Significance and Use
The CTA dosimetry system provides a means for measuring absorbed dose based on a change in optical absorbance in the CTA dosimeter following exposure to ionizing radiation (5, 7-14).
CTA dosimetry systems are commonly used in industrial radiation processing, for example in the modification of polymers and sterilization of health care products.
CTA dosimeter film is particularly useful in absorbed dose mapping because it is available in a strip format and if measured using a strip measurement device, it can provide a dose map with higher resolution than using discrete points.
Scope
1.1 This is a practice for using a cellulose triacetate (CTA) dosimetry system to measure absorbed dose in materials irradiated by photons or electrons in terms of absorbed dose to water. The CTA dosimetry system is classified as a routine dosimetry system.
1.2 The CTA dosimeter is classified as a type II dosimeter on the basis of the complex effect of influence quantities on its response (see ASTM Practice E2628).
1.3 This document is one of a set of standards that provides recommendations for properly implementing dosimetry in radiation processing, and describes a means of achieving compliance with the requirements of ASTM E2628 “Practice for Dosimetry in Radiation Processing” for a CTA dosimetry system. It is intended to be read in conjunction with ASTM E2628.
1.4 This practice covers the use of CTA dosimetry systems under the following conditions:
1.4.1 The absorbed dose range is 10 kGy to 300 kGy.
1.4.2 The absorbed-dose rate range is 3 Gy/s to 4×1010 Gy/s (1).
1.4.3 The photon energy range is 0.1 to 50 MeV.
1.4.4 The electron energy range is 0.2 to 50 MeV.
1.5 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.