Non-traditional statistical process control for commercial irradiation

Commercial irradiation typically involves applying electron beam or gamma radiation to a product with a view to sterilizing the product and killing any bacteria present. This is extremely important in the medical device industry where packaged products or pallets require irradiation between a minimum and maximum dose. As packaged product provides a level of shielding it is difficult to monitor such processes to ensuring that all prod- ucts on the pallet received a dose greater than the minimum and yet less than the maximum. This di±culty was solved for both the gamma ray and electron beam radiation facilities by the use of non-traditional Statistical Process Control (SPC) techniques. By combining standardized charts and group charts, a single control chart could accommodate both minimum and maximum doses while e®ectively monitoring the entire process. In addition, guidance tables were developed the allowed operations to determine a win- dow of suitable dosages that would simultaneously satisfy the irradiation requirements of di®erent groups of products.