Floyd Firestone

Developes the untrasonic machine call the "Reflectoscope"

Massachusetts Institute of Technology

electrical engineer office of Naval Research during WWII

University of Illinois

a role

Society of Vascular ultrasound

www.svunet.org

the concentration of force in an area

force / Area

the concentration of mass in a volume

mass(g) / volume (cm^3)

a measure of particle motion cm,mm

Speed * time

the time it takes for a wave to complete one cycle

NO, Source, .1 - .5us

1/f

the # of cycles per second.

NO, Source, 2 - 10MHz

1/t

Y/c=f

The strength of a wave measured in decibels. The difference between the max or min value and the average value of an accustic variable

 YES, Source, 1 - 3MPa

max or min variable value - average or 

max-min / 2

the rate of energy transfer or rate of work performed

YES, Source, 4-90mW

P=A^2

the concentration of energy in a sound beam. Beams power / cross section area

YES, Source, .01 - 300 w/cm^2

I=P(W)/area(cm^2)

the disctance of one cycle.

NO, Both, .15 - .8mm

Y=c/f (speed/freq)

the distance a sound wave travels through a medium in 1 sec.

NO, Medium, 1500 - 1600m/s

c=Y * f (p.speed=wl*freq)

a set of cycles that travel together

the amount of time it takes to complete one cycle. actual time from start to end of a pulse. "on time"

NO, source, .5 - 3.0 us

#of cyc * t or #of cyc/f 

time from the start of a pulse to the start of the next pulse. on time plus listening time. (temporal resolution, movie)

YES, Depth affected, 0.1 - 1.0ms

1/PRF (kHz)

the number of pulses per sec.

 YES, Depth affected, 1-10kHz

1/PRP (ms)

the distance occupied by one pulse. (image resolution)

NO, Both, 0.1 - 1.0mm

#of cyc * wavelength(mm)

% or fraction of time the system is transmitting a pulse.

YES, Depth affected, .2% - .5%

PD/PRP x 100

transmit, send or on time, 

receive, listening or off time.

axial 0.1mm-1mm

lateral 1.0mm-5mm

slice thickness 2.0mm-12mm

displays time along the horizontal axis and depth along the vertical axis. used to depict movement, especially in cardiac structures

1. artificial noise (plug)

2. absence of focusing

3. grating lobes (echoes travel at an angle to the main beam

4. side lobes (secondary echoes outside main beam)

1. noise caused by excess gain

(decrease gain, adjust TGC)

2. Banding caused by finely focused transduces or inaccurate TGC settings.

(change transducer/or TGC)

caused when sound strikes a strong interface gas or bowel.

solution:change to a higher frequency transducer, compress tissue gently to displace shadow, roll patient

caused by sound passing out a structure with acustic impedance that is markedly different from its neighbor causing a large amount of sound returned to the transducer. transducer placement over ribs.

 solution: try different acoustic windows, rotate patient, change frequency of transducer

occurs is a structure has a curved surface (liver/diaphragm)

solution:scan patient from another position

occurs when sound passses easily through an anechoic fluid-filled structure, without attenuation. bright echos posterior to structure.

solution:diminish the overall gain or slightly adjust the TGC, change to a higher frequency transducer

caused when an interface between a fluid-filled cyst and soft tissue is acutely angled and the beam strikes both the tissue and the fluid simultaneously. (gallbladder and cyst adjacent to one another)

solution:scan from a different angle

strong acustical interface from an air-bubble or metalliic cuture.

solution: scan from a different angle or rotate patient