physics 2nd sem. 25/30 Flashcards
storing images for reference
image archiving
image analysis includes:
traditional image quality factors such as:
density/image receptor exposure
contrast
recorded detail
distortion
when some factors act upon each other and cause issues
the pyramid problem
what are the 5 factors that can determine whether or not an image is acceptable
tech factor selection
subject density
contrast
pathology
film processing
what are the 4 major steps to the diagnostic problem-solving strategy
narrow the field by finding any suspicious areas
use info found to form a hypothesis
information seeking-test hypothesis
evaluate hypothesis…. solution??
important facts about ACCEPTANCE LIMIT CURVES
overexposure Errors are more acceptable than under because they can be corrected more easily via adding brightness or extracting info digitally
narrow limit = ⬆️ repeat rate
acceptance limits can vary by radiologists
wide limits make us careless
why can’t DIAGNOSTIC IMAGE Quality be defined?
too many variables
what is the primary purpose of an image?
to provide information about a medical condition
what are the three steps to the image critique method?
classify the image - is it within dx acceptance limits?
determine cause of the problem- if not acceptable determine if it is because tech factors, procedure, equipment
recommend Corrective action
if the image critique determines the cause is a technical factor problem …..what does this mean?
either you can’t see detail ( 1 ) or there is not enough detail ( geometric- definition, sharpness, resolution)
geometric problems are further classified as ….
recorded detail or distortion
problems with recorded detail are caused by:
focal spot size, SID, OID, IR used and pt motion
problems with distortion are categorized as
size ( Sid. OID) or shape distortion ( improper tube/part/IR alignment
image acquisition is _________ to each imaging modality.
unique
if the problem is a procedural factor it is caused by….
pt positioning or preparation
if the problem is determined to be an equipment malfunction it is caused by …..
quality control
incomplete plate erasure in the CR system or extreme over exposure can cause
phantom or ghost images
dust or material on an IR can cause …
light spots
what causes a white line along the length of travel on the image?
dust
reductions in resolution overall or in a specific area which tend to be accompanied by contrast scale reductions are called…
dropout artifacts
what causes drop out artifacts?
A build up of dust in the CR or laser unit on the light gate, mirror or reflective surface
what causes fogging in the digital system
background radiation due to sensitivity
what is another word for quantum mottle?
reticulation
when the manufacturer sets up a system they have certain settings to avoid these
algorithm artifacts
uneven scanning or transfer of film through and imaging system can cause…
laser film transport artifact
improper collimation , improper technique, beam alignment, scatter and extreme density differences can cause this
histogram analysis
what causes nonparallel collimation ?
when edges are not parallel to the sides of the imaging plate
poor grid alignment can cause these two things to occur
grid lines or poor image quality
