Introduction:

The introduction of the variable scan in the early 2000’s opened new opportunity for X-Ray beam delivery. The principle is to slow down the electron beam at the extremities of the scan to increase the X-Ray dose. Having a specific electron beam shape arriving on the X-ray target, optimized for the treated product, would lead to the best DUR for the product and/or the highest minimal dose, while optimizing energy consumption.

This paper presents a specific optimization algorithm that has been developed and tested to reach that objective. The theoretical approach will be presented, as well as some practical validation results on site.

Material and method:

Going from a homogenous electron dose distribution on the X-Ray target to an optimized one is now technical possible.

The algorithm is using the large homogenous source that is subdivided into elementary sources. The width of those elementary sources is function of their position along the X-Ray target. The further from the X-Ray target center, the smaller the size.

The algorithm is distributing the same total electron density as homogenous scan, but in a way that some areas will receive more electron density and that other area will receive less compared to homogenous scan.

The algorithm propose 2 different ways of optimization either by minimizing the DUR or by maximizing the minimum dose, which will allow a maximization of the global throughput.

Conclusion:

We developed a method to optimize the dose distribution with a product with variable scan in X-Ray. This dose optimization algorithm can be used to optimize the dose distribution based either on a DUR and / or on a maximization of the Dmin. With the adapted process control system, dynamic adjustments of scanning functions will be possible in a near future.