EPR systems for alanine dosimetry

DTU Dosimetry operates three electron paramagnetic resonance (EPR) spectrometers for traceable measurement of absorbed dose to water using alanine dosimeters. The technique is based on detection of stable free radicals formed in alanine during irradiation, where the absorbed dose is determined from the microwave absorption of unpaired electrons.

Alanine dosimetry is used across a wide dose range, from radiotherapy levels (~1 Gy) to high-dose radiation processing (>100 kGy) using alanine pellet dosimeters (typically ~60 mg, 4.8 mm diameter, 2.8 mm height) and alanine film dosimeters (thickness ~135 µm). Pellet dosimeters are used for high-energy photon, electron and X-ray measurements, while alanine films are applied for low-energy electron dosimetry.

The EPR systems provide high accuracy, stability and traceability, supporting both reference dosimetry and routine measurements. The systems are used in calibration, process validation, research and development, and form a central part of the laboratory’s measurement infrastructure.