Final answer:
In 3D ultrasound imaging, the term 'voxel' refers to the smallest element of the picture that is generated, representing a value in a three-dimensional grid.
Step-by-step explanation:
When using 3D ultrasound, the smallest element of the picture that is generated is known as a voxel. A voxel represents a value on a regular grid in three-dimensional space, similar to how a pixel represents a point in two-dimensional space. In the context of ultrasound imaging, voxels contain information about the ultrasound signal's intensity at specific three-dimensional coordinates within the scanned object, enabling the creation of a 3D representation.