Rad 354 chapt 12 screen filmradiography
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RAD 354 Chapt 12 Screen- FilmRadiography. Image forming rays: remnant beam/exit radiation – scattered radiation (partially absorbed/attenuated) and non-interacting. X-ray beam. RAD Film – 2 main parts: emulsion and base.

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RAD 354 Chapt 12 Screen- FilmRadiography

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Rad 354 chapt 12 screen filmradiography

RAD 354 Chapt 12Screen-FilmRadiography

  • Image forming rays: remnant beam/exit radiation – scattered radiation (partially absorbed/attenuated) and non-interacting


X ray beam

X-ray beam


Rad film 2 main parts emulsion and base

RAD Film – 2 main parts: emulsion and base

  • Base: rigid, non-shrinking base to support the emulsion – now made of plyester

  • Emulsion: Silver halide and gelatin. 98% is silver bromide, the rest is usually silver iodide


Latent image

Latent Image

  • Produced when the exit beam (remnant beam) exists the patient and interacts with the emulsion/image receptor

  • Takes place at the sensitivity spec (center) due to liberated charges traveling in the development center (spec or receptor)


Film receptor types

Film/Receptor Types

  • Digital –

    • Computed Radiography (CR) = Photostimulable Phosphor (PSP)

    • Direct Radiography (DR/DDR) = Solid State X-ray Detector (SSXD)

    • Film: Screen, Direct Exposure, Mammo, Laser, Duplication, Spot Film, Subtraction and Cine


Direct exposure

Direct Exposure

  • Non-screen film – sensitive to x-rays

    • Like “bite wings” at the dentist


Screen film sensitive to both light and radiation

Screen Film – sensitive to both light and radiation

  • Comes in a variety of contrast, latitude, spee and light color sensitivity

    • Larger silver halide crystals = faster speed and LESS DETAIL

    • Thick emulsion layer = faster speed and LESS DETAIL

    • Double emulsion layer – faster speed – prone to “CROSSOVER”


Color sensitivity

COLOR SENSITIVITY

  • Spectral matching = matching the color spectrum of light given off by screens to that of the emulsion

    • Calcium Tungstate Crystals (atomic #’s 60/70’s)

    • Rare Earth – AMU’s mainly in the 50’s (57-71)

    • Orthochromatic = green sensitive film

    • Panchromatic = sensitive to all color (photographic film)

    • Laser = sensitive to red light


Other type films

Other type films

  • Mammo/routine films = some mammo is single emulsion and single screen film and some double/double

  • Duplicating film – single emulsion, solaraized film

  • Cine = Dynamic motion (heart caths, etc.) 35mm

  • Spot film camera film = 70mm, 105mm


Darkroom safelights

Darkroom Safelights

  • Filter is spectral matched to filter out the light spectrum the film is SENSITIVE to (wratten 6-B = red safelight filter)

  • Usually 15 watt bulb

  • Should be no closer than 5 feet from work surface (some “feed trays” have a safelight that turns on after the film has progressed into the processor and out when a film begins to enter the processor)


Film storage

Film Storage

  • Boxes to be stored on end – NEVER flat!

  • 68F (20C) best at 50F (1-C) AND low humidity (40% or LESS)

  • Unexposed film is MUCH less sensitive to light, radiation, chemicals, heat, etc., than EXPOSED FILM!

  • Shelf life – limited (film begins to develop as soon as it is made)


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