<\/p>\n
Physics<\/p>\n
T=1\/f<\/p>\n
Hertz=cycles per second<\/p>\n
1 million hertz=1MHz<\/p>\n
Medical UTS=1-30 MHz<\/p>\n
Audible sound = 20-20000 Hz<\/p>\n
Impedance=C\/density<\/p>\n
<\/p>\n
Wave Length<\/p>\n
(insert equation)<\/p>\n
<\/p>\n
wave length is the distance between two peaks or valleys in the wave<\/p>\n
it is determined by speed divided by frequency<\/p>\n
For soft tissue,<\/p>\n
use speed of sound as 1540 m\/s<\/p>\n
change it to mm<\/p>\n
1.54 mm\/f (MHz) gives the answer in mm<\/strong><\/p>\n <\/p>\n air and lung has the lowest impedance, bone has the highest<\/p>\n <\/p>\n Reflection<\/p>\n Perpendicular Incidence<\/p>\n if materials with two different impedances are next to each other,\u00a0some of the beams energy will be reflected and some will be transmitted.<\/p>\n Non-Perpendicular Sound Beam Incidence \u00a0Can cause refraction<\/strong>, i.e. bending of the sound beam<\/p>\n Rayleigh Scatterers<\/p>\n structures smaller than the wavelength<\/p>\n they increase as frequency increases<\/p>\n <\/p>\n <\/p>\n Attenuation in tissue <\/strong><\/p>\n caused by reflection and scattering \u00a0and direct absorbtion<\/p>\n the higher the frequency, the higher the attenuation. almost proportional<\/p>\n <\/p>\n beam characterisitcs<\/p>\n near field=rough waves<\/p>\n far field=smooth waves<\/p>\n with increasing frequencies, the near field length increases<\/p>\n beam divergence is less at higher frequencies<\/p>\n the diameter of the probe also increases the NFL<\/p>\n <\/p>\n <\/p>\n Ring-Down Artifact<\/p>\n wherever small bubbles or partial liquids exist<\/p>\n look like comet tails<\/p>\n <\/p>\n Mirror Images<\/p>\n echo bounces off the bottom of the image hits an object\u00a0and bounces back to the bottom<\/p>\n <\/p>\n Doppler Spectral Mirroring<\/p>\n when gain is set too high\u00a0or when angle is perpendicular to flow<\/p>\n <\/p>\n Masses can show enhancement or shadowing<\/p>\n low attenuating masses generate large enhancement i.e. a cyst or fluid filled structure causes enhancement behind it<\/p>\n <\/p>\n Refraction<\/p>\n at the interface of tissues with different speeds of sound<\/p>\n bone has major refraction problems<\/p>\n fat which is slower than tissue<\/p>\n Edge shadowing of structures like GB is another example<\/p>\n <\/p>\n if a structure with a slower speed of sound is imaged everything distal to it will look further away<\/p>\n <\/p>\n wavelength = c\/f (just divide 1.54\/freq)<\/p>\n <\/p>\n Impedance=C\/density<\/p>\n <\/p>\n Intensity=mW\/cm2<\/p>\n <\/p>\n Incident Beam= 10 log (I2\/I1)<\/p>\n <\/p>\n axial and lateral resolution<\/p>\n Longitudinal discrimination the minimum separation of two targets in tissue in a direction parallel to the beam which results in their being imaged as two distinct structures<\/p>\n Relates to pulse length (about 3 wavelengths)<\/p>\n Made better with higher frequency (b\/c wavelengths are shorter)<\/p>\n Does not vary with depth<\/p>\n Axial resolution improves with increased damping, increased frequency, increased bandwidth, decreased pulse length<\/p>\n Transducers have a tendency to “ring” after being excited by an electrical impulse, creating an acoustic pulse which has an extended length in<\/p>\n Moreover, shortening the length of an ultrasound pulse while keeping the total energy of the pulse constant, results in a higher peak acoustic intensity. Thus a compromise is reached between the peak pressure to which tissue is exposed and the effective axial resolution of the ultrasound image.<\/p>\n relates to beam width<\/p>\n number of scan lines<\/p>\n wider transducer<\/p>\n higher frequency has a longer near zone and therefore narrower beam as long as area in focal zone<\/p>\n depth dependent<\/p>\n Shadowing of stones is lateral resolution<\/p>\n Near zone length is increased by increased frequency and wider transducer<\/p>\n <\/p>\n Lateral resolution better with increased frequency and focusing (also by curving transducer)<\/strong><\/p>\n <\/p>\n focal zone=where beam is narrowest<\/p>\n fresNel=near<\/p>\n fraunhFer=far<\/p>\n <\/p>\n focusing decreases bandwidth, improves lateral resolution not axial<\/p>\n focusing increases pulse length which hurts axial resolution<\/p>\n <\/p>\n increased transducer diameter=increased near zone length=better LATERAL resolution<\/p>\n <\/p>\n power does not affect it<\/p>\n receiver gain does not affect it<\/p>\n <\/p>\n convex=wider image in near field and increased resolution at depth<\/p>\n works just like lateral, relates to depth. has a focal zone as well<\/p>\n elevation=across the width of transducer=z thickness=slice thickness=mechanical focus by manufacturer<\/p>\n small cystic structures=elevational resolution<\/strong><\/p>\n can cause pseudo-sludge b\/c back of gb may wider beam than front<\/strong><\/p>\n <\/p>\n frame rate<\/p>\n no phantom for this one<\/p>\n to improve temporal resolution decrease scan line density<\/p>\n frame rate=images per second 10-50 is the norm<\/p>\n scan depth is operator control which affects frame rate<\/p>\n decreasing focal zones increases temporal resolution as does increased prf<\/p>\n <\/p>\n resolution of objects with similar reflective properties<\/p>\n contrast resolution-change of gray scale map<\/p>\n <\/p>\n <\/p>\n all frequencies have identical transit times and sound propagation speeds<\/p>\n Propagation \u00a0speed=speed of sound through substance, not user adjustable<\/p>\n Increased frequency=better spatial resolution and poorer penetration<\/p>\n <\/p>\n increase frequency to see shadows because the stone must be wider than sound beam to see shadows<\/p>\n As you increase the frequency and focus the beam, the beam width narrows; therefore better axial resolution<\/p>\n shortest wavelength=highest frequency<\/p>\n <\/p>\n As frequency increases, scattering, absorption, and attenuation all increase<\/p>\n <\/p>\n 2.5 Mhz to 5 Mhz probe, wavelength halves<\/p>\n <\/p>\n Scattering intensity=frequency 4th power<\/p>\n <\/p>\n If frequency is doubled, absorption is doubled<\/p>\n <\/p>\n Resonance frequency=voltage frequency and thickness of an element<\/p>\n <\/p>\n thin elements=high frequency<\/p>\n voltage of pulser determines final frequency<\/p>\n rate determines PRF<\/p>\n increased power=increased penetration, acoustic power, brightness, and voltage<\/p>\n Power=Energy\/Time<\/p>\n <\/p>\n half value layer=decrease 3DB, shallower with higher frequency, point at which beam intensity is reduced by half<\/p>\n <\/p>\n 10 Db decrease is 10% of original<\/p>\n 3 Db decrease is \u00bd of original<\/p>\n Tissue=1540 m\/s or 1.54<\/p>\n Bone=4080<\/p>\n increased density causes decreased propagation speed<\/p>\n molecules oscillate (compressions and rarefactions) to propagate sound<\/p>\n rarefactions=low pressure\/density formed during sound propagation<\/p>\n compression=elevated pressure during sound propagation<\/p>\n <\/p>\n the stiffer the material, the quicker the sound<\/p>\n ONLY MEDIA determines the SPEED of SOUND<\/p>\n <\/p>\n fat causes axial misrepresentation things look FURTHER AWAY, because fat is slower<\/p>\n lung has highest rate of attenuation<\/p>\n fat has slowest propagation \u00a0speed of tissue<\/p>\n <\/p>\n impedance increases if density increases or speed increases and affected by stiffness, unaffected by frequency<\/p>\n <\/p>\n air reflects all sound, 99.9% reflection coefficient<\/p>\n <\/p>\n Gel reduces impedance difference between transducer and skin<\/p>\n <\/p>\n unit of impedance=Rayl <\/strong><\/p>\n <\/p>\n Impedance=density(propagation speed)<\/p>\n Z=pc<\/p>\n <\/p>\n <\/p>\n Pulsed ultrasound-# of pulses to element per second=Pulse Repetition Frequency (PRF)<\/p>\n thickness of piezoelectric determines frequency<\/strong><\/p>\n <\/p>\n <\/p>\n <\/p>\n If number of cycles increase but wavelength stays the same, pulse duration is increased???<\/p>\n PRF=# of impulses to transducer\/second<\/p>\n <\/p>\n <\/p>\n <\/p>\n Period=time for one cycle<\/p>\n frequency=cycles per second<\/p>\n Period=1\/frequency<\/p>\n <\/p>\n <\/p>\n milli=10 -3<\/p>\n micro=10 -6<\/p>\n <\/p>\n <\/p>\n <\/p>\n absorption=sound converted to heat<\/p>\n <\/p>\n <\/p>\n transmission + reflection coefficient=100%<\/p>\n <\/p>\n RBC=rayleigh scatterer<\/p>\n <\/p>\n refraction=edge shadowing=different propagation \u00a0speeds<\/p>\n <\/p>\n reflection requires a difference in acoustic impedance<\/p>\n <\/p>\n Specular reflections=renal capsule or diaphragm. LARGE SMOOTH INTERFACE<\/p>\n Specular reflection=crap image from oblique angles<\/p>\n <\/p>\n Scattering=non-specular reflection<\/strong>-THIS IS WHAT ALLOWS IMAGING IN THE FIRST PLACE<\/p>\n <\/p>\n interference=summation of waves<\/p>\n <\/p>\n diffuse reflection=rough surface<\/p>\n <\/p>\n diffraction=passage through aperture <\/strong><\/p>\n <\/p>\n Refraction described by Snell’s law=angle of sound c oblique interface and different speeds. Refraction<\/p>\n <\/p>\n attenuation in soft tissue=0.5 dB\/cm\/MHz so as frequency goes up, attenuation goes up<\/p>\n have to double the depth b\/c it is roundtrip<\/strong><\/p>\n <\/p>\n High attenuation (gallstone)=shadow<\/p>\n Low attenuation (bladder)=enhancement<\/p>\n <\/p>\n \u00bd power distance (1\/2 value thickness) in cm water 380, blood 15, tissue 5, muscle 1, lung 0.05<\/p>\n <\/p>\n Increased pressure = increased intensity<\/p>\n <\/p>\n Absorption=sound to heat<\/p>\n <\/p>\n Normal incidence=perpendicular incidence<\/p>\n <\/p>\n Huygen’s instructive to deconstructive interference from each sound source<\/p>\n <\/p>\n air is best reflector<\/p>\n <\/p>\n <\/p>\n <\/p>\n Curie=temperature point at which ceramics go piezo<\/p>\n crystal material=lead zirconate<\/p>\n aperture focusing=# of elements changed<\/p>\n <\/p>\n Mechanically steered<\/p>\n Mechanically focused<\/p>\n only one mechanical focus on width of beam<\/p>\n Sector image, pointed top<\/p>\n Electronically Steered and focused<\/strong><\/p>\n mechanically steered<\/strong>, electrically focused<\/p>\n Beam is symmetrical about beam axis<\/p>\n Annular arrays are transducer assemblies with circular or ringlike elements, used to focus the beam. Annular arrays must be steered mechanically since they can only be fired in an outward-inward progression due to the rings. Annular arrays reduce section thickness artifacts<\/p>\n <\/p>\n Dynamic apodization=reduces side lobes makes all energy come from center of elements<\/p>\n subdicing=reduces grating lobes, breaking elements into sub-elements<\/p>\n reduces acoustic mismatch<\/p>\n matching layer should be 1\/4 of wavelength<\/p>\n dynamic receive focusing holds sound waves with others at same depth return<\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n dampens ringing<\/p>\n dynamic damping-stop crystal from ringing after it rings<\/p>\n gain-volume knob of stereo<\/p>\n TGC-works on received echoes at depth<\/p>\n rejection-lowers electric noise, rejects low level echoes<\/p>\n the whole pulsed thing is to allow depth calculations<\/p>\n elements only fire about 1% of the time<\/p>\n <\/p>\n reduce gain if background noise (i.e. not black background)<\/p>\n if it can be performed on a frozen image, it is POST PROCESSING<\/p>\n frame averaging-compares betweens frames and reduces random noise<\/p>\n tissue harmonics-improved contrast resolution, 2x transmitted frequency<\/p>\n Beam former apodization, beam steering, focusing aperture control?<\/p>\n interpolation-fills in skipped lines with decreased scan line density<\/p>\n <\/p>\n pulser to beam former to receiver to memory to display<\/p>\n <\/p>\n typical frame rate=10-50 Hz=10-50 frames per second<\/p>\n <\/p>\n improved signal to noise=frame averaging<\/p>\n <\/p>\n if only PRF is increased, frame rate will increase because it will take less time to fire all the pulses to make one frame. If too high, you get range ambiguity. New pulse fired before the first one returns<\/p>\n <\/p>\n Signal to noise-system sensitivity; greater this ratio, the smaller the signal that can be differentiated<\/p>\n <\/p>\n Rectification converts negative portion of signal to positive<\/p>\n <\/p>\n Increasing dynamic range decreases image contrast because more levels to assign colors<\/p>\n <\/p>\n Gain is at the receiver<\/p>\n <\/p>\n range equation d=1\/2 ct<\/p>\n <\/p>\n 3 DB decreased by 1\/2<\/p>\n <\/p>\n radio frequency to video=demodulater <\/strong><\/p>\n AKA amplitude or envelope detection<\/p>\n <\/p>\n transducer to electricity to acoustic pulses<\/p>\n duty factor<\/strong> is only time<\/p>\n increased PRF = increased duty factor<\/p>\n <\/p>\n threshold is another name for rejection<\/p>\n <\/p>\n read zoom-uses stored data<\/p>\n write zoom gets new data<\/p>\n <\/p>\n scan converter-makes 2d image<\/p>\n <\/p>\n Reverb-closely spaced reflections, like metal fragment<\/p>\n <\/p>\n motion<\/p>\n depth of reflections with respect to time<\/p>\n m-mode=time, motion pattern<\/p>\n <\/p>\n amplitude<\/p>\n width of spike=strength of the echo<\/p>\n amplitude\/distance (time) used in opthal<\/p>\n <\/p>\n Brightness<\/p>\n <\/p>\n brightness level limited by bit depth or bits per pixel<\/p>\n numbers of shades of gray=contrast resolution, bits per pixel<\/p>\n <\/p>\n television is 30 frames per second, 525 lines<\/p>\n <\/p>\n digital scan converter = image memory storage area\u00a0 # of pixels in matrix=better spatial resolution<\/p>\n <\/p>\n 8 bit=1 byte=256 shades of gray<\/p>\n <\/p>\n color needs 24 bis\/pixel<\/p>\n <\/p>\n if image is washed out, check processing equipment<\/p>\n <\/p>\n <\/p>\n memory to proportional voltages to brightness on monitor to digital to analog<\/p>\n <\/p>\n beat frequency=reference wave + reflected wave<\/p>\n <\/p>\n continuous wave doppler-no max velocity<\/p>\n pulsed wave-max velocity<\/p>\n <\/p>\n with pulse wave doppler,\u00a0frequency shift > 1\/2 PRF you get aliasing<\/p>\n <\/p>\n to improve sensitivity to slow ???; decrease PRF as slow frequency=low freq shifts can also decrease wall filter and increase the doppler frequency<\/p>\n <\/p>\n ensemble length=pulses per scan line<\/p>\n <\/p>\n spectral broadening-fill in of spectral window associated with turbulent flow<\/p>\n <\/p>\n indeterminate doppler angle-velocity estimate inaccurate<\/p>\n <\/p>\n max frequency shift at 0\u00b0 to flow; if angle is 90, no shift detected<\/p>\n <\/p>\n determine direction, phase quadrature detection<\/p>\n <\/p>\n <\/p>\n no range<\/p>\n <\/p>\n flow towards=red=POSITIVE SHIFT <\/strong><\/p>\n <\/p>\n increased wall filter=reduced display of low frequency<\/p>\n <\/p>\n Increased packet size=decreased frame rate, improved signal to noise<\/p>\n <\/p>\n Fourier Analysis-used to perform spectral analysis for pulsed doppler<\/p>\n <\/p>\n angle near 90\u00b0-you get spectral mirroring<\/p>\n <\/p>\n aliasing top clipped off seen at bottom–fix by increased PRF, i.e.\u00a0velocity scale, range, flow rate <\/strong><\/p>\n <\/p>\n <\/p>\n <\/p>\n doppler shift=difference between transmitted and received frequency<\/p>\n <\/p>\n change F=2 V cos<\/p>\n smaller the angle, the larger the shift<\/strong><\/p>\n <\/p>\n Nyquist limit=aliasing frequency<\/p>\n <\/p>\n reduce aliasing by increasing angle, lower zero baseline, increased PRF, decrease doppler frequency<\/p>\n <\/p>\n aliasing=shift >1\/2 PRF<\/p>\n <\/p>\n color doppler uses autocorrelation<\/p>\n <\/p>\n encodes amplitude<\/p>\n does not use phase<\/p>\n angle does not matter<\/p>\n only strength of frequency<\/p>\n <\/p>\n <\/p>\n spectral broadening= turbulent flow<\/p>\n color gate=axial length of the sampling volume<\/p>\n <\/p>\n spectral analysis-determines distribution and magnitude of frequency<\/p>\n <\/p>\n to better image deep vessels, decrease doppler frequency<\/p>\n <\/p>\n <\/p>\n partial volume artifact-from slice thickness that is too wide<\/p>\n ringdown=gas bubble<\/p>\n <\/p>\n string phantom-doppler velocity<\/p>\n <\/p>\n doppler flow phantom-velocity estimation, accuracy of flow directions<\/p>\n <\/p>\n hydrophone-acoustic output level<\/p>\n <\/p>\n sensitivity-ability to detect weak echoes<\/p>\n <\/p>\n Closely spaced targets at various distances from the probe=AXIAL resolution<\/p>\n <\/p>\n clear anechoic tubes oriented perpendicular =elevational resolution<\/p>\n <\/p>\n width of point target=lateral resolution<\/strong><\/p>\n <\/p>\n adjust to maximum output and gain when testing<\/p>\n <\/p>\n dead zone=distance from transducer to 1st echo<\/p>\n <\/p>\n focal point=best lateral resolution<\/p>\n <\/p>\n SMPTE-evaluates the display<\/p>\n <\/p>\n <\/p>\n 1\u00b0 C max increase in temperature<\/p>\n <\/p>\n SATA=lowest for pulsed-wave field<\/p>\n <\/p>\n increased focusing = increased heat<\/p>\n <\/p>\n SPTA=AIUM statement on mammalian in vivo\u00a0 100 mW\/cm=safe<\/p>\n <\/p>\n mech index <1=safe = likelihood of cavitation<\/p>\n <\/p>\n effects from <\/strong><\/p>\n cavitation<\/p>\n heating<\/p>\n mechanical interactions<\/p>\n acoustic streaming<\/p>\n NOT IONIZATION<\/p>\n <\/p>\n ALARA-as low as reasonably ACHIEVABLE<\/strong><\/p>\n <\/p>\n therm index-max rise in tissue<\/p>\n <\/p>\n SPPA and SARA-nor applicable to continuous wave<\/p>\n <\/p>\n hydrophone can measure amplitude<\/p>\n <\/p>\n duty factor= time actually transmitting<\/p>\n =pulse length*pulses per second<\/p>\n <\/p>\n mc gapasial units of peak negative pressure<\/p>\n <\/p>\n bone takes on most heat<\/p>\n <\/p>\n high frequency\/high intensity=increased thermal index<\/p>\n <\/p>\n acoustic streaming=circular motion of fluids in tissues<\/p>\n <\/p>\n <\/p>\n TIB > temp increase in bone<\/p>\n <\/p>\n SPTA for the eye is the lowest<\/p>\n <\/p>\n TIC for brain<\/p>\n <\/p>\n cavitation occurs with high\u00a0pressure and low frequency<\/p>\n <\/p>\n <\/p>\n (AIUM) Statement on clinical safety: “Diagnostic ultrasound has been in use for more than 40 years. Given its known benefits and recognized efficacy for medical diagnosis, including use during human pregnancy, the American Institute of Ultrasound in Medicine herein addresses the clinical safety of such use: No confirmed biological effects on patients or instrument operators caused by exposures at intensities typical of present diagnostic instruments have ever been reported.<\/p>\n <\/p>\n First, the acoustic intensity averaged over time (the Spatial Peak Temporal Average intensity, SPTA) is considerably higher in pulsed Doppler mode with many duplex scanners than in most imaging instruments. One survey reports values up to 750 mW\/cm2 ISPTA, but some pulsed Doppler systems are known to deliver SPTA intensities as high as 1,000 to 2,000 mW\/cm2.<\/p>\n <\/p>\n Second, the beam must be stationary during a Doppler examination will ‘dwell’ on a target area for a longer period than for imaging, sometimes for a period of minutes. Finally, it is widely felt that of all tissues, those of the fetus are likely to be among the most sensitive to biological effects of ultrasound, and Doppler has begun to play a part in the ultrasound examination of the fetus. Only recently has the U.S.Food and Drug Administration approved the marketing of a single-gate pulsed Doppler duplex system for fetal use, bringing questions to many users’ minds as to whether this modality is indeed safe for clinical use. There are two classes of interaction of ultrasound with tissue that it is relevant to consider.<\/p>\n <\/p>\n Heating \u00a01\u00b0C) are of no consequence. Local temperature rise will increase with the SPTA intensity but will also be affected by physiological factors such as local blood flow.<\/p>\n <\/p>\n more dangerous phenomenon of transient cavitation is certainly capable of destroying tissue but can only occur at high instantaneous (that is, spatial peak temporal peak, SPTP) intensities.<\/p>\n <\/p>\n SPTA intensities below 100 mW\/cm2<\/p>\n <\/p>\n Pulsed>Color>Mmode>B Mode<\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n Lectures and Stuff<\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n |\u00a0\u00a0 \u00a0\u00a0 |\u00a0\u00a0 \u00a0\u00a0 |<\/p>\n","protected":false},"excerpt":{"rendered":" Array<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[16],"tags":[],"yoast_head":"\n![\"\"](\"\/wp-content\/images\/part4\/clip_image001.gif\")
<\/h3>\n<\/span>Spatial resolution<\/span><\/h3>\n
<\/span>Axial Resolution<\/span><\/h3>\n
<\/span>Lateral Resolution<\/span><\/h3>\n
<\/span>Elevational Resolution<\/span><\/h3>\n
<\/span>Temporal Resolution<\/span><\/h3>\n
<\/span>Contrast resolution<\/span><\/h3>\n
![\"\"](\"\/wp-content\/images\/part4\/clip_image002.gif\")
<\/p>\n<\/span>Frequency<\/span><\/h3>\n
<\/span>Power<\/span><\/h3>\n
<\/span>Decreasing Db<\/span><\/h3>\n
<\/span>Propagation Speed<\/span><\/h3>\n
<\/span>Impedance<\/span><\/h3>\n
<\/span>Reflection & Refraction<\/span><\/h3>\n
<\/span>Attenuation<\/span><\/h3>\n
<\/span>Crystals & Elements<\/span><\/h3>\n
<\/span>Mechanical Sector<\/span><\/h3>\n
<\/span>Linear<\/span><\/h3>\n
<\/span>Phased array<\/span><\/h3>\n
<\/span>Annular array<\/span><\/h3>\n
<\/span>Side Lobes\/Grating Lobes<\/span><\/h3>\n
<\/span>Matching layer<\/span><\/h3>\n
<\/span>Focusing<\/span><\/h3>\n
<\/span>backing material<\/span><\/h3>\n
<\/span>Gain<\/span><\/h3>\n
<\/span>Processing<\/span><\/h3>\n
<\/span>Artifacts<\/span><\/h2>\n
<\/span>Pulse echo imaging<\/span><\/h2>\n
<\/span>M-Mode<\/span><\/h3>\n
<\/span>A-mode<\/span><\/h3>\n
<\/span>B-Mode<\/span><\/h3>\n
<\/span>Pixels<\/span><\/h3>\n
<\/span>Doppler<\/span><\/h2>\n
<\/span>Continuous wave Doppler<\/span><\/h3>\n
<\/span>power doppler<\/span><\/h3>\n
<\/span>Image Features and Artifacts<\/span><\/h2>\n
<\/span>Quality Assurance<\/span><\/h2>\n
<\/span>Safety<\/span><\/h2>\n
<\/span>ULTRASOUND EXPOSURE<\/span><\/h3>\n
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<\/a><\/p>\n