Modern Imaging Equipment Flashcards
Any imaging technique has a number of stages
Image acquisition
Imaging processing
Image display
Image storage
What is digital imaging
Technological advancement
Any method of imaging that creates an image that can be viewed/ stored on computer
Digital imaging advantages
Increased work flow
No need for processing chemicals
Can be transferred manipulated and enhanced digitally
Less radiation exposure
How an radiographic image is made
- Anatomy is positioned
- X ray exposure is made
- Beam is attenuated by patient and captured by receptor
- Analogue data to digital data
Analogue
Continuous signal that contains time varying quantities/ constant fluctuation
E.g. kitchen clock
Digital
Discrete value at each sampling point
E.g. digital wristwatch
Digital imaging methods
- CR
(Cassette based) - DR
(Image detector system)
Both use computers
What is CR
Method of capturing radiographic data from conventional X ray unit
Processing data digitally
To produce radiographic image
CR main components
CR Cassette
Imaging plate
CR reader
CR Cassette
A protective container for imaging plate
Available range of sizes smallest = wrist Cr 18x24cm largest = cxr 35x43cm
Icons identify correct orientation + barcode to link Cassette/ imaging plate and examination to patient examination
CR imaging plate
Found within Cassette
Stores the image ( X-ray photons excite phosphate atoms)
Stored energy dissipates quickly so should be out into Cr reader quickly
Cr imaging plates are sensitive to scattered radiation = avoid exposure, should be stored in optimal location regularly rotated
Regularly erased to prevent a build up of background signal
Imaging plate several layers
Protective layer = thin, plastic, protects phosphor layer
Phosphor layer = contains photostimulable phosphor = traps electrons during exposure of radiation
Reflective layer = released light in forward direction when in Cr reader
Base layer = semi rigid strengthen image plate
Backing layer == protects back of Cassette
CR reader
After exposure, CR Cassette is placed into CR reader - removes the imaging plates
Imaging plate is scanned with laser, release stores electrons
Analogue data into digital data for computer
Once read by laser imaging plate is exposed to white light, it erases the data from the plate so it can be used again
CR reader major components
Drive mechanism = move the imaging plate through scanning process
Optical system = laser, optical filters
Photomultiplier
Analogue- digital converter ADC
DR
Describes images recorded on an electronically readable device
DR is hard wired to image processing system = combines image acquisition & display
Image acquisition =(CR two stage process)
But I’m DR, detectors have combined image capture and read out capability
