Abstract
In recent years, medical diagnostic departments gradually changed their imaging modality to the digital radiography. Digital radiography has its advantages, for example, broad dynamic range of contrast, post-process functions, multiple ways of viewing images, electronic transferring data etc. The broad dynamic range made it more difficult to detect over-exposure or under-exposure. Therefore, optimization is important in radiological diagnosis in order to reach the lowest patient’s dose but yet to maintain the required image quality level. This is the principle of as low as reasonably achievable, ALARA. The purpose of this study was to investigate the optimization techniques in terms of radiation dose and image quality. First, realize how the technical conditions to influence image quality for the same X-ray machine, and then seek the optimal condition. Secondly, compare the optimal condition of X-ray machines for different manufacturers. Judge if it is proper to use automatic exposure control (AEC) setup of each X-ray machine finally. The results of this research prove that the higher tube voltage used under AEC, the lower radiation dose and image quality. After increasing the thickness of added filter, radiation doses obviously drop. For the comparisons between x-ray machines of three manufactures, Philips, Toshiba and Hologic, regard Philips’ machine using 102 kVp under AEC as more suitable condition. Finally, in the experiment of judging automatic exposure control, comparing automatic exposure control with neighboring tube currents, automatic exposure control will reach the optimal condition.