On luminescence stimulated from deep traps using thermally-assisted time-resolved optical stimulation in α-Al2O3:C

Nyirenda, A.N.; Chithambo, M.L.; Polymeris, George S.

doi:10.1016/j.radmeas.2016.01.016

Cited by 12 publications

(3 citation statements)

References 16 publications

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“…3,10 Previous works investigating the behavior of nanoDots have recommended or used blue LEDs instead of alternatives such as white or green LEDs for rapid clearance of the signal stored in OSLDs through optical bleaching 9,11 but have not accounted for nanoDots irradiated to a sufficiently high-dose range where supralinearity was reportedly observed (>1 Gy). 4,5 Optical bleaching using a light source containing blue/UV wavelengths may be problematic regarding the reuse of OSL nanoDots given the observation that UV and blue light stimulation was reported to induce the phototransfer of charge carriers from deep dosimetric traps, via the conduction band, to shallower dosimetric traps in various samples of Al 2 O 3 :C. 3,4,10,12 The use of a long-pass filter has been recommended from previous works 4,7 to optically bleach the OSLD while preventing the phototransfer of deep trap charge carriers but may require prohibitively long durations for complete optical bleaching, on the order of several hundreds or thousands of minutes depending on the accumulated dose history of the dosimeter and the irradiance of the bleaching source. This study seeks to expand on prior studies that were referenced by demonstrating that the regeneration of signal in OSLDs is caused by the exposure of the USA) to ascertain the mean signal stored in each nanoDot.…”

Section: Introductionmentioning

confidence: 99%

Preliminary Investigation into the regeneration of luminescent signal in nanoDot OSLDs

Liu

2020

J Applied Clin Med Phys

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Purpose Reuse of optically stimulated luminescent dosimeters (OSLDs) has been suggested in prior works by using a light source to erase the dosimeter’s signal (optical bleaching) and recharacterizing the dosimeter’s sensitivity based on its dose history. However, depending on the wavelength of the bleaching source and the dosimeter’s dose history this may be problematic due to the presence of deep dosimetric traps and the phototransfer mechanism observed in Al2O3. In this work we examine the regeneration of signal in OSL nanoDots, with prior irradiation history, following their bleaching from a light source containing blue wavelengths. Methods Irradiations were performed on 33 nanoDots at a dose range of 5–3000 cGy using 6 MV and 1000–3000 cGy using 220 kV x rays, with three nanoDots irradiated at each dose value. Following their irradiation, nanoDots were bleached using blue light for a period of 1 h. The postbleached signal in nanoDots was measured over a 27‐day period to track any changes in their measured signal due to the migration of charge carriers from deep dosimetric traps to shallower traps of the dosimeter. Results The growth extent and growth rate observed in bleached nanoDots were observed to be dependent on the dosimeter’s accumulated dose history and energy of the radiation source. The 12 nanoDots with prior irradiation history of 500, 1000, 2000, and 3000 cGy from 6 MV x rays exhibit an increase in measured signal that range from 220 to 5229 PMT counts when measured the first day postbleaching to 408–8710 PMT counts when measured on the 27th day postbleaching, which may be substantial depending on the application regarding the dosimeter's reuse. Conclusion These findings caution against the reuse and optical bleaching of nanoDots with prior irradiation history exceeding 100 cGy and demonstrate an energy, accumulated dose, and time dependence in the regeneration of signal in postbleached nanoDots with prior irradiation history.

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Section: Introductionmentioning

confidence: 99%

Preliminary Investigation into the regeneration of luminescent signal in nanoDot OSLDs

Liu

2020

J Applied Clin Med Phys

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“…Prompt measurement of the resultant PTTL glow curve enables an indirect measurement of the population of charges in the deep traps. PTTL procedures have been developed for variety of materials, including lithium fluoride (Kharita et al 1994;Charles 1983), quartz (Bailiff et al, 1977) and aluminium oxide (Akselrod and Gorelova 1993;Colyott et al 1996;Bulur and Göksu 1999;Polymeris and Kitis 2012;Nyirenda et al 2016;Chithambo et al 2017). The primary advantage of using this procedure is to avoid the effects of interfering black-body radiation and thermal quenching where the thermoluminescence (TL) peaks associated M A N U S C R I P T…”

Section: Introductionmentioning

confidence: 99%

Phototransferred TL properties of alumina substrates

Bossin

Bailiff

Terry

2018

Radiation Measurements

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“…A luminescência opticamente estimulada resultante da matriz irradiada, é monitorada em função do tempo de estimulação luminosa (NYIRENDA et al;. A intensidade de pico ou integral da área do sinal de luminescência emitida durante o período de estimulação é relacionada à dose absorvida pelo material desde a última exposição à luz (SOUZA, 2009).…”

Section: Análise Do Sinal Oslunclassified

Estudo e desenvolvimento de dosímetros luminescentes opticamente estimulados de a-Al2O3 com nanoestruturas de carbono e óxidos terras-raras para aplicação em radioterapia

Schuch¹

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AgradecimentosÀ minha querida orientadora Prof. Dra. Patrícia Nicolucci por ser minha referência acadêmica e clínica, por todos os ensinamentos transmitidos, pela paciência, apoio e amizade. Muito obrigada! À minha tia Ilda Diniz dos Santos por toda a dedicação, carinho e amizade. Sempre muito especial em todos os momentos da minha trajetória.Ao meu namorado Tiago Chaud por estar sempre ao meu lado com todo o carinho, cuidado, paciência, incentivo e apoio. À Dra. Cassiana Viccari Sacilotto por toda a atenção, incentivo e amizade. MV and a source of Iridium-192, in a wide dose range. All materials showed reproducibility of OSL signal (deviations less than 1%) and response homogeneity up to ± 95% (conferred for the dosimeter Al2O3 (0.02%ntC). All studied materials showed satisfactory sensitivity. Samples of Al2O3 (1%C), Al2O3 (0.02%ntC) and Al2O3 (0.02% npC) were used in a in vivo dosimetry pilot study in radiotherapy. The in vivo dosimetry performed with the developed OSL dosimeters suggest its possible use in clinical practice in Radiotherapy by establishing a measure protocol, calibrations for each beam and energy used and control of the planning system used for dose calculations.

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On luminescence stimulated from deep traps using thermally-assisted time-resolved optical stimulation in α-Al2O3:C

Cited by 12 publications

References 16 publications

Preliminary Investigation into the regeneration of luminescent signal in nanoDot OSLDs

Preliminary Investigation into the regeneration of luminescent signal in nanoDot OSLDs

Phototransferred TL properties of alumina substrates

Estudo e desenvolvimento de dosímetros luminescentes opticamente estimulados de a-Al2O3 com nanoestruturas de carbono e óxidos terras-raras para aplicação em radioterapia

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