Radiographic Exposures Final Flashcards
While DICOM is concerned primarily with images from the digital image acquisition modalities, HL-7 is concerned mainly with textual information from the __ and __.
HIS and RIS
Since PACS contains confidential patient data and information, it is essential that they be secured; hence,___ is of central importance in a digital hospital as well as in a PACS environment.
data security
Direct conversion digital radiography systems use detectors that convert x-Rays directly into___________ ___________.
electric signals
The conversion of analog signals into digital data is the function of the_____.
ADC Analog-to-digital-converter
What class of digital image processing allows measurements and statistics to be performed, as well as image segmentation, feature extraction and classification of objects?
Image analysis
Define voxel:
(volume element) the information contained in a volume of tissue that is converted into numerical values and expressed in pixels.
What does the width of a histogram imply regarding image contrast?
Wide-more contrast
Narrow-less contrast
When the PSP IP is erased by exposing it to a high intensity light beam to get rid of any residual latent image? (At what point in the digital image processing cycle?)
After laser scanning
What is likely to occur if there is substantial extraneous exposure on the plate?
histogram analysis error
Which exposure causes the system to rescale the image as if the plate is actually underexposed? (high-intensity, low-intensity?)
low-intensity exposure
In digital imaging what has more of an effect on image contrast than the kVp?
processing algorithm
Because of increased sensitivity to scatter radiation? The kVp should not exceed__for any nongrid radiography, including chest.
80
Acquiring one image on the smallest plate available avoids which recognition error?
exposure field recognition error
___occurs when a large number of pixels will be at the maximum digital value (black) so that there is no signal difference in the very high exposure areas, resulting in a loss of anatomical structures in that region.
Saturation
What is the standard expression for the receptor’s contribution to recorded detail?
Spatial resolution
What is the name of the structure that will detect the light from the CsI scintillator I the indirect flat-panel TFT detector?
sensing area
What indirect flat-panel TFT digital detectors, what is used to first convert X-Ray photons into the light photons?
Scintillator layer (CsI)
Which concept examines the response of the latent image receptor (screen-film detector or digital detector) to the radiation falling upon it?
exposure latitude
Which type of image is obtained initially from the detector and contains artifacts due to bad detector elements?
flat-field image
Too much edge enhancement produces image noise and creates ________.
“halo” effect
Define spatial resolution:
sharpness of an image
Define/describe the purpose of: modulation transfer function.
(MTF) mathematical function that measures the ability of a detector to transfer it’s spatial resolution characteristics to the image.
An MTF of ___ represents a perfect transfer of spatial and contrast information.
1
Which performance characteristic deals with the efficiency of a detector to convert the x-radiation signal at its entrance window into a useful image signal?
DQE