Estimation of Absorbed Dose During Process Interruption in Radiation Processing

Abstract

The quality control system enables the standardization of product quality. Dosimetry has an important role in the quality control of radiation processing. The area of radiation processing which is governed most strictly by regulations is radiation sterilization. This process is used as the example to describe the new method for establishing the effect of process interruption on absorbed dose in the Co-60 irradiation plant at the Vinca Institute of Nuclear Sciences. Establishing the effect of process interruption is one of requirements in international regulations, but there are no recommendations for its implementation. A new method has been worked out by graphical extrapolation. The advantage of this method is the ability to carry it out during the sterilization process. The ethanol-chlorobenzene (ECB) dosimeter is used to select the suitable place where absorbed dose is expected to be the most influenced by source transit, i.e. the most close to the source. In the same time, it should be convenient and reproducible for placing dosimeters. Alanine dosimeters were irradiated on this place in time intervals: 2 min., 4 min., 6 min., 8 min., 10 min. Measurements of time starts when the button to lift source is pressed and stops by pressing the button for process interruption (to sink source down). The absorbed doses were measured by ESR spectrometer. The function of absorbed dose versus irradiation time is linear as expected. The extrapolation back to zero time gives the maximal absorbed dose that can be delivered to product during source transit. In our experiment this absorbed dose obtained by this method is 154 Gy.