The energy dependence of BaSO4: Eu nanophosphors for thermoluminescence dosimetry of orthovoltage X-rays and low energy protons

Nattudurai, Ravikumar; Arous, Delmon; Edin, Nina Frederike Jeppesen; Pandey, Anant; Malinen, Eirik

doi:10.1016/j.radphyschem.2023.110928

Cited by 5 publications

(1 citation statement)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The photon energy response of a dosimeter is typically studied through experiments performed in x-ray beams. The results of these experiments are compared to widely used approaches for the energy response calculation such as the theoretical response, which is based on the mass energy absorption coefficients (Nattudurai et al 2023) or Z eff (effective atomic number) calculations (Crijns et al 2017) used as an indication of the radiation interaction with the composite material. Taylor in 2012 proposed an energy-dependent Z eff computation based on the correlation between the total cross section and the atomic number of the elements composing the material (Taylor et al 2012).…”

Section: Introductionmentioning

confidence: 99%

New optically stimulated luminescence dosimetry film optimized for energy dependence guided by Monte Carlo simulations

De Saint-Hubert,

Caprioli,

de Freitas Nascimento

et al. 2024

Phys. Med. Biol.

View full text Add to dashboard Cite

Optically stimulated luminescence (OSL) film dosimeters, based on BaFBr:Eu2+ phosphor material, have major advantages but as they are not made of tissue-equivalent materials they exhibit an energy-dependent over-response at low photon energies. In this work, the OSL energy-dependent response was optimized by lowering the phosphor grain size, seeking an optimal choice of phosphor concentration and film's thickness with sufficient sensitivity. This optimization process combines measurement-based assessments of energy response in narrow X-ray beams with in-silico metrics involving theoretical approaches and Monte Carlo (MC) dose simulations for for homogeneous phosphor distributions and for isolated phosphor grains of different dimensions, where the dose in the phosphor grain was calculated. In total 8 OSL films were manufactured with different BaFBr:Eu2+ median particle diameters (D50): 3.2 µm, 1.5 µm and 230 nm and different phosphor concentrations (1.6%, 5.3% and 21.3 %) and thicknesses (from 5.2 µm to 49 \µm). Films were irradiated in narrow X-ray spectra (N60, N80, N-150 and N-300) and the signal intensity relative to the nomimal dose-to-water value was normalized with respect to Co-60. Finally we experimentally tested the response of several films in Varian 6MV, 10x10 cm2 field, 0° gantry angle, 90 cm SSD, 10 cm depth.A reduced energy response was measured in X-rays for the smallest grain size with an inverse correlation between response and grain size. The N-60 irradiation showed a 43% reduction in the energy over-response when going from 3 µm to 230 nm grain size and 5% phosphor concentration. In-silico metrics calculation, using homogeneous dispersion of the phosphor, underestimated the experimental response and was not able to obtain the experimental correlation between grain size and energy response. Isolated grain size modeling allowed for a good agreement to experimental data, and enabled steering the production of optimized OSL-films to further test in clinical 6 MV beams.

show abstract

Section: Introductionmentioning

confidence: 99%