Solar ultraviolet radiation response of EBT2 Gafchromic, radiochromic film

Butson, Ethan; Yu, K.N.; Butson, Martin J

doi:10.1088/0031-9155/58/21/n287

Cited by 17 publications

(17 citation statements)

References 14 publications

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“…Accurate knowledge of the absorption spectrum of the radiochromic films and its behavior with dose helps to better understand their response to radiation . The optical absorption spectra of the EBT, EBT2, and EBT3 radiochromic films have been studied for their optical properties . In most of the existing literature, it has been shown that the irradiation of these films results in two principal absorption bands centered at 636 ± 3 and 585 ± 2 nm.…”

Section: Introductionmentioning

confidence: 99%

Spectral analysis of the EBT3 radiochromic films for clinical photon and electron beams

et al. 2019

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Purpose The purpose of this study was to investigate the spectral response of the EBT3 radiochromic films to different beam qualities for radiation therapy dosimetry. Dose, dose rate, and interbatch dependencies on the spectral response of the films were investigated as well. Methods Pieces of EBT3 films placed between layers of solid water phantoms were irradiated with 6 and 15 MV photon beams, 6 and 10 MV‐flattening filter free (FFF) photon beams, and 6 and 20 MeV electron beams at dose levels between 0.4 and 50 Gy. Net absorbance was measured as a function of wavelength from the spectra acquired in the wavelength range of 400–800 nm using a fiber‐coupled spectrometer and broadband light source. Results No significant change was observed in the absorption spectra of the EBT3 film from the same batch irradiated with the same amount of dose using different beam qualities. Also, no spectral change with dose rate was observed. The measured net absorbance per Gy was independent of beam quality in the 1–50 Gy dose range. Slight differences in the spectral shape and absorption band positions were observed in film samples from different batches. The net absorbance spectra showed two absorption bands centered around 634–636 nm (primary) and 583–585 nm (secondary). However, depending on the film batch, for doses above a certain level the primary absorption band appears to “split” into two bands centered around ~624–628 and ~641–645 nm. Conclusions The spectral shape of the EBT3 radiochromic films irradiated with photons (including FFF) and electron beams is beam quality and dose rate independent; however, it varies with dose level, batch, and spectroscopy system used.

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Section: Introductionmentioning

confidence: 99%

Spectral analysis of the EBT3 radiochromic films for clinical photon and electron beams

et al. 2019

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“…Because the active layer of a Gafchromic film reacts to UV rays, 17 , 18 UV irradiation is effective only if appropriately applied. For instance, UV irradiation can markedly improve the uniformity of Gafchromic EBT (16) .…”

Section: Introductionmentioning

confidence: 99%

Correction of nonuniformity error of Gafchromic EBT2 and EBT3

Katsuda

Gotanda

et al. 2016

J Applied Clin Med Phys

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This study investigates an X‐ray dose measurement method for computed tomography using Gafchromic films. Nonuniformity of the active layer is a major problem in Gafchromic films. In radiotherapy, nonuniformity error is reduced by applying the double‐exposure technique, but this is impractical in diagnostic radiology because of the heel effect. Therefore, we propose replacing the X‐rays in the double‐exposure technique with ultraviolet (UV)‐A irradiation of Gafchromic EBT2 and EBT3. To improve the reproducibility of the scan position, Gafchromic EBT2 and EBT3 films were attached to a 3‐mm‐thick acrylic plate. The samples were then irradiated with a 10 W UV‐A fluorescent lamp placed at a distance of 72 cm for 30, 60, and 90 minutes. The profile curves were evaluated along the long and short axes of the film center, and the standard deviations of the pixel values were calculated over large areas of the films. Paired t‐test was performed. UV‐A irradiation exerted a significant effect on Gafchromic EBT2 (paired t‐test; p=0.0275) but not on EBT3 (paired t‐test; p=0.2785). Similarly, the homogeneity was improved in Gafchromic EBT2 but not in EBT3. Therefore, the double‐exposure technique under UV‐A irradiation is suitable only for EBT2 films.PACS number(s): 87.53 Bn

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“…Application of radiochromic films for clinical X-ray dosimetry has, in essence, relied on dose-response curves (response in terms of film coloration) obtained through calibration. However, many intriguing properties of radiochromic films are not yet fully understood, including their responses to fluorescent light [3,4] and ultraviolet (UV) radiation [5][6][7][8]; the energy dependence of their responses [9][10][11][12][13]; the effects of polarization and scanning orientation [14][15][16]; and the effects of mechanical pressure [17] and auto-development [18], etc. In order to understand these intriguing properties, development of a theoretical model at both atomic and macroscopic scales is pertinent.…”

Section: Introductionmentioning

confidence: 99%

Modeling Coloration of a Radiochromic Film with Molecular Dynamics-Coupled Finite Element Method

et al. 2017

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Radiochromic films change color upon exposures to radiation doses as a result of solid-state polymerization (SSP). Commercially available radiochromic films are primarily designed for, and have become widely used in, clinical X-ray dosimetry. However, many intriguing properties of radiochromic films are not yet fully understood. The present work aimed at developing a theoretical model at both atomic and macroscopic scales to provide a platform for future works to understand these intriguing properties. Despite the fact that radiochromic films were primarily designed for clinical X-ray dosimetry, dose-response curves for the Gafchromic EBT3 film obtained for ultraviolet (UV) radiation were employed to develop our model in order to avoid complications of ionization, non-uniform energy deposition, as well as dispersed doses caused by secondary electrons set in motion by the indirectly ionizing X-ray photons, which might introduce added uncertainties to the model and overshadow the basic SSP processes. The active layer in the EBT3 film consisted of diacetylene (DA) pentacosa-10,12-diynoate monomers, which were modelled using molecular dynamics (MD). The degrees of SSP in the atomic scale upon different UV exposures were obtained to determine the absorption coefficients of the active layer, which were then input into the finite element method (FEM). The classical steady-state Helmholtz equation was engaged to model the reflection from the active layer using the FEM technique. The multifrontal massively parallel sparse direct solver (MUMPS) was employed to solve the present numerical problem. Very good agreement between experimentally and theoretically obtained coloration in terms of net reflective optical density was achieved for different UV exposures. In particular, for UV exposures larger than~40 J/cm 2 , the reflected light intensity decreased at a lower rate when compared to other UV exposure values, which was explained by the densely cross-linked structure under near-complete polymerization, and thus the lower efficiency for further bond formation between DA monomer strands.

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Solar ultraviolet radiation response of EBT2 Gafchromic, radiochromic film

Cited by 17 publications

References 14 publications

Spectral analysis of the EBT3 radiochromic films for clinical photon and electron beams

Spectral analysis of the EBT3 radiochromic films for clinical photon and electron beams

Correction of nonuniformity error of Gafchromic EBT2 and EBT3

Modeling Coloration of a Radiochromic Film with Molecular Dynamics-Coupled Finite Element Method

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