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Result : Searchterm 'transducer' found in 13 terms [] and 169 definitions [])
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Searchterm 'transducer' was also found in the following services: 
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News  (31)  Resources  (15)  Forum  (5)  
 
DivergenceMRI Resource Directory:<br> - UltraSound Physics -
 
The divergence is an ultrasound beam characteristic of the far field. The beam divergence angle, q, depends on the transducer frequency and diameter according to the following approximation:
sin q º 1.22 ld
where l is the wavelength of the ultrasound in the medium of propagation and d is the diameter of the transducer element.
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• Related Searches:
    • Main Lobe
    • Near Field
    • Bi-directional Flow
    • Amplitude
    • Spatial Average Intensity

 Further Reading:
  Basics:
Physics Tutorial: Ultrasound PhysicsOpen this link in a new window
   by www.physics247.com    
US Resources  
Safety - Probes Transducers - UltraSound Training Courses - Manufacturers - Research Labs - Heart
 
Doppler EffectMRI Resource Directory:<br> - UltraSound Physics -
 
Christian Johann Doppler first described the effect of motion of sound sources and the frequency change of the sound to the observer.
Doppler ultrasound uses this effect to detect and measure blood flow, and the major reflector is the red blood cell. Doppler ultrasound depends on the fact that if the reflecting surface is moving in relation to the transducer (blood flowing in a vessel) the frequency of the received ultrasound wave will be different from that of the transmitted wave. If blood cells are moving towards the transducer, they increase the frequency of the returning signal. As cells move away from the transducer, the frequency of the returning signal decreases.
See also Quadrature Detection and Doppler Techniques.
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 Further Reading:
  Basics:
Basic ultrasound for cliniciansOpen this link in a new window
March 2006   by folk.ntnu.no    
  News & More:
Transmission Line Matrix (TLM) modelling of medical ultrasound(.pdf)Open this link in a new window
   by www.era.lib.ed.ac.uk    
US Resources  
Universities - Gall Bladder - Prenatal - Software - Fetal - Preferential Sites
 
Doppler Interrogation FrequencyMRI Resource Directory:<br> - UltraSound Physics -
 
The Doppler interrogation frequency is the frequency of the transmitted acoustic energy relative to the measured Doppler frequency shift. This frequency is most but not necessarily, the nominal transducer frequency.
See also Doppler Effect and Doppler Ultrasound.
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Searchterm 'transducer' was also found in the following services: 
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News  (31)  Resources  (15)  Forum  (5)  
 
Doppler TechniquesInfoSheet: - Modes - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:<br> - Modes -
 
Doppler techniques are dependent on the transducers used. The transducer operating in continuous wave mode utilizes one half of the elements and is continuously sending sound energy while the other half is continuously receiving the reflected signals. If the transducer is being used in a pulsed wave mode, the whole transducer is used to send and then receive the returning signals.
Pulsed wave techniques allow the accurate measurement of blood flow at a specific area in the heart and the detection of both velocity and direction. Measurement is performed by timing the reception of the returning signals giving a view of flows at specific depths. The region where flow velocities are measured is called the sample volume. Errors in the accuracy of the information arise if the velocities exceed a certain speed. The highest velocity accurately measured is called the Nyquist limit.
See also Doppler Velocity Signal and Doppler Effect.
point Continuous Wave Doppler
Used for accurate measurement of high Velocity flow. A disadvantage is the poor range of resolution.
point Pulsed Wave Doppler
Used for the measurement of velocities at a specific location with a good range of resolution. A disadvantage is the imprecise measuring of high velocities.
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 Further Reading:
  Basics:
Doppler ultrasoundOpen this link in a new window
   by www.ob-ultrasound.net    
EXAMINATION TECHNIQUESOpen this link in a new window
   by www.medana.unibas.ch    
  News & More:
Transjugular intrahepatic portosystemic shuntOpen this link in a new window
   by en.wikipedia.org    
Evaluation of lower extremity bypass grafts with use of color duplex sonographyOpen this link in a new window
Thursday, 30 June 2005   by radiographics.rsna.org    
US Resources  
Musculoskeletal and Joint - Distributors - Endoscopic - UltraSound Technician and Technologist Schools - Preferential Sites - Pelvic
 
Doppler UltrasoundInfoSheet: - Modes - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:<br> - Modes -
 
Doppler ultrasound is a medical imaging technique for calculating the relative velocity between two points by measuring the frequency shift of a sound wave transmitted from one point to the other, based on the Doppler effect. Continuous or pulsed Doppler is frequently used to examine cardiovascular blood flow. The combination of routine 2D-mode and Doppler ultrasound allows a complete evaluation of the heart's anatomy and function (including the fetal heart). See also Doppler Fluximetry in Pregnancy.
Doppler ultrasound depends on the fact that if a moving object reflects the ultrasound waves, the echo frequencies are changed. A higher frequency is created if the object is moving toward the probe//transducer and a lower frequency if it is moving away from it. How much the frequency is changed depends upon how fast the object is moving. Doppler ultrasound shows the different rates of blood flow in different colors on a monitor in real time.
The major Doppler parameters are the peak systolic velocity and the end-diastolic velocity. The peak systolic velocity ratio compensates the variability between different patients and instrumentations.

Different Doppler and duplex techniques:
list_point color Doppler;
list_point color power Doppler;
list_point continuous wave Doppler;
list_point contrast enhanced Doppler imaging;
list_point directional color power Doppler;
list_point duplex;
list_point harmonic power Doppler;
list_point pulse inversion Doppler;
list_point pulsed wave Doppler;
list_point spectral Doppler;
list_point transcranial Doppler.
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• View the news results for 'Doppler Ultrasound' (4).



 Further Reading:
  Basics:
Noninvasive Evaluation of Peripheral Arterial DiseaseOpen this link in a new window
   by ej.rsna.org    
  News & More:
Principles in Doppler EchocardiographyOpen this link in a new window
   by www.echoincontext.com    
Evaluation of lower extremity bypass grafts with use of color duplex sonographyOpen this link in a new window
Thursday, 30 June 2005   by radiographics.rsna.org    
Carotid artery color doppler ultrasound: 80-90% stenosis of the proximal internal carotid artery secondary to large atherosclerotic plaquesOpen this link in a new window
   by rad.usuhs.mil    
US Resources  
Contrast Agents - Directories - Doppler UltraSound - Journals - Manufacturers - Education pool
 
Related Searches:
 • Analog Output Signal
 • Focus
 • Angle of Incidence
 • Pulsed Ultrasound
 • Reject
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