Editing Medical ultrasound (section)

=== Forming the image ===
To make an image, the ultrasound scanner must determine two characteristics from each received echo:
# How long it took the echo to be received from when the sound was transmitted. (Time and distance are equivalent.)
# How strong the echo was.

Once the ultrasonic scanner determines these two, it can locate which pixel in the image to illuminate and with what intensity.

Transforming the received signal into a digital image may be explained by using a blank spreadsheet as an analogy. First picture a long, flat transducer at the top of the sheet. Send pulses down the 'columns' of the spreadsheet (A, B, C, etc.). Listen at each column for any return echoes. When an echo is heard, note how long it took for the echo to return. The longer the wait, the deeper the row (1,2,3, etc.). The strength of the echo determines the brightness setting for that cell (white for a strong echo, black for a weak echo, and varying shades of grey for everything in between.) When all the echoes are recorded on the sheet, a greyscale image has been accomplished.

In modern ultrasound systems, images are derived from the combined reception of echoes by multiple elements, rather than a single one. These elements in the transducer array work together to receive signals, a process essential for optimizing the ultrasonic beam's focus and producing detailed images. One predominant method for this is "delay-and-sum" beamforming. The time delay applied to each element is calculated based on the geometrical relationship between the imaging point, the transducer, and receiver positions. By integrating these time-adjusted signals, the system pinpoints focus onto specific tissue regions, enhancing image resolution and clarity. The utilization of multiple element reception combined with the delay-and-sum principles underpins the high-quality images characteristic of contemporary ultrasound scans.<ref>{{cite book |last1=Szabo |first1=Thomas L. |title=Diagnostic Ultrasound Imaging: Inside Out |date=2004 |publisher=Academic Press |isbn=9780126801453}}</ref>