Basic physical principles of ultrasound: Difference between revisions
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{{CMG}} | {{CMG}}; {{AE}} {{AZ}} | ||
==Sound | ==Sound Waves== | ||
*Ultrasound uses high frequency energy to create sound waves, characterized by | *Ultrasound uses high frequency energy to create sound waves, characterized by | ||
**frequency: number of cycles per second (Hz) | **frequency: number of cycles per second (Hz) | ||
Line 11: | Line 11: | ||
**amplitude: height of sound wave (decibels) | **amplitude: height of sound wave (decibels) | ||
==Ultrasound | ==Ultrasound And Tissue Interaction== | ||
* | *'''Reflection''' | ||
**occurs when an ultrasound wave hits tissue. Part of the wave is reflected back to the transducer | :**occurs when an ultrasound wave hits tissue. Part of the wave is reflected back to the transducer | ||
**tissues with greater density reflect a greater portion of the beam | :**tissues with greater density reflect a greater portion of the beam | ||
**tissues at a 90 degree angle to the beam reflect a greater portion of the beam | :**tissues at a 90 degree angle to the beam reflect a greater portion of the beam | ||
* | *'''Acoustic impedance''' | ||
**tissues can be defined by their individual acoustic impedance | :**tissues can be defined by their individual acoustic impedance | ||
**AI = density x acoustic velocity | :**AI = density x acoustic velocity | ||
* | *'''Scatter''' | ||
**small structures lead to scattering of the ultrasound signal | :**small structures lead to scattering of the ultrasound signal | ||
**scattering radiates the beam in all directions, very little reaches back to the transducer | :**scattering radiates the beam in all directions, very little reaches back to the transducer | ||
*refraction: ultrasound waves can be deflected as they pass into a medium of different acoustic impedance | *refraction: ultrasound waves can be deflected as they pass into a medium of different acoustic impedance | ||
* | *'''Attenuation''' | ||
**when sound travels through a medium, intensity diminishes with distance | **when sound travels through a medium, intensity diminishes with distance | ||
**caused by absorption of the energy by the tissues, and conversion to heat | **caused by absorption of the energy by the tissues, and conversion to heat | ||
**also affected by acoustic impedance and mismatch in impedance between adjacent structures | **also affected by acoustic impedance and mismatch in impedance between adjacent structures | ||
==Ultrasound | ==Ultrasound Set-Up== | ||
*Energy source | *Energy source | ||
*Transducer: converts electrical pulses to vibrations and returned vibrations back to electrical pulses | *'''Transducer''' | ||
* | :It converts the electrical pulses to vibrations and returned vibrations back to electrical pulses | ||
* | |||
* | *'''Piezoelectric crystals''' | ||
* | :*It is found inside the transducer | ||
:*It compresses and expand the electric current that is applied, generating a sound wave | |||
:*Same crystals also act as receivers. An electric current is generated when a reflected wave hits a crystal. | |||
Image formation: based on the time interval between the ultrasound transmission and the arrival of the sound wave back to the transducer | Image formation: based on the time interval between the ultrasound transmission and the arrival of the sound wave back to the transducer | ||
==Resolution== | ==Resolution== | ||
* | *Axial- along the length of the ultrasound beam | ||
* | *Lateral- side to side resolution of the 2D image | ||
* | *Elevational- the thickness of the tomographic slice | ||
==Basics of Echocardiography== | ==Basics of Echocardiography== | ||
<div class="mw-collapsible mw-collapsed"> | |||
===Basics of Echocardiography-Part 1=== | |||
<div class="mw-collapsible-content"> | |||
'''Basics of Echocardiography'''-Part 1-Series 1 | |||
{{#ev:youtube|QdkJ6qzMfNE}} | {{#ev:youtube|QdkJ6qzMfNE}} | ||
'''Basics of Echocardiography'''-Part 1-Series 2 | |||
{{#ev:youtube|h4dZmbfXKJQ}} | {{#ev:youtube|h4dZmbfXKJQ}} | ||
</div></div> | |||
<div class="mw-collapsible mw-collapsed"> | |||
===Basics of Echocardiography-Part 2=== | |||
<div class="mw-collapsible-content"> | |||
'''Basics of Echocardiography'''-Part 2--Series 1 | |||
{{#ev:youtube|SaORcN29CtM}} | {{#ev:youtube|SaORcN29CtM}} | ||
'''Basics of Echocardiography'''-Part 2--Series 2 | |||
{{#ev:youtube|zZVBN2cdqSo}} | {{#ev:youtube|zZVBN2cdqSo}} | ||
</div></div> | |||
==Fetal Echocardiography== | ==Fetal Echocardiography== | ||
<div class="mw-collapsible mw-collapsed"> | |||
===A Descriptive Case Presentation === | |||
<div class="mw-collapsible-content"> | |||
* '''A Descriptive Case Presentation''' | |||
{{#ev:youtube|ZIk9GhWqqfE}} | |||
</div></div> | |||
<div class="mw-collapsible mw-collapsed"> | |||
===Transposition=== | |||
< | <div class="mw-collapsible-content"> | ||
* '''Transposition''' | |||
{{#ev:youtube|Rkm8e9q1GSc}} | |||
</div></div> | |||
<div class="mw-collapsible mw-collapsed"> | |||
===Fetal Cardiac Myxoma=== | |||
* Fetal Cardiac Myxoma | <div class="mw-collapsible-content"> | ||
* '''Fetal Cardiac Myxoma''' | |||
{{#ev:youtube|SdNw9yH9jBg}} | |||
< | </div></div> | ||
==The Guide to Pediatric Echocardiography== | ==The Guide to Pediatric Echocardiography== | ||
<div class="mw-collapsible mw-collapsed"> | |||
===Pediatric Echocardiography=== | |||
<div class="mw-collapsible-content"> | |||
{{#ev:youtube|mquEA6l2afs}} | |||
</div></div> | |||
==References== | |||
{{Reflist|2}} | |||
{{WikiDoc Help Menu}} | |||
{{WikiDoc Sources}} | |||
[[CME Category::Cardiology]] | |||
[[Category:Emergency medicine]] | |||
[[Category:Cardiology]] | [[Category:Cardiology]] | ||
[[Category:Imaging]] | [[Category:Imaging]] | ||
Latest revision as of 04:45, 15 March 2016
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmed Zaghw, M.D. [2]
Sound Waves
- Ultrasound uses high frequency energy to create sound waves, characterized by
- frequency: number of cycles per second (Hz)
- wavelength: distance between excitations (mm)
- amplitude: height of sound wave (decibels)
Ultrasound And Tissue Interaction
- Reflection
- occurs when an ultrasound wave hits tissue. Part of the wave is reflected back to the transducer
- tissues with greater density reflect a greater portion of the beam
- tissues at a 90 degree angle to the beam reflect a greater portion of the beam
- Acoustic impedance
- tissues can be defined by their individual acoustic impedance
- AI = density x acoustic velocity
- Scatter
- small structures lead to scattering of the ultrasound signal
- scattering radiates the beam in all directions, very little reaches back to the transducer
- refraction: ultrasound waves can be deflected as they pass into a medium of different acoustic impedance
- Attenuation
- when sound travels through a medium, intensity diminishes with distance
- caused by absorption of the energy by the tissues, and conversion to heat
- also affected by acoustic impedance and mismatch in impedance between adjacent structures
Ultrasound Set-Up
- Energy source
- Transducer
- It converts the electrical pulses to vibrations and returned vibrations back to electrical pulses
- Piezoelectric crystals
- It is found inside the transducer
- It compresses and expand the electric current that is applied, generating a sound wave
- Same crystals also act as receivers. An electric current is generated when a reflected wave hits a crystal.
Image formation: based on the time interval between the ultrasound transmission and the arrival of the sound wave back to the transducer
Resolution
- Axial- along the length of the ultrasound beam
- Lateral- side to side resolution of the 2D image
- Elevational- the thickness of the tomographic slice
Basics of Echocardiography
Basics of Echocardiography-Part 1
Basics of Echocardiography-Part 1-Series 1 {{#ev:youtube|QdkJ6qzMfNE}}
Basics of Echocardiography-Part 1-Series 2
{{#ev:youtube|h4dZmbfXKJQ}}
Basics of Echocardiography-Part 2
Basics of Echocardiography-Part 2--Series 1 {{#ev:youtube|SaORcN29CtM}}
Basics of Echocardiography-Part 2--Series 2
{{#ev:youtube|zZVBN2cdqSo}}
Fetal Echocardiography
A Descriptive Case Presentation
- A Descriptive Case Presentation
{{#ev:youtube|ZIk9GhWqqfE}}
Transposition
- Transposition
{{#ev:youtube|Rkm8e9q1GSc}}
Fetal Cardiac Myxoma
- Fetal Cardiac Myxoma
{{#ev:youtube|SdNw9yH9jBg}}
The Guide to Pediatric Echocardiography
Pediatric Echocardiography
{{#ev:youtube|mquEA6l2afs}}