Novel registration-based image enhancement for x-ray fluoroscopy

High image noise in low-dose fluoroscopic x-ray often necessitates additional radiographic-dose exposures to patients to include as part of the medical records. We present an image registration based approach for the generation of high-quality images from a sequence of low-dose x-ray fluoroscopy exposures. Image subregions in consecutively acquired fluoroscopy frames are registered to subregions in a pre-selected reference frame using a two-dimensional transformation model. Frames neighboring the reference image are resampled using a smooth deformation field generated by interpolation of the individual subregion deformations. Motion-corrected neighboring frames are then combined with the reference frame using a weighted, frequency-specific multi-resolution combination method. Using this method, image noise (localized standard deviation) was reduced by 38% in phantom data and by 29% in clinical barium swallow examinations. We demonstrate an effective method for generating a simulated radiographic-dose x-ray image from a set of consecutively acquired low-dose fluoroscopy images. The significant improvement in image quality indicates the potential of this approach to lower average patient dose by substantially reducing the need for additional exposures for patient records.