Digital

the blackening of film

the difference between adjacent densities.

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.

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.

the curve located the farthest to the left is the fastest film

• 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

analog to digital converter (ADC)

• Analog form-electons on detectors
• Digital- after it is has been converted by an ADC

Data processing done by the computer software.

• 1011
• 1 x 2^0=1
• 1 x 2^1=2
• 0 x 2^3=0
• 1x 2^4=16

=19

digital to analog converter (DAC)

analog

• -traditional xray machines
• -photostimulable phosphor storage imaging plates
• -CR Reader

CR has lower spatial resolution and higher contrast resolution

• Digital x-ray machine (new)
• flat panel detector

DR offers higher spatial resolution than CR. and film screen has the highest spatial resolution.

CR and DR have the widest

the radiograph looks normal under and over exposures do not effect DR

• 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

• 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!!

Input: keyboard, mice, microphones, bar code readers, touch screens, image scanners

Output: Monitors, printers, speakers

when a computer takes data from the user and processes it using a machine language of 1s and 0s known as binary code

1, 0

• - 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

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

• 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

it is a series of connections, controllers, and chips that create information highways of the computer

RAM. memory is measured in bytes

small rechargeable or lithium battery

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

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.

the power supply.

• DVD hols up to 7 times more data than does a CD.
• a DVD holds from 9.4 to 17 GB of data

• ROM- can only write
• R- can write 1 time but read a lot
• RW- can read and write many times

• Land-1- reflects
• Pit-0- does not reflect

• Soft- no sound
• Click- sound

is an individual controllable set of dot triads

many pixels

• 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

• 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.

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

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.

They are made up of many small fluorescent lights that are illuminated to form the color of the image.

CRT= leaset expensive. Bulky. more luminance than LCD

LCD= more expensive. less of a viewing angle. takes up less space

• Windows by Microsoft
• Macintosh OS
• UNIX/ Lunus

Real-time OS

2 or more objects sharing resources and information.

• LAN- local area network=least expensive and faster
• WAN- wide are network

• 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

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

• 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

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

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.

sends data only to those devices to which data is directed to. reads the data and selects the path intended to.

used in large networks. it is a physical WIRED connection from one network to the other.

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

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

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.

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

• Analog= information values that are continuous varying- can estimate.. film screen
• Digital= only can display information in few discrete values.. matrix number.. digital clock

Numbers that represent shades of gray X and Y

number of cycles per unit length, or the number of times a signal changes per unit length

its transfers spatial location domain into spatial frequency domain.

BC some operations perform task on one domain and not the other.. they each require a certain domain

• 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

single pixel. which makes a matrix. which makes a voxel

longer processing time, transfer time and storage requirements

as matrix size increases.. resolution increases

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.

bit depth increases, more shades of gray are able to be represented, thus contrast resolution increases.

• 1) scanning scans in raster patterns
• 2)sampling
• 3)quantization ADC assigns a number of each pixel which rep a shade of gray.

simply a graph of shades of gray of an image versus the number of pixels containing each shade of gray

a mapping function in which all pixels are changed to a new gray value.. may be used to increase or decrease contrast or brightness.

brightness decreases(image becomes darker)

calculating a new gray level for each pixel based on its original value

the output image pixel value is calculated using a small area of pixels surrounding the input pixel

it is a local processing operation.. and it is spatial frequency filtering the spatial location 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

allow the user to change the position or orientation of pixels

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

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

• Bandwidth- the data transfer rate of the network
• Node- individual device connected via the network
• Link-connectsion between nodes

• slowest- telephone modem
• fastest-fiber optics?

• 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

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

• 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

to reduce file size which reduces the storage requirements and transmission time.

• 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

• 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

the needs of the user

2 seconds..

DICOM---- HL7

allows users to remotely access images using internet browsing technology

fewer actual steps are involved in digital

Standard that allows different modalities within radiology to communicate with each other

provides a conformance statement that describes the capabilities of the device... look over worksheet

globally identifies each image set. to images do not get confused with other peoples images

standard that governs text based systems within health care so that communications between network components is possible

to facilitate communication between DICOM and HL7 compliant devices..plug and play

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

assure everything is working, good display function, updating passwords, system standards, ongoing educations to workers, communication with vendors, mapping workflow, quality control

• 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

changing data into information

contains both demographic info as well as images... order entry, clinal documenting, data repository, decision support, result reporting, and clinical messaging and email

a database that contains patient demographic information and assists in identifying and locating patient records

physical security, authentication, passwords, firewalls, antivirus software, spyware detection software, encryption, and wireless security measures