Alanine Dosimetry

Industrial Radiation Processing

Ionizing radiation is commonly used for the sterilization of medical products, pathogen reduction in meats and the disinfestation of imported fruits and vegetables. Recently irradiation has even been employed as a precautionary decontamination method for biological warfare agents in the mail (e.g., Anthrax). Ionizing radiation produces free radicals in many forms of matter and is quantitatively detected by an EPR spectrometer.

The amino acid L-alanine forms a very stable free radical when subjected to ionizing radiation. The alanine free radical yields an EPR signal that is dose dependent, yet is independent of the dose rate, energy type, and is relatively insensitive to temperature and humidity.

Alanine dosimetry has very high accuracy and low error, and has thus become a favored dosimetry technique in Gamma, Electron beam and X-ray irradiation facilities.

more on EPR e-scan systems

The Alanine EPR dosimetry procedure:

1.   Alanine dosimeters are put through the irradiator with product
2.   Dosimeters are retrieved and read in the EPR spectrometer
3.   The ratio of the alanine EPR signal to an internal reference
       yields the absorbed dose (combined uncertainty +- 2%)