LESSON 7 Flashcards
→ the receiver of the image being exposed
→ either film or digital
IMAGE RECEPTORS
can be intraorally or extraorally placed
IMAGE RECEPTORS
What are the types of IMAGE RECEPTORS?
Radiographic film
Digital Receptors
→ direct action or packet film
→ indirect action film used in conjunction with
intensifying screens in a cassette
Radiographic Film
→ solid-state sensors
→ phosphor plates
Digital Receptors
refers to the numeric format of the image content & its discreteness
DIGITAL RECEPTORS
(2) types of direct digital image receptors available
o Solid-State
o Photostimulable Phosphor Storage Plates
uses of DIGITAL RECEPTORS in Intraoral
periapical and bitewing
uses of DIGITAL RECEPTORS in Extraoral
panoramic and skull
advantages of what?
o eliminates chemical processing
o digital intraoral receptors require less radiation than film,
thus reducing patient exposure
o allows enhancements, measurements, and corrections not
available with film
DIGITAL RECEPTORS
disadvantages of what?
o the initial expense of setting up a digital imaging system is relatively high
o certain components are susceptible to rough handling and are costly to replace
o there is a risk of systems becoming obsolete or manufacturers going out of business
o the excellent image quality and comparatively low cost of a properly exposed & processed film keeps film-based radiography competitive with digital alternatives
DIGITAL RECEPTORS
These are under of DIGITAL RECEPTORS in?
INTRAORAL
EXTRAORAL
SOLID-STATE SENSORS
small, thin, flat, rigid rectangular boxes, usually black & similar in size to intraoral film packets
INTRAORAL
→ vary in thickness from about 5-7 mm
→ cabled to allow data to be transferred directly from mouth to
computer
o cables are usually 1-2 m long
INTRAORAL
not autoclavable and need to be covered with a protective plastic barrier envelope for infection control purposes
INTRAORAL
CCD
charge-coupled device
complementary metal oxide semiconductors
CMOS
individual pixels, consisting of a sandwich of P- and N-type silicon, are arranged in rows and columns called an array or matrix, above which is a scintillation layer
CCD (CHARGE-COUPLED DEVICE)
→ the x-ray photons hit the scintillation layers and are converted to light
→ the light interacts via the photoelectric effect with the silicon to create a charge packet for each individual pixel, which is concentrated by the electrodes
CCD (CHARGE-COUPLED DEVICE)
the charge pattern formed from the individual pixels in the matrix represents the latent image
o the image is read by transferring each row of pixel
charges from one row to the next
CCD (CHARGE-COUPLED DEVICE)
→ different in way that the pixel charges are read
o each CMOS pixel is isolated from its neighbor and directly connected to a transistor
→ less expensive
CMOS (COMPLEMENTARY METAL OXIDE SEMICONDUCTORS)
→ contain CCDs in long, thin, and linear arrays
→ the CCD array is incorporated into (2) different designs of
sensor
EXTRAORAL
o flat cassette-sized sensors designed to be retrofitted into
existing film-based panoramic equipment to replace
conventional cassettes
o individually designed sensors as part of completely new
solely digital panoramic or skull equipment
2 different designs of
sensor in EXTRAORAL
→ consists of a range of imaging plates that can be used for both intraoral and extraoral radiography
→ the plates are not connected to the computer by a cable
PHOTOSTIMULABLE PHOSPHOR STORAGE PLATES
→ once cleared (erased), the plates are reusable
→ intraoral plates need to be inserted into protection barrier
envelopes for control of infection purposes
PHOTOSTIMULABLE PHOSPHOR STORAGE PLATES
-direct action or packet film
-indirect action film used in conjunction with intensifying screens in a cassette
Radiographic Film
-solid-state sensors
-phosphor plates
Digital receptors
refers to the numeric format of the image content & its discreteness
DIGITAL RECEPTORS
there are (2) types of direct digital image receptors available:
o Solid-State
o Photostimulable Phosphor Storage Plates
advantages of DIGITAL RECEPTORS
o eliminates chemical processing
o digital intraoral receptors require less radiation than film,
thus reducing patient exposure
o allows enhancements, measurements, and corrections not available with film
Disadvantages of DIGITAL RECEPTORS
o the initial expense of setting up a digital imaging system is relatively high
o certain components are susceptible to rough handling and are costly to replace
o there is a risk of systems becoming obsolete or manufacturers going out of business
o the excellent image quality and comparatively low cost of a properly exposed & processed film keeps film-based radiography competitive with digital alternatives
small, thin, flat, rigid rectangular boxes, usually black & similar
in size to intraoral film packets
SOLID-STATE SENSORS (INTRAORAL)
vary in thickness from about 5-7 mm
→ not autoclavable and need to be covered with a protective
plastic barrier envelope for infection control purposes
SOLID-STATE SENSORS (INTRAORAL)
cabled to allow data to be transferred directly from mouth to computer
o cables are usually 1-2 m long
SOLID-STATE SENSORS (INTRAORAL)
→ consists of tiny silicon chip-based pixels and their associated electronics encased in a plastic housing
→ the underlying technology involves either of (2) types:
o CCD (charge-coupled device)
o CMOS (complementary metal oxide semiconductors)
SOLID-STATE SENSORS (INTRAORAL)
contain CCDs in long, thin, and linear arrays
SOLID-STATE SENSORS (ExTRAORAL)
the CCD array is incorporated into (2) different designs of
sensor:
o flat cassette-sized sensors designed to be retrofitted into
existing film-based panoramic equipment to replace
conventional cassettes
o individually designed sensors as part of completely new
solely digital panoramic or skull equipment
SOLID-STATE SENSORS (ExTRAORAL)
→ individual pixels, consisting of a sandwich of P- and N-type silicon, are arranged in rows and columns called an array or matrix, above which is a scintillation layer
→ the x-ray photons hit the scintillation layers and are converted to light
CCD (CHARGE-COUPLED DEVICE)
the light interacts via the photoelectric effect with the silicon to create a charge packet for each individual pixel, which is concentrated by the electrodes
CCD (CHARGE-COUPLED DEVICE)
the charge pattern formed from the individual pixels in the matrix represents the latent image
o the image is read by transferring each row of pixel
charges from one row to the next
CCD (CHARGE-COUPLED DEVICE)
→ different in way that the pixel charges are read
o each CMOS pixel is isolated from its neighbor and directly connected to a transistor
→ less expensive
CMOS (COMPLEMENTARY METAL OXIDE SEMICONDUCTORS)
→ consists of a range of imaging plates that can be used for both intraoral and extraoral radiography
PHOTOSTIMULABLE PHOSPHOR STORAGE PLATES
the plates are not connected to the computer by a cable
PHOTOSTIMULABLE PHOSPHOR STORAGE PLATES
→ once cleared (erased), the plates are reusable
→ intraoral plates need to be inserted into protection barrier
envelopes for control of infection purposes
→ as with using film, image production is not instantaneous with this
type of receptor
PHOTOSTIMULABLE PHOSPHOR STORAGE PLATES
→ intraoral film
→ sensitive primarily to x-ray photons; x-ray directly acts on the film
DIRECT-ACTION FILM
→ no screen is used to develop the image
→ used for the need of excellent image quality and fine
anatomical details are very important
DIRECT-ACTION FILM
TYPES of DIRECT-ACTION FILM
PERIAPICAL
BITEWING FILM
OCCLUSAL FILM
→ used to record the coronal portions of the maxillary and mandibular teeth in one image
→ useful for the detection of interproximal caries
PERIAPICAL
BITEWING FILM
OCCLUSAL FILM
BITEWING FILM
→ alveolar crests are visible which is valuable in the assessment of
periodontal disease
→ have a paper tab projection from the middle of the film on
which the patient bites on to support the film
PERIAPICAL
BITEWING FILM
OCCLUSAL FILM
BITEWING FILM
→ approximately 4 times larger than size 2 film (about 57x76 mm)
→ used to show the larger areas of the maxilla or mandible
→ usually held in position by having the patient bite lightly on the
film to support it between the occlusal surfaces of the teeth
PERIAPICAL
BITEWING FILM
OCCLUSAL FILM
OCCLUSAL FILM
T/F
film packets are typically available in quantities of 25, 100, or 150 films per container
T
made of non-absorbent paper or plastic and is sealed to prevent the ingress of saliva
OUTER FILM PACKET OR WRAPPER
the side of the packet that faces towards the x-ray beam
→ has either a pebbled or a smooth surface and is usually white
Tube Side
usually of two colors so that there is little chance of the film being placed the wrong way round in the patient’s mouth
Label Side
→ usually has a flap to open the film packet
→ the ff. is printed on the ___ side of the film
packet:
o a circle or dot that corresponds with the raised identification dot on the film
o the statement “opposite side toward tube”
o the manufacturer’s name
o the film speed
o the number of films enclosed
Label Side
→ is on either side of the film
→ protects the film from:
o light
o damage by fingers while being unwrapped o saliva that may leak into the film packet
BLACK FILM WRAPPER
placed behind the film to prevent:
o some of the residual radiation that has passed through the
film from continuing on into the patient’s tissues
o scattered secondary radiation, from x-ray photon interactions within the tissues beyond the film, scattering
back on to the film and degrading the image
LEAD FOIL SHEET
contains an embossed (herringbone) pattern so that should the film packet be placed the wrong way round, the pattern will
appear on the resultant radiograph
LEAD FOIL SHEET
→ the image receptor itself
→ also has an identification dot
FILM
Film Base is made of?
polyester plastic (polyethylene terephthalate)
→ 0.2 mm thick
→ acts as a support for the emulsion but
does not contribute to the final image; helps film to withstand heat, moisture, and chemicals in processing
→ transparent with blue tint to enhance image
Film Base
cellulose acetate
Film Base
Adhesive Layer
→ also found on both sides
→ part that is sensitive to radiation
Film Emulsion
consists of:
o Silver Halide Crystals
- 80-99% silver bromide
- 1-10% silver iodide
o Gelatin Binder/Matrix
Film Emulsion
protect emulsion from mechanical and chemical damage
Protective Layer
→ extraoral film
→ used in combination with intensifying screens in a cassette
INDIRECT-ACTION FILM
→ sensitive primarily to light photons, which are emitted by the adjacent intensifying screens
→ respond to shorter exposure of x-rays, enabling a lower dose of radiation to be given to the patient
→ used to examine large areas of skull & jaw
INDIRECT-ACTION FILM
→ sensitive primarily to light photons, which are emitted by the
adjacent intensifying screens
→ respond to shorter exposure of x-rays, enabling a lower dose of
radiation to be given to the patient
→ used to examine large areas of skull & jaw
INDIRECT-ACTION FILM
→ in boxes not packets and must be opened only in a dark room
→ film is separated from each other by pieces of thin paper
FILM PACKAGING
→ same construction as intraoral film; however, silver halide is
sensitive to light not radiation
→ has no identification dot so some form of additional
identification is required (ex.: metal letters, L or R, placed on the outside of the cassette or electronic marking)
FILM PACKAGING
Standard Silver Halide Emulsion
Sensitive to:
Blue Light
Modified Silver Halide Emulsion with Ultraviolet Sensitizers
Sensitive to:
Ultraviolet Light
Orthochromatic Emulsion
Sensitive to:
Green Light
Panchromatic Emulsion
Sensitive to:
Red Light
consist of fluorescent phosphors which emit light when excited by x-rays, embedded in a plastic matrix
INTENSIFYING SCREENS
→ hold the film
→ can be sturdy or soft
CASSETTES
→ film used for making a copy of an already exposed film → needs a unit/machine
DUPLICATING FILM
→ one side is dull while the other is smooth/shiny
o the dull side is the emulsion side and is what contacts the radiograph during the duplication process
DUPLICATING FILM
optimum temperature:
50-70 F
optimum relative humidity:
30-50%
