Dosimetry and Quality Control in Electron Beam Processing

Accurate dosimetry measurements are essential to the maximum success of commercial application of radiation processing. Such dosimetry must be involved in three different areas to assure proper final quality in the processing program. These are; 1) dosimetry related to the basic research on the radiation process involved, 2) dosimetric calibration of the radiation facility at the time of its commissioning and each major modification, and 3) radiation monitoring of the routine production process. Although careful attention is usually given to the first area and sometimes the second, the third area is often given too little importance. The research on a given radiation process should include, as a minimum, the measurement of such radiation quantities as absorbed dose, dose rate, apd dose distribution in the material. The facility calibration should define the complete radiation field characteristics such as radiation type, energy, dose rates, geometric distributions, and depth dose profiles for typical materials. The quality assurance monitoring of the production process should include measurement of the appropriate radiation quantities as well as operational parameters like dwell time, conveyor speed, etc. In particular, where the safety of the product is dependent upon the absorbed dose, such as in sterilization or food preservation, dosimetric monitoring is of vital importance. Quality assurance of the production process can be maintained by monitoring the radiation beam or field; or by measurement of the absorbed dose in the product; or by product testing after processing.