2/14/17 Lecture #4 Flashcards
What are three things used to capture radiographic images?
- Digital sensor
- Film
- Phosphor plate
What are the two things that film is composed of?
- Emulsion
- Base
What is the working part of the emulsion in film?
-Silver halide grains
What does the emulsion of film coat?
-Both sides of base
What are the two parts that the emulsion consists of?
- Silver halide grains
- Suspension vehicle
When a silver halide crystal is chemically altered when struck by an x-ray photon it creates what type of image?
-Latent image
What type of exposure is associated with intraoral films?
-Direct exposure
What are three things that sheet films are used for?
- Panographic
- TMJ
- Cephalometric
What does the indirect sheet film use to get exposed?
-Intensifying screen
Where do you put the dot found on the film packet?
-Towards the occlusal surface in PAs
What color of the film packet should be oriented toward the source of the radiation?
-Plain side
The bump found on the x-ray film is raised towards what?
-Source of radiation
When films are mounted the bumps are facing what?
-The person viewing the film
Intraoral film size 0 is used for what?
-Pedo
Intraoral film size 1 is used for what?
-Adult anterior
Intraoral film size 2 is used for what?
-Adult posterior
Intraoral film size 3 is used for what?
-Long posterior
Intraoral film size 4 is used for what?
Occlusal
The ____ the crystals of silver halide the ______ the film speed
- Larger
- Faster
What is the slowest film?
-C
What is the fastest film?
-F
If you have larger crystals that give faster film do you have higher or lower resolution?
-Lower
What type of screen do cassettes contain?
-Intensifying screens
What is the purpose of intensifying screens?
-Lowers the amount of radiation to expose film
Do you get decreased in or increased definition when you use intensifying screens?
-Decreased definition
Radiographic density on film is determined by what?
-How many photons strike the film emulsion
What do grids do?
-Reduce scatter radiation
What process of developing film is when it converts exposed silver halide crystals (latent image) to metallic silver grains?
-Developer
After you have sent the film through the developer what is the next step?
-Wash for 30 seconds and removes developer
What process of developing film is: removes undeveloped silver halide crystals, hardens and shrinks emulsion?
Fixer
After you have used fixer in the developing process what is the next step?
-Wash to remove fixer
After washing to remove the fixer what is the final step in film development?
-Drying to allow the film to be safe to handle and archive
T/F For every 10 degrees celsius increases in temperature the rate of reaction doubles in film development
True
If you have 68 degrees while developing and it takes 5 minutes to develop how long will it take at 78 degrees?
2 1/2 minutes
T/F Lower patient exposure is an advantage of digital
True
What type of digital sensor connects directly to a computer and provides immediate images?
-Direct
What type of digital sensor is a reusable phosphor plate that is used instead of film.
-Indirect
What are three types of digital sensors?
- PSP
- CCD
- CMOS
What format do most digital units acquire and store the electronic data?
-DICOM (Digital Image and Communication in Medicine)
How many shades of gray can the human eye detect?
60 shades
How many shades of gray can computer monitors display?
-256 shades
What type of resolution is the ability to distinguish different densities in an image?
-Contrast Resolution
What type of resolution is the ability to distinguish fine detail in an image and is usually measured by ability to distinguish individual line pairs?
-Spatial resolution
T/F Spatial resolution is theoretically better than digital images
True
What term describes the ability to capture a range of exposures, for example, the ability to capture subtle differences in tissue density from gingiva to enamel?
-Sensor latitiude
What has greater sensor latitude than other sensors or films?
-PSP
What is sensor sensitivity?
-The ability to respond to small amounts of radiation
How do sensors work?
-The X-ray photons are converted to visible light as they hit the CsI scintillator
In sensors when light photons hits the silicon layer what happens?
-Release electrons
Analog to digital conversion takes place as the _____ charge is removed and the electrons pass through the embedded circuit before returning to the silicon layer.
Positive
