Derivation of Scatter Kernel in CBCT Imaging System

An edge spread function method has been developed to determine the scatter kernel in kilo-voltage (kV) cone beam computed tomographic (CBCT) imaging system. We modeled the scatter as a depth dependent convolution kernel, and the kernel was derived for different object thickness up to 41 cm from measured data without assuming any empirical trial function for a Varian Trilogy CBCT system. The derived kernel can then be used for correcting the projection data, or incorporated in the reconstruction process.