Commercial radiation sterilisation has now been used for more than 50 years. During this period, the market for disposable medical products has undergone enormous growth, and with it, the use of ionising radiation as a method of sterilisation. Currently, approximately 40 – 50% of disposable medical products manufactured in developed countries are sterilised using some form of ionising radiation, but the growth in market share has been limited by the effects of existing sterilisation methods on the physical characteristics of the products being sterilised. In some cases, materials that are exposed to high doses of ionising radiation can change their physical characteristics, with certain polymers changing colour and/or becoming more brittle depending upon the dosage, while others can lose their structural integrity. Therefore, some medical devices currently have no alternative other than chemical gas sterilisation to achieve the necessary Sterility Assurance Level (SAL) which is defined as the probability of a product being non-sterile after sterilisation. Typically this is at least 10-6 for medical devices. Chemical gas sterilisation can also have an effect on the physical characteristics of the medical products being sterilised, and the possibility of harmful gases remaining in the packaging is a potential problem from time to time. There are an increasing number of types of polymers that are specifically designed for use in medical devices, which are very tolerant of sterilisation by ionising radiation as shown in the chart below.