narrative

sunglowcitrineΠολεοδομικά Έργα

15 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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Digital Image


Digital Image Qualities are affected by brightness, contrast, noise, and recorded detail.
Brightness is controlled by window level which
adjusts the mid
-
point of pixel values represented in the
image

on the monitor. Contrast is controlled by many factors. Increasing kVp, decreases contrast,
giving contrast a long scale; increasing OID, increases contrast giving a high scale of contrast; increasing
grid ratio, increases contrast; increasing filtratio
n, decreases contrast; increasing collimation, increases
contrast; a thicker patient decreases contrast.
Angling the tube or patient part, the anode heel effect,

motion
, focal spot size, SID, and mAs do not have any effect on contrast. Noise can be class
ified as
either black or white noise. Black noise can be scatter, background, or extreme overexposure. White
noise is underexposure also known as Quantum Mottle. Increasing OID, increases distortion size;
increasing SID, decreases distortion
; thicker pa
tient size increases distortion; tube angle elongates and
angling the body part foreshortens. Anode heel effect, motion, collimation, filtration, grid ration, focal
spot size, kVp, and mAs have no effect on recorded detail.



Film Image


Film Image Qualit
ies are affected by density, contrast, recorded detail, and distortion.
Density
and contrast are controlled by many factors. Increasing mAs, increases density; increasing kVp,
increases density; increasing OID, decreases density; increasing SID, decrease
s density; increasing grid
ratio, decreases density; increasing filtration, decreases density; faster film
-
screen combinations
increases density; increasing collimation, decreases density; cathode end has more density than the
anode end; thicker patients d
ecrease density. Increasing kVp, decreases contrast, giving contrast a long
scale; increasing OID, increases contrast giving a high scale of contrast; increasing grid ratio, increases
contrast; increasing filtration, decreases contrast; increasing collim
ation, increases contrast; a thicker
patient decreases contrast. Increasing OID, decreases detail; increasing SID, increases detail; increasing
focal spot size, decreases detail; faster film
-
screen combination decreases detail; increasing motion,
decrease
s detail; thicker patient decreases detail; angling tube and body part will decrease detail.
.
Increasing OID, increases distortion size; increasing SID, decreases distortion; thicker patient size
increases distortion; tube angle elongates and angling th
e body part foreshortens.