Introduction :

The first industrial scale X-Ray system installed in Switzerland used a specific 2-Level conveyor derived from Gamma, allowing the usage of the full X-Ray beam to treat the pallets in the so-called "4-passes” or “Product overlap”, turning the pallet by 180° and inverting their position on top and lower conveyor level.

More recently, the emergence of new X-Ray design in “single level” and very high pallets sizes above 2 meters height, introduced the need of a new way to deliver the beam to the product.

Material and method :

IBA has developed a new way to optimize the beam current intensity along the X-Ray target. Following a Monte Carlo dose optimization using elementary virtual sources, a specific shape of the electron beam profile can be computed and used. This specific shape is then converted into scanning speed of the electron beam reaching the X-ray target.

With different shapes of those electron beams, we could demonstrate that the DUR of a specific product can be optimized, as the minimum dose the product could receive. Compared to uniform electron beam scanning, a typical improvement of 20 to 25 % of the DUR could be expected for variable scan. The treatment of pallet product height that can go up to 2.5 to 2.8 m on a one level X-ray conveyor can be considered.

In this paper, we will present a new generation, better integrated in the Process Control System, where the scan, monitoring and protections can be adjusted product to product.  

Conclusion :

With the introduction of variable scan in X-Ray beam technology, a new way to optimize the DUR and/or the minimum dose is now available. This optimization opens the possibility to simplify the X-Ray conveyor while allowing better DUR and/or minimum dose on the treated product.