mA-Z
mAs is the primary factor controlling...
quantity
50 mA for 0.012 seconds = _____mAs
0.6 mAs
3/4 sec = ______ sec in decimal form
0.75 sec
insufficient mAs can result in an image with what
quantum mottle
when mAs is doubled, what happens to the spectrum emission curve
the amplitude doubles
what 2 qualities are image quality broken into?
photograpghic properties (visibility)
geometric properties (recognizability)
500 mA at ______ msec = 250 mAs
500 msec
You accidentally select 0.02 sec at 300 mA. What mAs will be delivered?
300 mA × 0.02 s = 6 mAs
mAs must be increased/decreased by __________ to be visible to the human eye
25-35%
how does increasing mAs affect patient dose
increases dose
unit of measurement of tube current
ampere (amp)
mA= 1/1000 amp
100mA at .2sec will produce the same exposure as _____ mA at 0.05sec
800 mA
A technique uses 20 mAs at 100 mA. What exposure time is needed?
Time = 20 mAs ÷ 100 mA = 0.20 s.
how to eliminate quantum mottle from an image
increase mAs
what effect will cutting the mAs in half on the resulting IR exposure
half the exposure intensity
formulas
mAs=
time=
mA=
mA x time
mAs/ mA
mAs/ time
_____mA at .2sec will double the exposure intensity produced by 200mA at 0.05sec
100mA
Your patient moved on the first exposure: 25 mAs at 0.25 sec. You want to shorten time to 0.1 sec. What new mA maintains the same mAs?
New mA = 25 mAs ÷ 0.10 s = 250 mA.
digital processing allows for ________ of inaccurate mAs selection
correction
-computer re scales exposure intensity and contrast
mAs and exposure intensity are ________ proportional
directly
describe two situations where a short exposure time would be advantageous
pt is unable to cooperate
breathing is erratic
480mA at _____sec will produce half the exposure intensity of 800mA at 0.003sec
0.0025 sec
The technique chart calls for 8 mAs. If your only time options are 0.01, 0.02, and 0.04 sec, what mA settings would work?
Options to get 8 mAs:
0.01 s → 8 ÷ 0.01 = 800 mA
0.02 s → 8 ÷ 0.02 = 400 mA
0.04 s → 8 ÷ 0.04 = 200 mA
law of reciprocity
any combination of mA and time that equals the same mAs, will produce the same intensity (density)
what machines use s numbers
fuji