UltraSound - Technology Information PortalTuesday, 30 May 2017


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Modes - UltraSound Training Courses - Resources pool - Thyroid - Services and Supplies - Journals
Acceleration IndexMRI Resource Directory:
 - UltraSound Physics -
(AI) This index is the ratio between the acceleration of the Doppler spectral waveform and the relative peak systolic velocity. The systolic acceleration is determined by the change in distance between the begin of systolic flow and the peak systolic velocity (cm/sec), divided by the acceleration time (AT - time interval from the onset of flow to the initial peak).
The acceleration index is reported in frequency units as KHz/sec or velocity units as cm/sec2.

• View the DATABASE results for 'Acceleration Index' (5).Open this link in a new window.

 Further Reading:
  News & More:
Ultrasound Imaging of Carotid Artery DiseaseOpen this link in a new window
   by rad.usuhs.mil    
Acceleration TimeMRI Resource Directory:
 - Vascular -
(AT) The acceleration time is the duration of upstroke from end-diastole to peak systole.
See Acceleration Index.

• View the DATABASE results for 'Acceleration Time' (3).Open this link in a new window.

US Resources  
Safety - Kidney - Quality Advice - Fetal - Vascular - Journals
Accuvix XQInfoSheet: - Systems -
TypesMRI Resource Directory:
 - Devices Machines Scanners Systems -

From Medison Co.,Ltd.;
'The Accuvix brand represents a new family name for high-end ultrasound system line from Medison. And it stands for '®Accurate Vision' and '®Accurate Diagnosis', which express the will to strive for accurate diagnoses with clear image realization.
Accuvix XQ is the first system to be released under the Accuvix brand, and the system initials XQ stands for '®Extreme Quality', the highest quality in terms of every aspect of system configurations and system components.'

Specifications for this system will be available soon.


• View the DATABASE results for 'Accuvix XQ' (2).Open this link in a new window.

Acoustic ImpedanceMRI Resource Directory:
 - UltraSound Physics -
(Z) The acoustic impedance is dependent on the density of the material in which sound is propagated through. When an ultrasonic wave crosses an interface between tissues with different acoustic impedance, the wave divides in 2 components, and the energy of the reflected components directly relates with the acoustic impedance.
The greater the impedance the more dense the material, and the greater the difference in acoustic impedance between two adjacent tissues the more reflective will be their boundary.
The acoustic impedance (the unit is "Rayl") is the product of the sound velocity and the physical dense.
The acoustic impedance is very high between air or bone and other body tissues, therefore not enough energy crosses these interfaces, and no information can be collected from organs placed behind them.
See also Mirror Artifact, Reverberation Artifact, Cross Talk and Ultrasound Physics.
Radiology-tip.comLinear Energy Transfer,  Photoelectric Effect
Radiology-tip.comSkin Depth,  Magnetic Susceptibility

• View the DATABASE results for 'Acoustic Impedance' (11).Open this link in a new window.

 Further Reading:
Ultrasound Physics Main differences between Ultrasound and X-rays, Velocity of sound in some Biological MaterialsOpen this link in a new window
   by www.drgdiaz.com    
Physics Tutorial: Ultrasound PhysicsOpen this link in a new window
   by www.physics247.com    
  News & More:
2007   by etd.adm.unipi.it    
Acoustic LensMRI Resource Directory:
 - UltraSound Physics -
The acoustic lens is placed at the time the transducer is manufactured and cannot be changed. The acoustic lens is generally focused in the mid field rather than the near or far fields. The exact focal length varies with transducer frequency, but is generally in the range of 4-6 cm for a 5 MHz curved linear probe and 7-9 cm for a 3.5 MHz curved transducer.
Placing the elevation plane (z-plane) focal zone of the acoustic lens in the very near or far field would improve the beam width at precisely those depths. However, this would degrade the beam width to a much greater and unacceptable degree at all other depths.
There are some chemicals in ultrasound couplants that can degrade the acoustic lens, destroy bonding, or change the acoustic properties of the lens. Problematic chemicals include mineral oil, silicone oil, alcohol, surfactants, and fragrances. Fragrance can affect the transducer's acoustic lens or face material by absorption over time into elastomer and plastic materials, thus changing the material's weight, size, density, and acoustic impedance. Surfactants can degrade the bond between the lens and the piezoelectric elements and contribute to the accelerated degeneration of the lens.
See also Retrolenticular Afterglow.

• View the DATABASE results for 'Acoustic Lens' (6).Open this link in a new window.

 Further Reading:
INTRODUCTIONOpen this link in a new window
   by www.fink.com    
  News & More:
Sound-field modification with acoustic lenses for high-intensity focused ultrasound therapyOpen this link in a new window
   by www.ncbi.nlm.nih.gov    
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