Piezoelectric Properties:

a "crystalline" material such as quartz that changes shape when an electric current is applied creating sound waves and when struck by sound waves creates electrical currents.

Types:

Nonimaging - transducers that are used in detection of blood flow such as a continuous wave transducer. The CW transducer, also called a Pedoff transducer, is two separate elements. One element is always transmitting while the other element is always receiving.

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Imaging - transducers that are used to image cardiac structures but also have the capability of using various Doppler techniques to detect blood flow. This transducer, sometimes called a duplex transducer, is made up of multiple elements spending part of the time transmitting and part of the time receiving sound energy. Continuous wave, pulse wave, high PRF, ColorFlow, m-mode, and 2D are the various modes that this type of transducer can perform.

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Materials:

Elements - commercial echocardiographs use ceramics such as barium titanate or lead zirconate titanate.

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4. Beam Properties:

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Sound wave profile - the wavefront generated by the transducer is a  3 dimensional beam that contains useful and unuseable components.

Longitudinal Waves - the wave in which the particle motion is parallel to the direction of the wave travel. A series of longitudinal waves make up the ultrasound beam.

Sheer Waves - waves that travel perpendicular to the direction of the sound beam. These occur mainly in the bone and are not considered in imaging soft tissue.

Side-Lobes - artifact that is generated from extraneous side beams.

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sound wave intensity variations and side lobe generation

Zones

1. Near - the region of a sound beam in which the beam diameter decreases as the distance from the transducer increases. This zone is called the Fresnel (Fra-nel, the s is silent) zone.
2. Focal - the region where the beam diameter is most concentrated giving the greatest degree of focus.
3. Far - the region where the beam diameter increases as the distance from the transducer increases. This zone is called the Fraunhoffer zone

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