Ultrasound Physics (SPI) Review Questions + Answers Graded A+

Ultrasound Physics (SPI) Review
Definition of Duty Factor? - ✔️✔️The percentage of time the pulse is on
-Unitless (just a number)
-For continuous wave, duty factor = 100%
-For pulsed wave, Duty Factor is less than 1%

What are the two types of Ultrasound Waves? - ✔️✔️1.) Electromagnetic - Wave
travels through a vacuum.
2.) Mechanical - Wave must travel through a medium.

Meaning of Anechoic? - ✔️✔️Dark, less echos.

Meaning of Echogenic? - ✔️✔️Full of echoes.

Meaning of Hyperechoic? - ✔️✔️More echoes than adjacent tissue.

Meaning of Hypoechoic? - ✔️✔️Less Echoes than adjacent tissue.

Meaning of Isoechoic? - ✔️✔️Similar/same echoes than adjacent tissue.

Meaning of Homogenous? - ✔️✔️Uniform Texture. (smooth)

Meaning of Heterogenous? - ✔️✔️Different levels of echogenicity.

Definition of Wavelength? - ✔️✔️The length of one cycle.
-Denoted by (Lamda)

Unit for Wavelength? - ✔️✔️m, cm, mm

Definition of Propagation Speed? - ✔️✔️The speed at which sound travels through a
medium

Unit for Propagation Speed? - ✔️✔️m/s or mm/microseconds

Propagation Speed depends on? - ✔️✔️Density, Stiffness.

Definition of Density? - ✔️✔️Concentration of matter.
-Inversely related to prop speed.

Definition of Stiffness aka "Bulk Modulus"? - ✔️✔️The resistance of a medium to
compression.
-Stiffness is directly proportional to speed.

,What are two kinds of Mechanical Waves? - ✔️✔️A.) Transverse
B.) Longitudinal

Ultrasound images are made up of typically how many scan lines? - ✔️✔️128 - 256
scan lines.
(more the better resolution)

Scanning format for Sector (shape)? - ✔️✔️Pie Shaped, Scan lines originate from the
same location and spread out as they travel.
.
/\
/\

Scanning format for Modified Sector? - ✔️✔️Scan lines originate from different points,
but close together.
///\\\
/// \\\

Scanning format for Linear? - ✔️✔️Scan lines originate from different points and travel
parallel to each other. |||||||
|||||||

Definition of PRF? - ✔️✔️-Pulse Repetition Frequency
-The number of cycles per second. (including listening time)

Units for PRF? - ✔️✔️Hz, kHz, MHz

Formula for PRF? - ✔️✔️PRP=__1__
PRF

Definition of PRP? - ✔️✔️-Pulsed Repetition Period
-The time from the beginning of one pulse to the beginning of the next pulse.

Units for PRP? - ✔️✔️s, ms, microseconds

Formula for PRP? - ✔️✔️PRP=__1__
PRF

Definition of Pulse Duration? - ✔️✔️The time the pulse is on.

Unit for Pulse Duration? - ✔️✔️Microseconds

, Formula for Pulse Duration? - ✔️✔️PD = n x T

Definition of SPL? - ✔️✔️-Spatial Pulse Length
-The length of one pulse

Unit for SPL? - ✔️✔️mm

Formula for SPL? - ✔️✔️SPL = n x (lamda) aka Wavelength


Formula for Duty Factor? - ✔️✔️DF = __PD__
PRP

Definition for Bandwidth? - ✔️✔️The range of frequencies found in a pulse.
-The shorter the pulse, more frequencies.

Definition for Fractional Bandwidth? - ✔️✔️Describes how large BW is compared to
frequency
-Unitless

Definition for Quality Factor? - ✔️✔️Way to rate a transducer, Quality of the transducer.
-The lower the QF, the better transducer.

Formula for Quality Factor? - ✔️✔️QF = __Fo__
BW

Definition of Power? - ✔️✔️The rate that work is performed.
-The rate of energy transfer

Units for Power? - ✔️✔️Watts (w, mw, Mw)

Formula for Power? - ✔️✔️P (proportional too) a²
P = Power
a = Amplitude

Definition of Amplitude? - ✔️✔️The maximum variation of a wave.
-The strength of a wave.
-Amplitude decreases as it travels through the body.

Unit for Amplitude? - ✔️✔️dB (decibels)
Pa (pascals)

Definition of Intensity? - ✔️✔️The concentration of energy.
-Depends on power and area.