Conventional freehand three-dimensional (3-D) ultrasound is a multi-stage process.
First, the clinician scans the area of interest. Next, the ultrasound data is used
to construct a 3-D voxel array, which can then be visualized by, for example, any-plane
slicing. The strict separation of data acquisition and visualization disturbs the
interactive nature of the ultrasound examination. Furthermore, some systems require
the clinician to wait for an unacceptable amount of time while the voxel array is
constructed. In this paper, we describe a novel freehand 3-D ultrasound system which
allows accurate acquisition of the raw data and immediate visualization of arbitrary
slices through the data. Minimal processing separates the acquisition and visualization
processes: in particular, at no stage is a voxel array constructed. Instead, the standard
graphics hardware found inside most desktop computers is exploited to synthesize arbitrary
slices directly from the raw B-scans.