Analysis of a Scan Conversion Algorithm for a Real-Time Sector Scanner

In a conventional digital ultrasound sector scanner, the sampling space is in polar coordinates while the display space is in Cartesian coordinates, which necessitates a coordinate transformation process. As a result, a number of artifacts appear in the displayed image. In this paper, we propose a new data space, to be called the uniform-ladder space, in which the sampling space is the same as the display space. In this new approach, sampled points are uniformly distributed in each horizontal line as well as in each radial ray so that the data are displayed as they are acquired without any interpolation process required. To implement the new real-time sector scanner, two frequency synthesizers with very high-speed switching time and a low-pass filter are required. The former determines the precise location of the data points in the new data space, and the latter fills the gap between pixels in the horizontal direction. Mathematical models of various interpolation schemes are devised to compare their performance.