Physics Quiz 1

V = F X W

Increase density = decrease velocity

Increase compressibility = decrease velocity

Increase stiffness = increase velocity

The number of pulses emitted per second

Unit: Hertz

Typical range: 1-10KHz

The time from the beginning of one pulse to the beginning of the next

Unit: Seconds

Time of producing and receiving echo

PRP = 1/PRF

The time during which the pulse actually occurs

Unit: Seconds

• PD = number of cycles X period
• PD = number of cycles / Frequency

The fraction of time the ultrasound pulse is being emitted during one pulse repetition period

The DF of Continuous Wave is 1(100%)

The DF of Pulse Wave is less than 1

DF = Pulse Duration/ Pulse Repetition Period

The length or space over which an ultrasound pulse occurs

Units : meter, mm

• Affects greatly of image resoultion
• -long SPL will interact with a tissue interface longer than a short SPL, which as blurred image

Fresnel Zone

Closer to the transducer

Collimated beam

Fraunhofer Zone

Farther to the transducer

Divergence of the beam

Ultrasound frequency and transducer diameter affect the length of near field and divergence of far field

Increase frequency and transducer diameter = increase near field length and decrease divergence of far field

Increase Transducer diameter = (frequency is constant) length of near field increase and decrease far field divergence