Phased array

A phased array ultrasound transducer is typically 2-3 cm long, consisting of 64-128 elements. It is a smaller assembly than a sequential array and can be either linear or curvilinear.

A sector field of view is produced by all elements firing to create a single waveform. Small delays in element firing allow for electronic field steering and focusing without moving the ultrasound probe. All elements will be fired multiple times with different degrees of steering to create an image. Echoes are detected by all elements and entered into an algorithm to form the image.

Line density decreases at the bottom of the image. The sensitivity of the image reduces at extremes of steering and lateral resolution is best in the center of the field of view due to a larger effective aperture.

The benefits of a phased array include; a small faced transducer allowing for imaging in small spaces and being able to change the focus of the ultrasound beam.