Method for establishing a sterilizing dose for radiation sensitive products

A method of determining a sterilization dose of radiation sufficient to ensure sterilization to a desired sterility assurance level (SAL) of an object comprising use of the expression:

• 10−yDose=10−xDose+((y−x)*PV*(RD/(x+log(BB))))
• where
• 10−y Dose represents the sterilization radiation dose required to achieve the desired SAL;
• y is a value representing the exponent of the desired SAL when said SAL is expressed in exponential form;
• 10−x Dose represents the radiation dose confirmed to result in a preselected probability of a surviving microorganism on the object;
• x is a value representing the exponent of the preselected probability of a surviving microorganism when said probability is expressed in exponential form;
• PV represents a proportionality value;
• RD represents the radiation dose that has been confirmed to result in the preselected probability of a surviving microorganism on the object;
• and
• BB represents the bioburden in colony-forming units.

A method for sterilizing objects with radiation, the method comprising the steps of determining a dosage of radiation sufficient to ensure sterilization to a desired sterility assurance level (SAL) and then applying said dosage of radiation to the objects, and wherein the step of determining said dosage includes the steps of:

• determining a bioburden upon one or more samples of the objects;
• determining an estimate of a radiation dose that results in a preselected probability of a surviving microorganism on the objects;
• confirming the estimate of the radiation dose that results in said preselected probability of a surviving microorganism on the objects by testing a quantity of the one or more samples of the objects at the radiation dose that was estimated;
• and
• calculating the radiation dosage for the desired sterility assurance level by adding a factor to the radiation dose that was confirmed to result in said preselected probability of a surviving microorganism on the objects and wherein the factor is proportional to the radiation dose that yields said preselected probability of a surviving microorganism on the objects and inversely proportional to a log of the bioburden.