Digital imaging week 3 cont. Flashcards
DICOM stands for
digital imaging and communication in medicine
DICOM is the standard for
handling, storing, printing and transmitting information in medical imaging
files can be exchanged between two entities that are capable of receiving images and patient data
DICOM files
in DICOM format
what provides some level of similarity in grayscale perception or appearance between display systems of different luminance
grayscale function
a part of DICOM that enables a piece of imaging equipment (a modality) to obtain details of patients and scheduled examinations electronically, avoiding the need to type such info x times
work list
ability to relay info between different multiple vendors and phone line communications
Interface
Part of workflow/ DICOM increases the speed of accessibility of images
delayed images
the rate of “missing” films has dropped from _ to _ since the implementation of PACS
8% to .3%
PACS stand for
picture Archiving and Communication Systems
HIS stand for
Hospital Information System
HIS aka
clinical Information System
comprehensive, integrated information system designed to manage the administrative, financial and clinical aspects of a hospital
HIS
HIS is used to achieve the best possible
support of patient care and administration by electronic data processing
RIS stands for
Radiology Information System
RIS is used by radiology departments to
store, manipulate and distribute patient radiological data and imagery
RIS contains
patient tracking and scheduling, result reporting and image tracking capabilities
images viewed on a computer are referred to as (MONITORS)
soft copy images
2 types of monitors used for digital image display (MONITORS)
Cathode Ray Tube (CRT)
Liquid Crystal DIsplay (LCD)
what regulates the image by using a light source behind the screen which shines on individual pixels controlling the amount of light transmitted
LCD monitor
LCD monitor is made of
Liquid crystal and amorphous silicon TFT’s are between glass plates on the front of the monitor which regulate pixel transparency
What does it allow?
pixels to change from black to transparent (full light)
Disadvantage for LCD’s
are harder to visualize the farther you get from the front of the monitor
what is the light given to the monitor while the ambient level is what is visualized by the tech
Luminance
The LCD monitors have a _ luminance and generates _ heat than a CRT monitor
higher
less
LCD’s also have _ , allowing for
less reflection
more ambient levels to be used
what is used to measure luminance
photometer
spatial resolution has the ability to
image small objects that have high subject contrast
contrast determined by the size, shape, & attenuating characteristics of subject (pt) and the energy of the beam
subject contrast
Spatial resolution formula
Matrix
spatial resolution in digital imaging is limited by the
size of the pixel
of pixels utilized in construction of digital image; imaging system to accurately display objets in 2 dimensions
spatial resolution on an image
Images with higher spatial resolution have a
greater # of pixels
The numeric value of the pixel is dependent
of the tissue composition
spatial resolution is expressed in
3 dimensions; x axis, y axis, and z axis (grayscale bit depth)
each pixel corresponds to a three dimensional volume of tissue called a
voxel
what type relationship between matrix size and resolution
direct relationship
each image is made of a
matrix
matrix contains
numerous pixels
the greater the matrix size, the greater the _
why?
resolution
a larger matrix provides smaller pixels
the matrix size is dependent on the
sampling frequency and the IR size
what are the two pixel sizes that are used in medical imaging
acquisition pixel size
display pixel size
Pixel size is dependent on the
sampling frequency
resolution is controlled by
matrix size
the larger the matrix size, the better the
spatial resolution
of photons striking the IP
Signal
A high SNR is _, a low SNR is _
desirable
undesirable
`the noisiest component of most digital systems is the
television camera
What does SNR stand for
Signal to Noise ratio
CNR means
contrast to noise ratio
the ability of an imaging modality to distinguish between various contrasts of an acquired image and the inherent noise in the image
CNR
what is desirable for CNR
a high CNR
measure of the total amount of contrast within the image; a high contrast image has a high frequency
frequency
subject contrast and acquired data contrast has a direct relationship; when subject contrast is high, acquired data contrast will also be high
contrast
disturbance in clarity
noise
systems ability to distinguish between similar tissues
contrast resolution
computer system must have _ range for optimal contrast resolution
sufficient dynamic range
the # of shades of gray that can be represented by the computer
dynamic range (wide latitude) of LCD monitor
the max. # of shades of gray that can be represented by a digital imaging system is the
numeric range of each pixel or “bit depth”
the actual dynamic range may be less than the
bit depth
the greater the dynamic range, the better the
contrast resolution
low dynamic range = _ contrast
high
High dynamic range= _ contrast which allows for a
low
wider latitude
what represents the # of bits used to reproduce image gray levels
bit depth
formula for Bit depth
8 bits=2 to the 8th power=256 gray scale levels
bit depth is determined by the _ based on the
manufacturer
imaging procedures the equipment is required for
random background info. that is detected but does not contribute to image quality
Noise
Noise appears as
quantum Mottle (grainy appearance)
Image noise has an _ relationship with contrast; increased noise
inverse
what are the 6 digital imaging quality factors
brightness gray scale resolution distortion exposure index noise
what is the intensity of light represented by each pixel on the IR ( replaces the word density)
brightness
difference in brightness between light and dark areas of an image
contrast
scatter is controlled by
correct use of grids
close collimation
optimal kV
what is recorded sharpness of structures
resolution
in addition to pixel size, _ is controlled by the display matrix
resolution
numeric value that represents the exposure that the IR received
exposure index
random disturbance that obscures image quality
noise
most manufactures have an exposure indicator that provides information on the average amount of radiation received is w/in “range” for _
acceptable range of exposure
post-processing manipulation
Kodak uses _ index
exposure
this # represents the exposure the IR represents the exposure the IR received
exposure index
must be w/in range to
post-process
Agfa uses
log-median exposure
what compares exposure level to baseline established for department
log median exposure
Fuji uses
S #
High S # means
low S # means
IR was underexposed
IP was overexposed
Phillips uses a
S #
High S # means
low S # means
IR was underexposed
IP was overexposed
