Term
|
Definition
| the rate at which sound is attenuated per unit depth |
|
|
Term
|
Definition
| Identify reflectors parallel to sound beam |
|
|
Term
|
Definition
| scattered sound waves that make their way back to transducer and produce an image on display |
|
|
Term
|
Definition
| Area of a sound wave where molecules are pushed closer together |
|
|
Term
|
Definition
| the process of reducing the number of cycles of each pulse in order to improve axial resolution |
|
|
Term
|
Definition
|
|
Term
|
Definition
| percentage of time that sound is actually being produced |
|
|
Term
|
Definition
number of cycles per second
Units:Hz,Khz,Mhz |
|
|
Term
|
Definition
| Device used to measure output intensity of a txdr |
|
|
Term
|
Definition
| Resistance of the propagation of sound through a medium |
|
|
Term
|
Definition
| Newton's principle that states an object at rest stays at rest and an object in motion stays in motion , unless acted on by an outside force |
|
|
Term
|
Definition
the power of the wave divided by the area over which it is spread; energy per unit area
Units:W/cm2 |
|
|
Term
|
Definition
| Interference pattern caused by scatterers that produce the granular appearance of tissue on a sonographic image |
|
|
Term
|
Definition
the maximum or minimum deviation of an acoustic variable from the average value of that variable; the strength of the reflector
Units; Pascals |
|
|
Term
|
Definition
| A decrease in amplitude, power, and intensity of the sound beam as sound travels through tissue |
|
|
Term
| Intensity reflection coefficient |
|
Definition
| the percentage of sound reflected at an interface |
|
|
Term
| Intensity transmission coefficient |
|
Definition
| percentage of sound transmitted at an interface |
|
|
Term
|
Definition
| Reflectors that are smaller than the wavelength of the incident beam |
|
|
Term
|
Definition
| the time it takes for one cycle to occur |
|
|
Term
|
Definition
| the rate at which work is performed or energy is transmitted |
|
|
Term
|
Definition
| force per unit area or the concentration of force |
|
|
Term
|
Definition
| the time during which the sound is actually being transmitted ; the "on" time |
|
|
Term
| Pulse repetition frequency |
|
Definition
| the number of pulses of sound produced in 1 second |
|
|
Term
|
Definition
| time from the beginning of one pulse to the beginning of the next pulse "on" and "off" time |
|
|
Term
|
Definition
| area in sound where molecules are spread wider apart |
|
|
Term
|
Definition
| phenomenon that occurs when sound waves are forced to deviate from a straight path secondary to changes within the medium |
|
|
Term
|
Definition
| describes the angle of transmission at an interface based on the angle of incidence and the propagation speeds of the two media |
|
|
Term
|
Definition
| length of a pulse from beginning to end |
|
|
Term
|
Definition
| Reflections that occur when the sound impinges upon a large, smooth reflector at 90 degrees |
|
|
Term
|
Definition
| Ability of an object to resist compression and relates to the hardness of the medium |
|
|
Term
|
Definition
| the total amount of sound (in dB) that has been attenuated at a given depth |
|
|
Term
|
Definition
| the length of a single cycle in sound |
|
|
Term
|
Definition
| Molecules in a medium vibrate at 90 to the direction of the traveling wave |
|
|
Term
Period and Frequency are _________
related |
|
Definition
|
|
Term
|
Definition
1
They are reciprocals when multiplied they equal 1 |
|
|
Term
|
Definition
Period= 1/Frequency
T= 1/f |
|
|
Term
|
Definition
| Frequency= Propagation speed/ Wavelength |
|
|
Term
| Stiffness and propagation speed are _________ related |
|
Definition
|
|
Term
| Density and propagation speed are __________ realted. |
|
Definition
|
|
Term
| List these media in order of propagation speeds slowest to highest: Water, Lungs, Liver, Soft Tissue, Bone, Air, Blood |
|
Definition
| Air, Lungs Water, Soft Tissue, Liver, Blood and Bone |
|
|
Term
| Formula for propagation speed: |
|
Definition
| Propagation speed = Elasticity/Density |
|
|
Term
| In clinical imaging wavelengths measure between |
|
Definition
|
|
Term
| Wavelength is ______ related to frequency and _________ related to period. |
|
Definition
Inversely-Frequency
Directly-Period |
|
|
Term
|
Definition
| Wavelength=Prop Speed/Frequency |
|
|
Term
What is the wavelength for a 1 and 2Mhz
txdcr |
|
Definition
1=1.54mm
2=0.77mm
Prop speed in soft tissue is treated as a constant 1.54 mm/ms or 1540 m/s |
|
|
Term
| Power is proportional to _______ |
|
Definition
amplitude squared
ex:amp doubles power quadruples |
|
|
Term
| Intensity is proportional to both _______ and _________ |
|
Definition
| power and amplitude squared |
|
|
Term
| Intensities range from ____ to ____ for diagnostic ultrasound |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
z=pc
p=density
c=prop speed |
|
|
Term
| In diagnostic imaging, the PRF has typical values between |
|
Definition
| 1000 and 10,000 Hz (1-10 Khz) |
|
|
Term
| Imaging depth and PRF are ______ related |
|
Definition
|
|
Term
| PRP and PRF are ______ related |
|
Definition
|
|
Term
| PRF and frequency are not related |
|
Definition
ex: train with 5 coaches = prf
2 passengers=freq (2Mhz)
no matter if frequency changes the PRF remains the same unless you change imaging depth |
|
|
Term
| Formula for Pulse Duration= |
|
Definition
PD=# of cycles x period
PD=nT |
|
|
Term
| PD is determined by the ________ only and _____ be changed by the sonographer. |
|
Definition
|
|
Term
|
Definition
Duty Factor=PD/PRP
UNITLESS |
|
|
Term
| In clinical imaging the DF is ____ |
|
Definition
|
|
Term
| A ultrasound system of 100% is |
|
Definition
Continuous wave
Pulsed ultrasound will always have a DF of less than 100% |
|
|
Term
|
Definition
| SPL=# of cycles x wavelength |
|
|
Term
| Wavelength and SPL are ______ related |
|
Definition
|
|
Term
| SPL and PD are ______ related |
|
Definition
|
|
Term
| Shorter SPL and PD results in improved |
|
Definition
| axial resolution and overall image quality |
|
|
Term
| Sound wave parameters determined by Sound source only: |
|
Definition
| Period, frequency, Amplitude, Power, and Intensity |
|
|
Term
| Sound wave parameters by medium: |
|
Definition
Propagation speed
Impedance |
|
|
Term
| Sound wave parameters determined by both source and medium |
|
Definition
|
|
Term
| Pulsed sound parameters determined by sound source: |
|
Definition
|
|
Term
| Pulsed sound parameters determined by sound source and medium: |
|
Definition
|
|
Term
| ______ is the conversion of sound energy to heat and is the greatest contributor to attenuation in tissue. |
|
Definition
|
|
Term
| Formula for Attenuation coefficient |
|
Definition
Total attenuation= Attenuation coefficient (Ac) x path length (L)
TA=F/2 X L |
|
|
Term
| Specular reflectors vs Nonspecular reflectors |
|
Definition
Specular- smooth surface
border is larger than incident wavelength angle dependent
Nonspecular-rough surface
border is smaller than incident wavelength
not angle dependent |
|
|
Term
| Synonyms for normal incidence |
|
Definition
| orthogonal, perpendicular and 90 degrees |
|
|
Term
| Formula for intensity transmission coefficient: |
|
Definition
ITC=1-IRC
MUST EQUAL 100% |
|
|
Term
| Formula for Intensity reflection coefficient |
|
Definition
| IRC=Ir/Ii= [Z2-Z1/Z2+Z1]squared |
|
|
Term
|
Definition
| redirection of the transmitted sound beam |
|
|
Term
|
Definition
Reflection-Normal incidence
Impedance mismatch
Percentage or intensity of sound reflected and transmitted at an interface
Refraction-Oblique incidence
prop speed mismatch
angle of transmitted sound |
|
|
Term
| The SP intensity is measured at the _____ of the beam |
|
Definition
|
|
Term
| The SA intensity is the _________ intensity across the face of the entire beam |
|
Definition
|
|
Term
| SP/SA factor or beam uniformity coefficient is the ______________ of the center intensity to the average _________. |
|
Definition
|
|
Term
| Temporal Peak is the intensity measured at the ___________ of the pulse and therefore is the _________ of all temporal intensities. |
|
Definition
highest intensity or peak
highest |
|
|
Term
| Formula for Beam uniformity ratio |
|
Definition
|
|
Term
| TA is the _____ of all temporal intensities |
|
Definition
|
|
Term
| ______ intensity is used when describing thermal bioeffects |
|
Definition
|
|
Term
|
Definition
|
|
Term
List intensities from lowest to highest
SPTA, SPTP, SAPA, SATA, SPPA,SATP |
|
Definition
| SATA>SPTA>SAPA>SPPA>SATP>SPTP |
|
|
Term
|
Definition
| the temperature at which the material will obtain peizoelectric properties |
|
|
Term
|
Definition
| applying electrical energy to the piezoelectric element causes it to resonate |
|
|
Term
| The resonating frequency of a diagnostic us txdr is typically between |
|
Definition
|
|
Term
| Formula for the frequency of the txdr for PW operation: |
|
Definition
Fo=c/2 x thickness
c=prop speed |
|
|
Term
|
Definition
| the inability to determine the depth of the reflector if the pulses are sent out toofast for them to be timed |
|
|
Term
| Constructive interference |
|
Definition
| occurs when in-phase waves meet; the amplitudes of the 2 waves are added together to form one big wave |
|
|
Term
|
Definition
| occurs when out-of-phase waves meet;the amplitude of the resultant wave is smaller than either of the original waves |
|
|
Term
| if out-of-phase waves have identical amplitudes they can |
|
Definition
|
|
Term
| the thicker the element the ___ the frequency |
|
Definition
|
|
Term
|
Definition
| states that waves are the result of the interference of many wavelets produced at the face of the txdr |
|
|
Term
|
Definition
| used to step down the impedance from that of the element to that of the patient's skin |
|
|
Term
| Backing material is composed of |
|
Definition
| epoxy resin impregnated with tungsten |
|
|
Term
| Sensitivity is the ability of a system to display |
|
Definition
|
|
Term
|
Definition
| range of frequencies within the beam |
|
|
Term
| More damping ___ the pulse and the ___ the bandwidth |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
decreases sensitivity of the transducer
increases bandwidth
reduces q-factor |
|
|
Term
| (H) damping= __SPL=__BANDWIDTH=___ Q-FACTOR=______AXIAL RESOLUTION |
|
Definition
| High damping= (L) spl= (H) bandwidth= (L) q-factor= Better axial resolution |
|
|
Term
|
Definition
| txdrs with a motor for steering the beam |
|
|
Term
| Mechanical txdrs have _____ freq and ____ focus |
|
Definition
| fixed frequency and fixed focus |
|
|
Term
| Mechanical txdrs produce a ________ image |
|
Definition
|
|
Term
| when using a mechanical txdr focusing was achieved by |
|
Definition
| either the shape of the element or by use of a lens (mirror) |
|
|
Term
| The major advantages of using a mechanical txdr was |
|
Definition
| inexpensive and small footprint |
|
|
Term
| Electronic scanning is performed with txdrs that have multiple elements that is referred to as an |
|
Definition
|
|
Term
| With electronic transducers the PZT is sliced in to ________ and connected ___________. |
|
Definition
subelements
connected to individual wires
this will allow the system to selectively excite elements as needed to shape and steer the beam (sequenced or phased) |
|
|
Term
| Linear sequenced or liner sequential array produces a ________ shape. |
|
Definition
|
|
Term
| A linear sequenced array the firing is _________, focusing is achieved ________, and is used for _______ and ________ studies. |
|
Definition
sequenced, electronically focused, and is used for vascular and small parts
Does not need steering however if needed can be achieved electronically |
|
|
Term
| With a linear sequenced array elements are arranged in a ________ and fired in a __________. |
|
Definition
line and fired in a sequence
ex;123...456..789... |
|
|
Term
| Curved sequenced array is also referred to as a ________,__________, or _________. |
|
Definition
| curviliniear, curved sequential array or convex |
|
|
Term
| Curved sequential array has a _______ shape image, firing is _______, focusing is __________, and is used for ________,______, and ________ studies. |
|
Definition
| curved, firing is sequenced it is electronically focused, and is used for abdomen, gynecology, and obstetrics |
|
|
Term
| A _______ txdr has a pie shape image and a _____ has a blunted top or trapezoidal image shape. |
|
Definition
|
|
Term
|
Definition
| the method of focusing and/or steering the beam by applying electrical impulsesto the piezoelectric elements with small time differences between shocks. |
|
|
Term
| All arrays are ______ focused. |
|
Definition
|
|
Term
| Linear phased arrays are also referred to as ___,_____,_____ and they are _______ or ______ in shape. The steering and focusing is achieved _________ by _________ and is used for ______,______,_________, and ________ exams. |
|
Definition
phased array,sector, or vector txdr
vector or sector shaped
electronic steering and focusing by phasing
used for cardiac, abdominal neonatal imaging and endocavity transducers |
|
|
Term
| Annular arrays are made up of a disc shaped element that is cut into ________ and is ______________ to act independently. |
|
Definition
|
|
Term
| The advantage of a annular array is that it has excellent __________. |
|
Definition
|
|
Term
| Annular array transducers are _________ steered, _______ focused by ________ and _______ shape image |
|
Definition
mechanically
electronically focused by phasing
sector shaped |
|
|
Term
| A continuous wave transducer uses two elements |
|
Definition
| 1-for producing sound and 1 for receiving sound cannot produce an image |
|
|
Term
|
Definition
| the ability of a system to distinguish between closely spaced objects |
|
|
Term
| Axial resolution is the minimum distance 2 reflectors can be, _________ to the beam, and still appear as 2 dots. |
|
Definition
|
|
Term
| Axial resolution may also be referred to as "LARRD" |
|
Definition
Longitudinal, Axial,
Radial, Range, and Depth |
|
|
Term
| Lateral resolution is the ability to accurately identify reflectors that are arranged ___________ to the sound beam. |
|
Definition
|
|
Term
| Lateral resolution may also be referred to as "LATA" |
|
Definition
| Lateral, Angular, Transverse, and Azimuthal |
|
|
Term
|
Definition
resolution in the third dimension of the beam; the slice thickness plane.
Also referred to as Slice- or Sectional thickness plane resolution |
|
|
Term
|
Definition
| the ability to differentiate one shade of grey from another |
|
|
Term
|
Definition
| also known as frame rate, is the ability to display moving structures in real time |
|
|
Term
| Formula for axial resolution: |
|
Definition
| Axial resolution=1/2 OF SPL |
|
|
Term
Characteristics of an unfocused single element:
At the face of the transducer , the beam diameter is _____________
At a distance of one near zone length, the beam diameter is equal to ________
At a distance of 2 NZL, the beam diameter again equals ________. |
|
Definition
equal to element diameter
equal to 1/2 of the diameter of the element
equals the element diameter |
|
|
Term
| ____ Freq ___ NZL ____DIVERGENCE IN FAR FIELD |
|
Definition
| High, Greater NZL, Least divergence in far field |
|
|
Term
| ___ Aperture, ____ NZL and ____ Divergence in far field |
|
Definition
| Larger Aperture, Greater NZL, Least Divergence in far field |
|
|
Term
| What 3 adjustments can be made to alter the frame rate in grayscale imaging |
|
Definition
Image depth (PRF)
Number of focal zones
Number of scan line per frame or line density |
|
|
Term
| PRF is ____ related to frame rate |
|
Definition
|
|
Term
|
Definition
FR=PRF/LPF
Lines per frame |
|
|
Term
|
Definition
| amplitude mode; the height of the spike on the image is related to the strength of the echo generated by the reflector |
|
|
Term
|
Definition
| Brightness mode; the brightness of the dots is proportional to the strength of the echogenerated by reflector |
|
|
Term
|
Definition
| the plane that is perpendicular to the beam path |
|
|
Term
|
Definition
|
|
Term
|
Definition
| the brightness, or amplitude, of the dots on the display |
|
|
Term
| It takes ____ microseconds for sound to travel to a depth of ___ cm and return. |
|
Definition
|
|
Term
| Formula for range equation: |
|
Definition
d=cxt/2
d=.77t
remember 13 ms rule |
|
|
Term
|
Definition
| Motion mode;used to display motion of the reflectors |
|
|
Term
| Beam former is the instrument that |
|
Definition
| controls the timing of the elements to shape and steer the beam for focusing controls apodization |
|
|
Term
| Apodization is the technique that |
|
Definition
| varies the voltage to the individual elements to reduce grating lobes |
|
|
Term
| The pulser also referred to as the pulse generator or transmitter controls the |
|
Definition
| strength, or amplitude, of the elctricity striking the elements |
|
|
Term
|
Definition
part of the beam former
generates the voltage that drives the transducer
directly controls the amount of power entering the patient |
|
|
Term
| The receiver also known as signal processor |
|
Definition
processes the return echoes
and has 5 processes
Amplification, compensation, compression, demodulation, and reject |
|
|
Term
| Amplification or overall gain |
|
Definition
| increases or decreases all echoes equally |
|
|
Term
| Compensation or depth gain compensation |
|
Definition
| Adjusts brightness of echoes to correct for attenuation with depth |
|
|
Term
|
Definition
| decreases the range of amplitude present within the system (opposite of dynamic range) |
|
|
Term
|
Definition
| makes signal easier for system to process. Includes rectification and smoothing |
|
|
Term
|
Definition
| eliminates low level echoes that do not contribute to useful information on the image |
|
|
Term
|
Definition
| converts analog to binary it is preprocessing |
|
|
Term
|
Definition
postprocessing converts binary back to analog
Settings can be changed after a image has been frozen this is post processing |
|
|
Term
|
Definition
| As low as reasonably achievable |
|
|
Term
| What 2 beneficial side effects does increasing the output power have |
|
Definition
1)higher amplitude return echoes for a better signal to noise ratio
2)improved depth penetration |
|
|
Term
|
Definition
| a way of processing the pulse to improve contrast resolution and reduce speckle |
|
|
Term
| Frequency compounding _________ the frequencies across the image to improve ______ and to reduce _________ |
|
Definition
averages
contrast and reduce speckle |
|
|
Term
|
Definition
| part of the machine that controls the timing of the echoes |
|
|
Term
|
Definition
| waves that are not pure sine waves |
|
|
Term
| Nonlinear propagation is a principle that __________ change in shape as they travel _______, though in a disproportionate way |
|
Definition
|
|
Term
Tissue harmonics:
______ propagation of sound
Harmonic signals are produced by _______, not the ________
_______ beam, ______ resolution
Second harmonics is _____ the transmitted (FUNDAMENTAL) _______
Elimination of ________ and _________
Harmonic beam is _________ (lower amplitude than the fundamental) but travels ________: from _____ to ______ |
|
Definition
Nonlinear
patient not the transducer
narrow beam, better lateral resolution
twice the transmitted frequency
near field artifacts (noise reverberation) and elimination of grating lobes
weaker and travels one way from pt to txdr |
|
|
Term
|
Definition
| turns negative voltages into positive voltages |
|
|
Term
|
Definition
| wraps an envelope around the signal to make it less bumpy |
|
|
Term
| Scan converter is the part of the machine that ___________ the signals from the _______; consists of the _-_ converter, __________, and _-_ converter |
|
Definition
|
|
Term
| Fill-in interpolation places _____ where there is ______ information based on adjacent scan lines. |
|
Definition
|
|
Term
| A ____ is the smallest amount of computer memory possible |
|
Definition
|
|
Term
|
Definition
|
|
Term
| A _____ is the smallest part of any picture. |
|
Definition
|
|
Term
| There are 2 different ways to magnifying the us image: |
|
Definition
|
|
Term
| write zoom is ____ processing. Enlarges the image by __________. |
|
Definition
pre processing
redrawing it |
|
|
Term
| Read zoom is a ____ processing function. Enlarges the image by _______ the pixels. |
|
Definition
post processing
magnifying |
|
|
Term
|
Definition
Write:
Preprocessing function
A-D converter
Image must be live
Higher quality zoom
Read:
Postprocessing function
D-A converter
Image may be frozen or live
Lower quality zoom
*Write zoom is the 'WRITE' WAY TO DO IT!! |
|
|
Term
|
Definition
| artifact caused by the beam bouncing between 2 strong reflectors |
|
|
Term
|
Definition
| caused by sound reflecting off of strong specular reflector and displaying an object on both sides of the reflector |
|
|
Term
|
Definition
| Beam reflects off of objects in body and makes two or more changes in direction before returning back to transducer |
|
|
Term
|
Definition
| Refraction artifact caused by sound refracting off of a curved surface. Eliminated/reduced by spatial compounding |
|
|
Term
|
Definition
| Extraneous energy not along path of main beam causes erroneous reflections |
|
|
Term
|
Definition
if speed of tissue is greater than 1540 m/s, the machine places the reflector at the wrong location on display
Remember: the machine uses d=0.77t |
|
|
Term
|
Definition
| potentially useful artifact occurs when sound traverses a highly attenuating structure. (identify stones) |
|
|
Term
|
Definition
| when sound travels through a weakly attenuating structure.Appears as an area of increased brightness distal to weak reflectors. |
|
|
Term
Slice thickness artifact
(Elevation plane artifact) |
|
Definition
| occurs as a result of the beam not being razor thin.Unintended echoes may appear in the image as the beam slices through structures adjacent to intended reflectors. |
|
|
Term
|
Definition
| disturbance on display that appears as an arc like moving bands caused by the ultrasound machine being placed too close to unshielded electrical equipment |
|
|
Term
|
Definition
caused by small structures
ie:adenomyomatosis |
|
|
Term
|
Definition
caused by small air bubbles
ie: gastric antrum |
|
|
Term
|
Definition
| the study of blood flow through the blood vessels of the body. |
|
|
Term
|
Definition
the difference in energy between two points (E1-E2)
E1-energy at the beginning of the vessel
E2-energy at the end of the vessel |
|
|
Term
|
Definition
| pressure energy created by the beating heart |
|
|
Term
| Law of conservation of energy |
|
Definition
| the total amount of energy in a system never changes,although it might be different form from which it started |
|
|
Term
|
Definition
| energy created by flowing blood.The potential energy is converted to kinetic energy minus the energy lost as a result of friction |
|
|
Term
Gravitational potential energy
(Hydrostatic pressure) |
|
Definition
| energy created as a result of gravity. In the cardiovascular system it is the weight of a column of blood. The heaviest pressure is at the bottom of the column because it has to support the weight of blood superior to it. |
|
|
Term
|
Definition
| energy lost as a result of friction, which occurs when something rubs against something else and heat is created |
|
|
Term
|
Definition
| energy lost as a result of branching of the blood vessels. In order for the blood cells to change direction, some of the initial energy is lost |
|
|
Term
|
Definition
KE=1/2PV2
Kinetic energy is equal to 1/2 of the product density (p) and the velocity (v) of the blood squared |
|
|
Term
| Hydrostatic pressure formula |
|
Definition
P=pgh
Hydrostatic pressure (p)=
product of height (h) of the column of blood
the density of the blood (p)
and gravity (g) |
|
|
Term
| The amount of flow in a blood vessel is _____ related to pressure gradient. |
|
Definition
|
|
Term
| The tunica intima is the _______ layer, made of ____________. |
|
Definition
inner layer (closest to passing blood)
endothelium |
|
|
Term
| The tunica media is the ______ layer and made up of ________ and __________. |
|
Definition
middle layer
smooth muscle and elastic tissue |
|
|
Term
| The tunica adventitia is the _________ layer and made up of ______ and has its own blood supply via the ___________. |
|
Definition
outermost layer
connective tissue
vasa vasorum |
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Definition
| a network of small blood vessels that supply blood to the walls of arteries and veins |
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Definition
| thr flow profile represented by blood typically flowing at the same velocity |
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Term
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Definition
| flow profile represented by blood that travels in nonmixing layers of different velocities, with the fastest flow in the center and the slowest flow near the vessel walls,most common type of flow in arteries |
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Definition
| chaotic, disorderly flow of blood |
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Term
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Definition
| time period of the cardiac cycle when the heart is contracting |
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Term
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Definition
| the formula used to quantitatethe presence of turbulence: Reynold numbers greater than 2000 typically indicate turbulence |
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Term
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Definition
Re=v2rp/n
product of the velocity of blood (v)
two times the radius (r) of the vessel, and the density (p) of the blood
divides by the viscosity (n) of the blood |
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Term
| Continunity equation states that the change in ________ as the area changes in order to maintain the __________ of blood flow. |
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Definition
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Term
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Definition
Q=VA
Q= Flow
V= Velocity
A= Area |
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Term
| Bernoulli's principle states: |
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Definition
| that an increase in velocity must be accompanied by a corresponding decrease in pressure |
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Term
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Definition
| the law that describes the relationship of resistance, pressure and flow |
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Term
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Definition
| a principle in elctronics in which flow is equal to the pressure difference divided by resistance. |
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Term
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Definition
I=V/R
I= Flow
V= Pressure differential
R= Resistance |
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Term
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Definition
| the point at which a stenosis is hemodynamically significant with a pressure drop distal to the stenosis |
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Term
| With a stensosis, it is more detrimental to have _________ than a ________ lesion becaus there is more of an ________ with two stenoses series. |
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Definition
2 stenoses in series
single
energy loss |
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Term
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Definition
| small but signifant gradient between the venules and the right atrium of the heart |
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Term
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Definition
| functional venous valves keeps the blood flowing in the proper direction: toward the heart |
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Term
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Definition
| contraction of the calf muscles propels blood from the soleal sinuses in the calf toward the heart |
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Term
| intrathoracic pressure changes |
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Definition
| inspiration causes a negative pressure in the thorax, essentially sucking the blood towar the heart |
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Term
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Definition
| the change in the frequency of the received signal related to motion of reflector |
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Term
frequency shift
(doppler shift) |
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Definition
| the difference between the transmitted and received frequencies. |
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Term
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Definition
reflected freq (Hz)- transmitted freq (Hz)
If + moving toward transducer
if - moving away from transducer |
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Term
| Doppler shift and frequency are _____ related |
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Definition
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Term
| fast fourier transform (FFT) |
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Definition
| a mathematical process used for analyzing and processing the doppler signal to produce the spectral waveform |
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Term
| the spectral display provides the following information: |
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Definition
| time, velocity, frequency shift, flow direction, and amplitude |
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Term
| time is displayed on the ____ on a spectral display |
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Definition
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Term
| Resistive Index is used to quantitate the _________ of the __________. |
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Definition
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Term
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Definition
RI=A-B/A
A- peak systolic velocity is subtracted from the
B- end diastolic velocity then divided by the
A- peak systolic velocity |
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Term
| Pulsatile index is used to determine how __________ over time |
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Definition
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Term
| the amplitude of the signal is represented by ___________ on the spectral display and is along the ___ axis |
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Definition
brightness of the dots
z-axis
(the brighter the dots on the spectral waveform the more red blood cells that make up the signal) |
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Term
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Definition
| the filling of the spectral window |
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Term
| angle correction is used to inform the machine what the __________ is, so that ________ can be accurately calculated. |
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Definition
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Term
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Definition
RI=A-B/A
A- peak systolic velocity is subtracted from the
B- end diastolic velocity then divided by the
A- peak systolic velocity |
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Term
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Definition
| combined grayscale, spectral, and color doppler information on the screen |
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Term
| Aliasing is a wrap around of the __________, where the positive shiftsare displayed as _________. |
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Definition
doppler signal
negative shifts |
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Term
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Definition
| the maximum frequency shift sampled without aliasing: equal to one half the PRF |
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Term
| 2 advantages of PW over CW doppler are: |
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Definition
1) ability to select a specific depth to sample by utilizing the range gate
2)ability to angle correct in order to accurately calculate the velocity of blood |
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Term
| How can you eliminate aliasing? |
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Definition
increase prf
decrease smaple depth
decrease frequency
increase the doppler angle
use CW transducer |
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Term
| Advantages to using a CW txdr |
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Definition
high sensitivity
no aliasing
able to measure very high velocities |
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Term
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Definition
| eliminate low level noise |
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