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Poster ‐ 24: Characterization of the energy dependence of high‐sensitivity MCP‐N TLD and Al2O3:C OSLD in‐vivo dosimetry systems for 40–100 kVp energies
Author(s) -
Poirier Yannick,
Kuznetsova Svetlana,
Barajas Eduardo Villarreal
Publication year - 2016
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 - 10.1118/1.4961798
Subject(s) - thermoluminescent dosimeter , dosimetry , materials science , nuclear medicine , reproducibility , beam energy , absorbed dose , beam (structure) , optics , physics , dosimeter , medicine , chemistry , chromatography
Purpose: To characterize the energy dependence of high‐sensitivity MCP‐N TLD and Al 2 O 3 :C OSLD dosimetry systems at low (40–100 kVp) energies for in‐vivo dosimetry. Methods: We assessed the variation of response with energy of two detectors in the 40–100 kVp energy range: high‐sensitivity MCP‐N TLDs (LiF:Mg,Cu,P) and OSLDs (Al 2 O 3 :C). The detectors were irradiated with an XRad 320ix biological irradiator under reference conditions. The delivered dose was 10 cGy for 7 beam qualities ranging from 40–100 kVp, 1.7–4.0 mm Al, and effective energies 26.9–37.9 keV. Both sets of detectors were also irradiated under reference conditions at 6 MV using a Varian Clinac 21Ex to assess the change in response from high‐energy beams. Results: The MCP‐N high‐sensitivity TLDs were relatively insensitive to energies in the kV range, as their response varied by ±5%, i.e. well within the reproducibility limits of these detectors. However, the OSLDs exhibited a linearly‐decreasing response with energy with a response 18.7% higher at 40 kVp than at 100 kVp for the same nominal dose. Compared to the 6 MV beams used in conventional radiotherapy, OSLDs responded 3.3–3.9 times higher depending on beam quality while the MCP‐N TLD response was unchanged within experimental uncertainty. Conclusions: Unlike the more commonly used TLD‐100, the high‐sensitivity MCP‐N TLDs exhibit little to no energy response. OSLDs are shown to be highly energy‐dependent, both from MV to kV and within the kV range.