Significance and Use
4.1 Various products and materials may be treated with ionizing radiation, such as gamma rays from 60Co or 137Cs sources, for numerous purposes, including microbial reduction and material modification. Dosimetry requirements may vary depending upon the irradiation application and the end use of the product.
4.2 For many products, the irradiation specifications include a minimum or maximum limit of absorbed dose, sometimes both: a minimum is set to ensure that the intended beneficial effect is achieved and a maximum limit is set for the purpose of avoiding product degradation.
4.2.1 For a given application, one or both of these values may be prescribed by regulations that have been established on the basis of available scientific data. Therefore, it is necessary to determine the capability of an irradiation facility to deliver the absorbed dose within prescribed limits prior to the irradiation of the product. Also, it is necessary to monitor and document the absorbed dose during each production run to verify compliance with the process specifications within a predetermined level of confidence.
4.2.2 Some examples of irradiation applications where dosimetry requirements are similar to those required for food irradiation or for radiation sterilization of health care products are:
22.214.171.124 Disinfection of consumer product;
126.96.36.199 Control of pathogens in liquids or solids; and
188.8.131.52 Research on material effects.
4.3 For other products, the irradiation specifications may depend on the evaluation of changes in the physical and chemical properties of the irradiated materials.
4.3.1 For these products, the requirements for dosimetry may be less stringent, but dosimetry data may be useful for quality control, transfer of the process to another facility or for comparison with data from other facilities.
4.3.2 Some examples of radiation applications where all of the dosimetry requirements stated in this practice may not be required are:
184.108.40.206 Cross-linking or degradation of polymers and elastomers;
220.127.116.11 Polymerization of monomers and grafting of monomers onto polymers; and
18.104.22.168 Enhancement of color in gemstones and other materials.
4.4 For some products, the requirements for dosimetry may be different.
4.4.1 An example of a radiation application with different requirements is:
22.214.171.124 The requirement to determine the absorbed dose in silicon or other materials different from water in radiation hardness testing of semiconductors or the modification of characteristics of semiconductor devices.
4.5 For some radiation applications, the irradiations may be performed at low or high temperatures, causing difficulties in dosimetry. For these applications, it may be necessary to perform dosimetry at ambient room temperatures and rely on process control to ensure that the absorbed dose is within the desired limits. In some cases it may be possible to use dosimeters for routine monitoring at the temperature used for the irradiation application if the dosimeter temperature during irradiation is sufficiently stable to allow correction for temperature effects on the dosimeter response.
1.1 This practice outlines the installation qualification program for an irradiator and the dosimetric procedures to be followed during operational qualification, performance qualification, and routine processing in facilities that process product with ionizing radiation from radionuclide gamma sources to ensure that product has been treated within a predetermined range of absorbed dose. Other procedures related to installation qualification, operational qualification, performance qualification, and routine processing that may influence absorbed dose in the product are also discussed. Information about effective or regulatory absorbed-dose limits is not within the scope of this practice.
Note 1—Dosimetry is only one component of a total quality assurance program for adherence to good manufacturing practices.
Note 2—ISO/ASTM Practices 51649 and 51608 describe dosimetric procedures for electron beam and X-ray (bremsstrahlung) irradiation facilities for radiation processing.
1.2 For the irradiation of food and the radiation sterilization of health care products, other specific ISO/ASTM or ISO standards exist. For food irradiation, see ISO/ASTM Practice 51204. For the radiation sterilization of health care products, see ISO 11137. In those areas covered by ISO/ASTM Practice 51204 or ISO 11137, those standards take precedence.
1.3 For guidance in the selection and calibration of dosimetry systems, and interpretation of measured absorbed dose in the product, see ISO/ASTM Guide 51261 and ASTM Practice E 666. For the use of specific dosimetry systems, see ASTM Practices E 1026 and E 2304, and ISO/ASTM Practices 51205, 51275, 51276, 51310, 51401, 51538, 51540, 51607, 51650, and 51956. For discussion of radiation dosimetry for gamma-rays and X-rays also see ICRU Report 14.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.