M. Farakath Khan1st year pg student

X RAY FILMS, INTENSIFYING SCREENS, GRIDS

CONTENTS Image receptors History Types Composition Film size Film speed Intensifying screen Digital receptors

HISTORY OF X RAY FILMS

X Rays -8 th nov 1895 –WIlHEIM CONRAD ROENTGEN

1st dental radiograph -1896 Glass photographic plates -1896-1913 1st commercially available prepackaged dental

x ray film -1913( Eastman kodak company) 1st machine made packet -1921 Regular, extra speed film, kodak -1923 Double coated emulsion -1925 Exposure time 6-8 seconds 50 yrs ago…..

Cellulose Triacetate Highly Flammable Emulsion would

crack & peel away from base when chemicals were too hot

INTERESTING FACTS

OTTO WALKHOFF -1ST Dental radiographExposure time -25 minutes

W.J.MORTAN -1ST Dental radiograph in US using a skull.C.EDMUND KELLS -1st practical use of radiograph in dentistry in 1896

in living persons.

IMAGE RECEPTORS

DIRECT EXPOSURE FILM

SCREEN FILMELECTRONIC

SENSORS

IOPABITEWING

OCCLUSSAL

EXTRAORALPANORAMIC CCD

CMOS FLAT

PANEL

PSP PLATE

A,B,C,D,E SPEED

DUPLICATING FILMS

SELF DEVELOPING FILM

INTAORAL FILM

X RAY FILM

PAPER FILM WRAPPERLEAD FOIL OUTER FILM WRAPPER

BASE

EMULSIONSingleDouble

Single film

Double film

Tongue side

Tube side

BASE0.18 mm thickPolyester polyethylene terephthalate.Uniformly translucent.Slight blue tint.Support.Flexible.Dimensional stability.Inert.

EMULSION(10 micrometer) Single emulsion, double emulsionSilver halide grains..(silver bromide 0.7 – 0.75 mm)Iodide –ultra speed film.(large diameter)Sulfur, gold –sensitivityInsight film –flat tabular crystals(1.8 micrometer)Ultra speed film –globular shaped crystals (1 micrometer )Vehicle – gelatinous, nongelatinous Gelatin matrix – cattle bone – porous.Gelatin supercoat – protective.Adhesive material.Raised dot.

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

SILVER HALIDE GRAINSD SPEED FILM F SPEED FILM

COLOUR CODES

INTRAORAL FILM PACKET

HITTORF CROOKES TUBE

E XTRA ORAL FILMSNot enclosed in moi stur e proof packetsCASSETTE- Holds film and intensifying screen

Rigid

FlexibleCASSETTE

CASSETTEFront cover

Back cover

EXTA ORAL FILM PACKET

Storagecool , dry placeopt temp – 50-70 degree FHumidity – 30%-50%shielded from light lead lined storage boxexpiry datefirst in first out rule.

X-ray Film Sensitivity Light X-rays Gamma Rays Gases Fumes

Heat Moisture Pressure Static Electricity Age

So what happens??

FILM FOG!!!! Unintended uniform

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

FILM SIZE (INTRA ORAL)Small Child # 0 (22*35 mm)Anterior teeth # 1 (24*40 mm)Adult # 2 (31*41 mm) Preformed long bitewing # 3 (27*54mm) Occlussal # 4 (57*76 mm)

periapical

EXTRAORAL FILM SIZE

In dental radiography5*7 inch(lateral oblique)8*10 inch(cephalometric film)Panoramic films5*12 inch6*12 inchSkull films10*12 inches61/2*81/2 inches

FILM SPEED(SENSITIVITY)Determined by1. Size of silver halide crystals2. Thickness of emulsion3. Presence of radiosensitive dyes.

More sensitive film-↓ mA – greater film speed.. Large Ag Br Crystals (faster film) – major factor

determining speed.

High contrast medium speed film-skull radiography.

Faster film- less image detail and exposure –panoramic radiography.

Less contrast and wide latitude –cephalometric radiography.

FILM SPEED(ANSI)A to FA- slowest filmF- fastest film American academy of oral and maxillofacial

radiology recommends E or F speed film to be used

E - film- twice fast than D film. F- film reduces radiation exposure 20%

compared to E and 70% compared to D speed film.

SPEED SLOW SPEED FILMS – A, B, C. Small grain, better definition, more exposure time

FAST SPEED FILMS – D (ultra speed) E (ekta speed) F (ultra ekta speed)

CHARACTERISTIC CURVE ( H and D curve)

Relationship between radiation exposure to the film and resulting film density.

FILM CONTRAST

Difference in densities between light and dark regions of radiograph

Film with high contrast more desirable for diagnosis

The manufacture have increased the speed of later generation E speed film.

FILM DEFINITION AND DETAIL

Depends on the size of silver halide crystals.Larger crystals-↓ exposure time-poor definition.

INTENSIFYING SCREEN

Screen film uses intensifying screenIntensifying screen absorbs x rays and emit visible light

which exposes screen film.Silver halide crystals sensitive to UV and blue light ( 300 to

500 nm)..so sensitive to screen that emit UV and blue light.

Green light – silver halide crystals are coated with sensitizing dyes to increase absorption.

Screen films uses flat tabular grains of silver halide grains.

SCREEN

COMPOSITION

Conventional calcium tungstate screens have

phosphors that emit BLUE LIGHT

RARE EARTH ELEMENTs

GREEN EMISSION – Gadolinium oxysulide, terbium activated

BLUE AND UV EMISSION – Yttrium tantalite, niobium activated.

SENSITIVITY

ADVANTAGESReceptor system 10-60 times more sensitiveLess radiation DISADVANTAGESLower resolutionMottling – irregular densityUnsharp image

DUPLICATING FILMINDICATION Dental Insurance Mobile Patients Medico legal CasesREQUERMENTS Duplicating Film Film Hangers Light Source( UV Preferred) Photographic Printing Frame

DUPLICATING FILMS

Supplied in 8*10 or 5*12 sheets, individually wrapped periapical size film.

Emulsion- present on one sideDirect positive emulsion.

PROCEDUREA photographic printing frame will hold original

radiograph against duplicating film

DIGITAL IMAGE RECEPTOR

• CCD• COMS• FLAT PANEL

DETECTORS

SOLID STATE TECHNOLOGY

PHOTO STIMULABLE PHOSPHOR

TECHNOLOGY

SOLID STATE TECHNOLOGY

Ability to generate a digital image in the computer without any other external device.

SST in medicine-digital radiographySST in dentistry –sensors

ADVANTAGE Rapid availability of images

DISADVANTAGE Bulk sensor Electronic cable

CCD1987 in dentistry.1st digital image receptor for introral imaging.Thin wafer silicon for image recording.Silicon arranged in rows and columns –MATRIXSCINTILLATION LAYER –Materials similar to rare earth

intensifying screen placed above matrix.X ray photons-scintillation layer-lightLight interacts via PHOTOELECTRIC effect with silicon to

create a CHARGE PACKET for individual pixel.The charge pattern formed from the individual pixels in the

matrix represents the LATENT IMAGE.Each sensor-1.5 -2.5 million pixels.(pixel size 20-70 microns)

CCD

SENSORS

CMOS

Similar to CCD in construction but differ in the way that the pixel charges are read.

The COMS pixel is isolated from its neighbor and directly connected to a TRANSISTOR.

The charge packet from each pixel is transferredto the transistor as a voltage enabling each

individual pixel to be assessed separately.

FLAT PANEL DETECTORSImaging Larger Areas Of

BodyPhoto conducting

Material (selenium)

PHOTOSTIMULABLE PHOSPHOR TECHNOLOGY

SIZE (PSP)

ADVANTAGES•Superior grey scale

resolution(256 shades of gray)

•Detail or resolution(6-22 lp/m)

•Decreased exposure•Increased speed of image

viewing•Decreased film cost

•No hazards•Increased efficacy(storage)•Enhancement of diagnostic

image•Patient education

Digital imaging

DISADVANTAGEInitial setup costImage quality –CR 12-20 lp/mm CCD 10 lp/mm( Resolving power – ability of radiograph to record

separate structures that are close together)Sensor sizeInfection controlWear and tear – PSPLEGAL ISSUES

THANK YOU..