Patent Number: 
Section: claims

1. A scanning device configured for backscatter imaging, the scanning device consisting essentially of:a radiation source, wherein the radiation source emits x-ray radiation; anda stationary shield plate and a single rotary shield body positioned respectively between the radiation source and a subject to be scanned, wherein the stationary shield plate is fixed relative to the radiation source, and the single rotary shield body is rotatable relative to the stationary shield plate; wherein:a ray passing area, permitting radiation beams from the radiation source to pass through the stationary shield plate, is provided on the stationary shield plate; anda ray incidence area and a ray exit area are respectively provided on the rotary shield body, wherein the ray incidence area is formed by a first spiral slit and the ray exit area is formed by a second spiral slit,wherein, during a process of rotating and scanning of the rotary shield body, the ray passing area of the stationary shield plate intersects consecutively with the ray incidence area and the ray exit area of the single rotary shield body to form scanning collimation holes; andwherein the width of each of the first and second spiral slits at their longitudinal ends is narrower than the width of each of the slits at a longitudinally center position, and the scanning collimation holes at both longitudinal ends of each of the first and second spiral slits are formed at an angle relative to the collimation holes at the longitudinal center position of each of the first and second spiral slits. 2. The scanning device configured backscatter imaging according to claim 1, wherein:the ray passing area of the stationary shield plate is a linear slit;the single rotary shield body is a cylinder; andwhen the single rotary shield body rotates at a uniform velocity, the scanning collimation holes consecutively move along the linear slit. 3. The scanning device configured for backscatter imaging according to claim 2, further comprising:a drive unit adapted for driving rotation of the rotary shield body, wherein the single rotary shield body is hollow or a solid cylinder. 4. The scanning device configured for backscatter imaging according to claim 2, wherein:a rotary axis of the single rotary shield body is located on a coplanar plane which is defined in common by the radiation source and the linear slit of the stationary shield plate. 5. The scanning device configured for backscatter imaging according to claim 1, wherein:the stationary shield plate is provided between the radiation source and the rotary shield body. 6. The scanning device configured for backscatter imaging according to claim 5, further comprising:a control unit which controls scanning velocity of the radiation beam by controlling rotary velocity of the single rotary shield body and acquires exit direction of the radiation beam by detecting rotary angle of the rotary shield body. 7. The scanning device configured for backscatter imaging according to claim 6, wherein:by limiting widths of the spiral slits of the single rotary shield body at different positions, shapes of the scanning collimation holes at different positions are controlled such that sectional shape of the radiation beam passing through the scanning collimation holes and irradiating on the subject to be scanned is controlled. 8. A scanning method for backscatter imaging, consisting essentially of:providing a radiation source which emits a radiation beam, wherein the radiation source emits x-ray radiation;providing a stationary shield plate and a single rotary shield body positioned respectively between the radiation source and a subject to be scanned, wherein the stationary shield plate is fixed relative to the radiation source, and the single rotary shield body is rotatable relative to the stationary shield plate; wherein a ray passing area permitting radiation beams from the radiation source to pass through the stationary shield plate is provided on the stationary shield plate, and a ray incidence area and a ray exit area are respectively provided on the rotary shield body, wherein the ray incidence area is formed by a first spiral slit and the ray exit area is formed by a second spiral slit; androtating the single rotary shield body such that the ray passing area of the stationary shield plate intersects consecutively with the ray incidence area and the ray exit area of the single rotary shield body to form scanning collimation holes;wherein the width of each of the first and second spiral slits at their longitudinal ends is narrower than the width of each of the slits at a longitudinally center position, and the scanning collimation holes at both longitudinal ends of each of the first and second spiral slits are formed at an angle relative to the collimation holes at the longitudinal center position of each of the first and second spiral slits. 9. The scanning method for backscatter imaging according to claim 8, wherein:the ray passing area of the stationary shield plate is a linear slit;the single rotary shield body is a cylinder; andwhen the single rotary shield body rotates at a uniform velocity, the scanning collimation holes consecutively move along the linear slit. 10. The scanning method for backscatter imaging according to claim 8, wherein:the stationary shield plate is provided between the radiation source and the rotary shield body. 11. The scanning method for backscatter imaging according to claim 10, further comprising the step of:controlling scanning velocity of the radiation beam by controlling rotary velocity of the rotary shield body, and acquiring exit direction of the radiation beam by detecting rotary angle of the rotary shield body. 12. The scanning method for backscatter imaging according to claim 11, wherein:by limiting widths of the spiral slits of the single rotary shield body at different positions, shapes of the scanning collimation holes at different positions are controlled such that sectional shape of the radiation beam passing through the scanning collimation holes and irradiating on the subject to be scanned is controlled.