Chapter 9Chapter 9

FilmFilm

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Film HoldersFilm Holders

FilmFilm X-ray film consists of a transparent, blue-X-ray film consists of a transparent, blue-

tinted base (cellulose acetate with 3% tinted base (cellulose acetate with 3% nitrocellulose), covered on both sides with an nitrocellulose), covered on both sides with an emulsion composed of gelatin containing emulsion composed of gelatin containing silver bromide, silver chloride & silver iodide silver bromide, silver chloride & silver iodide (halides).(halides).

There is a thin gelatin protective layer over There is a thin gelatin protective layer over the emulsion.the emulsion.

Today polyester plastic is the base used for Today polyester plastic is the base used for the film.the film.

Types of FilmTypes of Film There are four types of film that are There are four types of film that are

used in radiography.used in radiography. They are:They are:

Dental FilmDental Film

Photoflourographic FilmPhotoflourographic Film

Non-screen FilmNon-screen Film

Screen FilmScreen Film

Dental FilmDental Film Small, lightweight & packaged in Small, lightweight & packaged in

cardboard/plastic holders.cardboard/plastic holders. Also used in radiographic badges Also used in radiographic badges

to determine the amount of x-ray to determine the amount of x-ray exposure technicians receive.exposure technicians receive.

People are allowed 5 rads/rems per People are allowed 5 rads/rems per year.year.

Photoflourographic FilmPhotoflourographic Film

This is the film used in cameras to take This is the film used in cameras to take pictures of a fluoroscopic screen pictures of a fluoroscopic screen (barium study).(barium study).

It comes in rolls & is green or blue light It comes in rolls & is green or blue light sensitive.sensitive.

It has emulsion on only one side.It has emulsion on only one side. It is used for mass screening as in the It is used for mass screening as in the

army.army.

Non-screen FilmNon-screen Film This is sensitive to x-rays but not to light.This is sensitive to x-rays but not to light. They are used mainly in extremity x-rays They are used mainly in extremity x-rays

because the thicker body parts would require because the thicker body parts would require too much x-ray exposuretoo much x-ray exposure

We use extremity cassettes now instead of We use extremity cassettes now instead of this film typethis film type

Screens are used in cassettes with Screens are used in cassettes with intensifying screens, because cardboard intensifying screens, because cardboard holders do not produce light.holders do not produce light.

Non-screen FilmNon-screen Film If we put non-screen film in a If we put non-screen film in a

cassette with intensifying screens, cassette with intensifying screens, there would be some x-ray there would be some x-ray penetration, but not enough to give penetration, but not enough to give a good image.a good image.

The light from the screen would The light from the screen would have no effect upon this type of film.have no effect upon this type of film.

Screen FilmsScreen Films Only film used for x-rays of the Only film used for x-rays of the

spine.spine. It is sensitive to the light produced It is sensitive to the light produced

by the screens, but not to x-rays by the screens, but not to x-rays directly.directly.

Intensifying screens allow 40 times Intensifying screens allow 40 times lessless patient exposure. patient exposure.

Screen FilmsScreen Films Remember:Remember:

X-rays hit the crystals in the X-rays hit the crystals in the intensifying screens, the intensifying screens, the crystals phosphoresce & emit crystals phosphoresce & emit light & the light exposes the light & the light exposes the film.film.

Film HoldersFilm Holders

Types:Types:

CardboardCardboard

CassettesCassettes

Cardboard HoldersCardboard Holders Black cardboard envelopes that hold the Black cardboard envelopes that hold the

film during the exposure.film during the exposure. Non-screen film is used in these holders. Non-screen film is used in these holders. The holder has a tube side so that we can The holder has a tube side so that we can

expose the film correctly.expose the film correctly. The back side of the holder has a lead The back side of the holder has a lead

sheet in it to prevent scatter from bouncing sheet in it to prevent scatter from bouncing off the table and double exposing the film. off the table and double exposing the film.

Cardboard HoldersCardboard Holders These are used for extremities only.These are used for extremities only. Nothing greater than 10 cm in thicknessNothing greater than 10 cm in thickness The same rule as with the grid, any The same rule as with the grid, any

thing greater than 10 cm we need a thing greater than 10 cm we need a grid to prevent scatter.grid to prevent scatter.

Remember that extremity cassettes are Remember that extremity cassettes are available today rather than cardboard available today rather than cardboard holders.holders.

CassettesCassettes Light tight holders made of hinged metal & Light tight holders made of hinged metal &

bakelight frames that hold the film during bakelight frames that hold the film during exposures, with intensifying screens inside.exposures, with intensifying screens inside.

Intensifying screens are coated with CaIntensifying screens are coated with Ca++++ tungstate which glows when exposed to x-tungstate which glows when exposed to x-rays, which in turn exposes the film.rays, which in turn exposes the film.

Today Gadolinium & Lanthanum are used Today Gadolinium & Lanthanum are used instead of Cainstead of Ca++++ tungstate ( Rare earth tungstate ( Rare earth screens)screens)

CassettesCassettes Gadolinium& Lanthanum are rare earth Gadolinium& Lanthanum are rare earth

crystals that are more sensitive to x-crystals that are more sensitive to x-ray & give off more light, thereby ray & give off more light, thereby reducing patient exposure further.reducing patient exposure further.

intensifying screens are located on intensifying screens are located on both sides of the cassette, so the film both sides of the cassette, so the film is sandwiched between the screens.is sandwiched between the screens.

CassettesCassettes The tube side screen is thinner than The tube side screen is thinner than

the back side to allow less absorption the back side to allow less absorption of the x-rays, allowing more rays to hit of the x-rays, allowing more rays to hit the screen on the other side, the screen on the other side, increasing the exposure to the film.increasing the exposure to the film.

Screens come in a variety of speeds, Screens come in a variety of speeds, depending upon the size & number of depending upon the size & number of crystals.crystals.

CassettesCassettes Larger crystals & thicker layers make Larger crystals & thicker layers make

faster screens but cause a loss of faster screens but cause a loss of sharpness due to increased light sharpness due to increased light spread.spread.

We put dye in screens now that help We put dye in screens now that help decrease the spread of light.decrease the spread of light.

Small crystals & less layers result in the Small crystals & less layers result in the best film quality.best film quality.

CleaningCleaning Mild soap solution and a wad of Mild soap solution and a wad of

cotton is best.cotton is best. Make sure your screens are Make sure your screens are

clean to increase film quality.clean to increase film quality. Screens cost about $600.00 to Screens cost about $600.00 to

replace.replace.