FPGA-based computation of free-form deformations

This paper describes techniques for producing FPGA-based designs that support free-form deformation in medical image processing. The free-form deformation method is based on a B-spline algorithm for modelling three-dimensional deformable objects. We transform the nested loop in this algorithm to eliminate conditional statements, enabling the development of a fully pipelined design. Further optimisations include precalculation of the B-spline model using lookup tables, and deployment of multiple pipelines so that each covers a different image. Our design description, captured in the Handel-C language, is parameterisable at compile time to support a range of image resolutions and output precisions. An implementation on a Xilinx XC2V6000 device at 67MHz has a throughput which is 12.8 times faster than an Athlon based PC at 1400 MHz.