SPI review Flashcards
typical values for period
0.06-0.5 micro sec
typical values of frequency
2-15 MHz
Amplitude can have units of:
pascals, grams/cm^3, cm, dB
typical values for intensity
.001-100 watts/cm^2
typical value for wavelength
0.1-0.8mm
typical values for propagation speed
1500-1600 m/s
equation for wavelength
wavelength (mm)= 1.54 (mm/micro sec)/ frequency (MHz)
typical values for pulse duration
.5-3 micro sec
2-4 cycles
pulse duration=
cycles in pulse x period
typical values for PRP
100 micro sec to 1 msec
typical values of PRF
1000 to 10000 Hz
typical value of duty factor
0.1 % to 1 %
.001 to .01
Duty factor =
pulse duration/ PRP
What typ of imaging has high PRF, high duty factor, and short PRP?
shallow
typical values of spatial pulse length
0.1 to 1 mm
spatial pulse length=
number of cycles x wavelength
what type of imaging has low PRF, low duty factor, and long PRP?
deep
intensity most relevent to tissue heating?
SPTA
decibles have what type of scale?
relative
units for attenuation coefficient
dB/cm
attenuation coefficient in soft tissue
.5 dB/cm/MHz
impedance is ______ not _________.
calculated, not measured
typical values for impedance
1,250,000 and 1,750,000 rayls
refraction requires?
oblique incidence and different speeds
snells law
sine (transmission angle)=prop speed 2
_______________________________
sine (incident angle)=prop speed 1
A property of certain materials to create a voltage when pressure is applied?
piezoelectric effect
Q factor =
resonant freq/bandwidth
axial resolution equation in soft tissue
.77 x # cycles in pulse/ freq
A-mode
xaxis: depth
yaxis: amplitude
B-mode
xaxis: depth
zaxis: brightness
m-mode
xaxis: time
yaxis: depth
sector
mechanical steering
fixed focusing
1 crystal
image loss
mechanical
rectangular
no steering
fixed focusing
200 rectangular crystals
vert line dropout
linear switched
sector
electronic steering
fixed focusing
200 rectangular crystals
poor steering and focusing
linear phased array
sector
mechanical steering
electronic focusing
5 ring crystals
horiz line dropout
annular phased
blunted sector
no steering
fixed focusing
200 rectangular crystals
vert line dropout
convex sequential
blunted sector
electronic steering
electronic focusing
200 rectangular crystals
poor steering and focusing
convex phased
flat top sector
electonic steering
electronic focusing
200 rectangular crystals
poor steering and focusing
vector
frame rate is determined by what two factors?
speed of sound in a medium and depth of view
what is a beam former?
creates the firing patterns for phased array systems
The science of identifying and measuring those characteristics of an US field which are especially relevent to its potential for producing biological effects?
Dosimetry
Mechanistic approach is cause and effect, what is the emperical approach?
exposure and response
_______ beams are less likely to cause temp elevation in tissues.
focused
intesity limits for unfocused sound and focused sound?
unfocused: 100 mW/cm^2
focused: 1000 mW/cm^2
microbubbles get _______ during rarefractions. cavitation is more likely to occur in ______ than other tissues.
bigger
lung
Mechanical index is higher, more likely to produce cavitation with:
peak rarefraction pressure and lower frequency
bulk modulus also means what?
stiffness
