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Film Screen
Film Screen Review
| Question | Answer |
|---|---|
| Layers: 1) what is mechanical support? | 1) Base-glass was used prior to WWI, then cellulose Nitrate(Flammable),cellulose triacetate(tears easily), used since the 60's called safety film is Polyester |
| what is the purpose of the blue tint? | reduce radiologist eye strain |
| the combination of silver halide crystals and gelatin is called the? | Emulsion |
| what is the glue like substance of the emulsion? | Gelatin |
| what is the purpose of the gelatin? | make sure that the silver halide crystals are evenly dispersed |
| when you have a manufacturing error, that you have clumping of the silver halide crystals, what noise of quantum mottle called? | graininess |
| Layer: 2)Over Coat | protection |
| what are some rules for storing film? | First in first out, Check Expiration date, low humidity, cooler temp, |
| what are some things film is sensitive to? | heat, light, moisture |
| what part of the emulsion captures the latent image? | silver halide |
| what are the two types of halides? is the crystal perfect? | SILVER BROMIDE (AgBr) AND SILVER IODIDE (AgI). no, so you are able to develop it |
| what collects the silver? | sensitivity speck |
| once you run the latent image through the developer that converts the silver ions to what type of silver | Black Metallic |
| once its run through the developer only what type of image is it? | manifest |
| once it goes through the complete cycle its what? | Permanent |
| complete cycle includes what? | develope, fix, wash, dry |
| what's the films relativity ability to respond to an min. exposure | speed |
| built into the film depending on the crystal size, is the films ability to image density difference called? | film contrast |
| what is film latitude? | range of exposures |
| if we have high contrast vs. low contrast which of those has narrow latitude | high contrast |
| what do we mean by panchromatic film? | sensitive to all colors |
| if we have panchromatic film what color safe light do we want? | red |
| if we have a higher speed system what is the advantage of that | low patient dose, but you lose a little bit of resolution |
| what contrast film did they use to see density differences | high contrast |
| what is an artifact | unwanted density |
| if we have dirt of dust on the screen what color is the artifact | white |
| if we have static artifact what is the color | black |
| types of static artifact? | friction-tree, touching with end of finger-smudge, and fingernail-crown |
| what would a small black crescent shape mark be caused by? Large | fingernail, crinkle |
| what is the purpose of an intensifying screen | converts xrays to light |
| what is the advantage of the intensifying screen | less Mas, less wear and tear on the machines |
| what is the only disadvantage | lose resolution |
| what's the layer that redirects light that's given off isoptropically | reflective layer |
| we have the phosphor layer, if we use calcium tungstate, what color light does it give off? | blue |
| for spectral matching what color would you want to use | blue |
| if you have pure rare earth what color light would it give off. (yttrium,gadolinium) | green |
| whats the advantage of rare earth of calcium tungstate? | less patient dose, has a higher DQE, and higher conversion efficiency |
| whats the purpose of protective coat | allow for cleaning. destatic, and protect phosphor layer. |
| would crystal size effect speed? better resolution with smaller or larger crystals? | smaller, thinner layer, lose patient dose |
| what does reflective layer do to speed | increases it |
| what is the purpose of adding the yellow light absorption dye | put into the reflective layer, better resolution, good for extremity |
| speed or sensitivity of a screen is a | screens conversion efficiency |
| what is test pattern they use to test for resolution | line bar pattern |
| what do we mean in spectral matching | make sure the film is sensitive to the light that is given off |
| what is isotropic propagation | light emitted in all directions |
| DQE(absorption efficiency), if we have a higher DQE, do you use less or more MAS? | less, goes down. |
| conversion efficiency with screens | how well it converts xrays to light |
| Factors-what do manufactures use to compare and contrast screens, when it looks at exposure with a screen and without a screen | patient factor |
| what causes phosphor screen structure mottle | clumping of the phosphor |
| what is the third type of mottle | quantum-low mas |
| 3 causes of noise or mottle | film graininess, low mas, screen structure |
| what are some causes of poor screen contact | worn felt, cassettes broken down, warping |
| what would poor screen contact look like on an image. | area of blur |
| how can we check to see that it was screen contact | wire mesh test |
| which one phosphorescence or fluorescence is given off only during stimulation | fluorescence |
| what do screens have that makes lag of light after stimulation | phosphorescence |
| what is the purpose of film screen cassette technology | light tight, good film screen contact front side(radiolucent), Back(radio-opaque), lead in the back to prevent back flow |
| what does film screen cassette have that imaging plate doesn't have | blocker |
| what's the most important relationship in development | time, temp |
| what causes pi lines | dirty rollers |
| if you have emulsion on film its problem with what? | FIXER |
| guide shoe marks are what | dirt marks |
| if a film comes out and wet and sticky where are we missing hardener | fixer |
| if it comes out wet whats not working | dryer |
| if it comes out greasy, what haven't we done | wash |
| what is fog from | chemistry of over active chemicals, or radiation |
Created by:
johnsoni1986
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