Now the existing direct volume CT methods face two difficulties:first

how to get the projection data to reconstruct the 3D image exactly

including whether the scanning structure is practical;second

how to reduce the effect of Compton scatter on reconstruction image.To these difficulties

we propose a novel imaging mode of cone-beam volume CT in this paper.It adopts a columned plane source with X-ray grid scanning on it

and a group of point detectors distributing on a large circle plus an orthogonal arc.Through the columned plane source rotates one time

full projection data could be acquired.This paper gives the structure of the device

explains the shape and dimension of columned plane X-ray source in detail

shows the distributing of detectors

and proves that this structure satisfies the complete condition.Then according to the characteristics of this scanning structure

a fast reconstruction algorithm is given.The computer simulations indicate that in the condition of sufficient projections

this structure could achieve optimal combination of the following three:minimal rotating times

restrained Compton scatter

and improved image reconstruction.It greatly improves image reconstruction speed and precision compared with conventional scanning structures.