DANB Radiology Exam – Flashcards
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What is the base of dental film composed of?
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blue tinted polyester acetate
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What is the emulsion composed of?
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gelatin and silver halide crystals
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What determines the speed of dental films?
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size of crystals, thickness of emulsion, radiosensitive dyes
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What is the purpose of the lead foil?
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absorb scatter radiation and prevent fogging
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How does film speed correlate with definition and detail?
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faster film = lower definition and detail
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What speed films are most commonly used?
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D, E, F
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size film used for PA's on small children
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#0
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size film used for BW on adults when only one film is taken on each side
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#3
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size film used for anterior PA's for patients with narrow arches
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#1
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size film used for PA's on adults
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#2
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size film used for BW on adults
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#2
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size film used for occlusals on adults
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#4
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What is the purpose of the embossed dot
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to distinguish b/w patient's right and left side
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What is the latent image
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invisible image (remains like this until film is processed)
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What happens in the developer
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reduces the exposed silver halide crystals to black metallic silver
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What happens in the fixer
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removes the unexposed silver halide crystals
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how long does film stay in the developer
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5 min
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how long are films fixed
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10 min (dbl the development time)
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how long does the first rinse last
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20 seconds
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how long is the final rinse
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20 min
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what is the optimum processing temp.
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68 degrees F
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when can the films be exposed to white light
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after 2-3 min of fixing if needed
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what causes film fogging
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-old or contaminated processing solutions -exposure to chemical fumes -faulty safelight -scatter radiation
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what would cause a film to be too light
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-underexposure -underdevelopment -depleted developer solution -excessive fixation (takes all crystals off)
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what would cause a film to be too dark
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-overexposure -overdevelopment -developer is too strong -not enough fixation -exposure to white light -improper safelighting
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What causes a HERRINGBONE effect
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film placed backwards
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what would happen to a film that is placed in the fixer prior to development
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blank or clear (takes all of the crystals off)
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what is reticulation
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cracking of the emulsion caused by excessive temp diff. b/w any darkroom solutions
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how would a film appear if submerged totally in the developer but not in the fixer
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top of film delineated by a straight line then dark
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film submerged totally in fixer but not in developer
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part that was fixed but not developed would be clear
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what size bulb is used in safelight
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7 1/2 or 15 watt
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what type of safelight filter is acceptable
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GBX - 2
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how far from the work surface must the safelight be mounted
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4 feet
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diff. b/w direct and indirect exposure sensor?
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direct - directly obtaining a digital image by exposing intraoral sensor to x-rays to provide an image that can be viewed on a computer indirect - photostimuable phosphor plate sensor technology, obtaining a digital image in which an exposed phosphor plate is placed into a scanner and then converted into a digital image
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what film is used to diagnose interproximal decay
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BW
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what projection would you take for a patient complaining of pain in the lower left molar area
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left molar PA
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what is the purpose of a pano
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image the entire dentition, surrounding alveolar bone, sinuses, and the TMJ, examine large area of face and jaws, locate impacted teeth, retain root tips, evaluate trauma, lesions, and diseases, and assess growth and development
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what causes foreshortening
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excessive vertical angulation
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what causes elongation
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insufficient vertical angulation
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what causes overlapping
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incorrect horrizontal angulation
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what causes conecut
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not centered on sensor
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what causes clear film
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no exposure, or fixer before developer
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what causes missing crowns
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excessive vertical angulation
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what causes missing apices
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insufficient vertical angulation
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when mounting a film the dot is convex, on what side of the mouth would you find #32?
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left side
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how do you differentiate b/w max and mand molar when mounting
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- max molars have 3 roots, mand have 2 roots
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what size film is 7/8 x 1 3/8
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No. 0
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what size film is 15/16 x 1 9/16
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No. 1
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what size film is 1 1/4 x 1 5/8
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No. 2
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what size film is 1 1/16 x 2 1/8
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No. 3
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what size film is 2 1/4 x 3
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No. 4
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Explain PSP
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-Photostimuable Phosphor Plate aka storage phosphor system -indirect digital imaging -captures analog data then processed in a laser scanning device -light is then converted into electrical signal that the computer uses to create the digital image
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how does exposure time differ b/w adults and children
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cut exposure time by 1/3
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what type of projection is used to visualize the crestol alveolar bone on a patient with moderate to severe bone loss
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vertical BW
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max. centrals anatomy
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-nasal septum, ant. nasal spine, nasal fossa, median palatine suture, incisive foramen
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max lat. canine anatomy
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nasal fossa, max sinus
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max premolar anatomy
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max. sinus, zygoma
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max molar anatomy
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max sinus, zygoma, max tuberosity, coranoid process
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mand central anatomy
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genial tubercles, lingual foramen
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mand lateral/canine anatomy
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tori
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mand premolar anatomy
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mental foramen, mental ridge, mand canal
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mand molar anatomy
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mand canal, external oblique ridge, beg. of ramus
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what would cause increased magnification, decreased resolution and edge sharpness
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increased focal spot size, decrease source-object distance, & increased object-film distance
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according the principles of shadow casting, preferred object-film distance
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as close as possible
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according to principles of shadow casting, preferred source-object distance
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as far as practical
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according to principles of shadow casting, how should the film be placed in relation to the tooth?
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parallel
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according to principles of shadow casting, how should the central beam be directed
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perpendicular to the tooth and film
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what periapical technique offers the best diagnostic quality?
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paralleling; meets more principles of shadow casting
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what is penumbra
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shadow around the tooth
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how is vertical angulation established with the bisecting technique
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beam is perpendicular to the imaginary line that bisects the angle formed by the long axis and the film
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how is vertical angulation established with the paralleling technique
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perpendicular to the film, parallel to the bite portion of the stabe
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how does packet placement differ b/w bisecting and paralleling
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-bisecting - packet is as close to tooth as possible, but not parallel -parallel - packet is parallel to tooth, further away
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what is the proper patient position for BW's?
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ala-tragus line is parallel to the floor
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proper patient positioning for bisecting
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max arch ala-tragus parallel to floor mand arch
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proper patient positiong for paralleling
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doesn't matter
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what is the best method of reducing radiation to the patient
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rectangular collimation and fast film speed
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how far should the operator stand from the source of radiation
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6 ft
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what is the primary beam
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original, undeflected, useful beam
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what is done to the primary beam to make is useful
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filtration and collimation
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what is the purpose of collimation
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reduce size and shape of beam
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what is the collimator made out of
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lead
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what is the purpose of filtration
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absorb long wavelengths / soft radiation
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what are filters made out of
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aluminum
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what is inherent filtration
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produced by internal barriers in tube head (ex: glass and insulating oils)
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what is added filtration
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filters placed in PID after tubehead production
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how much total filtration is required of x-ray machines that operate lower than 70 kVp
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1.5 mm
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total filtration required of x-ray machines that operate above 70 kVp
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2.5 mm
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what is the source-skin distance of x-ray machine that operates at 75 kVp
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8-16 inches
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what is the maximum size of the x-ray beam at the patients face
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2.75 inches
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desired thickness of lead apron
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.25 mm
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how should the frequency of radiographic exposures be determined
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depends on the needs of the patient, established after intraoral exam
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how often are BW taken on children with high risk
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every 6 mths
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how does the reproductive capacity of a cell correlate with radiosensitivity
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rapidly producing cells are more sensitive to radiation
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what 3 types of cells are most radiosensitive
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WBC, RBC, immature reproductive cells
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what 3 types of cells are most radioresistant
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nerve, brain, muscle
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what types of cells must be effected in order for mutation to occur
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genetic cells
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what are the 2 units used to measure exposure to radiation
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coulombs/kilogram(C/kg) & Roentgen (R)
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what 2 unites are used to measure absorption
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gray & Rad
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what 2 unites are used to measure biologic effect and dose equivalent
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Sv & Rem
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what is the annual MPD for radiation workers
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50 mSv or 5 REM
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what is the annual MPD for pregnant dental assistant
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5 mSv or .5 REM 1/10th dosage of gen. public
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what are photons
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quantum of energy
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what part of the x-ray machine is responsible for providing the electrons
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filament
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how are x-rays formed in the tubehead
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-turn on machine -adjust settings -press exposure button -filament heats up/thermoionic emmision -electron cloud is formed -electrons flow from cathode to anode -electrons strike target -energy is converted into x-rays and heat
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what part of the x-ray machine helps remove heat
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copper stem, radiator and air space
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what is formed when high speed electrons strike the target
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x-ray and heat
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list the properties of x-rays
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-invisible -travel in straight lines -no mass/weight -travel and speed of light -no charge -interact w/ matter causing ionization -can penetrate opaque tissues and structures -can effect photographic film emulsion -can effect biologic tissue
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what looking at a PANO what causes a big smile
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chin down
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how should x-ray film be stored
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-original packaging -area sheilded from radiation -50-70 degrees F
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what are occlusal radiographs used to diagnose
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-locate retained roots -locate unerrupted or impacted teeth -evaluate for diseases and lesions -locate foreign bodies -reveal presence of salivary stones (sialothiths) -aid in evaluating fractures -size and shape of tori -aid in examining patients with trismus (patient can only open mouth a few mm) -evaluate borders of sinus -examine cleft palates -substitute for PA's for young children or patient who can't tolerate
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how often should developing solutions be changed
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every 4 weeks
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how does exposure time for edentulous patients compare to dentulous patients
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1/5 exposure time for edentulous
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how does exposure time for children compare to that of an adult
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1/3-1/2
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what is scatter radiation
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x-rays that have been deflected from an object and have changed paths
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what is secondary radiation
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x-rays that have gone thru an object and are now a newer weaker beam
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what equation is used to calculate the accumulated MPD
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5(n-18)
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what is the term to describe the overall blackness of a radiograph
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density
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what control factors effect the density of a radiograph
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mA & time
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what control factors effect contrast
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kVp
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if the kVp is increased from 75-90, what must be done to achieve a radiograph of comparible density
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-decrease mA & time
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if the source-object distance is cut from 16 to 8 , what must be changed to compensate
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method should be compensated for bisecting or paralleling
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You take a radiograph using 10 mA 30 impulses and 90 kVp, your dentist wants a radiograph with increased contrast and equal density. What settings would you use?
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decrease kVp by 15 and double exposure time 10 mA 60 impules 75 kVp
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which projection is used to view sinuses
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PANO
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what is the earliest sign of radiation exposure
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erythema
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which anatomical structures appear radiolucent
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soft tissue, air space
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which anatomical structures appear radiopaque
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dentin, enamel, bone
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what is the latent period
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time b/w exposure and 1st clinically observable symptoms
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who discovered x-rays
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Roentgen
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what are the short term effects of radiation exposure
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erythema, vomitting, nausea, hemorrage, diarrhea, hair loss
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what are the long term effects of radiation exposure
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cancer, cateracts, embryologic defects, genetic mutations, low birth weight
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what exposure is taken to determine jaw relationships in ortho treatment planning
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lateral cephalometric
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what is the purpose of taking radiographs of an edentulous patient
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-detect pathological lesions -establish position of mental foramen -establish position of mand canal -determine quality & quantity of alveolar bone present
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what exposure would be useful in identifying salivary stones in the submandibular gland
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mand occlusal
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what device is used to check quality of processing chemicals
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step-wedge or test film
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what NC agency is resposible for monitoring dental x-ray equipment
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DEHNR
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what are common sources of background radiation
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cosmic , naturally occuring radiation from earth, radiation for radioactive materials
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how are indirect exposure films exposed
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x-rays hit phosphor screen creating florescent light that exposes the film
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3 film holding devices used for paralleling
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dentsply rinn, XCP, XCP-DS, flow dental RAPD
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3 film holding devices used for bisecting
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dentsply rinn stabe, BAI, dental SUPA
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what is the ADA approved method of mounting dental radiographs
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labial
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what is the bremsstrahlung radiation
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aka general radiation; stopping or slowing of the electrons of the cathode stream as they collide with the nuclei of the target atoms
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what is characteristic radiation
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a form of radiation originating from an atom following removal of an electron or excitation of an atom
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what is the major diff. b/w particulate and electromagnetic radiation
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-particulate radiation: made of protons, neutrons, electrons and alpha and beta particles; has mass -electromagnetic radiation: made of photons; no mass
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which radiographic technique records the most accurate image of crowns, roots, and supporting structures in a selected area?
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periapical examination, paralleling technique
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A patient complains of pain in the upper molar region. What radiographic exposure should be made?
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periapical
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What type of x-rays have greater penetrating power, long or short wavelength?
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short
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in the darkroom, you unwrap a film and place a coin on top of the film for several minutes. when you process the film, you notice a slight, well-defined white circle on the film. what does this mean?
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failed safelight test, suggesting that the safelight conditions in the darkroom are fogging the film
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what would cause a properly exposed film to appear dark?
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-overdevelopment -temp. too high -time too long -developer concentration too high -inadequate fixation -accidental exposure to light -improper safelighting
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what are automatic processors faster than manual processing?
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b/c of its stability to produce a large volume of radiographs in a short amount of time
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when looking at radiographs that were taken several years ago, you notice a brownish stain which makes interpretation difficult. what caused this?
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insufficient or improper washing
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what is thermionic emission
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release of electrons when a material such as tungsten is heated to incandescence. electrons are boiled off from the cathode filament in the x-ray tube when electric current is passed through it
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what parts of the x-ray machine are included in the anode circuit
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copper stem tungsten target radiator
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what parts of the x-ray machine are included in the cathode circuit
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cathode filament focusing cup
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what factors would decrease edge sharpness and increase magnification
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far object-image receptor distance
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you process a set of BW's in the automatic processor. three of the BW's are of good quality, but fourth is completely blank. what probably caused this?
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no exposure to x-rays, electrical failure, malfunction of x-ray machine, or processing errors
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what looking at manually processed films, you notice small black spots on the films. what caused those spots?
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premature contact w/ developing chemicals. drops of developer or fixer that splash onto the work area and came in contact with the film.
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when mounting a FMS, you notice that one film is blank. another film is dark, the teeth look strange, and it is difficult to determine what film it is. what do you think happened?
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dark film is from over exposure and improper packet placement for strange looking teeth and not being able to determine what film is
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your dentist asks you to take a FMS on a 65 yr old edentulous patient. how many exposures will you take? which exposures are not necessary? what intraoral technique will you use? what might be better than a FMS?
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-take 14 radiographs -omit the BW -paralleling should be technique of choice -panoramic might be better than FMS
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when viewing a periapical radiograph, you notice that the image of the tooth is extremely long and well defined; however the apices are missing. what technique was used to take the radiograph? what caused the roots to appear long?
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-bisecting was used b/c of the distortion of the elongated root -the roots appeared long b/c the vertical angulation was inadequate
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with what type film are intensifying screens used?
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-extraoral film
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what type of film are rare earth screens paired with
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green light sensitive film (Kodak T-Mat)
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what type of film are calcium tungstate screens paired with
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blue light sensitive films
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how does resolutiong and detial of a panoramic radiograph compare with that of PA's and BW's
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not as sharp and detailed as the intraoral image
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what must a patient remove before taking a PANO
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oral piercings, earings, glasses, necklaces, facial piercings, hair pins, hearing aids, dentures, and retainers
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when mounting dental radiographs, what is the best way to differentiate max and mand films?
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-max teeth are longer -max molars have 3 roots, mand molars have 2 roots -most roots curve toward the distal -occlusal plane is straight or curved slight towards distal
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when interpreting radiographs, you notice a radiopaque extension or spur off the proximal surface of #30. what do you think this is?
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the mental ridge
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in which area of the tooth is interproximal caries often seen
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located on the tooth surface that contacts the adjacent tooth
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what type PID significantly reduces exposure to the patient
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rectangular collimations
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when using D speed film, you use 50 impulses of radiation. how many impulses would you use with E speed film?
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25
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what is a large dose of radiation given over a short period of time
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short-term dose
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what is small doses of radiation given over a long period of time
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long-term dose
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which dose of radiation is more biologically damaging
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chronic low-level exposures/long term dose; causing cancer, cataracts, low birth weight, genetic mutations, and embryological defects
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what is the name for the part of the target that is struck by electrons
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focal spot
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when manually processing dental film, you notice the temp. has gotten warmer as the day progressed. how should the developing time be changed?
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higher temp. increases film fog, so radiographer should consult a time-temp. development chart to adjust developing time appropriately; developing time will decrease
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what is the best method of protecting the thyroid gland from radiation?
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thyroid collar, lead and lead-equivalent sprons are availaable with or without an attached thyroid collar
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when should radiographs be taken on a pregnant patient
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only when necessary to help the dentist diagnose and treat oral diseases; elective xrays should be postponed until after delivery
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what is the most important step in panoramic radiography
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patient positioning
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what is the area of the skull that is in focus on a pano
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patient's dental arches; maxilla and mandile
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what quality control procedures should be performed on xray cassettes
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periodically examining cassettes and intensifying screens; extra oral cassettes should be checked for warping and light leaks
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an insurance company requests a patient's radiographs when examining a dental clain. you only have one copy of the radiographs. what should you do
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duplicate, which will go to the insurance comp.; office keeps best copy
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when duplicating radiographs, what side of the duplicating film is in contact with the radiograph to be duplicated
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the emulsion side of the film is placed against the orginal radiograph with the nonemulsion side up
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when viewing a duplicated radiograph, you notice that the duplicate is too dark. what should you do to duplicating time to lighten the film
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increase the exposure time
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what type of angulation is used when taking radiographs of the mand. arch
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negative
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what does alara stand for
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as low as reasonably achievable
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your dentist recommends that a patient have xrays taken, bu the patient refuses. what should be done
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document patient's refusal and have them sign
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what can be done to minimize gagging when taking radiographs
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do not suggest gagging, emphasize, use power of suggestions, apply distractiong techniques, give patient breathing instructions, reduce tactile stimuli, being exposures in the ant. region, place image receptor firmly and expertly, confuse the senses, utilize special products; substitute extraoral as needed
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what is the most commonly used personnel monitoring devide for dental offices
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film badges
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what info should be recorded on the dental radiographic mount
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patient's name, date, and other pertinent info
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when viewing a radiograph, the tooth looks normal in size and shape; however, there is a large blank space at the incisal edge and the apices are missing. what caused this error
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large blank space is due to reversed image error or chemical contamination missing apices is due to inadequate VA
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what causes teeth to appear very short and distorted
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excessive VA w/ PID positioned too steep enough away from zero degrees
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what is the x-ray at the center of the primary beam called
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central ray
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what type film is faster, intraoral or extraoral
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extra oral
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how are stabe film holders sterilized b/w uses
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sterilize film holder devices or discard disposable image receptor holding devices
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what PPE should be worn when exposing radiographs
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eyewear, mask, and gown
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when taking a paralleling radiograph of a patient with palatal tori, where is the film places
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on the back side of the tori
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what controls the speed with which the electrons travel from the cathode to the anode
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kVp
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what would cause the radiographic image to be blurred
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movement caused by the patient, slippage of the image receptor, or vibration of the tube head
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what can be done to increase the life span of processing solutions
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reg. replenishment and changing out expired solutiong with fresh chemicals at reg. intervals; monitor strength of chemicals on a daily basis
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what can be done to prevent air bubbles from being trapped on the surface of films during manual processing
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gently agitating the hanger up and down a few times
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how does radiation effect cells
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ionization
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what must be done to xray fixer priod to disposal
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remove silver
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you notice that the xrays you process are becoming successively lighter than the quality control film you compare it to. what should you do
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check the processing chemical, particularly the developer
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what radiographs are used to locate a salivary stone in the submandibular duct
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mandibular occlusal
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what radiographs are used to determine if a foreign object is located facially or lingually
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occlusal
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you notice on a PANO that the ant. teeth appear narrow and out of focus. what caused this
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patient positioned too far foward in the focal trough
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what is used to clean the screens inside of a cassestte
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soft cloth, non abrasive cleaner
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how many impulses are in .25 seconds
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15 impulses
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using a 16 inch cone focal-film distance, the diameter of the beam measured at the patient's face should be no larger than
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2.75 inch
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how does kVp affect patient exposure
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higher kVp = low exposure
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when taking a radiograph, you pull the end of the PID away from the patients face about 6 inches. how will this affect the radiographic image and patient exposure
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lighter image, patient exposed to larger beam which will increase exposure
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what factors affect the sharpness of the radiographic image
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focal spot size, target-image receptor distance, object-image receptor distance, motion, screen thickness, screen-film contact, and crystal/pixel size of intraoral image receptors
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what is the most likely cause of a film with very poor definition
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patient movement
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what anatomical structures appear radiopaque on a dental radiograph
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enamel, dentin, and bone
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what anatomical structures appear radiolucent on a dental radiograph
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air space and soft tissues
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what is the max. permissable fose for radiation workers in systeme interventional units
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50 mSv (5rem)
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what should be done prior to ordering radiographs for a patient
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clinical exam
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what is the main source of radiation exposure to the operator
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scatter/secondary radition
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after processing exposed dental film, you notice dark spots on the film. what caused this
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premature contact with developer
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what type lead apron should be used when taking PANO radiographs
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panoramic cape
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in which pericapical projection will the mental ridge be visible
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mandibular lateral/central
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on a mandibular molar PA , where is the mylohoid ridge located
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highest of the 2 ridges, about the level of the cervical 3rd, behind the 2nd and 3rd molars
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when taking a PANO radiograph, the patient is placed too far into the machine. how will the radiograph appear
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all of the ant. teeth will appear blurred and narrowed in width
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when viewing a PANO, you notice that the right TMJ is magnified, bu the left TMJ is normal. what caused this error
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patient positioned too far to the left
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when viewing a PANO, you notice that a lot of spine shows on both side of the film, what caused this
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positioning the arches too far foward
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which anatomic feature is visible on a PANO, bu not on a PA
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mand. foramen
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how can you differentiate the zygoma from the max sinus in a max posterior PA
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zygoma will be radiopaque, max. sinus will be a large area of radiolucency
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you notice that a radiograph taken several months ago is brown and spotted. what happened
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insufficient or improper washing
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a properly exposed film appears completely black. when was is exposed to white light
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before fixing
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when processing, two films overlap in the developer, but not in the fixer. how would the films appear
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clear/blue in the area of overlap b/c fixer will not remove all crystals
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you process four BW films. three of the films appear normal, but one is clear. what happened
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didn't push button completely
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what is the best way to reduce exposure to patient
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rectangular collimation
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when taking a radiograph, you pulls the cone out about 6 inches from the patient's face. what is the result
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increase the area of radiation exposure
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how does reducing exposure to the patient benefit the operator
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the less the patient is exposed, the less the operator is exposed
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how can exposure to the operator be reduced
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move farther from the radiation
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what film would be used to locate a foreign body in the bucco-lingual relationship
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occlucal
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what is the major use of cross sectional occlusal radiograph
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provides more info. about the location of tori, impacted and malpositioned teeth and the calcification of soft tissues
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what is the major use of topographical occlusal radiographs
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images conditions of the teeth and supporting structures when a larger area than a PA is needed; provides more info. than a PA about the alveolar crest and apical areas
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how do you determine how often to take radiographs
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evidence based selection criteria
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how often should an FMS be taken on an adult with no significant medical history
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take FMS on all new patients; recall adults with no sig. med. history only require BW and PA, if indicated
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what are three types of image receptors used in digital radiography
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CCD (direct) CMOS (direct) PSP (indirect)
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list the cells from most sensitive to least sensitive
answer
white blood cells red blood cells immature reproductive cells epithelial cells connective tissue cells bone cells nerve cells brain cells muscle cells
question
when viewing a molar BW, what should be on the distal of the film
answer
the most distal tooth should be captured in full as well as a few mm of bone level behind the most distal tooth
question
your film badge report shows that you have received a small amt. of radiation. what should you do
answer
stop taking xrays and evaluate all equipment and techniques to ensure safety
question
you use an exposure time of 10 impulses. how many seconds is this
answer
1/6th of a second
question
you change you kVp from 90 to 70 and leave all other factors the same. what is the result
answer
the wave length will be shorter, the quality and energy of the beam will be higher and the contrast will be lowe. the image will also have a higher density
question
you change from an 8 inch to an 16 inch focal film distance. how is the intensity of the beam affected
answer
1/4 as intense
question
how often must you replenish the solutions in an automatic processor
answer
for every 30 films processed 6-8 oz should be taken out and replaced with fresh solution
question
what is the purpose of replenishing the developer solution
answer
maintain acidity & alkalinity & prevent oxidation,
question
what size film is used to take an occlusal radiograph of a 6 yr old child
answer
#2
question
what size film is used to take a BW on a 3 yr. old
answer
#0
question
what radiograph is used to show contrast in soft tissues
answer
MRI
question
what size and how is the film places when taking a molar PA in the mixed dentition
answer
#1 or #2 placed so the edge of the receptor lines up behind the distal of the canine before the eruption of the permanent 2nd molar; after the eruption of the perm. 2nd molar, 2 posterior PA's should be taken per quadrant
