A key attribute for many healthcare products is sterility. Ionizing radiation, and predominantly gamma sterilization processing is utilized to achieve acceptable levels of microbial deactivation. There is a trend in industry to supplement gamma with alternative accelerator technologies such as X-ray.  

Organic polymers are commonly used to construct components in these products. While the effect of ionizing radiation on polymers is well documented, a research opportunity was identified in this area.ⁱ 

A series of studies were conducted to characterize polymer modification caused by both gamma and X-ray sterilization process parameters and to establish statical equivalency. The study was conducted across three polymer families; HDPE, LDPE and PP. Three grades of each were chosen, all with a proven industry track record.

One study objective was to assess polymer behavior at two common irradiation doses (30 and 55 kGy) bracketing routine sterilization process conditions. For this study, dose rate brackets standard processing levels akin to each irradiation technology.  

Another study objective was to assess any potential dose rate effect. To achieve this, two additional dose rate parameters at each dose level were reviewed. This study was undertaken for both irradiation technologies. 

Subsequent mechanical and chemical laboratory techniques were used to quantify any shift physico-chemical properties of each polymer and to ascertain equivalency across comparable test groups. Statistical analysis indicates a strong degree of equivalency between samples exposed to both Gamma and X-ray irradiation, irrespective of the processing parameters.

ⁱ​Also published in AAMI BI&T (January 2024) under title Effect of Gamma and X-ray Irradiation on Polymers Commonly Used in Healthcare Products