In Progress
Lesson 1 of 0
In Progress


andyrdhreviews September 14, 2020
  • Discovery and History of X-Radiation



  • Radiography is the making of radiographs by exposing an image receptor


  1. Radiology is the study of xrays and the techniques used to produce radiographic                           images.


  1. Radioactivity is the emission of ionizing radiation or particles caused by the                                 spontaneous disintegration (decay) of atomic nuclei *BOARD ALERT*


  1. Wilhelm Roentgen-Germany-discovered the x-ray Nov 8 1895-awarded a Nobel                         prize in physics in 1901 for the Crooke’s Tube (vacuum tube)


  1. X-ray Machine


  1. Three components of a dental x-ray machine



  1. Tube head (tightly sealed heavy metal and lead lined)
  2. designed to prevent excessive radiation exposure and electrical                                                       shock
  3. protects the x-ray tube from accidental damage
  4. prevents overheating from excess heat during x-ray production by                                                  providing a space filled with oil, gas and air
  5. transformers alter voltage of incoming electricity
  6. aluminum discs filter the longer-wavelength x-rays
  7. lead collimator restricts the size and shape of the x-ray beam
  8. position-indicating device (PID) aims and shapes the x-ray beam

the longer the PID produces an x-ray beam less divergent,                                                               decreases radiation exposure to client, and provides less image                                                   magnification



  1. Extension Arm (can revolve 360 degrees by the yoke)
  2. enables the tube head to be suspended
  3. hollow to allow electrical wires to run from control panel to the                                                      tube head


  1. Control Panel (regulates the exposure factors (mA, kVp, time)




Five major controls:

  1. Line switch

(1)       on/off switch

  1. Milliampere (mA) selector *BOARD ALERT*

(1)       determines the amount of x-rays produced

(2)       the higher the mA setting, the hotter the filament                                                                              becomes, resulting in a greater number of available                                                                          electrons

(3)       7 to 15mA

  1.         Kilovolt peak (kVp) selector *BOARD ALERT*

(1)       controls the current passing from cathode to anode

(2)       the higher the kVp setting the greater the                                                                                          penetrating power and speed of acceleration of                                                                                 electrons from the cathode to the anode

(3)       65 to 100kV

  1. Exposure Timer *BOARD ALERT*

(1)       establishes the time during which electons are                                                                                  available for the bombardment of target material

(2)       the higher the time setting, the more electrons                                                                                   available for x-ray production

  1. Exposure button

(1)       activates x-ray production process

(2)       automatically terminates exposure when finger                                                                                 ceases to press button

(3)       audible sound heard when pressed

(4)       indictor light is illuminated on control panel

(5)      60 impulses/second  *BOARD ALERT*


III.      Xray Productions


  1. Electricity-flow of electrons through a wire
  2. Direct current (DC):  a steady flow of electrons in one direction; not in                                        US *BOARD ALERT*
  3. Alternating current (AC): pulsing flow of electrons in both directions; in                                     US  *BOARD ALERT*
  4. Amperage-quantity of electric current
  5. Voltage-speed of electrons flowing from cathode to anode
  6. Increase in voltage=increases the speed electrons therefore the                                                        electrons strike the target with greater force and energy
  7. Step-down transformer-decreases voltage entering into tube
  8. Step-up transformer-increases voltage to propel electrons
  9. Autotransformer-before anode and cathode circuits (power                                                              constant) *BOARD ALERT*


  1. Three conditions must exist for x-rays to be produced
  2. A source of free electrons
  3. High voltage to impart speed to the electrons
  4. A target that is capable of stopping the electrons







Anode (+) Cathode (-)
Copper Stem Filament
Target Focusing cup
Step-up transformer Step-down transformer
kVp mA

When electrons move from cathode to anode end,

99% is absorbed and produces heat

1% leaves the tubehead (directed at patient)



  1. Physics of Radiation
  2. Atomic Structure
  3. Atom
  4. smallest particle of an element that still retains the properties of                                                      the element
  5. Composed of:

(1)       Electrons (negative charge)

(2)       Protons (positive charge)

(3)       Neutrons (no charge)

  1. Atoms

(1)       Electrons revolve around a nucleus in paths called shells or                                                             energy levels.

(2)       Protons and neutrons form the nucleus.

(3)       Binding energy-maintaining electrons in orbit by their                                                                     positive attraction of the protons

  1. Molecule

(1)       Combination of atoms


  1. Radiation
  2. Emission and movement of energy through space
  3. Ionization *BOARD ALERT*
  4.          an atom that gains or loses an electron and becomes electronically                                                  unbalanced
  5. Ion *BOARD ALERT*
  6. Charged particle that is positive or negative
  7. Ion pair *BOARD ALERT*
  8. Positive ion-atom from which an electron has been removed
  9. Negative ion-negatively charged electron separated from the atom




  1. Two types of Ionizing Radiation capable of producing ions:
  2. Particulate radiation *BOARD ALERT*
  3. tiny fast-moving particles
  4. have both mass and energy
  5. travel in straight lines

Ex. Proton, neutrons, alpha and beta particles



  1. Electromagnetic radiation *BOARD ALERT*
  2. the transmission of wave-like energy through space
  3. no mass

Ex. gamma, infrared, ultraviolet, x-rays



  1. Electromagnetic spectrum is arranged and measured according to wavelength,                               frequency, and velocity.



Credit: NASA’s Imagine the Universe


  1.          Wavelength *BOARD ALERT*
  2.          distance from one crest of a wave to the next
  3.          the shorter the wavelength, the greater are the energy and                                                                penetrating ability of the radiation



Credit: Britanica.com



  1.          Frequency *BOARD ALERT*
  2.          number of waves that pass a given point per unit of time
  3.          the higher the frequency, the more penetrating power




Credit: Electrical4U




  1.          Velocity *BOARD ALERT*
  2.          the speed of the wave





  1. Properties of Xrays
  2. Consist of photons
  3.          a single unit or bundle of energy have no mass or weight, are invisible,                                          and cannot be sensed.
  4. X-rays: *BOARD ALERT*
  5. Are invisible
  6. Travel in straight lines
  7. Travel at speed of light
  8. Have no mass, weight or charge
  9. X-rays Interact with matter causing ionization
  10. Can penetrate opaque tissues and structures
  11. Can affect photographic film emulsion (producing a latent image)
  12. Can affect biological tissue


  1. Xrays have the ability to penetrate materials or tissues depends on:
  2. Wavelength of the x-ray
  3. Thickness and density of the object
  4. Materials that are extremely dense will absorb more x-rays than thin                                               materials
  5.          Dense materials such as amalgam appear radiopaque (white/light                                                  gray)
  6.          Less dense materials such as the pulp chamber appear radiolucent

(black/dark gray)


  1. Types of Xrays Produced


  1. In a dental x-ray tube, the kinetic energy of electrons is converted to                                               electromagnetic energy by the formation of:
  2. General or bremsstrahlung radiation
  3.          Forms the majority of x-rays produced by dental x-ray machines
  4.          A high-speed electron is slowed and bent off its course by the                                                         positive pull of the nucleus and the kinetic energy lost is converted                                                        into an x-ray (B).


  1.          Characteristic radiation
  2.          Forms the minority of x-rays produced by dental x-ray machines
  3.          A high-speed electron hits and dislodges a K-shell electron then an                                                 electron from an outer shell fills in the place of the missing one                                                          and x-ray energy is released (C).




VII.     Description of X-rays


  1. Primary radiation *BOARD ALERT*
  2.          penetrating beam that is produced at the target
  3. primary or useful beam is the x-ray generated for the purpose of making a                                      radiographic image


  1. Secondary radiation *BOARD ALERT*
  2.          Formed as a result of primary radiation striking and interacting with                                               matter
  3. Not only not useful in the production of a radiographic image
  4. Can contribute to a lowered contrast, poor quality image


  1. Scatter radiation *BOARD ALERT*
  2. form of secondary radiation in which the direction of travel of the x-ray                                         has been altered as a result of interaction with matter; the beam is                                                           deflected
  3. Not useful
  4. Can cause unnecessary additional exposure to patient tissues and to the                                          careless operator who does not follow safety protocols


VIII.   Interaction of Xray with Matter


  1. Four possibilities


  1. No interaction (9%)
  2.          X-ray photon can pass through an atom unchanged and no                                                               interaction occurs.


  1. Coherent scattering (8%)
  2.          Incoming x-ray photon interacts with the electron by causing the                                                    electron to vibrate at the same frequency as the incoming x-ray                                                 photon. The incoming x-ray no longer exists. The vibrating                                                             electron emits a new, unmodified x-ray photon that is scatter but in                                                 a different direction.


  1.          Photoelectric effect (30%)
  2.          Incoming x-ray photon collides with an orbital electron and                                                 b.         conveys electromagnetic energy to the electron in the form of                                               c.         kinetic energy knocking the electron from its orbit creating an ion                                                            pair.


  1. Compton scattering (60%)
  2. Similar to the photoelectric effect
  3. Only a part of the x-ray energy is transferred to the electron
  4. A new, weaker x-ray photon is formed and scattered.



  1. Units of Radiation


  1. The International Commission on Radiation Units and Measurements (ICRU)

established standards that clearly define radiation units and radiation quantities

  1. Terms used to measure x-radiation are based on the ability of the x-ray to                                      deposit its energy in air, tissues of the body, or other substances.


  1. Two systems are used to define the radiation measurements
  2. Traditional units (older) *BOARD ALERT*
  3. Roentgen (R)
  4. Rad (radiation absorbed dose)
  5. Rem (radiation equivalent in man)


  1. Système International (SI) units (newer) *BOARD ALERT*
  2. Coulombs per kilogram (C/kg)
  3. Gray (Gy)
  4. Sievert (Sv)


Quantity SI Unit Traditional Unit

the measurement of ionization in air produced by x-rays

Coulombs per kilogram (C/kg) Roentgen (R)
Absorbed dose

the amount of radiation absorbed by a tissue

Gray (Gy)




Dose equivalent

the measure of biologic effects produced by different types of radiation

Sievert (Sv)







  1. Sources of Radiation


  1. Background radiation 50% of the overall exposure to the US population
  2.          Radon gas, the results of naturally occurring radionuclides found in soil
  3.          Terrestrial and Space sources, cosmic radiation from outer space
  4.          Internal sources natural exposure


  1. Medical applications 48% the overall exposure to the US population
  2.          Computed tomography
  3.                      Nuclear medicine
  4.          Interventional fluoroscopy
  5.          Conventional radiography/fluoroscopy


  1. Consumer, industrial and occupational exposures account for the remaining 2% of                        total exposure to the US population




Credits:  NCRPonline.org



  1. Quality Radiographs


  1. Principles of Shadow Casting *BOARD ALERT*
1.  Small focal spot Increase sharpness; Decrease magnification
2.  Long target-object distance Increase sharpness; Decrease magnification
3.  Short object-image receptor distance Increase sharpness; Decrease magnification
4.  Parallel object-image receptor Decrease distortion
5.  Beam perpendicular (right angle) to object-image receptor Decrease distortion


  1. Density *BOARD ALERT*
  2. Overall darkness (blackness) of the image
  3. PRIMARILY affected by mA and time
  4. Secondarily by kVp


  1. Contrast *BOARD ALERT*
  2. Refers to the difference b/w black and light areas
  3. Affected ONLY by kVp


  1. High Contrast *BOARD ALERT*




  1. Low Contrast *BOARD ALERT*



  1. Exposure Factors and Density


  1. Milliamperage *BOARD ALERT*
  2.          Determines QUANTITY of x-rays generated
  3.          Affects density

Increase mA=hotter=increase e-=increase density=darker image

Decrease mA=lighter image

  1. Exposure Time

Increase exposure time=increase density=darker image

Decrease exposure time=lighter image


                                    *BOARD ALERT*

  1. Exposure Time and Milliamperage Inverse Relationship
  2. mA increased exposure time must be decreased
  3. mA decreased exposure time must be increased


  1. Kilovolt Peak *BOARD ALERT*
  2.          Determines QUALITY of x-ray generated

Increase kVp=increase speed=more penetrating=more dense

Decrease kVp=less dense

  1. Rule of 15
  2.          Increased kVp by 15Decrease exposure time by 2
  3.          Decrease kVp by 15Increase exposure time by 2
  4. Inverse Square Law
  5.          Change in operator distance:

I1 = (D2)2       I1=Original intensity

________        I2=New intensity

I2 = (D1)2       D1=Original distance

D2=New distance


Intensity of Radiation is inversely proportional to the square of the                                               distance from the source of radiation

  1. when the distance is doubled, the beam is ¼ as intense
  2. when the distance is halved, the beam is four times more intense



  1. Pediatric Exposure
  2. Primary dentition-reduce adult exposure by ½
  3. Mixed dentition-reduce adult exposure by ½-1/4




  1. Two theories of Biological Effects: *BOARD ALERT*
  2. Direct theory (Direct Effect, Direct Hit)
  3.          1/3 of biological alterations from x-radiation
  4.          X-ray photon collide with cell chemicals (DNA, chromosomes,                                                      etc) and breaks them apart causing critical damage to molecule
  5.          Indirect theory (Radiolysis of water, Poison Water Theory)
  6.          Radiation can cause chemical damage to a cell by ionizing the                                                        water within it
  7.          Ionization causes water molecules to break into hydrogen and                                                         hydroxyl radical and reform into hydrogen peroxide.
  8. Dose-Response Curve: *BOARD ALERT*
  9.          Threshold Dose-Response Curve
  10.          Indicates a “threshold” amount (dose) of radiation, below which                                                     NO biological response (damage) would be expected




  1. Non-Threshold Dose-Response Curve
  2. Indicates that ANY amount (dose) of radiation, no matter how                                            b.         small, has the potential to cause a biological response (damage)




  1.          Linear v
  2.          The response is directly proportional to the dose (similar to Non-                                                    Threshold Dose)


  1. Effects of Radiation on Body Tissue
  2.          Stochastic Effect
  3.          Effects happen by chance not by the severity
  4.          Non-stochastic Effect (Deterministic)
  5.          Cause-and-effect relationship between radiation and side effects;                                                    increase doseincrease in severity
  6.          Somatic Effects *BOARD ALERT*
  7.          When damage occurs in the irradiated individual but not passed to                                                  offspring
  8.          Genetic Effects *BOARD ALERT*
  9.          Damages occur in hereditary tissues therefore the irradiated                                                            individuals show no damage but the offspring does
  10.          Short-term Effects *BOARD ALERT*
  11.          Large dose of radiation absorbed in a short time
  12.          Effects seen within minutes, days or months after exposure
  13.          Acute Radiation Syndrome (ARS)

Erythema, Nausea, Vomiting, Diarrhea, Hemorrhage, Hair loss

  1.          Long-term Effects *BOARD ALERT*
  2.          Small dose of radiation absorbed repetitively over a long time
  3.          Effects seen years after original exposure
  4.          Increased chance of:

Cancer, Defects, Low Birthweight, etc

  1.          Cumulative Effects *BOARD ALERT*
  2.          Increasing damage by each consecutive radiation exposure


  1. Sequence of Events following Radiation Exposure *BOARD ALERT*
  2.          Latent Period
  3.          Time between initial radiation exposure and before the first                                                             observable effect occurs
  4.          Period of Injury
  5.          Potential injuries:

Stoppage or abnormal of mitosis, clumping of chromosomes,                                                          formation of cancer cells

  1.          Recovery Period
  2.          Recovery can take place but some cells may not be able to return                                                    to its pre-irradiated state


  1. Outcome of Radiation Injury is dependent on: *BOARD ALERT*
  2.          Total Dose
  3.          Larger the doseMore severe damage
  4.          Dose Rate
  5.          Small dosesLess damaging than when given in a single large                                                       dose
  6. Area Exposed
  7.          Large area exposedMore tissue damage
  8. Mitotic Activity
  9.          Rapidly dividing cellsmore sensitive to radiation
  10.          Cell Metabolism
  11.          Higher metabolic cellsmore sensitive to radiation
  12.          Cell Differentiation
  13.          Immature cellsmore sensitive to radiation


Most Sensitive (Least resistant) Less Sensitive (Most resistant)
Lymphatics Nerve cells
Blood-forming cells Muscle cells
Reproductive cells Bone and Cartilage


  1. Critical Tissues for the radiographer include:

Skin of head/neck, bone marrow of the mandible, lens of the eyes, thyroid gland




  1. Prior to Exposure:
  2. Follow ADA Guidelines for Prescribing Dental Radiographs
  3. Evidence-based selection criteria should determine patient’s need for                                             dental radiographs
  4. Consider ALARA (As Low As Reasonably Achievable) *BOARD                                                ALERT*
  5. Notion that every dose of radiation may produce damage and                                                          radiation should be kept to the minimum needed to meet diagnostic                                            quality.
  6. Equipment Standards
  7. Filtration *BOARD ALERT*

(1)       Removes long wavelength (soft radiation)

(2)       Made of aluminum

(3)       Inherent filtration-produced by internal barriers in the tube                                                              head (glass, oil)

(4)       Added filtration-placement of aluminum disk in PID

(5)       Total filtration– inherent + added filtration

Units operating below 70kVp=1.5mm of aluminum

Units operating above 70 kVp=2.5mm of aluminum



Credit: Mosby 2011


  1. Collimation *BOARD ALERT*

(1)       Determines the size and shape of the beam

(2)       Made of lead

(3)       Round or Rectangular

(4)       Rectangular Collimation most important factor in reducing                                                              (~60%) unnecessary radiation but without good technique                                                                may increase the need for retakes from conecuts

(5)       Maximum size of beam at the patient’s face not to exceed                                                               2.75 in.


Credit: Pearson 2012


  1. Position Indicating Device (PID)

(1)       An extension of the tube head that is used to direct the x-                                                                 ray beam

(2)       Cylinder-lead-lined, open-ended, most common

(3)       Rectangular-lead-lined, open-ended, most effective in                                                                      reducing exposure to patient

(4)       Used to establish desired source-object distance by means                                                               of 8 (short), 12, 16” (long)

16” preferred for paralleling to reduce divergent x-ray                                                                     beam


  1. Exposure:
  2. Lead Apron
  3. Use with thyroid collar for intraoral and without for panoramics
  4. Must have an equivalent of 0.25mm lead
  5. Image Receptor
  6. Film

(1)       Use fastest speed film, “F” if available

(2)       Use largest film the patient will tolerate

(3)       Second most effective method of reducing radiation to the                                                               patient

  1. Digital Sensor

(1)       Use will further reduce patient exposure

  1. Use of an image receptor aiming device are recommended

(1)       Radiographer should NEVER hold the receptor

(2)       Patient digital retention method is unethical

  1. Technique Standard
  2. Paralleling vs. Bisecting
  3. Good techniqueless retakesreduced exposure to patient
  4. Exposure Factors
  5. Selection and manipulation of exposure factors
  6. Exposure Timer
  7.          Require continuous pressure to produce x-ray
  8.          Automatically resets
  9.          60 impulses=1second


  1. After Exposure:
  2.          Proper film handling
  3.          Retake Criteria


  1. Operator Protection: *BOARD ALERT*
  2.          Remain behind a shield/barrier during exposure
  3.          Distance
  4.          Most important safeguard for operator
  5. 6’ away from tube head
  6. 90-135 degree angle to the beam


Credit: Pearson 2016


  1. Maximum Permissible Dose (MPD) *BOARD ALERT*
  2.          Maximum dose of ionizing radiation that a body is permitted to receive                                          within a specific period
  3.          Radiation workers/Occupationally exposed workers


  1.          General public (pregnant/under 18-year-old radiation workers)

5mSv (0.5rem)/year


  1. Personnel monitoring device to measure and monitor radiation exposure


XIV.    Dental Film


  1. Composition of X-ray film *BOARD ALERT*


  1. Emulsion is composed of gelatin and silver halide crystals
  2. Gelatin

(1)       keeps crystals evenly suspended

  1. Crystals

(1)       compound of halogen (bromine or iodine) and 90-99%                                                                    silver bromine 1-10% silver iodine

(2)       crystals are sensitive to radiation and retain a latent image




  1. Types of Film


  1. Intraoral
  2. Exposed while in the oral cavity
  3. Size 0-4
  4. Packaging

(1)       1-2 films containing an identification dot

(2)       Black paper wrapping to protect from light

(3)       Embossed lead foil to absorb scatter radiation

(4)       Moisture-resistant outer wrapping (solid white side faces                                                                 radiation)




  1. Extraoral
  2. exposed while outside the oral cavity
  3. Sizes 8”x10”, 5-6”x12”
  4. Packaging

(1)       25, 50, or 100 to a box

(2)       not individually wrapped


  1. Emulsion Sensitivity *BOARD ALERT*


  1. Film speed is determined by the size of the silver halide crystals, thickness                                    of emulsion and radiosensitive dyes
  2. Speed ranges from D through F speed available (F=fastest) (F requires                                           60% of the exposure time of D-speed film)
  3. Faster film is less radiation exposure for the patient, but the emulsion has                                       larger crystals therefore image quality is less


  1. Screen film
  2. Used with extraoral radiographs
  3. Exposed by fluorescent type of light given off by special emulsion-coated                                      intensifying screens that are positioned between the film and the x-ray                                               source
  4. Calcium tungstate emits a blue light to expose the film
  5. Rare-earth crystals emits a green light to expose the film


Credit:  Pocketdentistry.com


  1. Film Storage and Protection *BOARD ALERT*
  2. X-ray film is sensitive to radiation, light, heat (50-70 degrees F), humidity                                                 (30-50%), chemical fumes and physical pressure
  3. Expiration date should be visible as stored
  4. Expired film may compromise the image quality
  5. Step Wedge:  Used to test the amount of radiation reaching the                           image receptor through each of the increments


  1. Film Processing


  1. Processing transforms the latent image.
  2. Developer *BOARD ALERT*
  3.          Reduces the exposed silver halide crystals within the film emulsion to                                            black and silver metallic
  4. Softens the emulsion


Developing agent

(reducing agent)



Preservative Sodium sulfite
Activator Sodium carbonate
Restrainer Potassium bromide


  1. Fixer *BOARD ALERT*
  2.          Removes the unexposed/undeveloped silver halide crystals
  3.          Hardens the emulsion


Fixing agent

(clearing agent)


thiosulfate *BOARD ALERT*

Preservative Sodium sulfite
Hardening agent Potassium Alum
Acidifier Acetic acid


  1. Manual Processing Steps *BOARD ALERT*
  2. Developing (optimum temp 68 degrees for 5 minutes)
  3. Rinsing 30 sec; stops further development; removes developer as to not                                         contaminate the fixer
  4. Fixing 10 min (wet read safe after 2 min but return to complete time)
  5. Washing 20 min; removes all chemicals
  6. Drying



  1. Automatic Processing Steps
  2. Feed to dry time is approximately 4-6 minutes.
  3. NO RINSE between developer and fixer *BOARD ALERT*



  1. Darkroom
  2. Provides area where x-ray films can be safely handled and processed
  3. Lighting
  4. Avoid fluorescent overhead lighting – tendency for afterglow                                                          might contribute to film fog.
  5. Safelight *BOARD ALERT*
  6. A special light emitting diode (LED) bulb or filtered white light                                                      bulb.
  7. 7.5 watt or 15-watt incandescent white light with safelight filter                                                      over it.
  8. Safelight filter removes short wavelengths in the blue-green region                                                 of the visible light spectrum.
  9. Minimum of 4 feet from the working area.
  10. 2 ½ minute exposure without fogging


  1. Quality Control for darkroom
  2.          Test includes:
  3.          Assessment of safe lighting
  4.          Checking for white light leaks
  5.          Processing chemistry maintenance
  6.          Detection of conditions as that create film fog


Use: Coin Test for safe light testing




  1. Film Orientation *BOARD ALERT*
  2. Mounting radiographs provides a systematic approach to viewing and                                            evaluating radiographs
  3. Films are placed in mounts then placed on viewbox for viewing.
  4. ADA recommends labial mounting
  5. dot is convex in mount and facing the operator
  6. patients right is the operators left; patients left is the operators right
  7. Lingual mounting
  8. dot is concave
  9. patients right is operators right


XVI.    Film- Processing Errors *BOARD ALERT*


  1. Herringbone pattern
  2.          The film was placed in the oral cavity with the incorrect side (colored vs.                                       white) facing the source of radiation. The herringbone pattern from the                                      lead foil imaged on the film.  The image was light because the radiation                                         had to penetrate through the lead foil to produce the image of the oral                                             structures.
  3. Film Identification Dot in the incorrect area
  4.          Embossed dot positioned towards the apical area instead of the occlusal                                         plane.
  5. Double Image
  6.          Exposing the same film more than one time
  7. Dark radiographs
  8. Film left in developer too long
  9. Too concentrated developer
  10. Light radiographs
  11. Film not left in developer long enough (underdeveloped)
  12. Weak developer concentration
  13. Old or contaminated developer
  14. Clear (blank) radiographs
  15. Film placed in fixer before developer
  16. Film in rinse water too long
  17. No radiation was emitted to expose the film
  18. Partially clear/dark
  19. Horizontal line; Film not completely submerged in solutions
  20. Circular; Bubbles formed on film so solutions could not penetrate
  21. Black radiographs
  22.          Prematurely exposed to white light
  23. Green radiograph
  24.          Films stuck together and chemicals cannot penetrate through emulsion
  25. Yellow-brown radiographs
  26.          Insufficient washing
  27. Markings
  28.          Dark
  29. creasing from pressure/bending
  30.          marks from uncleaned processor rollers
  31.          static electricity resembling branches
  32. crackling of the emulsion from different solution temperature-                                                        Reticulation
  33.          Light
  34. scratches from handling (nails, etc)
  35.          finger prints from oils and residual from gloves
  36. Fogged Film
  37.          Not protecting films before/after exposure from radiation
  38.          White light leaking in darkroom
  39.          Prolonged exposure to safelight
  40.          Glow from white light in darkroom (watch, cell phone, ceiling light)
  41.          Film stored in warm damp conditions or exposed to chemical fumes
  42.          Using expired film



XVII. Digital Radiography


  1. Digital imaging
  2. replaces the term radiograph
  3. now acquire an image not take a radiograph
  4. no physical form
  5. bits of information in a computer file


  1. Acquiring an Image
  2. X-ray Machine
  3. source of radiation
  4. Software and Computer
  5. used to capture, digitize, process, view and store the image
  6. Image Receptors *BOARD ALERT*
  7. Direct Digital Imaging-made up of a grid of light-sensitive cells  (pixels)

(1)       Charge-coupled device (CCD)

(2)       Complementary metal oxide semiconductor active pixel sensor (CMOS-APS)

(3)       wired or wireless

(4)       rigid

(5)       sizes 0-2

  1. Indirect Digital Imaging-plate that captures x-ray energy as analog data and indirectly produces a digital image on a computer screen when scanned

(1)       Photostimulable phosphor (PSP)

(2)       wireless

(3)       thin and flexible

(4)       sizes 0-4


  1. Up to 50%-90% radiation reduction when using digital versus                                                     traditional film


XVIII. Types of Intraoral Examination


  1. Periapical– images the entire tooth (2mm beyond) and surrounding bone
  2. Indications:
  3. suspected apical pathology
  4. trauma
  5. large carious lesions
  6. periodontal involvement
  7. endodontic therapy
  8. developmental anomalies (impacted teeth, unusual eruption, etc)
  9. unexplained sensitivity/bleeding/mobility
  10. Oriented vertically in the anterior; horizontally in the posterior
  11. Bitewing-records the coronal portions of the teeth and the alveolar bone of both the maxilla and mandible on a single radiograph
  12. Most common intraoral examination
  13. Indications:
  14. detecting interproximal caries
  15. detecting early periodontal disease
  16. Oriented horizontally; vertically with more extensive periodontal involvement
  17. Full Mouth-series or survey of the maxilla and mandible compiled of periapical and bitewing images
  18. Includes dentulous and edentulous areas
  19. Occlusal-images the entire or portion of the maxilla or mandible on a single radiograph
  20. Indications:
  21. pathologic conditions such as cysts
  22. trauma such as fractures
  23. impacted or supernumerary teeth
  24. locating foreign objects
  25. unexplained swelling/growth such as salivary stone


Maxillary Topographical Occlusal Radiograph Anterior +65 Vertical Angulation
Maxillary Topographical Occlusal Radiograph Posterior +45 Vertical Angulation
Mandibular Topographical Occlusal Radiograph Anterior -55 Vertical Angulation
Mandibular Topographical Occlusal Radiograph Posterior -45 Vertical Angulation
Mandibular Cross-sectional Occlusal Radiograph 0 Vertical Angulation



  1. Object Localization
  2. Definitive Method

(1)       based on principles of shadow casting that an object                                                                         positioned farther away from the receptor will be magnified                                                      and less clearly defined; if it is clear then it is likely to be                                                                on the lingual closest to the receptor

  1. Right-angle Method

(1)       expose a cross-sectional occlusal radiograph which places                                                               the receptor at a right angle to the arch there you will be                                                              able to see if the object is on the lingual or buccal

  1. Tube Shift Method (buccal-object rule) *BOARD ALERT*

(1)       2 images needed

(2)       S-same




(3)       If the object moves in the same direction as the tube shift                                                                then the object is on the lingual


XIX.    Intraoral Techniques *BOARD ALERT*


  1. Paralleling Technique (right-angle or long-cone)
  2. Technique of choice
  3. Satisfies more principles of shadow casting
  4. Application:
  5. the receptor is placed parallel to the long axis of the tooth
  6. the x-ray beam is directed perpendicular to the long axis of the tooth and the receptor
  7. the x-ray beam is then directed perpendicular through interproximal spaces of the teeth of interest
  8. the x-ray beam is centered over the image receptor


  1. Bisecting Technique (bisecting-angle or short-cone)
  2. Used for ease of image receptor placement when paralleling cannot be accomplished (patients with small mouths, exaggerated gag reflex, shallow palate, narrow arch, tori)
  3. Application:
  4. the receptor is placed against the lingual surface of teeth
  5. the x-ray beam is directed perpendicular to the imaginary bisector that divides that angle that is formed from the long axis of the tooth and the image receptor
  6. the x-ray beam is then directed perpendicular through interproximal spaces of the teeth of interest
  7. the x-ray beam is centered over the image receptor



  1. Limitations:  Distortion and superimposion of structures


  1. Intraoral Image Normal Anatomy *BOARD ALERT*



Radiolucent (rl) Radiopaque (rl)
fossa bone
foramen ridge
canal process
sinus tubercle
suture wall


  1. Maxilla
  2. Anterior
  3. incisive foramen (rl)- round-or pear-shaped opening                                                                                    appearing between the apices of the central incisors
  4. midpalatine suture (rl)- thin line that down the center                                                                       of the palate
  5. nasal fossa (rl)- large airspace divided in to two halves by the nasal septum
  6. lateral fossa (rl)- between the lateral incisor and                                                                               canine representing a decreased thickness of bone in that area
  7. anterior nasal spine (ro)- v-shaped projection from the                                                                     floor of the nasal fossa in the midline
  8. nasal septum (ro)- vertical line separating the right nasal fossa                                                        from left
  9. inverted Y (ro)- union of lateral border of nasal fossa and anterior wall of maxillary sinus in the area of the canine-premolar




  1. Posterior
  2. maxillary sinus (rl)-large air chamber inside the maxilla in the                                                        canine to molar area
  3. zygomatic process of maxilla (ro)- a braod U- or J-shaped band                                                      above or superimposed over maxillary roots of first and second                                                          molars
  4. zygoma (ro)- extends laterally and distally from zygomatic process
  5. maxillary tuberosity (ro)- extension of alveolar bone distal to                                                          maxillary molars
  6. hamulus (ro)- downward projection of the pterygoid plate
  7. coronoid process (ro)- mandibular structure appearing triangular or                                                pointed superimposed over maxillary tuberosity distal to molars



  1.       Mandible
  2. Anterior
  3. lingual foramen (rl)- small round opening in the center of the                                                          genial tuberacles apical to the mandibular central incisors
  4. mental fossa (rl)-depression on the labial aspect of mandibular                                                        incisor area
  5. genial tubercles (ro)- bony crests on lingual surface of mandible                                                     appearing round apical to mandibular central incisors
  6. mental ridge (ro)- horizontal line extending from the premolar                                                        region to the symphysis (midline) of mandible



  1. Posterior
  2. mental foramen (rl)- small round hole on the lateral side of the                                                        body of the mandible near the apices of the premolars
  3. mandibular canal (rl)- two thin parallel lines below the apices of                                                     the molars
  4. submandibular fossa (rl)- irregular shaped area below the                                                                mylohyoid ridge and the apices of the molars
  5. oblique ridge (ro)- horizontal line superimposed across the molar                                                    roots which is a continuation of the anterior border of the ramus
  6. mylohyoid ridge (ro)- horizontal line running inferior to the                                                            oblique ridge below apices of molars



XXI.    Intraoral Radiographic Technique Errors *BOARD ALERT*


  1. Missing apices
  2. receptor not placed high enough in the palate for maxilla or low enough in                                                 the floor for mandible (check stabe placement as well)
  3. vertical angulation inadequate (too flat)
  4. Missing crowns
  5. receptor placed below the incisal/occlusal edge
  6. vertical angulation excessive (too steep)
  7. if receptor placement is correct when bisecting, then you cannot miss                                             crowns
  8. Elongation
  9. happens with bisecting angle, vertical angulation inadequate (too flat)


Credits:  cdeworld.com

  1. Foreshortening
  2. happens with bisecting angle, vertical angulation excessive (too steep)


Credits:  pocketdentistry.com

  1. Overlapping
  2. not positioning the receptor parallel to the interproximal space of interest
  3. horizontal angulation directed mesiodistally=overlapping more excessive                                       in the posterior region of the image receptor


Credits:  ccnmtl.columbia.edu

  1. horizontal angulation directed distomesially=overlapping more excessive                                       in the anterior region of the image receptor


Credits:  eaglerockdentalcare.

  1. Unequal distribution/Slanting of Occlusal Plane
  2. periapicals, image receptor not parallel with incisal or occlusal plane
  3. bitewings, bitetab/block not centered on receptor
  4. bitewings, bitetab/block not flush on occlusal surface
  5. edge of receptor contacts and is forced by lingual gingiva or palate to tip
  6. receptor is placed on the tongue
  7. Conecut
  8. receptor is not center within the PID (beam)
  9. incorrectly assembling the receptor positioner
  10. not orienting the rectangular PID to match the receptor
  11. Blank image
  12. equipment malfunction
  13. not depressing the exposure button
  14. digital receptor in backwards
  15. Blurred images
  16. patient, tube head, receptor movement


XXII.  Types of ExtraOral Examinations *BOARD ALERT*


  1. Panoramic– Broad image of the entire dentition, alveolar bone, sinuses, and temporomandibular joints on one single radiograph
  2. Most common extraoral examination
  3. Based on tomography
  4. Indications:
  5. examining large areas in the face or jaw
  6. trauma, lesions and diseases
  7. impacted, supernumerary teeth, retained root tips
  8. growth and development
  9. Focal Trough
  10. 3-dimensional horse-shoe shaped area where the patients dentition is placed to get the sharpest image possible
  11. Basic components:
  12. Rotational tube head
  13. Image Receptor
  14. Patient positioners
  15. Control panel
  16. Patient positioning is critical


  1. Lateral Cephalometric-lateral skull
  2. Positioning
  3. Entire skull from the side
  4. Area of Interest
  5. Sinuses


  1. Posteroanterior Cephalometric-posterior skull
  2. Positioning
  3. Entire skull from posterior to anterior
  4. Area of Interest
  5. Frontal sinuses


  1. Waters
  2. Positioning
  3. Middle third of face (head tipped back; nose .75in from receptor)
  4. Area of Interest
  5. Maxillary, frontial and ethmoid sinuses


  1. Reverse Towne
  2. Positioning
  3. Forehead to receptor (head tipped down with mouth open)
  4. Area of Interest
  5. Condyle


  1. Submentovertex
  2. Positioning
  3. Frankfort plane perpendicular to the floor (xray from chin region)
  4. Area of Interest
  5. Base of skull, condyles, sphenoid sinus and zygoma


  1. Transcranial
  2. Positioning
  3. Similar to lateral ceph except xray beam is at +25 degrees
  4. Area of Interest
  5. Head of condyle, glenoid fossa, temporal bone, TMJ


  1. Cone Beam Computed Tomography (CBCT)
  2. Developed in 1990s
  3. Produces 3-dimensional image
  4. Indications:
  5. assessing for implants and orthodontics
  6. evaluation with tooth extraction and impaction
  7. guide for reconstructions


XXIII. Extraoral Image Normal Anatomy *BOARD ALERT*


            (will not repeat descriptions from Intraoral descriptions)


  1.       Maxilla
  2. Anterior Nasal Spine (ro)
  3. Incisive Canal (rl)- not often visible; tunnel from floor of nasl                                                         cavity inferior to alveolar ridge between maxillary incisors
  4. Incisive Foramen (rl)
  5. Infraorbital Foramen (rl)- round radiolucent opening in bone inferior to                                          border of orbit
  6. Nasal Cavity (rl)- pear-shaped located superior to maxilla incisor roots
  7. Nasal Septum  (ro)
  8. Orbit (rl)- large boney cavity of eye socket located superior or                                                        superimposed over maxillary sinus
  9. External Auditory Meatus (rl)- round opening in temporal bone located                                          anterior and superior to mastoid process
  10. Hamulus (ro)
  11. Lateral Pterygoid Plate (ro)- wing-like bony projection of sphenoid bone                                        located posterior to maxillary tuberosity
  12. Mastoid Process– (ro)- prominent rounded protrusion of temporal bone                                           located posterior and inferior to TMJ
  13. Maxillary Sinus (rl)
  14. Maxillary tuberosity (ro)
  15. Styloid Process (ro)- long bone extending downward from inferior surface                                                 of temporal bone, anterior to mastoid process
  16. Zygomatic process (ro)
  17. Articular Eminence (ro)-slight convex protrusion extending inferior from                                       zygomatic process of temporal bone; anterior to glenoid fossa
  18. Glenoid Fossa (rl)- slight concavity in zygomatic process of temporal bone                                    posterior to articular eminence
  19. Hard Palate (ro)- thick horizontal band superior to maxillary teeth


  1. Mandible
  2. Genial Tubercle (ro)
  3. Lingual Foramen (rl)
  4. Mental Fossa (rl)
  5. Mental Ridge (ro)
  6. Angle of the mandible (ro)- where body and ramus of mandible meet
  7. Condyle (ro)- dense rounded head and neck extension of ramus of                                                  mandible
  8. Coronoid Process (ro)
  9. Lingula (ro)- projection of bone located anterior and adjacent to                                                      mandibular foramen
  10. Mandibular Canal (rl)
  11. Mandibular Foramen (rl)- round opening in bone on lingual aspect of                                             ramus
  12. Mandibular Notch (ro)-concavity of bone between coronoid process and                                        condyle
  13. Mental Foramen (rl)
  14. Mylohyoid Ridge (ro)
  15. Oblique Ridge (ro)                  15.       Submandibular Fossa (rl)
  16. Inferior border of the mandible (ro)- dense band of thick cortical bone that                                     outlines lower border of mandible
  17. Cervical Vertebrae (ro)- appears on the extreme right and left of the image
  18. Hyoid Bone (ro)- horse-shoe shaped bone located in the neck region                                               inferior to mandible


  1. Air Spaces
  2. 1. Palatoglossal
  3. Nasopharyngeal
  4. Glossopharyngeal




XXIV. Extraoral Radiographic Technique Errors *BOARD ALERT*


  1. Blurred, thin, elongated anterior teeth and prominent vertebrae on both                                sides
  2. patient positioned too far anterior (forward) of focal trough
  3. not biting on bitestick correctly; not aligning vertical beam in anterior                                            sextant region


Credits: ijdr.in

  1. Magnified, widened anterior teeth, no vertebrae on image
  2. patient positioned too far posterior (back) from focal trough
  3. not biting on bitestick correctly; not aligning vertical beam in anterior                                            sextant region
  4. Narrowed teeth on one side (lateral) while the other side is magnified
  5. patient head is tipped
  6. midline beam is not aligned correctly


Credits:  pdfs.semanticscholar.org

  1. Exaggerated smile, condyles slant inward
  2. Frankfort plane/ala-tragus not aligned correctly; chin tipped down                                                  (inferior)
  3. Exaggerated frown, hard palate onscures the maxillary apices
  4. Frankfort plane/ala-tragus not aligned correctly; chin tipped up (superior)



  1. Bright white, triangular radiopacity on mandibular teeth
  2. lead apron


Credits:  dentalcare.com


  1. Ghost-like, square radiopacity on mandibular teeth
  2. vertebrae compressed; patient slumped


Credits: intechopen.com


  1. Too dark/Too light
  2. Exposure setting set incorrectly
  3. Vertical radiolucent line/Partial images
  4. Radiation stopped (hit shoulder, released button, incorrect setting)
  5. Large radiolucent oval over maxillary apices
  6. Tongue not in palate during exposure


Credits: ijdr.in

  1. Radiolucent oval over mandibular anterior teeth
  2. Lips not closed around bite stick during exposure


XXV.  Radiographic Appearance of Caries *BOARD ALERT*

  1. Incipient
  2. Radiolucent portion is less than halfway through enamel


  1. Moderate
  2. Radiolucent portion is more than halfway through enamel but does not                                           penetrate DEJ


  1. Advanced
  2. Radiolucent portion is less than halfway through dentin toward pulp


  1. Severe
  2. Radiolucent portion is more than halfway through dentin toward pulp


  1. Occlusal caries become evident and distinguised in the advanced and severe                                 stage
  2. Buccal/lingual caries become evident once it enters into the advanced stage
  3. Cemental caries become evident once it enters into the advanced stage
  4. Mistaken for Caries
  5.        Cervical burnout-Radiolucency at the thin cervical root surface inferior to                                      crown
  6. Mach Band Effect-Optical illusion of radiolucent lines caused by                                                    overlapping
  7. Non-metallic restorations-radiolucent appearance of composite, bases,                                           resins


XXVI. Radiographic Appearance of Periodontal Disease *BOARD ALERT*

  1.          Horizontal bone loss-buccal, lingual and interdental bone resorb at the                                          same rate


  1.          Vertical bone loss-bone resorbs at different rates between adjacent teeth                                       creating an angle



  1.                      Healthy-alveolar crest 1-2mm apical to CEJ



  1.          Mild Periodontitis-alveolar crest 2-3mm apical to CEJ



  1.          Moderate Periodontitis-alveolar crest 3-5mm apical to CEJ.                                                         Radiolucency evident in furcation of posterior teeth.



  1.          Severe Periodontontitis-alveolar crest greater than 5mm apical to CEJ.                                         Radiolucency evident in furcation of posterior teeth. PDL space widened.



XXVII.Radiographic Appearance of Anomolies and Lesions *BOARD ALERT*

  1. Anomalies
  2. Hypodontia-failure of a tooth or teeth to develop
  3. Hyperdontia-Extra teeth formed; supernumerary
  4. Dens in dente-tooth within a tooth
  5. Dilaceration-abormal root curvature
  6. Fusion-two adjacent teeth fuse together; joining of 2 pulp chambers


Credits:  sciencedirect.com

  1. Gemination-single tooth divides into 2 joined “teeth”; a single pulp                                                chamber


Credits:  researchgate.net

  1. Radiolucent Lesions
  2. Periapical pathology-radiolucency at apex
  3. Dentigerous (follicular) cyst-radiolucency at crown of an unerupted tooth


Credits:  directionsindentistry.com

  1. Nonodontogenic cyst-not of tooth origin
  2. incisive canal (nasopalatine) cyst-within incisive canal
  3. globulomaxillary cyst-between maxillary lateral and canine


Credits:  memorangapp.com

  1. Radiopaque Lesions
  2. Periapical ossifications
  3. condensing osteitis-irregular shaped radiolucency near apices of a                                                  non-vital tooth as a result of infection or irritation


Credits:  studyblue.com

  1. osteosclerosis-more regular shape at premolar region not                                                                 associated with infection or irritation; cause is idiopathic


Credits: journal of oral and maxillofacial radiology

  1. Hypercementosis-excessive cementum along root


Credits:  dentistry.osu.edu

  1. Pulp stones-calcification in the dental pulp
  2. Retained root
  3. Resorption
  4. Internal resorption-widening of the pulp chamber
  5. External resorption-resorption of a root
  6. Lucent-Opaque Lesion
  7. Odontoma-abnormal creation of cells and tissues


Credits:  drgstoothpix.com

  1. Other:
  2. Carotoid Stenosis-constriction of the carotid arteries by an accumulation                                        of plaque; may be recorded on panoramic image 45 degrees from angle of                                              mandible towards cervical vertebrae


Credits:  nature.com

  1. Osteoporosis-recorded changes in the width of cortical bone of the inferior                                    border of the mandible


XXVIII.Radiographic Appearance  of Dental Materials *BOARD ALERT*

  1. Metallic
  2. amalgam
  3. post and core


  1. retenion pin


  1. full metal crown vs. porcelin-fused to metal crown


  1. stainless steel crown


  1. Non-metallic
  2. composite
  3. ceramic/porcelain crown


  1. base/cements


  1. gutta percha