Card Set Information
An electronic version of the radiologist’s reading room and the file room:
Electrical signals from CR and DR are:
similar for both systems
Preprocessing takes place in the:
computer whre algorithms determine histogram
Postprocessing is done by:
A graphical representation of exposure values collected form the imaging plate:
Exposure data recognition processes only the:
optimal density exposure range
The data recognition program searches for anatomy recorded on the imaging plate by finding the ____ and then elimitating the ____.
collimation edges; scatter outside the collimation
Low kVp gives a ____ histogram while high kVp gives a ____ histogram.
On the histogram graph, the y-axis is the ____ and the x-axis is the ____.
# of pixels for each exposure; amount of exosure
The shape of a histogram is _____ specific.
Aliasing results in:
When exposure is greater or less than what is needed to produce an image, ____ occurs.
A table of the luminance values derived during image acquisition:
look-up table (LUT)
LUT is used to:
LUT can be graphed by placing the original values on the __axis and the new values on the ___ axis.
With a LUT, the brightness can be increased or decreased by:
moving the line up or down the y-axis
Latitude is also called:
margin of error
Latitude refers to the ____ that can be used and stillr esult in a diagnostic quality image.
range of exposure
The exposure latitude for digital imaging receptors is ___ than thatof screen/film exposures due to ____.
greater; dynamic range
Histograms show a wide range of exposure because of:
automatic resscaling of the pixels
More than 50% below ideal exposure results in:
More than 200% above ideal exposure results in:
What feature increases latitude while preserving contrast and vitually eliminates detail loss in dense tissues?
enhanced visualization image processing (EVP)
What is MTF?
Modulation transfer function
The ability of a system to record available spatial frequencies is known as:
Modulation transfer function
The sum of the components in a recording system cannot be:
greater than the system as a whole
What quantifies the contribution of each system component to the overall efficiency of the entire system?
A perfect system would have an MTF of:
1 or 100%
Phosphor light spreads which reduces system ____. The more light spread, the lower the ____.
efficiency, MTF/image quality
The initial digital image appears linear when graphed because:
all shades of gray are visible
Image contrast is controlled by using a parameter that changes the _____ of the _____.
steepness; exposure gradient
Detail or sharpness is referred to as:
spatial frequency resolution
Sharpness control is referred to as:
spatial frequency processing
Two major types of spatial frequency filtering:
edge enhancement and smoothing
____ occurs when fewer pixels in the neighborhood are included in the signal average.
After the signal is obtained for each pixel, the signals are ____ to shorten processing time and storage.
The more pixels involved in the averaging, the ____ the image appears.
The signal strength of one pixel is averaged witht he strength of ____.
adjacent pixels, or neighborhood pixels
High pass filtering is accomplished by:
amplifying frequencies of areas of interest
High pass filtering increases ____ and ____ and is useful for enhancing ___ structures, but can be noisy.
contrast, edge enhancement, large
Smoothing, also known as ____, occurs by averaging each pixels frequency with surrounding pixel values to remove ____.
low-pass filtering, high-frequency noise
Low-pass filtering is useful for viewing small structures such as:
fine bone tissues
The most common image processing parameters are those for:
brightness and contrast
____ controls how light or dark and image is and ____ controls the contrast.
Window level, window width
Unexposed borders around the collimation edges results in:
Removing the white unexposed borders results in an oerall smaller number of ____ and reduces the amount of ____.
pixels, information to be stored
Two basic types of magnification techniques in digital systems:
magnifying glass and zoom
The first PACS were used int he early ____ and generally served ____.
1980's, one single modality
PACS can be broekn into 3 parts:
image acquisition, display workstations, and archive servers
First modality of PACS:
An archive server is the ____ for PACS.
The central part of the PACS; houses all of the historic data along with the current data being generated:
The hardware and softwear infrastructure of a computer system is the :
In a PACS. the system architecture normally consists of:
acquisition devices, display workstations, and an image management system.
Three common PACS architectures:
client/server based, distributed systems, web-based systems
In a client/server based system, images are sent directly to the ____ after acquisition and are centrally located.
In this system, acquisition modalities send the images to a designated reading station and possibly to review stations, then sent to the archive server once the images have been read:
Distribuited or Stand-alone systems
Most interactive part of the PACS:
The brain of the archive system; contains the master database, controls movement of images and interfaces withthe RIS and HIS:
Two major types of film digitizers:
laser and CCD; both equal in quality but CCD cheaper
Common uses for film digitizers:
teleradiology, comparison with outside or old films, film duplication, computer aided diagnosis
Two major types of imagers (printers):
wet (chemical) laser printers and dry laser imagers
A plan for the systemic obsservation and assessment of the different aspects of a project service or facility to make certain that standards of quality are being met:
A comprehensive set of activities designed to monitor and maintain systems that produce a procuct:
Three major categories of Quality Control:
Acceptance testing, rountine maintenance, and error maintenance
PACS QC activities:
display quality form monitor and film, processing speed, network transfer speed, and data integrity
Who requires compliance with standards of practice to ensure quality in any imaging system?
american college of radiology