rtec a spring 2009 film cassettes & intensifying screens week 9
TRANSCRIPT
![Page 1: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/1.jpg)
RTEC A Spring 2009
FILM CASSETTES
& INTENSIFYING SCREENSWEEK 9
![Page 2: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/2.jpg)
Creating the IMAGE
• When x-rays pass through a patient's body, three things can happen:
• (1) the x-ray photon is transmitted, passing through the body, interacting with the film, and producing a dark area on the film;
• (2) the x-ray photon is absorbed in an area of greater tissue density, producing lighter areas on the film; and
• (3) the x-ray photon is scattered and reaches the film causing an overall gray fog.
![Page 3: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/3.jpg)
![Page 4: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/4.jpg)
Radiographic Images
• RADIOLUCENT - dark on image
–AIR, CO2 , Lungs
• RADIOPAQUE - white on image
–BARIUM, IODINE, Bones
![Page 5: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/5.jpg)
![Page 6: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/6.jpg)
• Primary Radiation exit from tube
• 100 % enters patient• 1% exits for form
image on cassette below
• REMNANT Radiation
![Page 7: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/7.jpg)
Cassettes
Cassettes serve 3 important functions:
1. Protect film from exposure to light
2. Protect film from bending and scratching during use.
3. Contain intensifying screens, keeps film in close contact to screen during exposure.
![Page 8: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/8.jpg)
Image formation
Remnant x-ray photons converted to light photons
Image before processing = Latent image
Made visible by chemical processing = Manifest image
![Page 9: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/9.jpg)
CASSETTE or FILM HOLDER
• The CASSETTE is used to hold the film during examinations. It consist of front and back intensifying screens, and has a lead (Pb) backing. The cassette is light tight
![Page 10: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/10.jpg)
![Page 11: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/11.jpg)
• ALWAYS KEEP THE COLLIMATED AREA SMALLER THAN THE SIZE OF THE CASSETTE
![Page 12: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/12.jpg)
Cassette Features - Front
• Exposure side of cassette is the “front”.
• Has the ID blocker (patient identification)
• Made of radiolucent material – easily penetrated by x-rays, lightweight metal alloy or plastic material made of resin.
• Intensifying screen mounted to inside of front.
![Page 13: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/13.jpg)
Cassette Features - Back
• Back made of metal or plastic
• Inside back is a layer of lead foil – prevents backscatter that could fog the film
• Inside foil layer is a layer of padding – maintains good film/screen contact
• Back intensifying screen mounted on padding
![Page 14: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/14.jpg)
Cardboard Cassettes
Direct x-ray exposure to film required• 25 to 400 times more radiation to create an
image on the film
• BETTER DETAIL THAN FILM SCREEN (NO BLURRING OF IMAGE FROM LIGHT)
• ALL EXPOSURE MADE FROM X-RAY PHOTONS
• BIG DOSE TO THE PATEINT
![Page 15: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/15.jpg)
Intensifying Screens
• Flat surface coated with fluorescent crystals called phosphors
• that glow, giving off light when exposed to x-rays.
![Page 16: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/16.jpg)
![Page 17: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/17.jpg)
![Page 18: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/18.jpg)
Image creation
• 1% of xray photons that leave patient
• Interact with phosphors of intensifying screens
• 100’s of light photons created to make image on film
• Light photons expose silver halide crystals in the film emulsion –
• Turn black metallic silver after procession
![Page 19: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/19.jpg)
Intensifying Screens Phosphors
• RARE EARTH – (emits green light)
• Developed in 1980’s
• Most efficient – most common in use today
• CALCIUM TUNGSTATE (blue light)
• Not as efficient
![Page 20: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/20.jpg)
Rare Earth Screens
• Gadolinium
• Lanthanum
• Yttrium
• Found in low abundance in nature
![Page 21: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/21.jpg)
INTENSIFYING SCREENSDISADVANTAGES:
• less detail than direct exposure
• (detail better with rare earth than
• calcuim tungstate screens)
ADVANTAGES:
1. Reduce patient exposure
2. Increase x-ray tube life
![Page 22: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/22.jpg)
![Page 23: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/23.jpg)
Screen Construction
• Polyester plastic base – support layer
• Phosphor layer – active layer
• Reflective layer – increases screen efficiency by redirecting light headed in other directions
• Protective coating
![Page 24: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/24.jpg)
Intensifying screens
![Page 25: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/25.jpg)
Phosphor Layer
• Active layer – x-ray photons converted to light photons
*Photoelectric Effect
![Page 26: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/26.jpg)
Screen Speed
• Efficiency of a screen in converting x-rays to light is Screen Speed.
![Page 27: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/27.jpg)
Screen Speed
• Greater efficiency = less exposure = faster
-Standard screen speed class of 100
-200 screen speed is twice as fast
• Speeds for routine work: 200 – 800
• Speeds for high detail: 50 - 100
![Page 28: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/28.jpg)
SCREEN SPEEDS
• FASTER SPEED – REDUCES PATIENT EXPOSURE
• FASTER SPEED - REDUCES IMAGE DETAIL (LIGHT BLURING AROUND IMAGE)
![Page 29: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/29.jpg)
FILM Standard Sizesin Inches• 14 X 17• 11 X 14• 10 X 12• 8 X 10
Metric:• 18cm x 24cm• 24cm x 30cm• 30cm x 35cm• 35cm x 43cm
![Page 30: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/30.jpg)
X-Ray Film
• Film is a media that makes a permanent record of the image.
• Image recorded on film is caused by exposure to photons:
![Page 31: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/31.jpg)
RADIOGRAPH• PERMANENT RECORD MADE USING
RADIATION
– RADIO- RADIATION (usually x rays)
– GRAPH PERMANENT RECORD
![Page 32: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/32.jpg)
• FIRST “FILM”• GLASS PLATES• WW 1 • CELLULOSE ACETATE• HIGHLY FLAMMABLE• EASILY TORN• RESPONSIBLE FOR
MANY FIRES IN HOSPITAL BASEMENTS
![Page 33: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/33.jpg)
X-ray Film cont’d
• Radiographic film is/was most common image receptor
• Two parts:
1. Base
2. Emulsion
![Page 34: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/34.jpg)
Film Construction - BASE
• Made of a polyester plastic• Must be clear, strong, consistent
thickness• Tinted pale blue or blue-gray (reduces
eye strain)• COATED ON 1 OR 2 SIDES WITH
EMULSION
![Page 35: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/35.jpg)
Film Construction - EMULSION
• Film emulsion can be on one side or both sides of base (single emulsion / double emulsion)
• Protective overcoat layered on top of emulsion
• Emulsion is a gelatin containing the film crystals
![Page 36: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/36.jpg)
FILM COMPOSTION
• SINGLE OR DOUBLE EMULSIONCOATED ON A BASE
EMULSION : GELATIN
• WITH SILVER HALIDE CRYSTALS
• BASE: SUPPORT
POLYESTER
![Page 37: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/37.jpg)
Film Emulsion
• Made of mixture of gelatin & silver halide crystals (fluorine, chlorine, bromine, & iodine)
• Most x-ray film emulsions made of :
silver bromide (90%) silver iodide (10%)
• Photographically active layer – activated by light & radiation to create image
![Page 38: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/38.jpg)
X-Ray Film Cross Section
![Page 39: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/39.jpg)
FILM CONSTRUCTION
• BASE WITH EMULSION
• CAN BE ON 1 (SINGLE EMULSION)
• OR 2 SIDES (DOUBLE EMULSION)
• MUST BE MATCHED WITH 1 OR 2 SIDED INTENSIFYING SCREENS
![Page 40: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/40.jpg)
IMAGE ON FILM
• SINGLE EMULSION = BETTER DETAIL
• DOUBLE EMULISON = LESS DETAIL
• PARALLAX
With double emulsion – an image is created on both emulsions – then superimposed – slight blurring of edges
![Page 41: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/41.jpg)
PARALLAX –PARALLAX –each emulsion has an image
single image overlaped – edges less sharp
![Page 42: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/42.jpg)
Film Characteristics• Size of silver halide crystals &
emulsion thickness determine speed of film and degree of resolution
• Speed – the response to photons
• Resolution – the detail seen
![Page 43: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/43.jpg)
Film Speed / Crystal size
• Larger crystals or Thicker crystal layer
Faster response= less detail, and
less exposure (chest x-ray)
• Finer crystals / thinner crystal layer
=Slower response, greater detail, more exposure (extremity)
![Page 44: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/44.jpg)
![Page 45: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/45.jpg)
![Page 46: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/46.jpg)
LIGHT VS DARK AREAS ON FILM
• DARK SPOTS – SILVER HALIDE CRYSTALS THAT HAVE BEEN EXPOSED TO PHOTONS – TURN TO BLACK METALLIC SILVER AFTER PROCESSING
• LIGHT AREAS – NO CRYSTALS EXPOSED – SILVER HALIDE IS WASHED AWAY WITH PROCESSING
![Page 47: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/47.jpg)
![Page 48: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/48.jpg)
FILM BIN - STORAGE
![Page 49: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/49.jpg)
Film Storage
• Clean, dry location
• 40 – 60 % Humidity 70 º Fahrenheit
• Away from chemical fumes
• Safe from radiation exposure
• Standing on edge
• Expiration date clearly visible
![Page 50: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/50.jpg)
![Page 51: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/51.jpg)
![Page 52: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/52.jpg)
X-ray Film Sensitivity
• Light
• X-rays
• Gamma Rays
• Gases
• Fumes
• Heat
• Moisture
• Pressure
• Static Electricity
• AgeSo what happens??
![Page 53: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/53.jpg)
FILM FOG!!!!
• Unintended uniform optical density on a radiograph because of x-rays, light, or chemical contamination that reduces contrast & affects density
![Page 54: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/54.jpg)
![Page 55: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/55.jpg)
POOR SCREEN CONTACT
• FOAM BACKING HELSP TO PLACE INTENSIFYING SCREENS IN DIRECT CONTACT WITH THE FILM – NO GAPS
• IF GAPS – MORE LIGHT CAN BE EMITTED IN SPACE, CAUSING THE IMAGE TO BE OF POOR DETAIL
![Page 56: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/56.jpg)
Intensifying Screen & Film Cross Section
![Page 57: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/57.jpg)
![Page 58: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/58.jpg)
![Page 59: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/59.jpg)
Spectral Sensitivity ORSPECTRAL MATCHING
Film is designed to be sensitive to the color of light emitted by the intensifying screens
• Blue – UV light sensitive film – CALCIUM TUNGSTATE screens
• Green, Yellow-Green light sensitive film -
RARE EARTH screens
![Page 60: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/60.jpg)
• The light photons generated in the intensifying screen are emitted by phosphor crystals.
• These crystals are significantly larger than the silver halide crystals in the film
• use of a screen reduces image sharpness somewhat
• Some examinations requiring extremely fine detail use screens with small crystals.
![Page 61: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/61.jpg)
![Page 62: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/62.jpg)
![Page 63: RTEC A Spring 2009 FILM CASSETTES & INTENSIFYING SCREENS WEEK 9](https://reader036.vdocuments.us/reader036/viewer/2022062308/56649db05503460f94a9e996/html5/thumbnails/63.jpg)
Questions?