Digital & Film Radiography 2 Flashcards
Describe in detail the components of an intra-oral film packet, from outside to inside, and explain the purpose of each layer.
Outer wrapper:
Prevents saliva from entering the packet
Indicates the front side of the packet for proper positioning
Protective black paper:
Shields film from light exposure
Prevents damage from finger contact
Additional protection against saliva
Radiographic film:
Core component where image formation occurs
Sensitive to both X-ray and visible light photons
Lead foil (backmost layer):
Absorbs excess X-ray photons from:
- Primary beam passing through the film
- Scattered radiation from patient tissues
Explain the detailed structure of radiographic film and how each layer contributes to image formation.
Protective coating (outermost):
Made of clear gelatin
Protects emulsion from mechanical damage
Emulsion layer:
Contains silver halide crystals in gelatin binder
Present on both sides of the base
Crystals act as “pixels” in final image
Generally provides higher resolution than digital
Adhesive layer:
Bonds emulsion to plastic base
Transparent plastic base:
Provides structural support for other layers
Maintains film integrity
How do silver halide crystals function in radiographic film, and what happens to them during processing?
1.Initial state:
Microscopic crystals embedded in gelatin
Sensitive to both X-ray and visible light photons
2.Exposure phase:
Crystals become sensitized when struck by X-ray/light photons
Create latent (invisible) image
3.Processing phase:
Sensitized crystals: Convert to black metallic silver (dark areas)
Non-sensitized crystals: Removed completely (light areas)
This differential processing creates image contrast
What determines film speed, and how does it impact radiographic imaging?
Definition:
Amount of X-ray exposure needed for adequate image
Higher speed = less radiation required
Determining factors:
Number of silver halide crystals
Size of silver halide crystals
Trade-offs:
Larger crystals = faster film but lower image quality
Smaller crystals = slower film but better detail
Practical implications:
E-speed film needs half the exposure of D-speed
F-speed is 20% faster than E-speed
Changing speeds requires either:
Professional recalibration of X-ray unit
Installation of primary beam filter
Explain the purpose, function, and limitations of intensifying screens in radiography.
Usage:
Used with “indirect action” film
Applied in extra-oral radiographs (panoramic, cephalometric)
Too bulky for intra-oral use
Function:
Release visible light when exposed to X-rays
Light creates latent image on film
Reduces required radiation dose
Limitations:
Reduces image detail compared to direct exposure
Becoming obsolete with digital technology
Trade-off between dose reduction and image quality
Detail the steps and requirements for proper film processing, including both manual and automated methods.
Developing:
Converts sensitized crystals to black silver
Temperature and concentration critical
First wash:
Removes residual developer
Fixing:
Removes unsensitized crystals
Hardens emulsion
Second wash:
Removes fixer residue
Drying:
Prepares film for handling/storage
Manual vs Automated Processing
Manual Processing:
Requires darkroom with absolute light-tightness
Precise chemical concentrations
Specific temperature control
Timed immersion
Proper ventilation
Chemical disposal protocols
Automated Processing:
Self-contained machine operation
More consistent results
Faster processing time
Higher initial cost
Uses sponge rollers instead of water washing
More controlled environment
Disadvantages and Advantages of Self-Developing Films?
Advantages
No darkroom or processing facilities required
Faster (eg. 1 minute)
Disadvantages
Poorer image quality
Image deteriorates more rapidly over time
No lead foil
Easily bent
Difficult to use in positioning holders
Relatively expensive
What is the reaction affected by?
time
temperature
solution concetration
What are common processing issues and their causes in film radiography?
at each stage
Developing Problems:
Pale images caused by:
Insufficient radiation exposure
Premature removal from developer
Cold solution
Diluted/old solution
Dark images caused by opposite conditions
Fixing Problems:
Inadequate fixing results in:
Greenish-yellow or milky appearance
Image browning over time
Washing Problems:
Insufficient washing allows:
Continued developer action
Continued fixer action
Progressive image deterioration
Compare the advantages and disadvantages of digital versus film radiography in clinical practice.
film Advantages/Disadvantages are the opposite of these points
Advantages of Digital:
Processing:
No chemical processing needed
Immediate image availability
Management:
Easy storage and archiving
Simple backup creation
Integration with digital records
Efficient sharing/transfer
Manipulation:
Post-processing capabilities
Enhancement options
Disadvantages of Digital:
Technical Limitations:
Lower resolution
Risk of pixelation
Requires specialized monitors
Practical Concerns:
Risk of data corruption
Poor quality printouts
Potential for misleading enhancement
Higher initial cost
