Radiation sterilization dose of medical devices

Loaded with B. pumilus ATCC 27142 spores, a hollow fiber dialyser and a parallel plate dialyser, both of ''dry type'', were irradiated by γ-ray to determine the D values of the spores, which led to the following results. 1. The D value of the B. pumilus spores attached to the cellulose diacetate hollow fibers was found to be 0.17 Mrad, while that of the same spores attached to the Cuprophan membranes was 0.22 Mrad at the maximum. 2. When attached to the polycarbonate or the ABS housings, or the polyethylene spacers, the spores showed a D value of 0.16 Mrad in all cases. 3. The D value of the spores attached to a glass fiber filter, as a control, proved to be 0.15 Mrad. From these results, it may be said that the ''dry type'' dialysers employing cellulose diacetate hollow fibers or Cuprophan membranes can safely be sterilized by a dose of 2.0 Mrad, with a sterility assurance level being <10-6. (author)