QUESTIONS AND SOLUTIONS RATED A+
✔✔methods with highest thermal risk/ lowest mech risk - ✔✔CW and PW spectral
✔✔Methods with lowest thermal risk/ highest mech risk - ✔✔B mode
✔✔Isppa - ✔✔mech risk
✔✔highest Isppa - ✔✔190W/cm^2
✔✔Ispta - ✔✔thermal risk
✔✔highest Ispta - ✔✔720mW/cm^2
✔✔AIUM TI recommendations - ✔✔11-14wks spectral only with clear benefit
TI >0.7 only 5-10min max
✔✔snell's law - ✔✔if prop speed increases at media border, refracted angle is greater
than incident
✔✔Huygen's Principle - ✔✔waves are a result of many small wavelets at transducer
face based on constructive interference
✔✔Aperture - ✔✔number/ width of crystals creating a beam
✔✔FR - ✔✔=PRF/#lines per frame
✔✔Frame Rate - ✔✔frames created per second
✔✔Frame Time - ✔✔amount of time taken to create one frame
✔✔Nyquist Limit - ✔✔=PRF/2
✔✔hydrostatic pressure - ✔✔=pgh
✔✔Re - ✔✔=v2rp/n
✔✔Reynold's turbulence - ✔✔2000
✔✔continuity eq - ✔✔Q=va
✔✔Bernoulli's - ✔✔pressure decreases with velocity increase
, ✔✔Pressure gradient (eq) - ✔✔=4v^2
✔✔Doppler shift (eqn) - ✔✔=2fvcos0/c
✔✔Poiseuille's - ✔✔Q=pressure grad/resistance
✔✔Resistance (eq) - ✔✔8Ln/pi r^4
✔✔RI - ✔✔=PSV-EDV/PSV
✔✔PI - ✔✔=PSV-EDV/mean v
✔✔aliasing - ✔✔wrap around due to undersampling of doppler shifts
✔✔Tips to get rid of alias - ✔✔1. inc PRF
2. Dec freq
3. Move baseline
4. Inc angle
5. Dec depth
6. Use CW
✔✔Types of attenuation - ✔✔1. absorption
2. reflection
3. scatter
✔✔refraction - ✔✔redirection of sound beam due to oblique incidence at a border with
different prop speeds
✔✔Resonant Freq Factors - ✔✔prop speed of element
thickness of element
✔✔3 Benefits of broad bandwidth - ✔✔1. multi hz imaging
2. freq tuning
3. THI
✔✔Bandwidth THI - ✔✔dec ax res due to long SPL
✔✔Pulse Inversion THI - ✔✔maintains ax res but dec temp res due to two out of phase
pulses instead of one long one
✔✔THI - ✔✔based on non-lin prop of sound in most intense portion of beam which
creates second order harmonics in tissues