IMPROVED IMAGE QUALITY UTILIZING DUAL PLATE COMPUTED RADIOGRAPHY

A method of improving image quality in computed radiography (CR) using dual plate exposure has been developed. Two CR image plates are used to increase the fraction of X-ray quanta absorbed from the beam. Spati al registration and combination of images from the two plates leads to an image with improved signal-to-noise ratio characteristics. A cross correlation technique is used to register spatially the images from t he front and rear plates. The modulation transfer function and noise p ower spectrum were measured for the single plate and combined dual pla te images. Results indicate a potential increase of approximately 60% in the detective quantum efficiency (DQE) of the dual plate combined i mage compared with the single plate image. The improvement of DQE at h igh spatial frequencies is dependent on the accuracy of the registrati on of the two images. The actual improvement in imaging performance wa s measured using a contrast detail test piece. A computerized method w as used to measure the imaged detail signal-to-noise ratio of the deta ils of different dimension. Results indicate an improvement of 21% in the signal-to-noise ratio of the details imaged with the dual plate ar rangement compared with the single plate. This indicates that this tec hnique can result in a significant increase in image quality for the s ame exposure level. Alternatively this technique could allow reduction in exposure while maintaining the same image quality achievable with the single plate system.