Processing Display and Storage

raw data

whatever the system obtained before any sort of processing occured

when does pre processing occyre

before image is displayed

what is pre-processing

automatic fast function of imaging system that makes graph of exposure data we have and compares it to a preset forum and cleans it up

Analog-to-DIgital Converter

digitation of electronic signalh

how many digits are in the biinary code

2 (0 & 1)

Digitization process

scanning

receptor is divided into a matrix of pixels

Digitization process

sampling

measures each pixel for the amount of exposure

Digitization process

quantization

assigns a numerical value to each density

dynamic range

number of shades an imaging system can produce

dynamic range is identified by…

bit depth of each picel

increase in display of greater shades in grey has ______ dynamic range and _____ contrast resoluition

greater; better

as exposure increase _____ increases

densities

body

useful range of densities

toe

underexposed

shoulder

overexposed

digital exposure lattitude is

wide

in digital exposure you can underexposure by%

50%

in digital exposure you can overexpose by:

400%

when are pixel values counted

during sampling

how are values arranged in a bar graph

according to frequency

Histogram analysis

prior

reference histograms within system

Histogram analysis

neural

based on exams taken, it will start averaging so that it is more specific to your department

Exposure field recognition (EFR)

identifies edges of exposed area; recognizes sudden change in pixel values

What are the requirements for exposure field recognition

• accurate collimation

• alignment of exposure field with the image receptor

exposure field recognition errors

• histogram analysis error

• re-mapping error

landmark identification

identifies edges of anatomical part; densities outside of anatomical landmarks are discarded prior to histogram analysis

value of interest

determines what info can be removed and can staylo

lookup table

biggest influence for contrast with digital imaging due to anatomic rescaling (fixes contrast)

rescaling

evens out exposure and remaps it based on lookup table

flat fielding

even out densities so that it is more uniformed; smooths out tiles

interpolation

eliminates missing pixel information

segmentation

ability of PSP plate to identify multiple exposures on one plate

soft marker

annotated markerhar

hard marker

lead marker

image inversion

reverse colors

region of interest

calculated pixel value for a selected area of interest

magnifiction

zooming in on an image

edge enhancement

enhances edge of structureswhat i

what is the effect of using too much edge enhancement

• halo effect

• loss of detail

High pass filterig

makes the edges of the structure stand out to the background; introduces some noise

equalization

compression of dynamic range; removes lightest and darkest exposures

masking

blacking out white background

smoothing

noise reduction; suppresses mottle on image (decreases contrast)

subtraction

leaving some structures in an image while eliminating others

low passing filters

computer only keeps low frequency in an image

window width and level

adjusts darkness and contrastwi

window width

number of shades displayed

Window level

where on the scale the window is set

computer processing unit (CPU)

“brains” or “Control Panel” of computer system

Motherboard

main circuit board

software

application that make certain operations ‘run’ on a computer system

computer network

chain of computers and components that all work in conjunction with one another

Health Level 7 (HL7)

standardized computer language for transmission of hospital information

Digital Imaging and Communications in Medicine (DICOM)

standarized computer language for transmission of images

What enables imaging systems from different manufacturers to communicate

DICOM

DICOM Commands

• retrieve (query) images for a specific patient

• worklist of images

• send images

• print images

DICOM Header

series of text info attached to the image

local area network (LAN)

transmit images within a hospital

Wide area network (WAN)

multiple LAN interconnected (spans large area)

Information Flow

• HIS

• RIS

• Acquisition Workstation

• PACS

• Diagnostic Workstation

HIS

store and display hospital and patient info (umbrella)

RIS

specific to radiology

Teleradiology

remote transmission and viewing images

storage classification

online

data stored on hard drives with quick access and transfer times

Storage classification

nearline

jukebox uses robotic arms to retrieve tapes and insert them into a drive to read or write data

storage classification

offline

a removable tape or optical media that is manually stored and retrieved

storage short-term

online; active

storage long term

nearline; archive

byte

combined group of 8-bits

Random Access Memory (RAM)

data can be stored at random (‘active storage’)

Read only Memory (ROM)

contains info supplied by manufactured

Redundant array of independent discs (RAID)

large storage system

secondary memory

• flash drive

• juke box

Picture Archiving & Communications System (PACS)

electronic network for communication between image modalities, display stations. & storage

PACS advantage

• archiving capability

• transmit or move images throughout facility

• ability of system to pre-fetch studies

average digital radiography study

about 5 MB

CRT Monitor

converts electrical signal into visible image

spatial resolution of CRT Monitor

1-2 lp/mm

Plasma Monitor

modern display monitor

pixel layer

made up of 3

• red

• green

• blue