C9: Knobology Flashcards
what is multihertz
the ability to change the frequency without changing the probe you’re scanning with
what happens to the machine when scanning w/ harmonics on
when scanning w/ harmonics, the machine will send out a fundamental frequency and receive double that frequency when the echo returns
when should you be scanning w/ harmonics
whenever penetration allows…. harmonics is limited by depth
harmonics is like HD
what are the 2 items that are improved when you increase transmit power
signal to noise ratio and sensitivity
do TGC or gains improve signal to noise ratio
no… they compensate for attenuation
whats the function of LGCs
compensate for side to side non uniformities in image brightness due to different pathways
difference b/w TGC and LGC
LGC alters echo intensities from individual scan lines on the periphery of the image…. TGC compensate time delays or depth
function of the focus
adjusts the depth of near field to improve the lateral resolution
what is co-processing
a way to reduce the effect of a low frame rate due to multiple foci
what is persistance
‘frame averaging’… improved SNR and decreases FR
also gets rid of acoustic speckle
what are the 2 types of zoom
Write zoom: zooming before the image is written into memory… improves resolution
Read zoom: zooming after the image is committed to memory… degrades resolution
what are maps
a way of redistributing the number of shades of grey displayed on the monitor so that emphasis can be given to particular values…. maps can be used to brighten all low level echos but ignore others above a certain threshold
are maps a pre or post processing function
can be either
what is compound imaging
a combination of beam steering and frame averaging that can improve SNR and eliminate artifacts
whats another term for compound imaging
spatial compounding or SonoCT
