LESSON 7 Flashcards by Love Dog

→ the receiver of the image being exposed

→ either film or digital

IMAGE RECEPTORS

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can be intraorally or extraorally placed

IMAGE RECEPTORS

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What are the types of IMAGE RECEPTORS?

Radiographic film

Digital Receptors

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→ direct action or packet film
→ indirect action film used in conjunction with
intensifying screens in a cassette

Radiographic Film

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→ solid-state sensors
→ phosphor plates

Digital Receptors

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refers to the numeric format of the image content & its discreteness

DIGITAL RECEPTORS

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(2) types of direct digital image receptors available

o Solid-State

o Photostimulable Phosphor Storage Plates

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uses of DIGITAL RECEPTORS in Intraoral

periapical and bitewing

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uses of DIGITAL RECEPTORS in Extraoral

panoramic and skull

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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

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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

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These are under of DIGITAL RECEPTORS in?

INTRAORAL

EXTRAORAL

SOLID-STATE SENSORS

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small, thin, flat, rigid rectangular boxes, usually black & similar in size to intraoral film packets

INTRAORAL

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→ 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

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not autoclavable and need to be covered with a protective plastic barrier envelope for infection control purposes

INTRAORAL

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CCD

charge-coupled device

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complementary metal oxide semiconductors

CMOS

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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)

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→ 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)

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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)

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→ 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)

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→ contain CCDs in long, thin, and linear arrays
→ the CCD array is incorporated into (2) different designs of
sensor

EXTRAORAL

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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

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→ 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

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→ 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

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

→ 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%