lecture 3- computer systems, networks, display parameters

PACS (picture archiving and communication system)

centralizes mgt of medical images, allows secure storage and access of digital images and reports

stores locally or online; integrates w other systems

DICOM (digital imaging and communications in medicine)

“universal language”

allows storing, transmitting, viewing medical images and related data

exchange of images; allows integration of devices into PACS

RIS (radiology information system)

networked software system for managing medical images and associated data

allows efficient workflow to radiology department

support pt mgt, billing, data archiving

EHR (electronic health record)

single record that can be accessed by multiple healthcare providers

update in real time

comprehensive info; diagnoses, images, clinical notes, etc

potential issues of EHR

inconsistency bw providers, outages, security concerns

HIS (hospital information system)

aka HMS

administrative, financial, clinical functions

computer networks

system of connected devices that can share resources and communicate with each other

can be wired or wireless; provides data security

many computer networks are what type?

star network

display parameters

pixel, voxel

pixel (picture element)

2 dimensional (height, width)

single point on a flat image

voxel

3d, tiny cube of data within a 3d image; slice thickness in CT or MRI (depth)

in a PET scan, each pixel on the 2d image corresponds to…

the 3d volume of the scanned object

an image matrix is

pixels arranged into rows and columns- a 2 dimensional grid

a 128 × 128 matrix contains how many pixels?

16,384

pixel dimensions depend on

both the field of view and matrix dimensions

at the same FOV, a larger matrix prod. smaller pixels

display parameters: resolution

spatial resolution describes ability to distinguish small, closely spaced structures

smaller pixels = finer spatial sampling

image resolution also depends on what three things?

imaging system, patient motion, image processing

increasing matrix size alone does not..

guarantee better resolution

a coarse matrix can obscure ___, and a finer matrix can preserve ___

obscure detail through pixelation;

preserve detail already present in the acquired data

matrix selection must balance

spatial sampling, count statistics, storage requirements

pixel width =

horizontal FOV/number of columns

pixel height =

vertical FOV/number of rows

voxel volume =

pixel width x pixel height x voxel depth

for square pixels, voxel volume =

(FOV / matrix dimensions)² x voxel depth

pixel and voxel dimensions are measured in what?

pixel: mm

voxel volume: mm³

bit depth

number of bits used to indicate the color of a single pixel

each pixel’s color is stored as a

binary value

the number of bits determines

how many different colors can be displayed

more bits =

more precise colors

higher bit depth allows for

smoother gradients and more accurate color representation

bit/color depth: 3 bit has how many colors

8 colors

bit/color depth: 8 bit has how many colors

256

bit/color depth: 24 bit has how many colors

16,777,216 colors

how to calculate storage size: what needs to be known

matrix size, acquisition mode/ bits per pixel/ bit depth

word mode is how many bits/bytes?

16 bits, 2 bytes

how to calc storage size

total pixel count (matrix size)

multiply total pixels by bit depth (to get total bits)

convert to right units (bits to bytes) if necessary

if mult frames/images, multiply by number of images