dr. mustafa zuhair mahmoud mr. ali alhailiy image critique نقد صورة الاشعّه 1

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Lecture No.2X Ray films

Dr. Mustafa Zuhair MahmoudMr. Ali Alhailiy

Image Critiqueاالشّع�ه صورة نقد

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X-ray Film

1. Film Construction:

• X-ray film is constructed of four layers basically which are:

1. Base.2. Adhesive layer.3. Emulsion.4. Overcoat (protective) layer.

Assistant Prof. Dr. Mustafa Zuhair Mahmoud

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X-ray Film




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X-ray Film



1. Base: 150 to 300 m thick. Lucent. Made of polyester. Blue in color result in less eye strain and fatigue.


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X-ray Film



2. Emulsion: This is the active layer. Homogeneous mixture of gelatin and silver halide crystals. The gelatin acts as a suspension agent and prevents the crystals from

adhering to one another. And allow the light to pass throw when viewing the image.

Two emulsion layers on each side of the film base (1/2000 in thickness).


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X-ray Film



3. Adhesive layer: Very thin layer of solution of cellulose ester and gelatin in water and acetone,

put on the base. Function of adhesive (substratum) layer to adhere the layers of emulsion to

the base.


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X-ray Film



4. Overcoat (protective) layer: The purpose of the overcoat of an x-ray film is to protect the emulsion layer.


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X-ray Film

2. Film Types (Clinical Usage):

A. Direct Exposure Film:


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X-ray Film



Used without intensifying screens.

Used mainly for extremities, previously for mammography.


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X-ray Film



Requires 10 – 100 times more the exposure dose.

The emulsion is thicker than screen film.

Renders excellent detail.


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X-ray Film


B. Mammographic Film:


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X-ray Film


B. Mammographic Film:

Single emulsion.

Fine grain (crystal shape).


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X-ray Film


C. Video Film:


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X-ray Film


C. Video Film:

Exposes images displayed on a video monitor.


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X-ray Film

2. Film Type (Clinical Usage):

D. Laser Film:


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X-ray Film


D. Laser Film:

Uses a laser printer.

Provides excellent image quality.


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X-ray Film


D. Laser Film:

Sensitive to red light.

Must be processed in complete darkness.


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X-ray Film


E. Duplication film:


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X-ray Film


E. Duplication film:

Single emulsion film.

Used for producing copies of radiographs.


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X-ray Film


F. Subtraction Film:


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X-ray Film



A type of single emulsion film used with angiography.


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X-ray Film



One type prepares a positive copy of the image.

The other type enhances subject contrast and detail.


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X-ray Film


G. Cine Film:


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X-ray Film


G. Cine Film:

Used with cardiac catheterization.


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X-ray Film


G. Cine Film:

Produced in 16 and 35mm sizes.

Also used for radiography of the esophagus.


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X-ray Film


H. Spot Film:


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X-ray Film


H. Spot Film

Produced in 70 and 105mm sizes.

Used in fluoroscopy with a spot film camera.


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X-ray Film


I. Dental Film

Periapical Dental Film

Bite-wing Dental FilmAssistant Prof. Dr. Mustafa Zuhair Mahmoud

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X-ray Film


I. Dental Film

Occlusal Dental Film Orthopantomographic (OPG) Dental Film


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X-ray Film


I. Dental Film

Exposed either intraorally or extraorally.

Intraoral films are small, double-emulsion films.

Extraoral films are large, single-emulsion films.


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X-ray Film

3. Film Type (Exposure):

A. Screen Film:

Films exposed to combination of X-ray and light (screen film).


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X-ray Film


B. Non Screen Film:

Films exposed to x-ray only (non screen film).


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X-ray Film


C. Fluoroscopy and Copying Films:

These Films are exposed to light only.

Coated by the emulsion in one side and called single sided films.


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X-ray Film

5. Film Handling and Storage:

Each of the following can have a negative effect upon film contrast.

1. Improper handling. Causes artifacts.


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X-ray Film



2. Heat and humidity. Too much humidity can cause the emulsion to swell.


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X-ray Film



2. Heat and humidity. Too little humidity can cause static to develop the film.


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X-ray Film



2. Heat and humidity. Too much heat can fog film.


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X-ray Film



3. Light and radiation. Exposure to each can fog film decreasing contrast.


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X-ray Film



4. Shelf life. Film loses speed, contrast and begins to fog with age.


CR Cassettes Comprises of:

• 1. A protective outer cassette case

• 2. A PSP plate

• 3. A chip for temporary storage of patient information

Photo-Stimulable Phosphor (PSP)

• A phosphor is a substance that exhibits the• phenomenon of phosphorescence (sustained• glowing after exposure to light or energised• particles such as electrons).• • The most common types of phosphor in

these• plates are BaF:Eu++. (Barium Fluoro

Europium)

CR Plate Structure

Protective Coat

Electron beam cured to reduce the amount oflaser beam reflection that occurs during secondary excitation.

Phosphor Layer

The thickness of this layer has a direct impacton image quality.PSP is made either of BaF:Eu++ or BaFI:Eu++

Anti-Halo Layer

This layer is to prevent back-reflection of the of the laser light into the phosphor.It is normally a blueish colour. Can you think why?Absorption, because the laser is normally red.

Support Layer

This polyurethane (PET) layer gives strengthand support to the plate.

Laminate

This layer provides further support.

CR Cassettes

• Hard outer cassettes provide durability and functionality.

• These are commonly made either of plastic or carbon fibre,both of which have good radio-lucency in proportion to theirsupport qualities and durability.

Communication• Patient ID is normally• inputted on a PC• workstation and transferred• or wrote to an embedded• chip within the cassette by• magnetics or radio-waves• • This information is then read• by the reader during the• reading process.

Communication• Barcode scanners arecommonly used toautomatically identifycassettes.

• This speeds up theadministration process.

Readers

The Reading Process

• 1. Primary excitation• 2. Secondary excitation• 3. Photomultiplication• 4. Digitisation• 5. Plate erasing

Excitation

Excitation is theelevation of the energylevels of a substancefrom its normal or“ground” state• There are two levels of excitation in CR plates:– Primary– Secondary

Primary Excitation

The x-rays pass through the upper layer to the phosphor.• The x-rays react with these molecules, causing inner shell electrons to become outer shell electrons.• Most of these drop back to their initial state (70%)• The rest (30%) get trapped in electron traps• These traps are caused by the addition of impurities into the Barium Fluoro Halide (i.e., Europium)• This is effectively stores the imagewithin the plate (the latent image)

Secondary Excitation

• The plate is removed from the cassette and passes by a laser

• beam. This beam reacts with the trapped electrons

Secondary ExcitationThe laser stimulates the phosphor plate enoughto release the trapped electrons to their orignalstate. This causes light to be emitted.• The light produced is channeled to aphotomultiplier using optics (lenses and mirrors)• The number of light photons produced bysecondary excitation is directly proportional tothe number of electrons that were trapped in thestorage phosphor.

A red laser is used for secondary excitation, but green light is emitted.There is then a filter for omitting non-green light (i.e., specular reflections from theprimary laser)

The Photomultiplier

Extremely sensitive detectors.These amplify or multiply light signals intosignals up to 100,000,000 times

Digitisation

A/DConvertorPMT

Plate Erasing

. A white light source, typically a fluorescent lamp with an attached colour filter, quickly erases the image plate.• Now the plate can be reused.

dr. mustafa zuhair mahmoud mr. ali alhailiy image critique نقد صورة الاشعّه 1

Documents

xray film

film construction

film base

laser film

subtraction film

cine film

video film

duplication film