This document discusses a project to generate digitally reconstructed radiographs (DRRs) from 3D anatomical models using GPU processing. DRR generation is currently a bottleneck in medical applications like 2D/3D registration for scoliosis evaluation. The project aims to develop fast DRR algorithms by implementing single-pass ray casting on the GPU using CUDA or OpenGL shading language. This could improve performance enough for clinical use. The current solution uses ray casting and depth peeling on the GPU. Work plans to modify this to the reported faster single-pass approach and compare CUDA and GLSL implementations. Faster DRRs are expected to enable new medical applications.