Term
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Definition
Any number raised to the zero power, or the exponent is 0 is 1.
Ex. 10^0=1 |
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Term
| Multiplying with Exponents |
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Definition
When the base is the same add the exponents.
Ex. 10^2 * 10^2= 10^4 |
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Term
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Definition
Take the reciprocal.
Ex. 10^-2= 1/10^2 |
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Term
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Definition
When the base is the same subtract the exponents.
Ex. 10^4/10^2=10^2 |
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
c, 10^-2
Reciprocal: hecto |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| An increase in one variable results in an increase in the related variable. |
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Term
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Definition
An increase in one variable results in a decrease in the related variable.
All inverse relationships are non-linear. |
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Term
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Definition
The power to which a base number must be raised to get the desired number.
Log10(100)=x: 10^x=100, 10^2=100, x=2 |
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Term
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Definition
Log(x*y)= Log(x)+Log(y)
Log(x/y)= Log(x)-Log(y) |
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Term
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Definition
Log(1)=0 Log(5)=0.7
Log(2)=0.3 Log (10)=1.0
Log(4)=0.6 |
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Term
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Definition
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Term
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Definition
| A mechanism which transfers energy from one place to another. |
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Term
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Definition
| A wave resulting from a sudden impact or impulse of energy. |
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Term
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Definition
When a wave is created from a somewhat repetitive source.
Ex. ultrasound from a transducer. |
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Term
First Classification of Waves
How a Wave Propagates |
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Definition
1.Mechanical Waves: need a medium
2.Electromagnetical: vacuum or medium |
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Term
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Definition
| A transfer of energy through a varying electromagnetic field. Will travel in a vacuum or medium. Heat,Light,X-ray, Gamma,TV signal |
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Term
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Definition
A physical interaction between the wave
(energy) and the media which the wave travels through. Must have a medium!
Ocean waves, sound |
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Term
| Propagation of Mechanical Waves |
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Definition
| Propagation implies a change in location(of energy concentration) per time. |
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Term
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Definition
Particle moves across or perpendicular
to the wave's propagation direction. |
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Term
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Definition
| Particle motion is along the direction of the wave propagation. |
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Term
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Definition
| "Close" Areas of high concentration in a longitudinal wave. |
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Term
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Definition
| "Spread out" Areas of low concentration in a longitudinal wave. |
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Term
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Definition
Changes due to mechanical interactions with the medium.
1.Pressure 2.Density 3.Distance 4.Temperature |
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Term
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Definition
Force per area. P=F/A
Pa(pascals)
Atm(atmospheres)
mmHg(millimeters of mercury) |
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Term
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Definition
p=m/V
mass unit/volume unit; g/cm^3
Density up-Speed down |
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Term
|
Definition
Some wave energy is lost to heat.
Celsius 0-100 freeze-boil
Farenheit 32-212 freeze-boil |
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Term
| Particle Motion (Distance) |
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Definition
| Particles oscillate about their original location, they DO NOT actually travel, the energy does. |
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Term
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Definition
| Describe the features of a particular sound wave. 1.Frequency 2.Period 3.Propagation Velocity 4.Wavelength 5.Amplitude 6.Power 7.Intensity |
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Term
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Definition
Event/Time: Cycles/Sec
Hertz(Hz)=1/sec the inverse is sec.
Determined by source(transducer), not effected by the media, not changed by the sonographer. |
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Term
|
Definition
Infrasonic: 0-20Hz
Audible: 20-20,000Hz
Ultrasonic: >20kHZ
Diagnostic: 2-12MHZ |
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Term
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Definition
The time needed to complete a single cycle. P=1/f
Units of time. |
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Term
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Definition
| The rate at which the wave travels through the medium. Based on the medium. Distance/time: m/s |
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Term
| Propagation Velocities to Know |
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Definition
Air: 330 m/s
Lung: 300-1200 m/s
Fat: 1450 m/s
Soft Tissue: 1540 m/s
Tendon: 1850 m/s
Bone: 2000-4000 m/s |
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Term
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Definition
| The physical distance from one peak compression to the next peak compression. Units of length. |
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Term
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Definition
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Term
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Definition
| The parameters a sonographer can change. Amplitude, Power, Intensity. |
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Term
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Definition
The maximum variation of a(acoustic) variable from its mean value. Units are that of the acoustic variables.
Amp= Max-Min/2, Mean= Max+Min/2 |
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Term
| Characteristics of a Medium (3) |
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Definition
1.Elasticity
2.Compressibility
3.Stiffness |
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Term
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Definition
| Jeans vs. Spandex. The ability for a solid object to return to its original shape after distortion by a force. |
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Term
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Definition
| Foam ball vs. golf ball. A measure of how much the volume of the material changes under a given pressure. |
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Term
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Definition
| A materiel that cannot be compressed much. The inverse of elasticity or compressibility. Stiffness up-Speed up |
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Term
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Definition
The decrease in the ratio of the stress to the strain.
High BM=incompressible+inelastic+stiff
Low BM=compressible+elastic+not stiff
BM up-Speed up |
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Term
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Definition
| Ability to distinguish two structures that are parallel to the sound beam & close together. Depends on spatial pulse length (λ*# of cycles). |
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Term
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Definition
The rate at which work is performed, the rate of energy transfer. Determined by the source. Watts.
P∝Amp^2 |
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Term
|
Definition
The concentration of energy within a sound beam. Determined by source. Watts/cm^2. P∝I∝Amp^2,
I=Power/Beam Area |
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Term
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Definition
| A logarithmic power ratio. Ratio implies division of 2 numbers. |
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Term
| Power Form of dB Equation |
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Definition
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Term
| Amplitude Form of the dB Equation |
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Definition
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Term
| Relationship of f to Amplitude |
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Definition
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Term
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Definition
A decrease in wave amplitude (or intensity) due to the mechanical wave interaction with the medium.
Dependent upon: Pathlength (greater distance traveled,more attenuation) & frequency (higer f more attenuation). |
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Term
| Components of Attenuation(3) |
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Definition
1.Absorption
2.Reflection
3.Refraction |
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Term
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Definition
A conversion of energy from the sound wave into heat within the medium.
Dependent upon: Viscosity (higher viscosity,higher absorption) & f (higher f higher absorption). |
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Term
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Definition
| A change in energy propagation direction such that some of the energy returns in the general direction of the source. The foundation for Diagnostic Ultrasound, we receive and process reflected energy to create images. |
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Term
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Definition
The amount of attenuation per centimeter. Units: dB/cm.
Increase f, we increase the attenuation coefficient. |
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Term
| Attenuation Coefficients to Know |
|
Definition
1.Soft Tissue: .5dB/(cm-MHz)
2.Muscle: 1.0dB/(cm-MHz)
3.Blood: .125dB/(cm-MHz) |
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Term
|
Definition
The time needed for an Ultrasound
"pulse" to travel to the reflector and return to the transducer. Use: 2d=r*t. Also, go-return time. |
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Term
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Definition
| 13μsec (6.5μsec there-6.5μsec back). |
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Term
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Definition
The angle formed between the wave front and the interface of the reflecting structure is called the incident angle.
The angle formed between the line perpendicular to the reflector and the wave direction. |
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Term
| Incidence for Specular Reflection. |
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Definition
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Term
|
Definition
P:Perpindicular
O:Orthognal
R:Right Angle
N:Ninety Degrees |
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Term
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Definition
Equal to the angle of incidence, except
use the reflected wave front and direction. |
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Term
|
Definition
1.Specular
2.Scattering
3.Rayleigh Scattering |
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Term
|
Definition
Mirror like, incident angle ALWAYS equals the reflected angle. Occurs with a smooth surface that is large in comparison to the wavelength.
Must have: 1.PORN 2.Impedence Mismatch |
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Term
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Definition
| Back Scattering. Occurs when the surface reflector is rough with respect to the wavelength. |
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Term
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Definition
| Occurs when the reflecting structures are very small in comparison to the wavelength. Also f dependant, equal f^4. Ex. Blood. |
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Term
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Definition
| Z=Density*C, Units: kg/(m^2*sec)=Rayls |
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Term
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Definition
The reflected energy plus the transmitted energy will equal the total
energy. |
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Term
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Definition
(Z2-Z1/Z2+Z1)^2= % Reflected energy.
If Z2=Z1 then no reflection.
If Z2 is much bigger than Z1 then 100%
reflection. |
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Term
|
Definition
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Term
|
Definition
Is effectively the bending of the wave at an interface of two media. Due to a change in propagation speed when a wave's incident angle is other than 0°.
Must have an Oblique incidence and a difference in propagation speeds. |
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Term
| Snell's Law of Refraction |
|
Definition
Predicts the amount of refraction that will occur. Ci/Ct=sinθi/sinθt
1500m/s/1500m/s=1 |
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Term
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Definition
Pathlength*Attenuation Coefficient
*Frequency |
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Term
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Definition
| "On" all of the time, 2 crystals, can't send and receive at the same time. Range ambiguity: unable to locate the depth of an object. |
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Term
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Definition
| A pulse is a collection of cycles that travel together. "On & OFF", can send and receive. Range resolution(specificity). Used in all diagnostic ultrasound,except CW Doppler. |
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Term
| Parameters of a Pulsed Wave (6) |
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Definition
| 1.Pulse Duration 2.Pulse Repetition Period 3.Pulse Repetition Frequency 4.Duty Factor 5.Spatial Pulse Length 6.Axial Resolution. |
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Term
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Definition
The amount of time for which a transmit pulse lasts. From the start of one pulse, to the end of that pulse. Does not include listening time.
Cannot be changed. |
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Term
| Pulse Repetition Period (PRP) |
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Definition
| The time until a transmitted pulse is repeated. From the beginning of one pulse to the beginning of the next pulse, includes listening time. Can be changed by changing listening time. |
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Term
|
Definition
| PD = Period * #of Cycles. |
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Term
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Definition
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Term
| Pulse Repetion Frequency (PRF) |
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Definition
| The number of pulses that occur in 1 sec. Related to imaging depth. Can be changed. |
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Term
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Definition
The percentage of time that a system transmits sound. DF=PD/PRP
The largest duty factor would be 100%, always transmitting. |
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Term
| Spatial Pulse Length (SPL) |
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Definition
| The length or distance that a pulse occupies in space. The distance of Pulse Duration. Important to axial resolution. |
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Term
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Definition
| Longitudinal Axial Range Radial Depth |
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Term
| LARRD Resolution Equation |
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Definition
LARRD = SPL/2. Compare Axial Resolution
number to distance between structures. If the AR# is smaller than the distance
we can see the structures independantly. Short pulse means good Axial Resolution. |
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Term
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Definition
Need
1.Pulsed Wave:to reduce range ambiguity.
2.Acoustic Line:a single beam transmitted in a specific direction.
3.Receive Line:returning echoes registered by a system from a single line. |
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Term
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Definition
| The data displayed on the screen. |
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Term
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Definition
| An image is the picture generated by sequentially transmitting many acoustic lines in various directions and then reconstructing the received data (a frame). |
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Term
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Definition
The amount of time it takes to complete 1 frame.
Frame Time = # Lines*PRP |
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Term
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Definition
The reciprocal of frame time, the amount of frames per second. Hertz.
Frame Rate= 1/Frame Time |
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Term
|
Definition
| The ability to accurately locate moving structures at any particular instant in time. Higher the frame rate worse the Temp. Res. Lower the frame rate better the Temp. Res. |
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Term
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Definition
| The more scan lines, the longer it would take to create one image, or frame. |
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Term
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Definition
| The shallower the depth, the less amount of time it would take to send and receive an echo. |
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Term
|
Definition
The ability or inability to distinguish
between two structures or to visualize an activity. |
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Term
| Scanned Vs. Non-scanned Modalities |
|
Definition
1.Scanned modalities acquire information over a plane(or volume in 3D), non-scanned modalities acquire information only along a line.
2.Temporal Resolution is degraded with scanned modalities.
3.The risk of thermal bioeffects is usually much greater with nonscanned modalities. |
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Term
|
Definition
| Each Color Display Line is comprised of multiple acoustic lines referred to as a packet or ensemble. As a result the frame time is generally greater, degrading temporal resolution. |
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Term
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Definition
| The range of fequencies over which a device can operate. Imaging transducers have a Wide Bandwidth due to backing material. |
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Term
|
Definition
| BW= Max. freq. - Min. freq. |
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Term
| Fractional Bandwidth (FBW) |
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Definition
|
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Term
|
Definition
QF=1/FBW = Operating freq./BW
Represents the degree of damping. Imaging transducers are Low-Q, 2-3 pulses. |
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Term
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Definition
|
|
Term
| Bandwidth and Ultrasound Modes |
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Definition
| Widest to most narrow: B-mode,color Doppler,spectral PW Doppler, CW spectral Doppler. |
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Term
| Value of Greater Bandwidth |
|
Definition
| 1.Flexibility 2.Dynamic Frequency Tuning |
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Term
|
Definition
| CW Doppler requires very little bandwidth. It has greater penetration and sensitivity. |
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Term
|
Definition
The ability to operate at different frequencies. Optimizes resolution and penetration. Aka: Multi-Hertz Operation
and Frequency Agility. |
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Term
| Dynamic Frequency Tuning (BW) |
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Definition
| Transmit over the whole bandwidth, then receive frequency from higher to lower with increasing depth. Aka: Sliding Receive Filters. |
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Term
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Definition
| Any device which converts one form of energy to another form of energy. Ex: nerves,lights,speakers,heaters. |
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Term
|
Definition
| Mechanical deformation results when an electric field is applied to certain crystal materials, or a varying electrical signal is produced when the crystal structure is mechanically deformed. |
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Term
| Pulse Wave Frequency and Crystal Thickness |
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Definition
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|
Term
| PW Operating Frequency Equation |
|
Definition
f(o){MHz}=C{mm/usec}/2t(mm)
t=crystal thickness
C=in crystal |
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Term
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Definition
| f(o)=Transducer f=Drive Voltage f |
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Term
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Definition
| A single pulse produces multiple cycles of ringing. |
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Term
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Definition
| Larger diameter, larger beamwidth, deeper focus. |
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Term
|
Definition
| The ability to distinguish two structures that are perpindicular to the sound wave and close together. |
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Term
| Lateral Resolution Equation |
|
Definition
Lateral Resolution=Lateral Beamwidth
Higher frequencies form narrower beams improving lateral resolution. |
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Term
|
Definition
| The ideal thickness is a quarter of the wavelength. |
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Term
|
Definition
| 1.Lenses 2.Curved Elements 3.Electronic Focusing 4.Mirrors |
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Term
|
Definition
| Convert electropotential (voltage) into acoustic waves and acoustic waves back into voltage. |
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Term
|
Definition
| Shortens spatial pulse length improving axial resolution. |
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Term
|
Definition
| Minimizes the acoustic impedance mismatch from crystal to tissue and tissue back to crystal. |
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Term
|
Definition
Transmit: Delivers voltage to crystal.
Receive: Delivers echo voltage to system receivers. |
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Term
|
Definition
| Helps to focus beam in the elevation plane. |
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Term
|
Definition
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Term
|
Definition
Heating the crystal and aligning the molecules with an electrical field.
Increases the Efficiency. |
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Term
|
Definition
| The temperature at which a material will lose efficiency as a piezoelectric material. 300C (572F) for PZT. |
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Term
|
Definition
Aka: Focal Depth, Depth of Focus, Fresnel Zone. Where the beam converges.
NZL(mm)=D^2(mm)*f(o){MHz}/6 |
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Term
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Definition
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Term
|
Definition
|
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Term
|
Definition
| Lateral Angular Azimuthal Side-by-Side Transverse. |
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Term
|
Definition
Blind Doppler, CW(2 crystals).
Disadvantage: No image
Advantage: Very Sensitive
Echo: curved
Vascular:Pencil |
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Term
|
Definition
| Turning on and off swithches, groups of elements are activated over time (in sequence) to scan across the patient. |
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Term
| Linear Switched Array Transducer |
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Definition
| Obsolete. Straight,Sequenced,Multiple Crystals. |
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Term
|
Definition
| Crystal is pointed in different directions over time,via a motor, to produce an image. |
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Term
|
Definition
First used in cardiac imaging to get around the ribs.
Disadvantage: Fixed Focus. |
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Term
| Mechanical(Phased) Annular Array Transducer |
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Definition
Mechanical Steering, Phased (Electric) Focused, Rings, Multiple Crystals.
Disadvantage: Rings were hard and expensive to make. |
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Term
|
Definition
| Electronic control is done by using small time(phase) delays between the excitation pulses which drive each element. By changing the delay pattern the beam can be steered and focused. |
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Term
|
Definition
Uses electric steering(Phasing) to create a sector scan. Most often used for cardiac imaging. TEE Transducer is one type.
Advantage: Small transducer footprint.
Disadvantage: Narrow near field image. |
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Term
| Phased Array Linear Transducer |
|
Definition
Phased(Electric) Focus and Steering, Multiple Crystals, Straight.
Advantage:Bigger near field image, can be linear(unsteered) or can be somewhat steered and focused. |
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Term
| Curved Linear Phased Array Transducer |
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Definition
Convex, Straight, Phased(Electric) Focus, Multiple Crystals.
Mainly used for abdomen.
Advantage: Variable Focus
Disadvantage: Expensive |
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Term
|
Definition
Pro: Very repeatable characteristics.
High Freq. of natural resonance.
Highly efficient.
Cons: Generally a high impedance compared to tissue (30-40 Mrayls).
This means a high amount of impedance mismatch, and reflection. |
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Term
|
Definition
Protects the patient and sonographer from shock.
Protects the crystals from damage. |
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Term
|
Definition
| The location where the sound beam reaches its minimum diameter. |
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Term
|
Definition
The region surrounding the focus.
Where the beam is narrow and the picture is relatively good. |
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Term
|
Definition
Aka: Fraunhofer Zone.
The region beyond the focus.
Where the beam diverges. |
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Term
|
Definition
Amplitude Mode
Very precise measurement of distance(depth). Shows an upward deflection when the signal returns. |
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Term
|
Definition
First form of gray scale imaging.
Showed depth and intensity of reflection. |
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Term
|
Definition
| Think motion. Displays the changing position of reflectors with the respect to time. |
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Term
|
Definition
| More elements side by side than up and down. Improved elevation resolution. |
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Term
|
Definition
| Performs 3-D scans. Same number of crystals side by side as up and down. |
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Term
|
Definition
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