A Novel X­ray Dual­Energy Computed Tomography Scan Mode

and Reconstruction Algorithm

Baolei Li1,2 Yaojun Zhang1

(1. The First Research Institute of Ministry of Public Security of P.R.C., Beijing 100048, China baolei_li@yahoo.com.cn

2. School of Mathematical Sciences, Peking University, Beijing 100871, China)

Abstract

X­ray dual­energy CT (computed tomography) imaging technique is one important material detection and recognition method in the field of security inspection. X­ray dual­energy imaging can be divided into two types, one type is true dual­energy imaging and another type is pseudo dual­energy imaging. The material detection performance of true dual­energy imaging is better than pseudo dual­energy imaging. However, true dual­energy CT scan need more time because high energy scan and low energy scan must be implemented separately according to this imaging mode. Pseudo dual­energy CT imaging only need one time scan to get the dual­energy projections using sandwich detectors. Based on the disadvantages of current technique, one novel scan mode is proposed. The proposed method just need one time high energy CT scan and low energy projection of just one projection view. Compare to the true dual­energy scan, the scan time can be reduced about 50%. Compare to the pseudo dual­energy scan, the sandwich detectors are not necessary and so the system cost can be reduced. The scan mode is designed for the inspection of simple objects such as the packaged liquid. The feasibility of the scan mode and reconstruction algorithm is validated by the simulation experiment results.

Keyword: security inspection; X­ray dual­energy computed tomography; scan mode; pre­reconstruction