Digital Radiography Flashcards
What is the difference between digital and film radiography?
Difference in the x-ray beam is dealt with after it has interacted with the patient
What different x-ray receptors are used in digital radiography?
Phosphor plate
Solid-state sensor
What sizes do phosphor plates come in and what is each size for?
Size 0 - anterior periapicals
Size 2 - bitewings, posterior periapicals
Size 4 - occlusal radiographs
How is an x-ray shadow converted into an image?
When x-ray beam passes through an object some of the x-ray photons are attenuated, creating an x-ray shadow
The shadow is basically the image information held by the x-ray photons after the beam has passed through an object
The image receptor detects this shadow and uses it to create an image
Describe a digital image
Displayed as a grid of pixels
Each pixel can only display one colour at a time
The more pixels you have, the more detailed/accurate your image can be
Describe the greyscale bit depth
Radiographs typically are processed in at least 8 bits
Meaning there are 256 shades of grey
What is DICOM?
Digital Imaging and Communications in Medicine
International standard format for handling digital medical images
Essentially an alternative to JPED, GIF etc
How are digital images managed?
PACS
Picture Archiving and Communication System
What affects how digital radiographs are viewed?
Environment - subdued lighting, avoid glare
Monitor - clean, adequate display resolution, high enough brightness, suitable contrast level
What is the SMPTE test pattern?
Society of Motion Picture and Television Engineers
Can be used to assess the resolution, contrast and brightness of your monitors
Describe image creation using phosphor plates when inside the patient’s mouth
Receptor exposed to x-ray beam
Phosphor crystals in receptor excited by the x-ray energy resulting in the creation of a latent image
Describe image creation using phosphor plates when inside the scanner
Receptor scanned by a lapsed
The laser energy causes the excited phosphor crystals to emit visible light
This light is detected and creates the digital image
What are the types of solid-state sensory?
CCD - charge-coupled device
CMOS - complimentary metal oxide semiconductor
How is an image created using solid-state sensory?
Latent image created and immediately read within the sensor itself
Final image created virtually instantly
What is an identification dot?
Located in the corner of receptor to aid orientation of image
How is cross-infection control implemented in intra-oral receptors?
Receptors have single use covers to prevent saliva contamination
Receptor still disinfected between use
What are the advantages of phosphor plates?
Thinner, lighter and flexible
Wireless
More stable and comfortable
What are the disadvantages of phosphor plates?
Variable room-light sensitivity
Risk of impaired image
Latent image needs to be processed in scanner separately
Handling similar to film
What are the advantages of solid-state sensors?
Bulky and rigid
More durable
Need replaced less often
No issues with room-light control
What are the disadvantages of solid-state sensory?
Usually wired
Smaller active area
More expensive
What are the advantages of digital radiography?
No need for chemical processing
Easy storage and archiving of images
Easy back-up of images
Images can be integrated into patient records if digital
Easy sharing of images
What are the disadvantages of digital radiography?
Worse resolution
Requires good computer monitors for optimal viewing
Risk of data corruption (solved by backing up)
Hard copy print-outs generally have lower image quality
Image enhancement can create misleading images
