4.1 Polymethylmethacrylate dosimetry systems are commonly used in industrial radiation processing, for example, in the sterilization of medical devices and the processing of foods. In these applications, doses fall mostly within the 0.1 to 100 kGy working range of the family of PMMA dosimeters.

4.2 Properly selected PMMA dosimeter materials provide a means of directly estimating absorbed doses in near water-equivalent substances, such as plastics, cotton, paper, gut, and rubber. The doses are normally expressed in terms of dose in water (see 4.7). Under the influence of ionizing radiation, chemical reactions take place in the material, creating and/or enhancing absorption bands in the visible and/or ultraviolet regions of the spectrum. Optical absorbance determined at selected wavelengths within these radiation-induced absorption bands is quantitatively related to the corresponding absorbed radiation dose. Examples of appropriate wavelengths used for analysis of specific dosimeters are provided in Table A1.1.

4.3 In the application of a specific dosimetry system, absorbed dose is obtained by using an experimentally determined calibration curve or response function. These are derived by measuring sets of dosimeters irradiated to known absorbed doses that adequately span the range of utilization of the system (see 7.7.2).

4.4 Polymethylmethacrylate dosimetry systems require calibration traceable to national or international standards. See ISO/ASTM Guide 51261.

4.5 During calibration and use, possible effects of conditions such as temperature, light exposure, energy spectrum, and absorbed dose rate are taken into account.

4.6 Unprotected PMMA dosimeter material is sensitive to changes in humidity, and cut pieces are therefore individually sealed in water-impermeable pouches during manufacture. They must be kept in these sealed pouches during irradiation.

4.7 Absorbed dose in materials other than water may be determined by applying conversion factors in accordance with ISO/ASTM Guide 51261.

NOTE 1 - For a comprehensive discussion of various dosimetry methods applicable to the radiation types and energies discussed in this practice, see ICRU Reports 14, 17, 34 and 35.

1. Scope

1.1 This practice covers procedures for using hermetically-sealed polymethylmethacrylate (PMMA) dosimeters for measuring absorbed dose in materials irradiated by photons or electrons in terms of absorbed dose in water.

1.2 This practice covers systems that permit absorbed dose measurements under the following conditions:

1.2.1 The absorbed dose range is 0.1 to 100 kGy.

1.2.2 The absorbed dose rate is 1 X 10 ² to 1 10⁷ Gys ¹.

1.2.3 The radiation energy range for photons is 0.1 to 50 MeV, and for electrons 3 to 50 MeV.

1.2.4 The irradiation temperature is 78 to +50°C.

1.3 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.

Index Terms

absorbed dose; dose; dosimeter; dosimetry system; electron beam; gamma radiation; ionizing radiation; irradiation; PMMA; polymethylmethacrylate; radiation; radiation processing; radiation sterilization ; ICS

ICS Code

Citing ASTM Standards

[Back to Top]