Program Information
Progress Towards a 2D OSL Dosimetry System Using Al2O3:C Films
M F Ahmed1*, E Schnell2 , S Ahmad2 , M Akselrod3 , S Brons4 , S Greilich5 , J Osinga5,6 , O Jakel5 , E Yukihara1 , (1) Physics Department, Oklahoma State University, Stillwater, OK 74078, (2) Department of Radiation Oncology, University of Oklahoma Health Science Center, Oklahoma City, OK 73104,(3) Landauer, Inc., Stillwater Crystal Growth Division, Stillwater, OK 74074, (4) Heidelberg Ion-Beam Therapy Center and Department of Radiation Oncology, Heidelberg, Germany, (5) Division of Medical Physics and Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany, (6) Department of Dosimetry for Radiation Therapy and Diagnostic Radiology, Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany
Presentations
WE-AB-BRB-8 (Wednesday, July 15, 2015) 7:30 AM - 9:30 AM Room: Ballroom B
Purpose: To develop a 2D dosimetry system based on the optically stimulated luminescence (OSL) of Al₂O₃: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 ¹²C 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 ¹²C 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 Al₂O₃:C OSL film can be beneficial for dosimetry in radiation therapy applications, especially for small field dosimetry.
Funding Support, Disclosures, and Conflict of Interest: 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.
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