Screen Film Radiology
Screen Film Radiology
Screen Film Radiology
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MAGNIFICATION EFFECT<br />
long OID<br />
short OID<br />
There is always a magnification, but the same object may appear with different size<br />
depending on its location in the body<br />
The differential magnification is also reduced by using long SOD<br />
and image receptor close to the patient<br />
SIGNAL TO NOISE RATIO (SNR)<br />
Less<br />
Noise<br />
SNR =<br />
IMPROVING SNR<br />
Signal<br />
Inherent object contrast<br />
Amplitude of the signal (difference in contrast versus the local background)<br />
Amplitude of the noise (random fluctuation of the signal)<br />
The better the SNR<br />
The better the visibility<br />
LOSS OF CONTRAST<br />
RESOLUTION<br />
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