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WE‐AB‐BRB‐08: Progress Towards a 2D OSL Dosimetry System Using Al2O3:C Films
Author(s) -
Ahmed M F,
Schnell E,
Ahmad S,
Akselrod M,
Brons S,
Greilich S,
Osinga J,
Jakel O,
Yukihara E
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4925849
Subject(s) - optically stimulated luminescence , dosimetry , optics , wedge (geometry) , materials science , detector , pencil (optics) , photon , dose profile , calibration , pencil beam scanning , dosimeter , beam (structure) , nuclear medicine , physics , medicine , proton therapy , quantum mechanics
Purpose: To develop a 2D dosimetry system based on the optically stimulated luminescence (OSL) of Al 2 O 3 :C films for medical applications. Methods: A 2D laser scanning OSL reader was built for readout of newly developed Al2O3:C films (Landauer Inc.). An image reconstruction algorithm was developed to correct for inherent effects introduced by reader design and detector properties. The system was tested using irradiations with photon and carbon ion beams. A calibration was obtained using a 6 MV photon beam from clinical accelerator and the dose measurement precision was tested using a range of doses and different dose distributions (flat field and wedge field). The dynamic range and performance of the system in the presence of large dose gradients was also tested using 430 MeV/u 12 C single and multiple pencil beams. All irradiations were performed with Gafchromic EBT3 film for comparison. Results: Preliminary results demonstrate a near‐linear OSL dose response to photon fields and the ability to measure dose in dose distributions such as flat field and wedge field. Tests using 12 C pencil beam demonstrate ability to measure doses over four orders of magnitude. The dose profiles measured by the OSL film generally agreed well with that measured by the EBT3 film. The OSL image signal‐to‐noise ratio obtained in the current conditions require further improvement. On the other hand, EBT3 films had large uncertainties in the low dose region due to film‐to‐film or intra‐film variation in the background. Conclusion: A 2D OSL dosimetry system was developed and initial tests have demonstrated a wide dynamic range as well as good agreement between the delivered and measured doses. The low background, wide dynamic range and wide range of linearity in dose response observed for the Al 2 O 3 :C OSL film can be beneficial for dosimetry in radiation therapy applications, especially for small field dosimetry. This work has been funded by Landauer Inc. Dr. Eduardo G. Yukihara also would like to thank the Alexander von Humboldt Foundation for his support at the DKFZ.