39 terms

ch11 geometric factors affecting RD

recorded detail
sharpness of the lines of the image
good recorded detail
sharp lines
poor recorded detail
fuzzy or blurry edge around lines
recorded detail also referred to as...
spatial resolution
another term for spatial resolution
digital imaging recorded detail
spatial resolution determined by...
matrix size, pixel size, and gray scale bit depth
7 factors affecting recorded detail
SID, OID, Focal Spot Size
Screen & Film speed, Contact of screen & film
Motion (stat orders from surgery follow cutting mistakes)
properties of image visibility
photographic properties - density and contrast
properties of image sharpness
geometric properties - distortion and recorded detail
visibility of detail is controlled by...
everything that affects density, contrast, and distortion
define visibility of detail
overall quality of the finished radiograph; term used to describe how well the image is seen
measurement of recorded detail;
ability of an imaging system to record 2 adjacent structures as separate structures
resolution grid
device used to measure resolution; flat piece of metal with slits cut into it
line pair
one metal line & slit or space next to it
unit of measurement for line pairs
line pairs per millimeter (lp/mm)
edge gradient
term that describes the amount of recorded detail; refers to how sharp the edge of an object is on film
what happens to recorded detail when edge gradient increases?
recorded detail increases
what happens to recorded detail when unsharpness increases?
recorded detail decreases
borders of a fine structure are not optimally seen
blur, unsharpness, imperfect, unsharp shadowing surrounding umbra
main part of the image; distinctly sharp area of a shadow
geometric factors that affect RD
focal spot size, OID, SID
what happens to RD when focal spot size increases?
RD decreases
what is relationship between focal spot size and RD?
indirectly proportional
true or false. a small OID produces better recorded detail
what happens to RD when OID is increased?
relationship between OID and RD
indirectly proportional
what happens to penumbra and resolution as SID increases?
penumbra reduced, resolution increases
increasing source to image receptor distance does what to amount of geometric unsharpness?
true or false. a small SID produces better RD
increased SID does what to RD?
increased, thus directly proportional
recorded detail & size distortion are affected by what?
as distortion increases, what happens to RD and what is relationship?
RD decreases, thus inversely related
film and screen are classified by..
a slow speed/ screen system will demonstrate what resolution quality than a faster one?
better resolution
relationship between screen speed and RD
inversely related
unsharpness formula
u = focal spot size x OID/ SOD
note: SOD = SID - OID
recorded detail improves with what?
small focal spot size, short OID, long SID
radiographs show more unsharpness with what?
large focal spot, long OID, short SID