SDD – Focused and Planar Arrays

Focused sensor arrays
Planar array

As more elements are added to an array of sensors, the total area occupied by the array increases.  At close working distances, the outer sensors present a poor geometry to the beam-spot.  Entry angles can be large and shadowing may occur from window mounts and on-chip collimators.  Focused array

To counter these problems, RaySpec developed the ‘focused array’ whereby each sensor is mounted such that its plane lies tangential to a sphere of radius equal to the optimum source distance.

7 x 65mm2 SDD - Focused Array
7 x 65mm2 SDD – Focused Array

In this design each sensor has optimum geometry with x-rays entering along the axis and all subtend the same solid angle at the target. Although there is one optimised source position (focus), the detector may be used over a wide range of working distances with the geometry remaining improved compared to a planar array.