The Evaluation of High Dose and Dosimetric Characteristics of Optical Stimulated Luminance Dosimeters in the 60CO Unit
S Han1 2*, K Kim1 2, S Park1, H Jung1 2, S Lee1 2, H Kim1 2, C Yi3, M Kim1 2, Y Ji1 2, (1) Korea institute of radiological &medical sciences, Seoul (2) University of science & techology(3) Korea Research Institute of Standards and Science, DaejeonSU-E-T-38 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: We aimed to evaluate optical stimulated luminance dosimeters (OSLD) to estimate high dose in 60Co unit and to compare to advanced study about OSLD
Methods:OSLDs were grouped into three groups by radiation sensitivity (serial No.) and each groups consisted of dosimeters with variation of radiation sensitivity within ± 1.5% among them by sampling. When we evaluated dosimetric characteristics of OSLD, indicated used OSLD groups in list of evaluation of the dosimetric characteristics of them. OSLD had supra-linear response from more than 3 Gy. So the correlation of between dose delivered from 60Co and count was fitted by quadratic function. We compared to calculation dose and delivery dose in more than 3 Gy
Results:The reproducibility was 0.76% of the coefficient of variation, the batch homogeneity was within 1.5 % of the coefficient of variation and the depletion by repeat reading was 0.04% per reading. The half time of count decay curve after irradiation according to reading time was 0.68 min. (1 Gy), 1.04 min. (5 Gy), and 1.10 min. (10 Gy), respectively and the count decay was stable after 11 min, After stability, coefficient of variation was within 0.4% .The removal rate of count by optical annealing time (30min.) after OSLD reading was 88% (1 Gy), 90% (5 Gy), and 92% (10 Gy), respectively and was 99% when they were annealed for 4hour. The diff. % of between delivery dose form 60Co unit and calculated dose from fitting model was within ± 4.0%. But the OSLDs irradiated dose above 20 Gy changed their radiation sensitivity. So it is necessary to use carefully them and to calibrate radiation sensitivity of them
Conclusion:Considering to uncertainty of count for procedure, if delivery dose was calculated, it is feasible to use OSLD for evaluation of high dose in 60Co unit.
Funding Support, Disclosures, and Conflict of Interest: Acknowledgement : This research was supported by the Ministry of education, Science and Technology(MEST)