What shape is a pixel in a digital image? Flashcards
Square
What shape is a pixel in a digital image?
Square
What is image resolution?
The size of an image pixels by pixels.
What is a binary system?
A system using 1s and 0s to represent data
How many bits are in a byte?
8
What is bit depth?
The number of bits used for data in one pixel
Name a limiting factor in bit depth.
Storage capacity, processing speed
What bit depth is required to produce an image with 8 possible colours?
3
how many colours can a 6 bit image show
64
how many channels are in a typical colour image
3
Approximately how many colours can be shown by a modern monitor?
16 million
What is the difference between a bitonal and greyscale image?
Bitonal is black and white only whereas grey scale has tones between.
what are the three numbers you need to know to calculate file size
width height and bit depth
how many byte are in a megabyte
1 million
how many bytes are in a kilobyte
8 million
pacs stands for
picture archiving and communication system
how many years do we keep images for an adult
8 years
how many years do we keep images for a child
till their 25th birthday
Name three devices for storing digital data
USB stick, floppy disk, hard drive, tape media, cd etc
name another device for storing digital data
USB stick, floppy disk, hard drive, tape media, cd etc
name three types of optical disks
blue ray, CDs and DVD
name three disadvantages of optical disks
Damage, need for optical drive, small storage capacity, cannot be rewritten, can be lost.
what type of storage media is SD
Flash/solid state.
name two advantages of USB sticks
Mobile, cheap, work with many systems.
name two disadvantages of USB sticks
Easy to corrupt, easy to lose, formatting issues, small capacity.
where is tape media used in medical image storage
Long term storage off site
why do hard drives use so much power
Because they are always spinning when on.
what is the major problem with hard drives
They have limited lives.
what is a SSD
Solid state drive.
what does RAID stand for
Redundant array of inexpensive disks
what is the advantage of RAID
A hard drive can fail but data is not lost
what does DICOM stand for
Digital Imaging and Communications in Medicine
name three pieces of information that are stored (other than image) that are stored in DICOM file
Patient name, DOB, Patient Number, Machine used for acquisition, Date, Hospital Site, Time
etc.
What does ADC stand for?
Analogue to digital converter
What are the two types of DR system?
indirect and direct x ray
why do you need a erasure cycle in a CR reader
Because not all the electrons are released from the energy trap by the laser.
name one advantage of CR over DR
Cheaper, less complex/prone to fault, more people trained in it, compatible with existing
buckys, highly flexible, lightweight detectors.
name another advantage of CR over DR
Cheaper, less complex/prone to fault, more people trained in it, compatible with existing
buckys, highly flexible, lightweight detectors.
what colour of light comes out of a CR plate
Blue or violet
what are NIPS
Needle imaging plates
what does CCD stand for
Charge coupled device
what does TFT array stand for
Thin film transistor
Computed Radiography (CR
Uses an imaging plate coated with storage phosphors
Electrons are promoted to the conduction band of the phosphor by the x-ray photons
Released when they are supplied with energy
Energy comes in the form of a laser reader
Upon being released light is emitted
Light is captured and read by a photodiode
