Digital and film radiography Flashcards
What size receptor is used for which radiograph?
0 = anterior periapical
2 = BW, posterior periapical
4 = occlusal
How does the x-ray shadow form an image on the digital receptor?
digital receptor split into grid, each square given a value depending on intensity of x-ray beam
Value corresponds to intensity, 0 = black and 255= white
Benefit and con of more pixels?
pro = better resolution
Con = more storage space needed so increased cost
How many shades of grey are available in radiograph?
8 bit so 256 shades
What is the format for digital images - radiographs?
DICOM
Digital imaging and communications in medicine
What does PACS stand for?
picture archive and communication system
What two types of sensors are there? What are main differences?
Solid state sensors - connected to computer via wire
Phosphor plates - not connected to computer and must be passed through scanner to be read
How do phosphor plates produce an image?
phosphor crystals excited by x-ray photons to create a latent image
Then scanned by laser, phosphor crystals emit visible light which is detected
How do SSS produce image?
Latent image created and instantly read within sensor itself
How is cross infection control maintained
Purpose made covered for receptors to prevent saliva contamination, still disinfected between use
Pros for phosphor plates vs SSS?
Lighter and more flexible
Cheaper
Wireless and more comfortable
Larger active area
Pros for SSS vs PP?
No issue with room light control
More durable, replaced less often
Does not require to be put through a scanner
What are the components and function of the intra oral film packet?
Film - sensitive to photons and light, interact with emulsion to provide latent image that can be viewed after chemical processing
Protective black paper to prevent light exposure
Lead foil to absorb excess x-ray photons
Outer wrapper to prevent saliva ingress
What absorbs the x-ray photons in the film?
silver halide crystals embedded in gelatin binder
What is film speed?
relates amount of x-ray exposure needed to produce adequate image
Higher speed = less radiation needed
Affected by number n size of silver halide crystals
