Radiation processing is carried out under fixed path conditions where (a) a process load is automatically moved through the radiation field by mechanical means or (b) a process load is irradiated statically by manually placing product at predetermined positions before the process is started. In both cases the process is controlled in such a manner that the process load position(s) and orientation(s) are reproducible within specified limits.
Some radiation processing facilities that utilize a fixed conveyor path for routine processing may also characterize a region within the radiation field for static radiation processing, sometimes referred to as “Off Carrier” processing.
Radiation processing may require a minimum absorbed dose (to achieve a desired effect or to fulfill a legal requirement), and a maximum dose that can be tolerated (while the product, material or substance still meets functional specifications or to fulfill a legal requirement).
Dose mapping is used to characterize the radiation process and assess the reproducibility of absorbed-dose results, which may be used as part of operational qualification and performance qualification.
Dose mapping is used to determine the spatial distribution of absorbed doses and the zone(s) of maximum and minimum absorbed doses throughout a process load, which may consist of an actual or simulated product.
Dose mapping is used to establish the relationship between the dose at a reference position and the dose within the minimum and maximum dose zones established for a process load.
Dose mapping is used to verify mathematical dose calculation methods. See Guide E 2232
Dose mapping is used to determine the process shutdown and startup transit dose effect on the distribution of absorbed dose and the magnitude of the minimum and maximum doses.
Dose mapping is used to assess the impact on the distribution of absorbed dose and the magnitude of the minimum and maximum doses resulting from the transition from one process load to another where changes, for example, in density or product loading pattern may occur.
1.1 This document provides guidance in determining absorbed-dose distributions in products, materials or substances irradiated in gamma, X-ray (bremsstrahlung) and electron beam facilities.
Note 18212;For irradiation of food and the radiation sterilization of health care products, other specific ISO and ISO/ASTM standards containing dose mapping requirements exist. For food irradiation, see ISO/ASTM 51204, Practice for Dosimetry in Gamma Irradiation Facilities for Food Processing and ISO/ASTM 51431, Practice for Dosimetry in Electron and Bremsstrahlung Irradiation Facilities for Food Processing. For the radiation sterilization of health care products, see ISO 11137: 1995, Sterilization of Health Care Products Requirements for Validation and Routine Control Radiation Sterilization. In those areas covered by ISO 11137, that standard takes precedence. ISO/ASTM Practice 51608, ISO/ASTM Practice 51649, and ISO/ASTM Practice 51702 also contain dose mapping requirements.
1.2 Methods of analyzing the dose map data are described. Examples are provided of statistical methods that may be used to analyze dose map data.
1.3 Dose mapping for bulk flow processing and fluid streams is not discussed.
1.4 Dosimetry is only one component of a total quality program for an irradiation facility. Other controls besides dosimetry may be required for specific applications such as medical device sterilization and food preservation.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the resp......
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