Resolution improvement and detail enhancement for computed tomography scout images

New applications currently demand utilizing computed tomography (CT) scout images for diagnostic purposes. However, many CT scout images cannot be used diagnostically due to their poor resolution, particularly in the direction of table movement, and loss of detail when displayed with one view. We present two methods to address these two problems. First, spatial resolution generally can be improved with image restoration techniques. Based on the principles of Wiener filtering and inverse filtering, a modified Wiener filtering approach is presented in the frequency domain. The concept of an equivalent target point spread function is also introduced, which makes the restoration process steerable. Consequently, balancing resolution improvement with noise suppression is facilitated. Relevant experiments compare the image quality with traditional inverse filtering and Wiener filtering. The modified Wiener filtering method has been shown to restore the scout image with higher resolution and lower noise. In addition, CT scout images have a wide dynamic range, from 0 to 105 intensity values. They are difficult to display in full detail with only 8 bits (256 intensities). An image fusion approach is developed to preserve and enhance details of CT scout images. The enhanced image is obtained by high-boosting one fused image from another, both of which are computed by fusing a set of preenhanced subimages which derived from the original, using different fusion rules. Image fusion is performed pixel by pixel by the discrete wavelet transform. Final experiments compare the image quality of the resolution-improved and detail-enhanced image and the noise level with those of the original image. Results show that more details, easily observed by a radiologist, are present in the restored and enhanced image than in the original. 0 2005 SPIE and IS&T.