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Title: SU-E-T-672: Real-Time In Vivo Dosimeters Using LiPCDA and Optical Fibers

Abstract

Purpose: To investigate dosimeter prototypes made with lithium pentacosa-10,12-diynoate (LiPCDA, the material used in GafChromic EBT films) and optical fibers for their suitability in real-time in vivo measurements. Methods: The prototypes, made with 500 µm plastic optical fibers and 8.5 µm thickness of LiPCDA at fiber tip, were irradiated with a 6 MV beam. To investigate the efficacy of pre-irradiation calibration, the probes were irradiated to 2 Gy twice, with 5 minutes in between. Net optical density values (netOD) around the main absorbance peak were compared, and effect of correcting second measurement by the first was assessed. Ageing was assessed by irradiating two prototypes to 2 Gy and comparing the netOD to that obtained for 15 prototypes from the same batch 12–14 months earlier. To measure angular dependence, the probes were pre-irradiated with beam perpendicular to fiber axis and then, 5 minutes later either perpendicular or parallel to fiber axes. The thickness-corrected netOD measurements were compared. Results: Standard deviation of netOD for probes of the same batch was measured to be 5–6%. When netOD was corrected for material thickness by using results from the first irradiation, the standard deviation decreased to 1.3%. This was comparable to the uncertainty in measurementsmore » observed with a single probe and is attributed to variations in light output, spectrometer noise and splitter-to-probe connection variations. Comparison of netOD values obtained a year apart failed to illustrate statistically significant decrease in sensitivity due to ageing (0.38 ± 0.03 and 0.3656 ± 0.0003). NetOD measured with MV beam parallel to fiber was within error of netOD measured with MV beam perpendicular to fiber. Conclusion: Current prototype construction allows for shelf life of at least one year. With material thickness corrected for, the prototypes can measure dose with an uncertainty below 2% at a given energy and dose rate. This work has been funded by the Ontario Centres of Excellence Market Readiness grant. The authors have no conflict of interest to declare.« less

Authors:
;  [1]; ; ;  [2]
  1. Princess Margaret Cancer Center, Toronto, ON (Canada)
  2. National Optics Institute, Quebec, Quebec (Canada)
Publication Date:
OSTI Identifier:
22538180
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 42; Journal Issue: 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 62 RADIOLOGY AND NUCLEAR MEDICINE; BEAMS; DOSE RATES; DOSEMETERS; FILM DOSIMETRY; GY RANGE 01-10; IN VIVO; IRRADIATION; OPTICAL FIBERS; PROBES; THICKNESS

Citation Formats

Rink, A, Jaffray, DA, Croteau, A, Caron, S, and Mermut, O. SU-E-T-672: Real-Time In Vivo Dosimeters Using LiPCDA and Optical Fibers. United States: N. p., 2015. Web. doi:10.1118/1.4925035.
Rink, A, Jaffray, DA, Croteau, A, Caron, S, & Mermut, O. SU-E-T-672: Real-Time In Vivo Dosimeters Using LiPCDA and Optical Fibers. United States. doi:10.1118/1.4925035.
Rink, A, Jaffray, DA, Croteau, A, Caron, S, and Mermut, O. Mon . "SU-E-T-672: Real-Time In Vivo Dosimeters Using LiPCDA and Optical Fibers". United States. doi:10.1118/1.4925035.
@article{osti_22538180,
title = {SU-E-T-672: Real-Time In Vivo Dosimeters Using LiPCDA and Optical Fibers},
author = {Rink, A and Jaffray, DA and Croteau, A and Caron, S and Mermut, O},
abstractNote = {Purpose: To investigate dosimeter prototypes made with lithium pentacosa-10,12-diynoate (LiPCDA, the material used in GafChromic EBT films) and optical fibers for their suitability in real-time in vivo measurements. Methods: The prototypes, made with 500 µm plastic optical fibers and 8.5 µm thickness of LiPCDA at fiber tip, were irradiated with a 6 MV beam. To investigate the efficacy of pre-irradiation calibration, the probes were irradiated to 2 Gy twice, with 5 minutes in between. Net optical density values (netOD) around the main absorbance peak were compared, and effect of correcting second measurement by the first was assessed. Ageing was assessed by irradiating two prototypes to 2 Gy and comparing the netOD to that obtained for 15 prototypes from the same batch 12–14 months earlier. To measure angular dependence, the probes were pre-irradiated with beam perpendicular to fiber axis and then, 5 minutes later either perpendicular or parallel to fiber axes. The thickness-corrected netOD measurements were compared. Results: Standard deviation of netOD for probes of the same batch was measured to be 5–6%. When netOD was corrected for material thickness by using results from the first irradiation, the standard deviation decreased to 1.3%. This was comparable to the uncertainty in measurements observed with a single probe and is attributed to variations in light output, spectrometer noise and splitter-to-probe connection variations. Comparison of netOD values obtained a year apart failed to illustrate statistically significant decrease in sensitivity due to ageing (0.38 ± 0.03 and 0.3656 ± 0.0003). NetOD measured with MV beam parallel to fiber was within error of netOD measured with MV beam perpendicular to fiber. Conclusion: Current prototype construction allows for shelf life of at least one year. With material thickness corrected for, the prototypes can measure dose with an uncertainty below 2% at a given energy and dose rate. This work has been funded by the Ontario Centres of Excellence Market Readiness grant. The authors have no conflict of interest to declare.},
doi = {10.1118/1.4925035},
journal = {Medical Physics},
number = 6,
volume = 42,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}