Radiology Flashcards
Ionization
Process by which an atom gains or loses an electron to become charged
Particulate Radiation
involves particles that have a mass and travel in a straight line at high speed
cannot reach the speed of light
may have a charge
Electromagnetic Radiation
electric and magnetic fields of energy that move through space in waves
only high energy waves have ionizing capacity
travels at the speed of light and has no mass or charge
ie. x-rays
Wavelength
Distance between peaks of one wave to another
Measures energy of the radiation
longer wavelength = low frequency = low energy
shorter wavelength = high frequency = high energy
Transformer
Regulates energy in a circuit
can be step-up or step-down or autotransformer
Ampere
Number of electrons flowing
measured in miliamperage
Quantity of the beam
Increases density
Voltage
force that moves electrons
measured in kVp (peak voltage of an alternating current)
determines speed and penetrating power
Quality of the beam
increases density
Cathode
NEGATIVE CHARGE
controlled by mA
tungsten filament: emits e- when heated
molybdenum cup: focuses e- in a narrow beam pointed at anode
Anode
POSITIVE CHARGE
controlled by kVp
- Tungsten target: spot where e- hit to produce xrays
- Focal spot: x-rays from cathode are directed here
- Copper stem: dissipate excess heat
Which way do x-rays flow?
Cathode to Anode
(dont PANIC)
Positive anode, negative cathode
Tube Head
Contains transformers and insulating oil
Position-Indicating Device
(PID)
lined with a metal layer to direct x-ray beam
Primary Radiation
Photos directed at target
Secondary Radiation
AKA Scatter radiation
Radiation reflecting off object
Compton Scatter
Most x-ray interactions with matter
Ionization occurs
A photon interacts with an outer shell e-
Photon loses e-
Photoelectric Effect
about ⅓rd of interactions
photon interacts with inner shell e-
ionization occurs
photon is absorbed and e- is ejected
Coherent Scatter
8% of x-ray interactions
photons interact with an outer shell e-, matter is not altered
photons continue to travel with no loss of energy
ionization DOES NOT occur
Standard vs SI Units
MEASUREMENT OLD UNITS SI UNITS
Exposure in air Roentgen Coulomb/Kg
Absorbed dose Rad Gray (Gr)
Dose equivalent Rem Sievert (Sv)
*1 Sv = 100 rem
1 Gy = 100 rad
Direct Theory
- radiation damages the protein, lipid, carbohydrate, and DNA molecule of a cell and causes cell death
- Accounts for ⅓rd of biological damage
Indirect Theory
- Radiation interacts with water in cells and produces free radicals (H and OH)
- these free radicals are very unstable and can bond to form toxic compounds (H2O2)
- Accounts for ⅔rds of radiation damage
Somatic vs Genetic Effect
Somatic effect occurs when somatic (non-sex cells) are harmed by radiation
Genetic effect occurs when sex-cells are harmed by radiation, affecting future offspring
Stochastic Effect
Probability of occurrence increases with dose but severity is not dependant on dose
Effects are random
Non-Stochastic Effect
AKA Deterministic effect
severity of damage depends on the dose
predictable effects
Inherent Filtration
glass tube
oil
0.5-2mm aluminum
Added Filtration
depends on kVp used
>70kVp =2.5mm of aluminum
<70kVp=1.5mm of aluminum
Collimation
Metal barrier with an aperture that restricts the size and shape of x-ray beam
Rectangular collimation exposes 60% less than a round PID
Fast Film
F-Speed film produces 60% less radiation exposure
Digital receptors are about twice as fast as E-speed film
faster film has larger silver halide crystals which may lower the quality of the image
Intensifying Screens
Screens coated in phosphors
phosphors convert photon energy into visible light photons
ALARA
As Low As Reasonably Achievable
exposure should be kept to a minimum and radiographs should be prescribed as needed on an individual basis
Dosimeter
film badge that measures exposure to radiation. Worn at waist level
Maximum Permissible Dose
(MPD)
dose of radiation NOT expected to produce any significant radiation effects
MPD for an occupational person: 5rem/year or 50mSv/year
MPD for a non-occupational person: 10% less than above (0.5rem/year or 5mSv/year)
Maximum Accumulated Dose = 5rem x N - 18, where N=age
Inverse Square Law
the intensity of a beam at any given point is inversely proportional to the square of the distance of the source
*invert the squared number only if the source is farther
eg. 2x farther; the beam is ¼x as intense
3x closer; the beam is 9x as intense
Density
Darkness of an xray
proportional to exposure time, mA, and kVp
NOTE: time and mA are inversely related
ie. if time is increased, mA must be decreased and vice versa
Contrast
difference between lighter and darker shades of grey on a radiograph
dependant on kVp
high/low scale contrast: black and white
low/high scale contrast: many shades of grey
best for detecting caries
Sharpness
&
Penumbra
Sharpness can be increased when focal spot is small and object to receptor distance is short
Penumbra: blurred structures on a radiograph
Fix the error:
Overlap
change horizontal angulation
Fix the error:
Elongation
caused by underangulation
therefore increase the angulation
Fix the error:
Foreshortening
caused by overangulation
therefore decrease the angulation
Bisecting Technique
film is placed as close to the teeth as possible
central ray is directed perpendicular to an imaginary plane that bisects the angle between the film and teeth
Paralleling Technique
Film is parallel to long axis of tooth,
central ray is directed perpendicular to film
Occlusal Radiographic Technique
Mandibular: negative 55° vertical angulation, central rays directed through chin
Maxillary: positive 65° vertical angulation, central rays directed through tip of nose
SLOB Rule
Same Lingual Opposite Buccal
2 images compared
Tube head and object moved in the same direction ⇒ object is located lingually
Tube head and object moved in the opposite direction ⇒ object is located buccally
Identify the Error
Patients chin is tipped up too high
Identify the Error
Patients chin is tipped too low
Identify the Error
Patients tongue isnt at roof of mouth
Identify the Error
Patient is too far forward
Identify the Errors (2)
- Patients back is hunched
- Patient is too far back
Identify the Error
Lead apron artifact
Processing Film:
Developing (4 parts)
5 minutes at 68°F
- Reducing Agent: hydroquinone or elon - reduces exposed silver halide crystals into black metallic silver
- Alkalizer: sodium carbonate - softens film emulsion and speeds up action
- Restrainer: potassium bromide - inhibits development of unexposed silver halide crystals
- Preservative: sodium sulfite - a preservative that prevents oxidation
Processing Film:
Rinsing
Dilutes the developer and slows development process
removes alkali activator
30 seconds in running water
Processing Film:
Fixing (4)
10 minutes OR twice developing time
- Fixing agent: sodium thiosulfate - clears unexposed silver halide crystals
- Hardener: potassium alum - shrinks and hardens emulsions
- Acidifier: acetic acid - keeps medium acidic and stops additional development
- Preservative: sodium sulfite - prevents oxidation
Processing Films:
Washing
Wash in running water for 10 mins and set to dry
Ensures removal of thiosulfate ions
Automatic Processing
Developer, fixer, water, drying chamber
Developing solution works at higher temperatures more rapidly
Processing Errors:
Film Too Dark
Too much development time
Temperature too high
Processing Errors:
Film Too Light
Not enough development solution
Temperature too low
Exhausted developer solution
Processing Errors:
Cracked Emulsion
Sudden temperature change between developer and fixer
Processing Errors:
Darker Areas
Developer solution touches film before processing procedure
Processing Errors:
Lighter Areas
Fixing solution touches film before processing procedure
Processing Errors:
Yellow/Brown Stains
exhausted solutions
insufficient washing
Processing Errors:
Straight White Boarders
developer cutoff caused by incomplete immersion in developer
Processing Errors:
Straight Black Boarder
fixer cutoff caused by incomplete immersion in fixer
Processing Errors:
Outline of Another Film
Films stuck together in solutions
Processing Errors:
White Spots
air bubbles trapped during processing
Processing Errors:
Thin, Black, Branchlike Lines
static caused by opening film too quickly and low humidity
Processing Errors:
Fogged Film
improper safelight
light leaking into darkroom
outdated film
Incisive Foramen
Nasal Septum
Nasal Spine
Maxillary Sinus
Inverted Y
Nutrient Canals
Mental Ridge
Coronoid Process
Maxillary Tuberosity
Lingual Foramen
Zygomatic Process
Mandibular Canal
External Oblique Ridge
Restoration Type?
Amalgam Restoration
Restoration Type?
Gold Crown
Restoration Type?
Retention Pins
Restoration Type?
Gutta Percha
Restoration Type?
Silver Point
Composite Restorations
Restoration Type?
Porcelain Crown
Restoration Type?
Implant
Identify the Pathology
Odontoma
- most common tumor
- tx: curettage
- no recurrence
Identify the Pathology
Ameloblastoma
- most common clinical odontogenic tumor
- Soap-bubble appearance
- Asymptomatic
- 30-70y/o
- tx: enucleation and curettage; high recurrence after curettage only
- Can metastasize and become lethal
Identify the Pathology
Cemento-osseous Dysplasia
- periapical, anterior mandible
- asymptomatic
- may be confused with simple bone cyst
Identify the Pathology
Condensing Osteitis
- AKA focal sclerosis
- widening of PDL
- tx: ext or endo therapy
Identify the Pathology
Pagets Disease
- abnormal resorption and deposition of bone
- idiopathic
- “cotton wool” radiograph appearance
- tx: suppression of bone resorption and deposition (bisphosphonates)
Identify the Pathology
Radicular Cyst/ Periapical Cyst
- NON-VITAL tooth
- tx: RCT, apicoectomy, EXT with curettage
Identify the Pathology
Dentigerous Cyst
- around the crown of an impacted tooth
Identify the Pathology
Odontogenic Keratocyst
- *highest recurrence rate
- arises from dental lamina
- 60-80% of cases on mandibular
- tx: enucleation or curettage
Identify the Pathology
Lateral Periodontal Cyst
- well-circumscribed
- Asymptomatic
- 75-80% in mand
- recurrence is unusual
- lateral to roots of vital teeth
- tx: enucleation
Identify the Pathology
Globulomaxillary Cyst
- fusion of medial nasal process with maxillary process
- epithelium becomes trapped during fusion
- between max cuspid and incisor
- inverted pear shape
Identify the Pathology
Nasopalatine Duct Cyst
- heart shape
- most common non-odontogenic cyst of oral cavity*
- anterior midline of maxilla
- symptoms include swelling and pain, may be asymptomatic
- tx: surgical enucleation with biopsy (not diagnosed radiographically)
- Recurrence is rare
