Radiographic Film & Radiographic Film & Intensifying ScreensIntensifying Screens

DarkroomDarkroom

Darkrooms 4 Basic FunctionsDarkrooms 4 Basic Functions

Number 1 FunctionNumber 1 Function

StorageStorage

Unexposed filmUnexposed film

ObjectivesObjectives

Review FilmReview Film

Review Intensifying ScreensReview Intensifying Screens

Technique Changes for Screen SpeedsTechnique Changes for Screen Speeds

What is the function of radiographic film?What is the function of radiographic film?

What is exit radiation? What is another What is exit radiation? What is another name for exit radiation? name for exit radiation?

What is an IR? Name some examplesWhat is an IR? Name some examples

X-Ray FilmX-Ray Film

Film is a media that makes a Film is a media that makes a permanent record of the permanent record of the image.image.

Image recorded on film is Image recorded on film is caused by exposure to caused by exposure to photonsphotons

X-ray Film cont’dX-ray Film cont’d

Radiographic film is/was most Radiographic film is/was most common common image receptorimage receptor

Two parts:Two parts:1. Base1. Base2. Emulsion2. Emulsion

• FIRST “FILM”• GLASS PLATES• WW 1 • CELLULOSE NITRATE• HIGHLY FLAMMABLE• EASILY TORN• RESPONSIBLE FOR

MANY FIRES IN HOSPITAL BASEMENTS

• CELLULOSE TRIACETATE

Early Film baseCellulose Triacetate

• Highly Flammable• Emulsion would crack

& peel away from base when chemicals were too hot

• RETICULATION

Film Construction - BASEFilm Construction - BASE

Made of a polyester plasticMade of a polyester plastic Must be clear, strong, consistent Must be clear, strong, consistent

thicknessthickness Tinted pale blue or blue-gray (reduces Tinted pale blue or blue-gray (reduces

eye strain)eye strain) COATED ON 1 OR 2 SIDES WITH COATED ON 1 OR 2 SIDES WITH

EMULSIONEMULSION

Film Construction - EMULSIONFilm Construction - EMULSION Film emulsion can be on one side or Film emulsion can be on one side or

both sides of base (single emulsion / both sides of base (single emulsion / double emulsion)double emulsion)

Protective overcoat layered on top of Protective overcoat layered on top of emulsionemulsion

Emulsion is a gelatin containing the film Emulsion is a gelatin containing the film crystalscrystals

Emulsion is the “active” layer of filmEmulsion is the “active” layer of film

FILM COMPOSTIONFILM COMPOSTION

SINGLE OR DOUBLE EMULSIONSINGLE OR DOUBLE EMULSIONCOATED ON A BASECOATED ON A BASE

EMULSION : GELATIN EMULSION : GELATIN WITH SILVER HALIDE CRYSTALSWITH SILVER HALIDE CRYSTALS

BASE: SUPPORT (POLYESTER)BASE: SUPPORT (POLYESTER)

Film EmulsionFilm Emulsion Made of mixture of gelatin Made of mixture of gelatin

& silver halide crystals & silver halide crystals (fluorine, chlorine, (fluorine, chlorine, bromine, & iodine)bromine, & iodine)

Most x-ray film emulsions Most x-ray film emulsions made of :made of :silver bromide (98%) silver bromide (98%) silver iodide (2%)silver iodide (2%)

Photographically active Photographically active layer – activated by light layer – activated by light & radiation to create & radiation to create imageimage

Silver halide crystalsSilver halide crystals Crystals are cubic Crystals are cubic in structurein structure

Crystal lattice Crystal lattice containing ionscontaining ions

Film constructionFilm construction

Film is manufactured to have specific Film is manufactured to have specific characteristics of speed, contrast & characteristics of speed, contrast & resolutionresolution

Film is also manufactured to be sensitive Film is also manufactured to be sensitive to specific colors of light = spectral to specific colors of light = spectral matchingmatching

Direct-exposure film = thicker emulsion Direct-exposure film = thicker emulsion with more silver halide crystalswith more silver halide crystals

X-Ray Film Cross Section

FILM CONSTRUCTIONFILM CONSTRUCTION

BASE WITH EMULSIONBASE WITH EMULSION CAN BE ON 1 (SINGLE EMULSION)CAN BE ON 1 (SINGLE EMULSION) OR 2 SIDES (DOUBLE EMULSION)OR 2 SIDES (DOUBLE EMULSION)

MUST BE MATCHED WITH 1 OR 2 MUST BE MATCHED WITH 1 OR 2 SIDED INTENSIFYING SCREENSSIDED INTENSIFYING SCREENS

Image formationImage formation

X-ray photons converted to light X-ray photons converted to light photonsphotons

Image before processing = Image before processing = latent imagelatent imageMade visible by chemical processingMade visible by chemical processingAfter proper chemical processing = After proper chemical processing = manifest manifest

imageimage

IMAGE ON FILMIMAGE ON FILM

SINGLE EMULSION = BETTER DETAILSINGLE EMULSION = BETTER DETAIL

DOUBLE EMULISON = LESS DETAILDOUBLE EMULISON = LESS DETAIL

PARALLAX PARALLAX With double emulsion – an image is With double emulsion – an image is

created on both emulsions – then created on both emulsions – then superimposed – slight blurring of edgessuperimposed – slight blurring of edges

PARALLAX –PARALLAX –each emulsion has an imageeach emulsion has an image

single image overlaped – edges single image overlaped – edges less sharp less sharp

Radiation interacts releasing e-Radiation interacts releasing e- Silver atoms buildup Silver atoms buildup

at the sensitivity at the sensitivity center, building the center, building the latent image centerlatent image center

The group of silver The group of silver atoms is called the atoms is called the latent image centerlatent image center

LIGHT VS DARK AREAS ON FILMLIGHT VS DARK AREAS ON FILM

DARK SPOTS – SILVER HALIDE DARK SPOTS – SILVER HALIDE CRYSTALS THAT HAVE BEEN CRYSTALS THAT HAVE BEEN EXPOSED TO PHOTONS – TURN TO EXPOSED TO PHOTONS – TURN TO BLACK METALLIC SILVER AFTER BLACK METALLIC SILVER AFTER PROCESSINGPROCESSING

LIGHT AREAS – NO CRYSTALS LIGHT AREAS – NO CRYSTALS EXPOSED – SILVER HALIDE IS EXPOSED – SILVER HALIDE IS WASHED AWAY WITH PROCESSINGWASHED AWAY WITH PROCESSING

Processing Processing

The term applied to the chemical reactions The term applied to the chemical reactions that transform the latent image into a that transform the latent image into a manifest imagemanifest image

FILM FILM direct exposure & screen-film or film-screendirect exposure & screen-film or film-screen

SIZESSIZES 14 X 1714 X 17 14 X 1414 X 14 11 X 1411 X 14 10 X 1210 X 12 8 X 108 X 10

Film SizesFilm Sizes

Standard “inches”:Standard “inches”: 8” x 10”8” x 10” 10” x 12”10” x 12” 11” x 14”11” x 14” 14” x 17”14” x 17”

Metric:Metric: 18cm x 24cm18cm x 24cm 24cm x 30cm24cm x 30cm 30cm x 35cm30cm x 35cm 35cm x 43cm35cm x 43cm

Screen-FilmScreen-Film Most widely used IR ?? Most widely used IR ??

Many Types of Film Used in Medical Many Types of Film Used in Medical Imaging Table 11-1Imaging Table 11-1

Screen-Film has several characteristics to Screen-Film has several characteristics to consider: contrast, speed, spectral consider: contrast, speed, spectral matching, anticrossover dyes, and safe matching, anticrossover dyes, and safe light requirementslight requirements

ContrastContrast

Manufactured in multiple levels Manufactured in multiple levels High-contrast (black-and-white image)High-contrast (black-and-white image) Low-contrast (more gray)Low-contrast (more gray)

Exposure LATITUDE = the range of Exposure LATITUDE = the range of exposure techniques that produce an exposure techniques that produce an acceptable image (medium, high or acceptable image (medium, high or higher)higher)

So what is the difference?So what is the difference?

Depends on the size and distribution of the Depends on the size and distribution of the silver halide crystalssilver halide crystals

High-contrast = smaller crystals, uniform High-contrast = smaller crystals, uniform grain sizegrain size

Low-contrast = larger crystals, wider range Low-contrast = larger crystals, wider range of sizes of sizes

Film SpeedFilm Speed

Single vs Double emulsionSingle vs Double emulsion

Size of CrystalsSize of Crystals

Thickness of emulsionThickness of emulsion

Intensifying screen usedIntensifying screen used

Screen Speed

• Efficiency of a screen in converting x-rays to light is Screen Speed.

Film SpeedFilm Speed

Greater efficiency = less exposure = fasterGreater efficiency = less exposure = faster-Standard screen speed class of 100-Standard screen speed class of 100-200 screen speed is twice as fast-200 screen speed is twice as fast

Speeds for routine work: 200 – 800Speeds for routine work: 200 – 800 Speeds for high detail: 50 - 100Speeds for high detail: 50 - 100

Film CharacteristicsFilm Characteristics Size of silver halide crystals & Size of silver halide crystals &

emulsion thickness determine speed emulsion thickness determine speed of film and degree of resolutionof film and degree of resolution

Speed – the response to photonsSpeed – the response to photons Resolution – the detail seenResolution – the detail seen

Screen speed vs Spatial resolutionScreen speed vs Spatial resolution

Film Speed / Crystal sizeFilm Speed / Crystal size

Larger crystals or Thicker crystal Larger crystals or Thicker crystal layerlayer

Faster response= less detail, andFaster response= less detail, and less exposure (chest x-ray)less exposure (chest x-ray) Finer crystals / thinner crystal layerFiner crystals / thinner crystal layer

=Slower response, greater detail, =Slower response, greater detail, more exposure (extremity)more exposure (extremity)

FILM SPEEDSFILM SPEEDS

FASTER SPEED – REDUCES PATIENT FASTER SPEED – REDUCES PATIENT EXPOSUREEXPOSURE

FASTER SPEED - REDUCES IMAGE FASTER SPEED - REDUCES IMAGE DETAIL DETAIL

IMAGE ON FILMIMAGE ON FILM

Crossover is when the exposure of the Crossover is when the exposure of the emulsion by light is from the opposite side emulsion by light is from the opposite side of the intensifying screen of the intensifying screen

Causes increased blur on the imageCauses increased blur on the image

CROSSOVERCROSSOVER Reducing crossover Reducing crossover

by adding a dye to the by adding a dye to the basebase

Reducing CrossoverReducing Crossover

Changing the shape of the crystal Changing the shape of the crystal improved light absorption and reduced improved light absorption and reduced crossovercrossover

Loss of DetailLoss of Detail

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

Film is either blue-sensitive or Film is either blue-sensitive or green-sensitive green-sensitive

Rare earth-Rare earth- green emittinggreen emitting screens must screens must use a red filteruse a red filter

Direct-Exposure FilmDirect-Exposure Film

Thicker emulsion and more crystalsThicker emulsion and more crystals Not sensitive to lightNot sensitive to light Not commonly used because of increased Not commonly used because of increased

patient dosepatient dose

Very detailed imagesVery detailed images

Laser FilmLaser Film

Uses the digital electronic signal Uses the digital electronic signal The intensity of the laser beam is varied in The intensity of the laser beam is varied in

direct proportion to the strength of the direct proportion to the strength of the image signal = image signal = LASER BEAM LASER BEAM MODULATIONMODULATION

The more intense the signal the darker the The more intense the signal the darker the imageimage

Laser printersLaser printers

Provide consistent image quality for Provide consistent image quality for multiple film sizes. Most lasers only print multiple film sizes. Most lasers only print on 14 X 17 regardless of initial IRon 14 X 17 regardless of initial IR

Printers can be linked to multiple users Printers can be linked to multiple users (CT, MRI, US & Computed Radiology)(CT, MRI, US & Computed Radiology)

Laser FilmLaser Film

Is silver halide film sensitive to the red light Is silver halide film sensitive to the red light emitted by the laseremitted by the laser

Laser film is light sensitiveLaser film is light sensitive

Laser film must be handled in the Laser film must be handled in the darkroom in total darkness… Why? darkroom in total darkness… Why?

Blue or Green filter would workBlue or Green filter would work

Duplicating filmDuplicating film

Single-emulsion film (active layer toward Single-emulsion film (active layer toward the initial radiograph)the initial radiograph)

Exposure to light reduces OD on Exposure to light reduces OD on duplicating film (short time = dark film)duplicating film (short time = dark film)

Light is exposed through the initial Light is exposed through the initial radiographradiograph

FILM BIN - STORAGEFILM BIN - STORAGE

Film StorageFilm Storage

Clean, dry location, light tight locationClean, dry location, light tight location 40 – 60 % Humidity 70 40 – 60 % Humidity 70 º º FahrenheitFahrenheit Away from chemical fumesAway from chemical fumes Safe from radiation exposureSafe from radiation exposure Standing on edgeStanding on edge Expiration date clearly visible. Film can be Expiration date clearly visible. Film can be

stored for about 45 days, use the first-in stored for about 45 days, use the first-in first-out rulefirst-out rule

Film Handling Film Handling

Do not bend or crease Do not bend or crease Hands must be cleanHands must be clean Film is sensitive to pressure and scratchesFilm is sensitive to pressure and scratches

What happens if any of these happen?What happens if any of these happen?

X-ray Film SensitivityX-ray Film Sensitivity

LightLightX-raysX-raysGamma RaysGamma RaysGasesGasesFumesFumes

HeatHeatMoistureMoisturePressurePressureStatic Static

ElectricityElectricityAgeAge

So what happens??

FILM FOG!!!!FILM FOG!!!!

Unintended Unintended uniform optical uniform optical density on a density on a radiograph radiograph because of x-rays, because of x-rays, light, or chemical light, or chemical contamination that contamination that reduces contrast & reduces contrast & affects densityaffects density

QUESTIONS ?

Intensifying ScreensIntensifying Screens

CassettesCassettes

Cassettes serve 3 important functions:Cassettes serve 3 important functions:1.1. Protect film from exposure to lightProtect film from exposure to light2.2. Protect film from bending and scratching Protect film from bending and scratching

during use.during use.3.3. Contain intensifying screens, keeps film Contain intensifying screens, keeps film

in close contact to screen during in close contact to screen during exposure.exposure.

CASSETTE or FILM HOLDERCASSETTE or FILM HOLDER The CASSETTE is The CASSETTE is

used to hold the film used to hold the film during examinations. during examinations. It consist of front and It consist of front and back intensifying back intensifying screens, and has a screens, and has a lead (Pb) backing. lead (Pb) backing. The cassette is light The cassette is light tighttight

Cassette Features - FrontCassette Features - Front Exposure side of Exposure side of

cassette is the “front”.cassette is the “front”. Made of radiolucent Made of radiolucent

material – easily material – easily penetrated by x-rays, penetrated by x-rays, lightweight metal alloy lightweight metal alloy or plastic material or plastic material made of resin.made of resin.

Intensifying screen Intensifying screen mounted to inside of mounted to inside of front.front.

Cassette FeaturesCassette Features Back Back

Back made of metal or plasticBack made of metal or plastic Inside back is a layer of lead foil – Inside back is a layer of lead foil –

prevents backscatter that could fog the prevents backscatter that could fog the filmfilm

Inside foil layer is a layer of padding – Inside foil layer is a layer of padding – maintains good film/screen contactmaintains good film/screen contact

Back intensifying screen mounted on Back intensifying screen mounted on paddingpadding

Has the ID blocker (patient identification)Has the ID blocker (patient identification)

Image creationImage creation

1% of xray photons that leave patient 1% of xray photons that leave patient Interact with phosphors of intensifying Interact with phosphors of intensifying

screens screens 100’s of light photons created to make 100’s of light photons created to make

image on filmimage on film Light photons expose silver halide crystals Light photons expose silver halide crystals

in the film emulsion in the film emulsion Turn black metallic silver after processionTurn black metallic silver after procession

Intensifying ScreensIntensifying Screens

Flat surface coated with Flat surface coated with fluorescent crystals fluorescent crystals called phosphorscalled phosphors

that glow, giving off that glow, giving off light when exposed to light when exposed to x-rays.x-rays.

Intensifying Screens PhosphorsIntensifying Screens Phosphors

RARE EARTH – (emits green light)RARE EARTH – (emits green light) Developed in 1980’sDeveloped in 1980’s Most efficient – most common in use todayMost efficient – most common in use today

CALCIUM TUNGSTATE (blue light)CALCIUM TUNGSTATE (blue light) Not as efficient Not as efficient

Rare Earth ScreensRare Earth Screens

GadoliniumGadoliniumLanthanumLanthanumYttriumYttriumFound in low Found in low

abundance in natureabundance in nature

Cardboard Cassettes Cardboard Cassettes Direct x-ray exposure to film requiredDirect x-ray exposure to film required 25 to 400 times more radiation to create an 25 to 400 times more radiation to create an

image on the filmimage on the film

BETTER DETAIL THAN FILM SCREEN (NO BETTER DETAIL THAN FILM SCREEN (NO BLURRING OF IMAGE FROM LIGHT)BLURRING OF IMAGE FROM LIGHT)

ALL EXPOSURE MADE FROM X-RAY ALL EXPOSURE MADE FROM X-RAY PHOTONSPHOTONS

BIG DOSE TO THE PATEINTBIG DOSE TO THE PATEINT

INTENSIFYING SCREENSINTENSIFYING SCREENSDISADVANTAGES:DISADVANTAGES: less detail than direct exposure less detail than direct exposure (detail better with rare earth than (detail better with rare earth than calcuim tungstate screens)calcuim tungstate screens)ADVANTAGES:ADVANTAGES:

1.1. Reduce patient exposureReduce patient exposure2.2. Increase x-ray tube lifeIncrease x-ray tube life

Screen ConstructionScreen Construction

Polyester plastic base – support layerPolyester plastic base – support layer Phosphor layer – active layerPhosphor layer – active layer Reflective layer – increases screen Reflective layer – increases screen

efficiency by redirecting light headed in efficiency by redirecting light headed in other directionsother directions

Protective coatingProtective coating

Intensifying screensIntensifying screens

Phosphor LayerPhosphor Layer

Active layer – x-ray photons Active layer – x-ray photons converted to light photonsconverted to light photons

*Photoelectric Effect*Photoelectric Effect

Screen SpeedScreen Speed

A relative number that describes how A relative number that describes how efficiently x-rays are converted into usable efficiently x-rays are converted into usable lightlight

Ranges from 100 (slow) to 1200 (fast)Ranges from 100 (slow) to 1200 (fast)

Screen SpeedScreen Speed

Greater efficiency = less exposure = fasterGreater efficiency = less exposure = faster-Standard screen speed class of 100-Standard screen speed class of 100-200 screen speed is twice as fast-200 screen speed is twice as fast

Speeds for routine work: 200 – 800Speeds for routine work: 200 – 800 Speeds for high detail: 50 – 100Speeds for high detail: 50 – 100 Increasing speed also increases image Increasing speed also increases image

noisenoise

SCREEN SPEEDSSCREEN SPEEDS

FASTER SPEED – REDUCES PATIENT FASTER SPEED – REDUCES PATIENT EXPOSUREEXPOSURE

FASTER SPEED - REDUCES IMAGE FASTER SPEED - REDUCES IMAGE DETAIL INCREASES NOISE (LIGHT DETAIL INCREASES NOISE (LIGHT BLURING AROUND IMAGE) BLURING AROUND IMAGE)

Technique Changes Technique Changes

Relative Speed = Film speed & Screen Relative Speed = Film speed & Screen speedspeed

mAs 1 mAs 1 = = RS 2 RS 2 mAs 2 RS 1mAs 2 RS 1

They are inversely relatedThey are inversely related

Image NoiseImage Noise Speckled background on the imageSpeckled background on the image Caused when fast screens and high kVp Caused when fast screens and high kVp

techniques are used. Noise reduces image techniques are used. Noise reduces image contrastcontrast

The percentage of x-rays absorbed by the The percentage of x-rays absorbed by the screen is the screen is the detective quantum efficiency detective quantum efficiency (DQE) (DQE)

The amount of light emitted for each x-ray The amount of light emitted for each x-ray absorbed is the absorbed is the conversion efficiency (CE)conversion efficiency (CE)

SCREEN SPEEDSSCREEN SPEEDS

Quantum Mottle causing a grainy, mottled Quantum Mottle causing a grainy, mottled or splotch imageor splotch image

Often results of using very fast-speed Often results of using very fast-speed screen-film systemsscreen-film systems

The light photons generated in the The light photons generated in the intensifying screen are emitted by intensifying screen are emitted by phosphor crystals. phosphor crystals.

These crystals are significantly larger These crystals are significantly larger than the silver halide crystals in the filmthan the silver halide crystals in the film

use of a screen reduces image use of a screen reduces image sharpness somewhatsharpness somewhat

Some examinations requiring extremely Some examinations requiring extremely fine detail use screens with small fine detail use screens with small crystals. crystals.

Image Quality

Rare Earth ScreensRare Earth Screens

Have higher DQE (detective quantum Have higher DQE (detective quantum efficiency). Higher x-ray absorption efficiency). Higher x-ray absorption abilities.abilities.

Have higher CE (conversion efficiency). Have higher CE (conversion efficiency). More light emitted per x-ray absorbed by More light emitted per x-ray absorbed by the screen. the screen.

Spatial resolution

• The use of intensifying screens lowers spatial resolution compared with direct-exposure radiographs.

• Spatial resolutionexpressed by thenumber of line pairsper millimeter (lp/mm)

The higher the lp/mm the smaller the object that can be imaged Very fast screens = 7 lp/mm

Fine-detail screens= 15 lp/mm

Direct-exposure screens = 50 lp/mm

Screen speed vs Spatial resolutionScreen speed vs Spatial resolution

Wire mesh test – check for screen-film contact.

• Warped cassette –poor contact

Care of ScreensCare of Screens

Image artifacts can appear if screens are Image artifacts can appear if screens are modifiedmodified

Small scratches can leave artifactsSmall scratches can leave artifacts Dirty screens can leave artifactsDirty screens can leave artifacts Screens should be cleaned once each Screens should be cleaned once each

month with manufacturer’s cleaner with month with manufacturer’s cleaner with antistatic compoundsantistatic compounds

Film Processing Film Processing

Safe LightSafe Light

15 Watts15 Watts Red filterRed filter Must be 3-6 feet Must be 3-6 feet

from counter top or from counter top or feed tray of feed tray of processorprocessor

Used to be amber Used to be amber or orange filteror orange filter

Processing TimeProcessing Time

3 minutes 90 seconds

Processing FilmProcessing FilmTable top ProcessorsTable top Processors

TABLE TOP PROCESSOR

Can process as fast as 60 seconds

PROCSSING CHEMICALSPROCSSING CHEMICALS Solutions are PRE- MIXEDSolutions are PRE- MIXED Outside Company usually provides service- Outside Company usually provides service-

Weekly or monthlyWeekly or monthly Solutions should be Solutions should be replenishedreplenished as necessary & as necessary &

changed regularlychanged regularly Solutions must be monitored (Daily QC strip).Solutions must be monitored (Daily QC strip).

Replenishment tanksReplenishment tanks

AUTOMATIC PROCESSINGAUTOMATIC PROCESSING TRANSPORTATION TRANSPORTATION

SYSTEMSYSTEM

DEVELOPERDEVELOPER

FIXERFIXER

WASHERWASHER

DRYERDRYER

REPLENISHMENT REPLENISHMENT SYSTEMSYSTEM

Automatic ProcessorAutomatic Processor

Processor Chemistry OverviewProcessor Chemistry Overview

DeveloperDeveloper – converts latent image into – converts latent image into manifest imagemanifest image

FixerFixer – clear the film of unexposed, – clear the film of unexposed, undeveloped silver bromide crystals, undeveloped silver bromide crystals, promotes archival qualitypromotes archival quality

WashWash – rid the film of residual chemicals – rid the film of residual chemicals

Developer SolutionDeveloper Solution(6 Ingredients)(6 Ingredients)

1.1. Reducing Agent:Reducing Agent: reduce reduce exposedexposed silver silver halide to black metallic silverhalide to black metallic silver

-Hydroquinone (Blacks)-Hydroquinone (Blacks)-Phenidone (Grays)-Phenidone (Grays)

2. 2. Activator:Activator: softens gelatin, maintains softens gelatin, maintains alkalinealkaline pH (increase pH) pH (increase pH)

-Sodium Carbonate-Sodium Carbonate

Developer SolutionDeveloper Solution

3. 3. Hardener:Hardener: prevents damage to the film prevents damage to the film from over swelling of gelatin in automatic from over swelling of gelatin in automatic processors.processors.

-Gluteraldehyde-Gluteraldehyde4. 4. Preservative:Preservative: Antioxidant that prevents Antioxidant that prevents

oxidation of developeroxidation of developer-Sodium Sulfite-Sodium Sulfite

Developer SolutionDeveloper Solution

5. 5. Restrainer:Restrainer: prevents chemical fog in prevents chemical fog in new developernew developer

-Potassium Bromide-Potassium Bromide6. 6. Solvent:Solvent: dissolves & ionizes the dissolves & ionizes the

developer chemicalsdeveloper chemicals-Water-Water

Fixer SolutionFixer Solution(5 Ingredients)(5 Ingredients)

1.1. Clearing Agent:Clearing Agent: dissolves undeveloped dissolves undeveloped silver halidesilver halide

--Ammonium ThiosulfateAmmonium Thiosulfate2. 2. Tanning Agent:Tanning Agent: shrinks, hardens, shrinks, hardens,

preserves emulsionpreserves emulsion-Aluminum Salt-Aluminum Salt

Fixer SolutionFixer Solution

3. Activator:3. Activator: neutralizes developer, neutralizes developer, maintains acidic pH (decrease pH)maintains acidic pH (decrease pH)

-Acetic Acid-Acetic Acid4. Preservative:4. Preservative: prevents oxidation, prevents oxidation,

prolongs solution lifeprolongs solution life-Sodium Sulfite-Sodium Sulfite

5. Solvent:5. Solvent: dissolves other ingredientsdissolves other ingredients-Water-Water

WashWash Rid the film of residual chemicalsRid the film of residual chemicals Residual chemicals on the film will discolor Residual chemicals on the film will discolor

radiograph over time.radiograph over time. Cold water processors are less efficient in Cold water processors are less efficient in

removing chemicals – Warm water removing chemicals – Warm water processors much better.processors much better.

Agitation during wash process is essentialAgitation during wash process is essential

Fixer RetentionFixer Retention(Not Washed Off)(Not Washed Off)

Dev. Rinse Fix Wash

Dryer

Processing cycle

Dev

Developing

Rinse

Rinsing (stop bath)

Rinsing in manual processingRinsing in manual processing

Immediately after development the film is Immediately after development the film is dipped in the water in order to:dipped in the water in order to:

i.i. Stop developmentStop developmentii.ii. To wash the developer from the surface To wash the developer from the surface

of the film – (reduces developer carry of the film – (reduces developer carry over to fixer)over to fixer)

Rinsing in Automatic Rinsing in Automatic processing?processing?

No rinsing stageNo rinsing stage The developer is removed from the film The developer is removed from the film

surface by passing it through the special surface by passing it through the special type of rollers called “squeegee rollers”type of rollers called “squeegee rollers”

Alkaline Developer is neutralized by the Alkaline Developer is neutralized by the acid in the fixeracid in the fixer

FixingFixing

Fixer

Film

Film

Functions of fixingFunctions of fixing To stop any further developmentTo stop any further development Clears the image (making the background Clears the image (making the background

transparent to light)transparent to light) Makes the image permanent (fixed)Makes the image permanent (fixed) (no more sensitive to light) (no more sensitive to light) by Removing the undeveloped silver by Removing the undeveloped silver

bromide crystals from the emulsionbromide crystals from the emulsion Hardens the emulsionHardens the emulsion

Fixer constituentsFixer constituents

SolventSolvent Fixing agentFixing agent AcidAcid HardenerHardener BufferBuffer PreservativePreservative Anti-sludging agentAnti-sludging agent

Functions of fixer Functions of fixer constituentsconstituents

ConstituentConstituent FunctionFunctionSolventSolvent(water)(water)

Carrying medium for the Carrying medium for the active ingredientsactive ingredientsControls the acidity by Controls the acidity by diluting diluting

Fixing agentFixing agent(Sodium (Sodium Thiosulphate Thiosulphate /Ammonium /Ammonium ThiosulphateThiosulphate

Combines with insoluble Combines with insoluble AgBr to form soluble AgBr to form soluble compounds (Ammonium compounds (Ammonium Argento-Thiosulphate & Argento-Thiosulphate & NHNH44BrBr

AcidAcid(Acetic acid – pH 4.0 (Acetic acid – pH 4.0 – 4.5)– 4.5)

To stop developmentTo stop developmentTo provide suitable To provide suitable working environment working environment for hardening agentsfor hardening agents

HardenerHardener(Aluminium chloride (Aluminium chloride & aluminium & aluminium sulphate)sulphate)

Hardens the Hardens the emulsion to limit emulsion to limit water absorption, to water absorption, to reduce drying time, reduce drying time, to minimize physical to minimize physical damagedamage

BufferBuffer(Sodium (Sodium acetate & acetate & acetic acid)acetic acid)

Controls the pH in a precise Controls the pH in a precise range in order to:range in order to:i. Prevent sulphurizationi. Prevent sulphurizationii. Neutralize the developer ii. Neutralize the developer iii. Optimum hardening iii. Optimum hardening

PreservativePreservative(Sodium (Sodium sulphite)sulphite)

Retards the decomposition of Retards the decomposition of thiosulphate and delays the thiosulphate and delays the onset of sulphurizationonset of sulphurization

Anti-Anti-sludging sludging agent (Boric agent (Boric acid)acid)

Reduces the formation of Reduces the formation of sludge of insoluble aluminium sludge of insoluble aluminium compounds by the aluminium compounds by the aluminium salts used as the hardnersalts used as the hardner

Factors affecting FixationFactors affecting Fixation

The quality and quantity of fixation depends The quality and quantity of fixation depends on the:on the:

Constitution and activity of fixing solutionConstitution and activity of fixing solution Fixer temperatureFixer temperature Fixing timeFixing time

Constitution & activity of fixing Constitution & activity of fixing solutionsolution

At a given temperature the activity of fixer solution At a given temperature the activity of fixer solution depends on:depends on:

Fixing agentFixing agent Concentration of fixing agentConcentration of fixing agent Amount of hardener presentAmount of hardener present The amount of soluble silver compounds and The amount of soluble silver compounds and

soluble halides presentsoluble halides present pH pH

Fixer temperatureFixer temperature The activity of fixing agents increases with The activity of fixing agents increases with

temperature. temperature. But high temperatures cause emulsion But high temperatures cause emulsion

swelling and becomes susceptible to swelling and becomes susceptible to damage.damage.

However precise control of temperature is However precise control of temperature is not necessarynot necessary

Fixing timeFixing time The fixing time should be long enough to The fixing time should be long enough to

complete the fixing process.complete the fixing process. The required time for complete fixation The required time for complete fixation

depends on thedepends on thei. activity i. activity

i. type of film emulsion i. type of film emulsion iii. Agitation of fixer solutioniii. Agitation of fixer solution

Replenishment of FixerReplenishment of Fixer

Replenishment of fixer is necessary toReplenishment of fixer is necessary toi.i. Maintain the activityMaintain the activityii.ii. Maintain the volumeMaintain the volume

The rate of replenishment depends onThe rate of replenishment depends oni.i. Area/number of films processedArea/number of films processedii.ii. Type of emulsion/filmType of emulsion/filmiii.iii. Type of imageType of image

Replenishment of chemicalsReplenishment of chemicals

Manual processingManual processing

Suitable quantity is Suitable quantity is added manually at added manually at regular intervalsregular intervals

Automatic processingAutomatic processing

Added automaticallyAdded automaticallyby the replenishmentby the replenishmentpumps at a given pumps at a given rate for each film rate for each film processedprocessed

WashingWashing

Removes the fixing solution contaminated Removes the fixing solution contaminated with silver complexes and ammonium with silver complexes and ammonium halides from the film surface and from film halides from the film surface and from film emulsionemulsion

Running water is used to maintain a Running water is used to maintain a concentration gradient and to improve the concentration gradient and to improve the diffusion rate of chemicals from the diffusion rate of chemicals from the emulsion to wateremulsion to water

Factors affecting washing Factors affecting washing efficiencyefficiency

Type of film emulsionType of film emulsion Condition of fixing solutionCondition of fixing solution Condition of waterCondition of water Agitation of waterAgitation of water Temperature of waterTemperature of water Washing timeWashing timeThiosulphate level of < 3 microgram/square cm is Thiosulphate level of < 3 microgram/square cm is

recomendedrecomended

DryingDrying Removes all of the Removes all of the surface watersurface water and most of and most of

the water retained in the the water retained in the emulsionemulsionManual processingManual processing:- Keep the film in a drying :- Keep the film in a drying

cabinet in which hot air is circulated. Takes cabinet in which hot air is circulated. Takes about 10-15 minutesabout 10-15 minutes

Automatic ProcessingAutomatic Processing:- Surface water is removed :- Surface water is removed by squeegee rollers ; evaporation removes the by squeegee rollers ; evaporation removes the emulsion water.emulsion water.

25 sec in a 90 sec cycle25 sec in a 90 sec cycle

Factors affecting drying time & Factors affecting drying time & efficiencyefficiency

The wetness of the emulsion; governed The wetness of the emulsion; governed by: by: i. hardness of the emulsion i. hardness of the emulsion ii. emulsion thicknessii. emulsion thickness

The drying conditions; governed by:The drying conditions; governed by:i. Air humidityi. Air humidity

ii. Air Temperatureii. Air Temperature iii. Air circulation – rate of changeiii. Air circulation – rate of change

SummarySummary

If a film is not processed properly the If a film is not processed properly the whole effort made in the x-ray room or in whole effort made in the x-ray room or in the ward to obtain a good radiograph will the ward to obtain a good radiograph will be lostbe lost

It is essential to pay similar attention to It is essential to pay similar attention to film processing as you pay at the x-ray film processing as you pay at the x-ray room or in the ward when taking the x-ray room or in the ward when taking the x-ray

SensitometrySensitometry

Describing photographic Describing photographic performanceperformance

Why is the study important?Why is the study important?

To produce images with optimum contrast To produce images with optimum contrast that reveal high details of the object that reveal high details of the object examined.examined.

Optimum contrast?Optimum contrast? Low contrast (long scale contrast)Low contrast (long scale contrast) High contrast (Short scale contrast)High contrast (Short scale contrast)

Low contrastLow contrast

X-ray imagesX-ray images

What is Sensitometry?What is Sensitometry?

The scientific study of the The scientific study of the responseresponse of of photosensitive material to different levels photosensitive material to different levels of exposures.of exposures.

How is it done?How is it done? Producing a Producing a sensitometric stripsensitometric strip and plotting and plotting

a characteristic curve.a characteristic curve.

Sensitometric stripSensitometric strip

A film containing number of areas with A film containing number of areas with different optical densities from white (fully different optical densities from white (fully transparent) to black (fully opaque)transparent) to black (fully opaque)

How to produce a sensitometric strip and the characteristic curve?

1.Expose a film to different amounts of known exposures starting from a minimum and increasing at a known rate (ratio / wedge factor) up to a maximum.

2. Process the film3. Measure the densities4. Tabulate the result & Study the response

by plotting a curve (density Vs Log relative exposure

1

2

3

4

1 2 3 4Log relative exposure

Den

sity

Shoulder

Toe

Characteristic curve

GF

GF = Gross Fog

DMax

Straight line portion

Questions?