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what is film density?
the blackening of film
what is contrast?
the difference between adjacent densities.
what is film speed?
the amount of density a film produces for a given amount of exposure.. it takes less exposure to produce a given density with a faster film.
what is exposures latitude?
the range of exposures that produce densities in the diagnostic range.
-- as slope of the straight line portion increases, contrast increases, but exposure latitude decreases or becomes more narrow.
if the characteristic curve for 2 films were plotted on the same curve.. which would be the faster curve?
the curve located the farthest to the left is the fastest film
what are the film/ screen limitations?
- Density-- overexposed=to dark ; underexposed=to light
- contrast resolution-- atomic number of tissue must be greater than 10% in order to see
- fixed display--the display of a film on a view box is fixed.. in order to change must repeat
- archival requirements--manual handling for archival and retrieval.. lg storage needs
the signal is in analog form and must be converted to a digital form. what must convert it?
analog to digital converter (ADC)
What point is the image in analog or digital form?
- Analog form-electons on detectors
- Digital- after it is has been converted by an ADC
What is the binary system? and know how to convert it.
Data processing done by the computer software.
- 1 x 2^0=1
- 1 x 2^1=2
- 0 x 2^3=0
- 1x 2^4=16
When digital images must be first converted to an analog image before it can be displayed on a monitor. what accomplishes this?
digital to analog converter (DAC)
what form is an image that is displayed on a monitor? analog or digital?
What components make up CR?
- -traditional xray machines
- -photostimulable phosphor storage imaging plates
- -CR Reader
how does CR compare to film screen when talking about spatial resolution and contrast resolution?
CR has lower spatial resolution and higher contrast resolution
What components are necessary for DR?
- Digital x-ray machine (new)
- flat panel detector
When comparing DR to CR which offers the highest spatial resolution? and between that and film screen what has the highest of them all.
DR offers higher spatial resolution than CR. and film screen has the highest spatial resolution.
between CR, DR, and film/screen what has the widest exposure latitude?
CR and DR have the widest
when you over or under exposure digital what does the radiograph look like?
the radiograph looks normal under and over exposures do not effect DR
what is IMACS?
- image management and communication systems.. AKA PACS
- - it is in charge of sending the image from the acquisition modality to the monitor for display and diagnosis
what is QA/QC and what is special about it?
- activities are designed to ensure patient dose is as low as reasonable achievable to ensure good quality and reduce cost
- -- VERY MFG SPECIFIC IN DIGITAL
film screen - all machines do the same steps to check machine and processor, but when dealing with digital it is VERY MFG specific to how to check the machine and processor!!
What are some Input devices:
What are some Output devices:
Input: keyboard, mice, microphones, bar code readers, touch screens, image scanners
Output: Monitors, printers, speakers
What is Binary code?
when a computer takes data from the user and processes it using a machine language of 1s and 0s known as binary code
if the transistor circuit is closed and current passes through it is assigned what value number? and if the circuit is open and current does not pass through, it is assigned a value of what?
What are the 2 major functions of the box are?
- - to hold all of the components in a relatively cool, clean and safe environment
- - to shield the outside environment from the radio frequencies being emitted by the electronic components of the computer
What is the brain of the computer and what does it do?
the CPU aka microprocessor.. small chip found on the motherboard.. and its main job is to read date from storage, manipulate the date and move the data back to storage or send it to external devices
What does the BIOS do?
- it is a basic input/ and output system
- - runs the startup diagnostic system
- - makes sure all the peripherals are functioning properly
- - oversees the basic function of receiving and interpreting signals
- - acts as the intermediary between the operating system and hardware
What is the Bus?
it is a series of connections, controllers, and chips that create information highways of the computer
What is temporary memory AKA ? and what is memory measured in?
RAM. memory is measured in bytes
What does CMOS use to retain information about the PC's hardware while the computer is turned off?
small rechargeable or lithium battery
What does a sound card do? and what does it interpret?
it contains all of the circuitry for recording and reproducing sound on the PC.. it interprets many different files types such as the WAV files.. MP3 files and MIDI files
What does the network card do?
it enables the PC to connect to other PCs that are on the same network.. it can come as an expansion card plugged into a slot or part of the motherboard.
When there is a power surge, what takes the blunt force of the power?
the power supply.
How does a DVD compare to a CD when dealing with storage capacity?
- DVD hols up to 7 times more data than does a CD.
- a DVD holds from 9.4 to 17 GB of data
What are the 3 main types of CD/DVD drives?
- ROM- can only write
- R- can write 1 time but read a lot
- RW- can read and write many times
what is a Land and Pit?
- Land-1- reflects
- Pit-0- does not reflect
What are the 2 basic types of keyboards?
- Soft- no sound
- Click- sound
What is a pixel?
is an individual controllable set of dot triads
What is a matrix?
What is dot pitch? and how does it relate to resolution?
- Dot pitch is the measurement of how close the dots are located to one another within a pixel.
- the smaller the dot pitch of a display, the finer the resolution
what is refresh rate(vertical scanning rate) ? and how does it relate to flicker?
- refresh rate is a measure of how fast the monitor rewrites the screen or the number of times that the image is redrawn on the display each second.
- refresh rate helps control the flicker is seen by the user... the higher the refresh rate the less flicker seen.
How does CRT create the image?
consists of a cathode and anode within a vacuum tube. cathode boils off a cloud of electrons, and then a potential difference is placed on the tube. a stream of electrons is sent across to the anode, which is the case of the monitor is a sheet of glass coated with a phosphor layer. electrons then strike the phosphor on the glass. causing glass to emit a color based intensity where most electrons strike. .. does this all in a raster scan pattern
How does LCD emit an image?
LCD produces images by shining or reflecting light through a layer of liquid crystal and a series of color filters. when a current is applied to the liquid crystal. it aligns and allows light in varying intensities through to the next layer of glass through color filters. Light forms the colors and images seen on display.
How does plasma screens emit an image?
They are made up of many small fluorescent lights that are illuminated to form the color of the image.
between CRT and LCD how do they compare?
CRT= leaset expensive. Bulky. more luminance than LCD
LCD= more expensive. less of a viewing angle. takes up less space
What are the 3 major operating systems?
- Windows by Microsoft
- Macintosh OS
- UNIX/ Lunus
What TYPE of operating system of modern X-ray equipment use?
What is a network?
2 or more objects sharing resources and information.
What is the difference between a LAN and a WAN?
- LAN- local area network=least expensive and faster
- WAN- wide are network
What are the typical classifications of networks? and do they do?
- Peer to Peer- each computer on the network is considered equal.
- Server/ Client based - SERVER-centralized computer (SERVER) controls the operations, files, and sometimes the programs= distributes everything
- CLIENT- server returns only the results back to the client - only what is needed/requested
What is a sever? Thin Client? and thick Client?
server= computer that manages resources for other computers, servers, and networked devices
Thin Client= a component found on a network that requests services and resources from a server
Thick Client= computer that can work independently from the network
What are the different types of cables?
- Coaxial= similar to tv cable center conduction wire surrounded by insulation and grounded shield and braided wire.
- Twisted Pair= wire similar to telephone wire. used for LAN
- Fiberoptic= uses glass threads to transmit data on a network- easily to damage
- Wireless= used infrared or radio freq. no cabled are needed but each device must contain wireless transmitters/receiver.. wall thickness and distance must be taken into account
What is a network interface card? and what does it do?
It provides the interface between the computer and the network medium.. it provides physical connections between the network and computer to establish and manage data
What does a network hub do?
send and receives data to all devices connected to it.(connects several pieces of equip).. does not know what it is or where it goes simply just sends it.
What does a network switch do?
sends data only to those devices to which data is directed to. reads the data and selects the path intended to.
What does a network bridge do?
used in large networks. it is a physical WIRED connection from one network to the other.
What does network router do?
reads portion of the messages and directs them to there intended target. even if target is on a separate network and uses a different network protocol
what is an IP address?
devices used to communicate. the address is made up of 4 octets that range from 0 to 255.. the first sets indicates the network class
What is the OSI a model of?
open systems interconnection model need to understand the basic principles of network connections. bc of this mode different types of networks can be connected and transmit data from one another.
What is unique about a Bus, Ring, token ring, Star, and mesh?
BUS-a network in which all devices are physically attached to and listen for communication on one single wire. if one wire is down everything is down- devices connected in a circle.
RING- devices are connected in a circle. each device goes around in circle always the same direction .. if there is break in the circle it goes down
TOKEN RING- connected in a circle. when computers are ready to send a message the computer send an empty toke and passes it to be filled with the message.. can be ignored.
STAR- connected to a central hub or switch. most common
MESH- multiple passageways. what internet uses
What is the difference between Analog and Digital?
- Analog= information values that are continuous varying- can estimate.. film screen
- Digital= only can display information in few discrete values.. matrix number.. digital clock
What is spatial location domain?
Numbers that represent shades of gray X and Y
What is spatial Frequency domain?
number of cycles per unit length, or the number of times a signal changes per unit length
How is the Fourier transform used?
its transfers spatial location domain into spatial frequency domain.
Why does we have to transfer from one domain to the other?
BC some operations perform task on one domain and not the other.. they each require a certain domain
What is Image enhancement, image restoration, image analysis and image compression?
- Image enhancement- change the image so that it meets the demands of viewers usually it facilitates the diagnoses made by the radiologist.
- Image restoration- improves quality of images that have been degraded. filtering a blurred image to make it sharper
- Image analysis- allows for measurements and statistic as well as image segmentation
- Image compression- reduces the size of the image file which will then reduce transfer time and storage needs
What does matrix pixel and voxel mean?
single pixel. which makes a matrix. which makes a voxel
What happens when matrix size increases?
longer processing time, transfer time and storage requirements
How does matrix size relate to spatial resolution?
as matrix size increases.. resolution increases
how does matrix size, FOV, and spatial resolution relate?
matrix size increase.. FOV remains the same.. pixel size decreases.. spatial resolution increases
spatial resolution also increases when FOV decreases and matrix size remains the same.
What does bit depth do to contrast resolution?
bit depth increases, more shades of gray are able to be represented, thus contrast resolution increases.
What are the steps in digitizing an image? how does a ADC fit into theses steps
- 1) scanning scans in raster patterns
- 3)quantization ADC assigns a number of each pixel which rep a shade of gray.
What is a histogram?
simply a graph of shades of gray of an image versus the number of pixels containing each shade of gray
what is a Look Up Table (LUT)?
a mapping function in which all pixels are changed to a new gray value.. may be used to increase or decrease contrast or brightness.
as window leveling increases what does brightness do?
brightness decreases(image becomes darker)
How are point processing operations performed?
calculating a new gray level for each pixel based on its original value
How are local processing operations performed?
the output image pixel value is calculated using a small area of pixels surrounding the input pixel
What is convolution? and an example of it.
it is a local processing operation.. and it is spatial frequency filtering the spatial location domain
How are global processing operations done? and what is an example of it? how must we get the data into frequency domain.
- they use all the pixels in the input image to calculate the gray level for one pixel in the output image.
- ex) spatial frequency filtering in the frequency domain
- -- Fourier transform
What do geometric operations do?
allow the user to change the position or orientation of pixels
What is the application service provider?
they provide on the service provider company to do all the work.. they pay per month or per use. there is not IT requirements of the hospital. good for small hospitals
What is the difference between inherently digital modalities and frame grabbing modalities?
Inherently digital modalities- are those that use a scanner to acquire the image date at full spatial resolution and grayscale
frame grabbing modalities- digitize the analog signal obtained from the image receptor
what is Bandwidth? Node? and Link?
- Bandwidth- the data transfer rate of the network
- Node- individual device connected via the network
- Link-connectsion between nodes
what is the slowest link and what is the fastest link?
- slowest- telephone modem
- fastest-fiber optics?
what is privacy? authentication? integrity?
- Privacy- ensures access only to those people for whom the information is intended
- Authentication-allows the message recipient to verify the identity of the sender and the sender to verify the identity of the recipient
- Integrity- ensures that the information received has not been altered deliberately or accidentally
What is the difference between short and long term? and how can they be connected
short term storage is usually provided by RAID it consist of jukebox containg sever magnetic or optical disks that are controlled by a robotic arm
Long term- digital linear tape (DLT) are often used for long term
can be connected by storage area network (SAN) uses a fiber optic network
What is online? nearline? and offline? and what types of media do they use?
- Online- storage can not be removed and provides immediate access to images (RAM)
- Nearline- storage is removable and has a longer retrieval time (RAID)
- Offline- refers to stroage devices that must be retrieved by a person and loaded onto a drive cheapest and largest capacity
What is the purpose of the compression?
to reduce file size which reduces the storage requirements and transmission time.
what is compression ratio? and what type compression do radiologists read from?
- compression ration is ratio of the storage capacity required for the original image compared to storage capacity required for compressed files.
- they read from lossless compression
what is the difference between portrait and landscape?
- portrait- pixels are displayed in the vertical directions than in the horizontal direction
- Landscape- pixels are displayed in the horizontal directions rather that vertical directions
what is workstation quality matched to?
the needs of the user
what is the desirable display time?
what is PACS image based systems standard? what is RIS text based system starndard?
What does a web server do?
allows users to remotely access images using internet browsing technology
How does the number of steps in workflow for film/screen compare to digital?
fewer actual steps are involved in digital
What is DICOM?
Standard that allows different modalities within radiology to communicate with each other
What is a DICOM conformance statement?
provides a conformance statement that describes the capabilities of the device... look over worksheet
What is the purpose of the UID?
globally identifies each image set. to images do not get confused with other peoples images
What is HL7?
standard that governs text based systems within health care so that communications between network components is possible
What is the purpose of integration health enterprise (IHE)?
to facilitate communication between DICOM and HL7 compliant devices..plug and play
What are FDA and HIPAA Regulations?
FDA- require mfg to submit a pre market approval and registration of both the product and facility
HIPAA- deals with the use of disclosure of protected health information-- makes system security
What are typical actives of PACS administrator?
assure everything is working, good display function, updating passwords, system standards, ongoing educations to workers, communication with vendors, mapping workflow, quality control
What is a Modem? what is the difference between modulation and demodulation?
- A modem is used to send and receive signals from computers
- modulation- converting digital signal from the computer into analog to be sent over communication ling to another computer
- demodulation- analog converted to digital
What is informatics?
changing data into information
what is a electronic health record (EHR)? and what are its components
contains both demographic info as well as images... order entry, clinal documenting, data repository, decision support, result reporting, and clinical messaging and email
What is a master patient index (MPI)?
a database that contains patient demographic information and assists in identifying and locating patient records
What are some common security measures?
physical security, authentication, passwords, firewalls, antivirus software, spyware detection software, encryption, and wireless security measures