Commissioning of optically stimulated luminescence dosimeters for use in radiotherapy

The Australian Clinical Dosimetry Service (ACDS) is a government initiative to provide all radiation therapy centers in Australia with access to free and independent dosimetric audit services. Based out of the Australian Radiation Protection and Nuclear Safety Agency, the ACDS commenced audit operations in 2010. The objective of this work was to commission Optically Stimulated Luminescence Dosimeters (OSLDs) as a replacement for Thermoluminescence Dosimeters (TLD) for use in the ACDS's remote auditing program, with a view to extending their application to higher level dosimetry in anthropomorphic phantoms. The In-Light nanoDots™ OSLD system from Landauer Inc. was commissioned using both the Australian National Linear Accelerator, an Elekta Synergy II, and an Eldorado Co-60 unit. The linearity, signal depletion, fading, energy dependence, reproducibility and resetting of nanoDot™ dosimeters were determined for clinical photon and electron beams. NanoDots™ OSLDs demonstrate; supralinearity dependent on the overall accumulated dose. Little signal depletion per readout (0.03% per read). Reproducible fading, characterised by an initial transient signal decay over a period of 16 min post irradiation, followed by a predictable logarithmic decay resulting in signal decrease of 3% over several months. Little dependence on energy or modality over the clinical range. Optical resetting tests show negligible change in sensitivity post reset for up to five cycles. Modern OSLDs such as the nanoDots™ dosimeters provide a viable alternative to the established TLD technology with comparable accuracy and greater efficiency. The efficiency, reusability and accuracy of nanoDot™ dosimeters makes them an ideal candidate for the large-scale dosimetry operations currently undertaken by the ACDS. ► We detail the commissioning process for use of OSLD in radiotherapy. ► OSLD shows promise as a replacement for TLD. ► OSLD provides an efficient tool in large scale dosimetry operations. ► The physical properties of OSLD are detailed and reported.