A simulation study on basis material composition for dual energy CT imaging at high-energy level

Quantitative dual energy computed tomography (DECT) allows to obtain both density and atomic number and thus can provide information about material composition. In this paper, a DECT reconstruction method for high energy X-rays (1 ∼ 10MV) is proposed based on a basis material decomposition model. Our method is to be adapted for cargo inspection. The difference from conventional DECT methods is derived from considering pair-production effect in reconstruction. This is unnecessary for DECT in usual energy level (lower than 1MV). Therefore, an approximation of the attenuation process is made: attenuation of photoelectric effect is ignored in our reconstruction due to its tiny contribution to total attenuation of multi-MV X-ray beams. Under this assumption, we set up our mathematical models based on the framework of the basis material method for DECT. Numerical experiments are performed to validate the effectiveness of our method. Results shows that our assumption and method are reasonable and feasible to be applied to real data. Discussion of the results and possible improvements for future work are presented in the end.