NECESSITY OF UNIFORM ACOUSTIC LAYER ON ULTRASOUND PROBESWHAT IS AN ACOUSTIC LAYER ?????
- It is a gray (other colors also) colored part looking like rubber attached to the tip of the ultrasound probe.
- It is the intermediate material between the piezoelectric material and the object.
- Also called acoustic lens and matching layer (for some probes).
- It is designed to have adequate acoustic impedance value using a combination of different resins and is deposited uniformly on the tip of the probe.
- The suggested membrane thickness is 0.0002 inches
WHAT ARE THE FUNCTIONS OF AN ACOUSTIC LAYER?
- Maintain the acoustic impedance between the piezoelectric material and the object.
- Prevent the ultrasound wave from spreading and focused them in a slice direction to improve the resolution (Beam focusing).
- Act as protection barrier for piezoelectric crystals.
WHAT HAPPENS IF THE LAYER IS NOT UNIFORM ????
- Poor Beam focusing : If the layer is not uniform over the surface then the transmitted ultrasound wave get spread over the plane which will lead to decrease in resolution.
- Impedance mismatch : Changes in thickness will create impedance difference
- It devastatingly lengthens the ultrasound wave and ring down time.
|US IMAGE OF URINARY BLADDER BY A NON-UNIFORMLY LAYERED PROBE
|US IMAGE OF URINARY BLADDER BY UNIFORMLY LAYERED PROBE