ASTM/ISO 51607-04

4.1 The alanine-EPR dosimetry system provides a means for measuring the absorbed dose. It is based on the measurement of specific stable free radicals in crystalline alanine generated by ionizing radiation.

4.2 The dosimeter contains crystalline alanine and registers the absorbed dose by the formation of alanine-derived free radicals. Identification and measurement of alanine-derived free radicals are performed by EPR spectroscopy.

4.3 The measurement of free radicals by EPR spectroscopy is nondestructive. Alanine dosimeters can be read out repeatedly and hence can be used for archival purposes.

NOTE 1 - For a comprehensive discussion of various dosimetry methods and materials applicable to the radiation types and energies discussed in this practice, see ASTM Practice E 668, ISO/ASTM Practices 51204, 51400, 51431, ISO/ASTM Guide 51261, and ICRU Reports 14, 17, 34, 35, 37, 44 and 60.

4.4 Alanine-EPR dosimetry systems are used as referenceor transfer-standard or routine dosimetry systems in radiation applications that include: sterilization of medical devices and pharmaceuticals, food irradiation, polymer modifications, medical therapy and radiation damage studies in materials.

4.5 The EPR signal amplitudes of irradiated alanine dosimeters have been shown to be equivalent for photon and electron absorbed doses (4).

1.1 This practice covers materials description, dosimeter preparation, instrumentation, and procedures for using the alanine-EPR dosimetry system for measuring the absorbed dose in the photon and electron irradiation processing of materials. The system is based on electron paramagnetic resonance (EPR) spectroscopy of free radicals derived from the amino acid alanine. It is classified as a reference-standard dosimetry system (see ISO/ASTM Guide 51261)).

1.2 This practice covers alanine-EPR dosimetry systems for dose measurements under the following conditions:

1.2.1 The absorbed dose range is between 1 and 10 ⁵ Gy.

1.2.2 The absorbed dose rate is up to 10² Gy s¹ for continuous radiation fields and up to 5 10 ⁷ Gy s¹ for pulsed radiation fields ().

1.2.3 The radiation energy for photons and electrons is between 0.1 and 28 MeV (, , ).

1.2.4 The irradiation temperature is between 60 and + 90°C (, ).

1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

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.