(Sunday, 7/14/2019) 2:00 PM - 3:00 PM
Room: 302
Purpose: This study aims to develop a convenient, robust, and label-free method to individually calibrate and track TLDs.
Methods: 376 TLDs were individually identified using our optical fingerprinting technology, which recognizes stamped TLD chips based on their surface textures. To characterize the individual dose response, all chips were irradiated at 0 Gy, 1 Gy, 4 Gy, 8 Gy, 16 Gy on a calibrated clinical MV linac. Upon returning to the inventory after each dosimetric study, the TLD surface images were matched with previously captured fingerprints in the database for identification. The individual calibration curve was then established from the 5 data points and fingerprint matching. The same-TLD dose response repeatability was tested by irradiating 60 randomly selected TLD on a 300kVp irradiator for three times. In addition, fifteen TLDs were irradiated to receive 1 Gy, 4 Gy, 8 Gy, and 16 Gy, respectively on the same kV irradiator. Their individual calibration profiles were used to calculate received doses.
Results: The accuracy of identifying TLDs based on their fingerprints was 100%. In the repeatability test, among sixty TLD chips, 23 (38%) chips, 28 (47%) chips, and 9 (15%) chips have relative standard deviation (RSD) of the raw reading smaller than 1%, between 1% and 2%, and between 2% and 3% respectively. Raw reading data was converted to dose based on individual calibration curve for each TLD chip. The RSD of dose are between 0.4% to 3.1% while the RSD of readings are between 4% to 5% without individual calibration.
Conclusion: In this work, we developed a novel label-free fingerprinting method to identify individual TLD chips without relying on the complicated and fragile inventory management method to track individual TLDs. This method will improve the accuracy, efficiency and usability of TLD dosimetry.
Funding Support, Disclosures, and Conflict of Interest: NIH R01CA230278 NIH R44CA183390 NIH R01CA188300
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