A spectroscopic study of the chromatic properties of GafChromic™EBT3 films

Callens, Maarten; Crijns, Wouter; Simons, V.; Wolf, Ingrid De; Depuydt, Tom; Maes, Frederik; Haustermans, Karin; D'hooge, Jan; D’Agostino, Emiliano; Wevers, Martine; Pfeiffer, Helge; Abeele, Koen Van Den

doi:10.1118/1.4941312

Cited by 29 publications

(76 citation statements)

References 52 publications

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“…The complete vis‐absorption spectrum of EBT3 films can be reconstructed by a sum of Lorentzian functions. This was previously demonstrated in an empirical way by Devic et al, and based on the chemical nature of the PDA molecules by Callens et al In this work, the latter approach is used as it allows to extract a measure of the concentration of the PDA phases because the Lorentzians correspond to electronic and vibronic transitions from the ground state to excited states. The absorbance

{scriptA}_{p} false(italicλ; n false)

resulting from absorption by a single PDA color phase, denoted by the subscript “ p ” ( p = blue or p = red), is given by Eq.…”

Section: Methodsmentioning

confidence: 87%

“…The vis‐absorption spectrum of EBT3 films results from the absorption properties of two phases of the PDA polymer, i.e., the blue phase and the red phase . These polymer color phases represent distinct geometrical conformations of the polymer backbone which are discernible by their color .…”

Section: Methodsmentioning

confidence: 99%

“…

V_{p}

is a scaling factor of all vibronic transitions and

a_{p; k}

is the relative contribution of each vibronic transition. For more details on the modeling of the absorption spectrum from the electronic properties of PDA, the authors wish to refer to Ref …”

Section: Methodsmentioning

confidence: 99%

“…Moreover, if the medium is a mixture of several attenuating species, the absorbance is proportional to the concentration of all species which do not necessarily have the same dose dependence. In the case of EBT3 films, a spectroscopic study has indeed shown that two distinct conformations of the PDA polymer with different absorption properties are formed . The complex relation between the polymer concentration and the absorbance is important to consider when the single‐hit model is applied to model the dose dependence of the absorbance, or the optical density of an RGB channel, as the single‐hit model describes the dose dependence of the polymer content.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the dose dependence of the vis-absorption spectrum of EBT3 GafChromic™ films

et al. 2017

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Purpose: The aim of this work was to model the dose dependence of the darkening of GafChromic TM EBT3 films by combining the optical properties of the polydiacetylene polymer phases, and a modified version of the single-hit model, which will take the stick-like shape of the monomer microcrystals into account. Second, a comparison is made between the quantification of the film darkening by flatbed scanning and by UV-vis absorption spectroscopy. Method: GafChromic TM EBT3 films were irradiated with a 6 MV photon beam at dose levels between 0 and 50 Gy. The radiation-induced darkening of the films is quantified by a flatbed scanner, and by UV-vis absorption spectroscopy in the wavelength range of 220-750 nm. From the UV-vis absorption spectra, the contribution of each polymer phase to the absorbance was deduced. Next, the dose dependence of the polymer content is described by a modified single-hit model where the size distribution of polymerizable centers is approximated by way of the size distribution of the monomer microcrystals in the film. Results: The absorption properties of the film can be accurately quantified by UV-vis spectroscopy for dose levels between 0 and 10 Gy. Over 10 Gy, the absorption spectrum saturates due to the limited sensitivity of the spectrometer. The modified single-hit model was successful in describing the increasing polymer concentration with radiation dose, using a log-normal distribution for the length of the stick-like monomer microcrystals. The dose dependence of the polymer content, deduced from the UV-vis absorption spectrum, differs from that of the flatbed scanning method and is more sensitive to changes in dose. Conclusion: The dose dependence of the polymer concentration can be modeled by taking into account the distribution of active centers using the microstructure of the active layer for dose levels between 0 and 10 Gy. The dissimilar dose dependence of the polymer concentration and the absorbance must be accounted for when modeling darkening from the kinetics of the photopolymerization reaction.

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{scriptA}_{p} false(italicλ; n false)

resulting from absorption by a single PDA color phase, denoted by the subscript “ p ” ( p = blue or p = red), is given by Eq.…”

Section: Methodsmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

“…

V_{p}

is a scaling factor of all vibronic transitions and

a_{p; k}

is the relative contribution of each vibronic transition. For more details on the modeling of the absorption spectrum from the electronic properties of PDA, the authors wish to refer to Ref …”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling the dose dependence of the vis-absorption spectrum of EBT3 GafChromic™ films

et al. 2017

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“…The symbols correspond to the experimental data while the lines to the mathematical function that better describes the experiment. As observed, the optical density for each colour channel is described by a polynomial of different degree from 2 to 4, which could be associated to the optical absorption spectra of the EBT3 film [13]. …”

Section: Methodsmentioning

confidence: 99%

Absorbed dose distribution in liquid water for a CyberKnife VSI using radiochromic EBT3 film

Hernández-Guzmán

Aragón-Martínez

Gómez-Muñoz

et al. 2016

AIP Conference Proceedings

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A new analytical model for the response curve in megavoltage photon beams of the radiochromic EBT3 films measured with flatbed scanners

Rodríguez

Garcia-Pinto

Martínez

et al. 2022

J Applied Clin Med Phys

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The aim of this work is to study a new analytical model which describes the dose-response curve in megavoltage photon beams of the radiochromic EBT3 film measured with two commercially available flatbed scanners. This model takes into account the different increase of the number of two types of absorbents in the film with absorbed dose and it allows to identify parameters that depend on the flatbed scanner and the film model, and parameters that exclusively depend on the production lot. In addition, the new model is also compared with other models commonly used in the literature in terms of its performance in reducing systematic calibration uncertainties. Methods and materials:The new analytical model consists on a linear combination of two saturating exponential functions for every color channel. The exponents modeling the growing of each kind of absorbent are film model and scanner model-dependent, but they do not depend on the manufacturing lot. The proposed model considers the different dose kinetics of each absorbent and the apparent effective behavior of one of the absorbents in the red color channel of the scanner. The dose-response curve has been measured using EBT3 films, a percentage depth dose (PDD) calibration method in a dose range between 0.5 and 25 Gy, and two flatbed scanners: a Microtek 1000 XL and an EPSON 11000 XL. The PDD calibration method allows to obtain a dense collection of calibration points which have been fitted to the proposed response curve model and to other published models. The fit residuals were used to evaluate the performance of each model compared with the new analytical model. Results:The model presented here does not introduce any systematic deviations up to the degree of accuracy reached in this work. The residual distribution is normally shaped and with lower variance than the distributions of the other published models. The model separates the parameters reflecting specific characteristics of the dosimetry system from the linear parameters which depend only on the production lot and are related to the relative abundance of each type of absorbent. The calibration uncertainty is reduced by a mean factor of two by using this model compared with the other studied models.

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A spectroscopic study of the chromatic properties of GafChromic™EBT3 films

Cited by 29 publications

References 52 publications

Modeling the dose dependence of the vis-absorption spectrum of EBT3 GafChromic™ films

Modeling the dose dependence of the vis-absorption spectrum of EBT3 GafChromic™ films

Absorbed dose distribution in liquid water for a CyberKnife VSI using radiochromic EBT3 film

A new analytical model for the response curve in megavoltage photon beams of the radiochromic EBT3 films measured with flatbed scanners

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