Digital & Film Radiography 1 Flashcards
What is the fundamental difference between digital and film radiography in terms of how they handle X-rays?
The main difference lies in how the X-ray beam is handled after patient interaction, specifically in terms of:
How the image is captured
How it’s converted into a visible image
How it’s stored
Digital has largely replaced film radiography, though some general dental practitioners and dental hospitals still use film.
What are the main types of X-ray receptors used in dental radiography and their characteristics?
two
Digital Receptors (multiple-use):
Phosphor plate
Solid-state sensor
Film Receptors (single-use):
Direct action film
Indirect action film
How do receptor sizes vary in dental radiography, and what are their common applications?
Receptor sizes vary by manufacturer but generally follow these patterns:
Size 0: Used for anterior periapicals
Size 2: Used for bitewings and posterior periapicals
Size 4: Used for occlusal radiographs
Phosphor plate sizings typically match film sizes.
Explain the concept of an “X-ray shadow” and how it relates to image formation.
An X-ray shadow is:
- Created when X-ray photons are attenuated as they pass through an object
- Contains the image “information” held by the remaining X-ray photons
- Is detected by the image receptor and used to create the final image
- Forms the basis for both digital and film radiography
How does a digital receptor convert X-ray shadow into a digital image?
The process involves:
- The receptor measures X-ray intensity in a defined grid pattern
- Each grid area is assigned a value (typically 0-255)
- Values correspond to different shades of grey (0 = black, 255 = white)
- These values are converted into pixels in the final image
What is the relationship between pixels and image quality in digital radiography?
- More pixels = higher resolution = better detail
- There’s a limit to useful resolution increase
- Higher resolution images require more storage space
- Manufacturing challenges limit how small pixels can be made
- Image quality improvement must be balanced against practical limitations
What is bit depth in digital radiography, and why is it important?
- Typically at least 8 bits in radiographs
- Determines number of available grey shades
- 8 bits allows for 256 (2^8) shades of grey
- More bits enable more subtle differentiation in tissue densities
- Affects the diagnostic quality of the image
What is DICOM and why is it important in medical imaging?
DICOM (Digital Imaging & Communications in Medicine) is:
- An international standard format for digital medical images
- Enables compatibility between different systems and manufacturers
- Stores both image data and important metadata (patient ID, exposure settings, date)
- Facilitates image transmission, storage, retrieval, printing, processing, and display
- Serves as a medical alternative to common formats like JPEG or GIF
Describe PACS and its main components in healthcare imaging.
PACS (Picture Archiving & Communication System):
Main Components:
Input from imaging modalities (radiography, CT, MRI, US)
Secure network for patient information transmission
Workstations for image interpretation
Archives for image and report storage
Implementation varies:
Scotland: nationwide NHS PACS
England: separate PACS for each NHS trust
Not connected to dental practices
Compare and contrast phosphor plates and solid-state sensors.
Phosphor Plates:
- Thinner, lighter, usually flexible
- Wireless design for stability and comfort
- Sensitive to room light
- Requires separate scanning process
- Handling similar to traditional film
Solid-State Sensors:
- Bulkier and rigid
- Usually wired
- Smaller active area for same physical size
- No room-light sensitivity issues
- More durable but more expensive
- Provides instant image creation
How does image creation work with phosphor plates?
two phases
The process occurs in two phases:
In Patient’s Mouth:
Receptor exposed to X-rays
Phosphor crystals excited, creating latent image
In Scanner:
3. Laser scans receptor
4. Excited crystals emit visible light
5. Light detection creates final digital image
What are the types of solid state sensors?
- CCD (charge-coupled device)
- CMOS (complimentary metal oxide semiconductor)
How do solid state sensors work?
- Connected to computer - Usually wired but can be wireless
- Latent image created & immediately read within the sensor itself
- Final image created virtually instantly
What is the identification dot?
located in corner of receptor to aid orientation of image
only effective if receptor was positioned correctly during exposure
What are the essential handling and infection control practices for digital receptors?
Infection Control:
Use purpose-made covers (single-use)
Different types for different receptors
Always disinfect between uses
Handling:
Hold by edges, not flat surfaces
Avoid scratches, tears, bending, creases
Prevent fingerprints
Damage affects all subsequent images
May render receptor unusable if damaged
