Imaging Of Cone-beam CT Based On The DR Imaging System

Digital Radiography (DR) imaging equipment has been widely used in clinicalpractice and gradually spread to the primary medical institutions in our country.Accurate performance assessment of DR imaging equipment is the prerequisite toensure its rational clinical application, so it has important application value.The International Electrotechnical Commission adopted modulation transferfunction(MTF) for performance evaluation of DR imaging equipment, andrecommended knife-edge method as one of the MTF measurement method.Knife-edge method has advantages in accurately obtaining the low-frequencycharacteristics of MTF, but the error in tilt angle measurement of the knife-edgeobject prevents accurate MTF estimation in high frequencies. This problem hasbecome one of the major concerns in this research area around the world.A novel method for precise MTF measurement based on interpolation floatingtechnique was proposed in this paper. By investigating the quantitative relationshipamong the interpolation floating value, the variation of the line spread function (LSF),and the attenuation characteristics of the MTF curves in the presence of noise, wedemonstrated that the tilt angle measurement error caused the interpolation numberdeviation from the ideal benchmark interpolation and resulted in worse smoothness ofthe LSF curves and higher attenuation level of the MTF curves than the actual one.The MTF measurement error due to the edge angle measurement error was effectivelyrelieved by using the interpolation floating method. This method has great applicationvalue because it reduced the tough requirements in high-precision angle measurementof MTF estimationAccording to the cone-beam CT imaging theory and the performance evaluationresults of the DR system, a multi-dimensional and semi-automatic cone-beamimaging platform was built for three-dimensional imaging of small animals. Thecalibration phantom was designed for the calibration of the cone-beam CT system.After calibration and optimization, a precise rotation of the imaging chamber with therotation accuracy of0.00125degrees was achieved. This greatly improved theaccuracy of cone-beam imaging process. The3D cone-beam CT reconstruction of thevivo little mouse was achieved by our system, and the spatial distribution of the bones, organs and cavities of the little mouse could be clearly distinguished in thereconstructed results.