The present invention includes a radiation source, each with a radiation source and a fixed shielding plate and the rotating shield is located between the scanning target, the fixed shielding plate is fixed with respect to the radiation source, the rotating shield is fixed to provide a scanning device is rotatable relative to the shield back scattering imaging for radiation beam. The fixed shielding plate, the radiation beam from the radiation source is disposed radiolucent area allows to pass through the fixing shielding plate, the rotary shield, the radiation incident area and a radiation emission region is disposed respectively, rotating shield in the process of the body is scanned by rotating, radiation transmissive area of ​​fixed shielding plate constitutes a scanning collimated hole radiation incident area and radiation emission region of the rotating shield and continuously intersecting. Radiation transmitting area of ​​the fixed shielding plate is linear slot, rotating shield is cylindrical body, each radiation incident area and a radiation emission region, a series of discrete holes disposed along a spiral line. The present invention further provides a method of scanning a radiation beam back scatter imaging.