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

León-Marroquín, Elsa Y.; Mulrow, Daniel; Khan, Rao; Darafsheh, Arash

doi:10.1002/mp.13330

Cited by 23 publications

(41 citation statements)

References 36 publications

(132 reference statements)

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“…The net absorbance of the EBT3 film irradiated with 25 cGy was also analyzed using the same method, and bands were centered at 583 and 634 nm. The obtained results were congruent with previously reported results . The absorption value at λ max increased with the dose.…”

Section: Resultssupporting

confidence: 93%

“…Each uncertainty is expressed using the following equations:

{SD}_{fit} (%) = \frac{\sqrt{n e t O D^{2} \cdot S D_{a}^{2} + n e t O D^{2 n} \cdot S D_{b}^{2}}}{D_{fit}} \cdot 100

{SD}_{\exp} (%) = \frac{(a + n \cdot b \cdot n e t O D^{n - 1}) \cdot S D (n e t O D)}{D_{fit}} \cdot 100

where a, b, and n are the fitting parameters defined in Eq. () and SD a and SD b are the SDs of fitting parameters a and b, respectively . The uncertainties of the CLOD were calculated using two dose–response curves for low dose regions up to 50 cGy and whole dose regions.…”

Section: Methodsmentioning

confidence: 99%

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Contact lens‐type ocular in vivo dosimeter for radiotherapy

et al. 2019

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Purpose This study aimed to (a) develop a contact lens‐type ocular in vivo dosimeter (CLOD) that can be worn directly on the eye and (b) assess its dosimetric characteristics and biological stability for radiation therapy. Methods The molder of a soft contact lens was directly used to create the dosimeter, which included a radiation‐sensitive component — an active layer similar to a radiochromic film — to measure the delivered dose. A flatbed scanner with a reflection mode was used to measure the change in optical density due to irradiation. The sensitivity, energy, dose rate, and angular dependence were tested, and the uncertainty in determining the dose was calculated using error propagation analysis. Sequential biological stability tests, specifically, cytotoxicity and ocular irritation tests, were conducted to ensure the safe application of the CLOD to patients. Results The dosimeter demonstrated high sensitivity in the low dose region, and the sensitivity linearly decreased with the dose. The responses obtained for the 10 and 15 MV photon beams were 1.7% and 1.9% higher compared to the 6 MV photon beam. A strong dose rate dependence was not obtained for the CLOD. Angular dependence was observed from 90° to 180° with a difference in response from 1% to 2%. The total uncertainty in error propagation analysis decreased as a function of the dose in the red channel. For a dose range of 0 to 50 cGy, the total uncertainties for 5, 10, and 50 cGy were 14.2%, 8.9%, and 5%, respectively. Quantitative evaluation using the MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) method presented no cytotoxicity. Further, no corneal opacity, iris reaction, or conjunctival inflammation was observed. Conclusions The CLOD is the first dosimeter that can be worn close to the eye. The results of cytotoxicity and irritation tests indicate that it is a stable medical device. The evaluation of dose characteristics in open field conditions shows that the CLOD can be applied to an in vivo dosimeter in radiotherapy.

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Section: Resultssupporting

confidence: 93%

“…Each uncertainty is expressed using the following equations:

{SD}_{fit} (%) = \frac{\sqrt{n e t O D^{2} \cdot S D_{a}^{2} + n e t O D^{2 n} \cdot S D_{b}^{2}}}{D_{fit}} \cdot 100

{SD}_{\exp} (%) = \frac{(a + n \cdot b \cdot n e t O D^{n - 1}) \cdot S D (n e t O D)}{D_{fit}} \cdot 100

Section: Methodsmentioning

confidence: 99%

Contact lens‐type ocular in vivo dosimeter for radiotherapy

et al. 2019

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“…Interbatch variations were computed over a 30 nm wavelength range around the 636 and 585 nm absorption bands (i.e., over 621–651 nm and 570–600 nm spectral range). In contrast to the EBT3 films, no interbatch differences on the position of the absorption bands were observed in the EBT‐XD films.…”

Section: Resultsmentioning

confidence: 68%

“…The spectra were acquired while both deuterium and halogen sources were simultaneously turned on, to provide adequate light intensity over the visible spectrum. More details of the setup are provided in our previous study …”

Section: Methodsmentioning

confidence: 99%

“…The spectra were measured over five different regions of interest (ROIs) on the film. For each ROI, 50 spectra (with an acquisition time of 500 ms) were collected and their median is calculated, as described in the previous work . The uncertainty in the measured absorbance was assessed by standard deviation of the median spectra corresponding to the five ROIs.…”

Section: Methodsmentioning

confidence: 99%

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Response characterization of EBT‐XD radiochromic films in megavoltage photon and electron beams

et al. 2019

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Purpose The purpose of this study was to investigate the beam quality dependence of the EBT‐XD radiochromic films for megavoltage photon and electron beam irradiations by studying their spectral response. Dose, dose rate, and interbatch dependencies were investigated as well. Methods EBT‐XD and EBT3 radiochromic films were cut into 5 cm2 × 5 cm2 pieces, placed between solid water phantoms, and irradiated with 6 and 15 MV photon beams, 6 and 10 MV flattening filter free photon beams, and 6 and 20 MeV electron beams at dose levels between 0.5 and 50 Gy. In order to measure the spectral response, the films were illuminated by a deuterium and tungsten‐halogen lamp and net absorption was measured in 400–800 nm spectral range using a fiber‐coupled optical spectrometer. Film samples were then analyzed using a flatbed scanner in the red, green, and blue channel to obtain the optical density of the films. Results The net absorption spectra of the EBT‐XD and EBT3 films showed two absorption bands centered at 635 and 585 nm, characteristic of the EBT model. However, for a given dose, the EBT‐XD films showed lower net absorbance compared to the EBT3 films. At a given dose level, the net absorption spectra and dose–response curves for EBT‐XD films showed only slight variations across various beam qualities. When a calibration curve obtained from a given beam quality is used to measure dose from films irradiated with other beam qualities, the maximum uncertainty in the calculated dose, in ranges 5–40 and 8–50 Gy for red and green channels, respectively, were ~3.1% and ~2.4%. Conclusions The response of the EBT‐XD films is dose rate independent but batch dependent. No significant beam quality dependence was observed in EBT‐XD films in the dose range up to 50 Gy.

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Monte Carlo simulations of EBT3 film dose deposition for percentage depth dose (PDD) curve evaluation

Robinson

Esplen

Wells

et al. 2020

J Applied Clin Med Phys

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Purpose: To use Monte Carlo (MC) calculations to evaluate the effects of Gafchromic EBT3 film orientation on percentage depth dose (PDD) curves. Methods: Dose deposition in films placed in a water phantom, and oriented either parallel or perpendicular with respect to beam axis, were simulated with MC and compared to PDDs scored in a homogenous water phantom. The effects of introducing 0.01-1.00 mm air gaps on each side of the film as well as a small 1°-3°tilt for film placed in parallel orientation were studied. PDDs scored based on two published EBT3 film compositions were compared. Three photon beam energies of 120 kVp, 220 kVp, and 6 MV and three field sizes between 1 × 1 and 5 × 5 cm 2 were considered. Experimental PDDs for a 6-MV 3 × 3 cm 2 beam were acquired. Results: PDD curves for films in perpendicular orientation more closely agreed to water PDDs than films placed in parallel orientation. The maximum difference between film and water PDD for films in parallel orientation was −12.9% for the 220 kVp beam. For the perpendicular film orientation, the maximum difference decreased to 5.7% for the 120 kVp beam. The inclusion of an air gap had the largest effect on the 6-MV 1 × 1 cm 2 beam, for which the dose in the buildup region was underestimated by 21.2% compared to the simulation with no air gap. A 2°film tilt decreased the difference between the parallel film and homogeneous water phantom PDDs from −5.0% to −0.5% for the 6 MV 3 × 3 cm 2 beam. The "newer" EBT3 film composition resulted in larger PDD discrepancies than the previous composition. Experimental film data qualitatively agreed with MC simulations. Conclusions: PDD measurements with films should either be performed with film in perpendicular orientation to the beam axis or in parallel orientation with a~2°tilt and no air gaps.

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

Cited by 23 publications

References 36 publications

Contact lens‐type ocular in vivo dosimeter for radiotherapy

Contact lens‐type ocular in vivo dosimeter for radiotherapy

Response characterization of EBT‐XD radiochromic films in megavoltage photon and electron beams

Monte Carlo simulations of EBT3 film dose deposition for percentage depth dose (PDD) curve evaluation

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