate for magnification: target-film distance is increased

TECHNIQUE Bisecting Technique
Bisecting-angle technique or short-cone technique Principles Film is placed along lingual surface Tooth & film form an angle Visualize a plane that bisects this angle Central ray is directed perpendicular to this imaginary bisector Film holders are optional

TECHNIQUE Bisecting Technique: Angulation Horizontal
Position of the tubehead in a side-to-side plane Central ray directed through the contact areas of the teeth Incorrect position results in overlapped contact areas (horz overlap) Vertical Positioning in the up & down plane Foreshortened images: Teeth appear shortened, too much vert angulation Elongated images: teeth appear longer, not enough vert angulation

TECHNIQUE Localization Techniques Purpose & Use 2-D of 3-D object
Does not depict B-L relationship Used to locate: foreign bodies, impacted teeth, unerupted teeth, retained roots, root positions, salivary stones, jaw fractures, broken needles & instruments, filling materials Buccal Object Rule 2 films at diff angulations 1 w/normal angulation and 2nd changing either vert or horz angles Object seen in 2nd film moves in same direction as the shift of the PID, the object is positioned to the lingual

TECHNIQUE Take 2 radiographs at 2 different angles can determine if an object is buccal or lingual to together teeth in the arch SLOB Rule: Same lingual, opposite buccal The lingual object moves in the same direction as the tubehead The buccal object moves in the opposite direction as the tubehead

TECHNIQUE Exposure Problems Unexposed film Film appears clear
Film exposed to light Film appears black Overexposed film Film appears dark Underexposed film Film appears light

NBQ If the object film distance was too great during exposure, then which of the following technical errors is most likely to appear on a processed radiograph? a. Cone cut b. Elongation c. Magnification d. Foreshortening e. Proximal overlapping

NBQ Another maxillary anterior PA is attempted by the dental hygienist and this time the roots of #7-10 are elongated. How would the hygienist go about correcting this error? a. Increase vertical angulation b. Decrease vertical angulation c. Increase horizontal angulation d. Decrease horizontal angulation

TECHNIQUE Technique Errors: PA’s Incorrect film placement
Absence of apical structures Dropped film corner Angulation problems Incorrect horz angulation Incorrect vert angulation Cone cut

TECHNIQUE Technique Errors: BWX’s Incorrect film placement
Incorrect horz angulation (horz overlap) Incorrect vert angulation Cone cut

TECHNIQUE Miscellaneous Errors Film bending Film creasing
Incorrect positioning of pt’s finger Double exposure Movement Reversed films

Panoramic Basic Concepts Purpose & Use
Shows a wide view of the upper and lower jaws on a single film Extraoral: film is positioned outside the body Both film & tubehead rotate around the patient Purpose & Use Eval impacted teeth Eval eruption patters, growth, development Detect diseases, lesions, conditions of the jaws Eval extent of large lesions Eval trauma

Panoramic Fundamentals Tomography Focal trough Tomo = section
Radiographic technique that allows the imaging of one layer or section of the body while blurring images from structures in other places Focal trough Image is clearest

Panoramic Pros Cons Field size Simplicity Patient cooperation
Minimal exposure Cons Image quality Focal trough limitations Distortion Equipment cost

Panoramic Patient positioning Straight vertebral column
End-to-end tooth position (bite block) Midsagital plane: imaginary line that divides face into LF-RT, perpendicular to floor Frankfort plane: imaginary plane that passes the top of the ear canal and the bottom of the eye socket, parallel to the floor Tongue to roof of mouth

What happened?

What’s wrong with this picture?

Panoramic Ghost Image Radiopaque artifact seen on a pano film
Produced when a radiodense object is penetrated twice by the x-ray beam Seen on opposite side of the film Indistinct, larger and higher image

Panoramic Common Errors Tongue & Lip Positioning
Lips should be closed: dark shadow obscures ant teeth Tongue against palate: dark shadow obscures the apices of maxillary teeth

Panoramic Common Errors Frankfort Plane
Chin too high: reverse smile line, downward curve, max incisors blurred, condyles off to side of image Chin too low: exaggerated smile line or jack-o-lantern, curved upward, mand incisors blurred, condyles may not be visible, condyles off top of image

What is the issue here?

Panoramic Common Errors Positioning of Teeth Midsagital Plane
Too far anterior: ant teeth skinny / out of focus Too far posterior: ant teeth fat / out of focus Midsagital Plane Head not centered left-to-right Teeth unequally magnified One side (side closest to film) smaller Other side (side farthest from film) larger Positioning of Spine Pt’s spine must be straight: radiopacity in center of film

What happened?

RADIOGRAPHIC INTERPRETATION
Definition: types of bone Cortical (compact) bone Sense outer layer of bone Radiopaque Cancellous Soft spongy inner bone Composed of trabeculae that forms a lattice-like network of inter-communicating spaces filled w/ bone marrow

Definitions: prominences Process: marked prominence or projection Ridge: linear prominence or projection of bone Spine: sharp, thorn-like projection of bone Tubercle: small bump or nodule of bone Tuberosity: rounded prominence of bone

Definitions: depressions Canal: tube-like passageway through bone that contains nerves and blood vessels Foramen: opening or hole in bone that permits the passage of nerves and blood vessels Fossa: broad, shallow, scooped-out or depressed area of bone Sinus: hollow space, cavity or recess in bone

Misc Septum: boney wall or partition that divides 2 spaces or cavities, radiopaque Suture: immoveable joint that represents a line of union between adjoining bones of the skull, thin radiolucent line

LANDMARKS: MAXILLA Incisive foramen (nasopalatine) Median palatal suture Nasal cavity (fossa) Canine fossa Nasal septum Floor of nasal cavity Anterior nasal spine Inferior nasal conchae Maxillary sinus and floor max sinus Maxillary tuberosity Hamulus Zygomatic process maxilla Zygoma

LANDMARKS: MANDIBLE Genial tubercles Nutrient canals Mental ridge Mental fossa Mental foramen Mylohyoid ridge Mandibular canal Internal oblique ridge External oblique ridge Submandibular fossa Coronoid process

LANDMARKS: PANO MAXILLA
Mastoid process of temporal bone Styloid process External auditory meatus Glenoid fossa (mand fossa) Articular eminence (tubercle) Max tuberosity Infraorbital foramen Orbit Incisive canal and foramen Anterior nasal spine Nasal cavity, septum Hard palate Max sinus Zygomatic process of maxilla Zygoma Hamulus

LANDMARKS: PANO MANDIBLE
Mandibular condyle Coronoid notch Coronoid process Mandibular foramen Lingula Mandibular canal Mental foramen Hyoid bone Mental ridge Mental fossa Genial tubercle Inferior border mandible Mylohyoid ridge Internal/External Oblique Ridge Angle of mandible

LANDMARKS: PANO AIR SPACES
Palatoglossal air space Nasopharyngeal air space Glossopharyngeal air space

X-Ray Landmarks ##14 ##12 ##4 ##7 ##12 ##7 ##8 ##11 ##13 ##5 ##5 ##5
##6 ##1 ##2 ##3 ##10 ##9

ANSWERS Lingual Foramen Genial tubercles 3-unit bridge Palate
Mandibular Canal Mental Foramen Maxillary Sinus Coronoid process Third molar Mastoid air cells Articular eminence Pterygomaxillary fissures Lateral pterygoid plate Orbital floor

4 12 13 14 15 13 12 3 6 6 1 2 7 8 5 5 9 10 11

ANSWERS Mandibular Foramen Styloid Ligament Palate Nasal fossa
Hyoid bone Air space External oblique ridge Internal oblique ridge 3-unit bridge Angle of mandible Ramus Condyle Mandibular notch Coronoid process Retention ortho wire

#14 with root canal & crown #2 with crown Max sinus Trabeculae
8 6 Anterior Nasal Spine Nasal Fossa #13 root canal & crown #14 with root canal & crown #2 with crown Max sinus Trabeculae Zygomatic process of maxilla Nasopalatine Foramen Median palatine suture 5 6 2 1 7 10 10 9 7 7 3 4

Recent extraction site Implant Abutment Molar with root canal
#5 Recent extraction site Implant Abutment Molar with root canal Maxillary sinus Root apex Zygomatic process Maxillary tuberosity 6 7

I Possible periapical abscess Lamina dura PDL
Inferior border of mandible Mandibular Canal 1 1 2 5 3 4 4

Board review dh227 RADIOLOGY Lisa Mayo, rdh, bsdh

Similar presentations

Presentation on theme: "Board review dh227 RADIOLOGY Lisa Mayo, rdh, bsdh"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Board review dh227 RADIOLOGY Lisa Mayo, rdh, bsdh

Similar presentations

Presentation on theme: "Board review dh227 RADIOLOGY Lisa Mayo, rdh, bsdh"— Presentation transcript:

Similar presentations

About project

Feedback