Imaging Flashcards
How many dimensions can an ultrasound beam be focussed in
3
How many beams make up A mode
1
Difference between linear and curvilinear array
Linear is straight curvilinear get curved apart deeper the structure
Why might an image appear darker at a depth of 5cm in B mode
Attenuation
How does the probe create images
Piezoelectric crystals change shape with changing voltage it receives
What is M mode
Motion mode, one line vs time
How many dimensions is B mode
2D
How many frames per second to create an image in B mode
10-30
Orientation of beams in a curvilinear array?
Perpendicular to probes surface (90degs)
What does gain do?
Amp pixels in image (you can select at which depth you want to amplify)
What is colour Doppler duplex
Image plus colour doppler
What does change in freq mean Doppler
Towards probe increase freq, decrease freq away from probe
Are red blood cell frequency shifts audible
Yes
How to optimise Doppler with probe
Change orientation
Can ultrasound detect RBCs
Yes
How is the no. of RBCs moving displayed
Grey level
What is waveform made up of?
Freq shift/velocity vs time
Are colour ultrasound beams perpendicular to pulsed Doppler beams?
No
What angle would you steer pulsed Doppler beam for zero Doppler shift?
Perpendicular to flow in vessels
What type of issue is aliasing?
Sampling
Is aliasing always problematic?
No, as can be used to show high freq e.g stenosis
What does the waveform of a vein look like?
No pulsatility
The flow direction component of colour Doppler is parallel to the colour beams true or false
True
