Characterization of calibration curves and energy dependence GafChromic<sup>TM</sup>
 XR-QA2 model based radiochromic film dosimetry system

Tomic, Nada; Quintero, C.; Whiting, Bruce R.; Aldelaijan, Saad; Bekerat, Hamed; Liang, LiHeng; DeBlois, F; Seuntjens, J; Dević, Slobodan

doi:10.1118/1.4876295

Cited by 46 publications

(40 citation statements)

References 18 publications

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“…The first step in the image analysis was the application of a median filter with a 3 × 3 pixel kernel: this procedure reduces the impulse noise in the image and removes any single dead pixels . The film response was then evaluated in terms of reflectance change, according to the method proposed by Tomic et al The final film net reflectance change, net∆R, was defined as

n e t Δ R = Δ R - Δ R^{Control}

where ∆R is the reflectance change for a film exposed to x rays, calculated as

Δ R = \frac{1}{2^{16}} [P V_{italicBefore} - P V_{italicAfter}]

and ∆R Control is calculated using Eq. for an unexposed control film, which quantifies reflectance changes due to effects other than those due to x‐ray exposure.…”

Section: Methodsmentioning

confidence: 99%

Internal breast dosimetry in mammography: Experimental methods and Monte Carlo validation with a monoenergetic x‐ray beam

et al. 2018

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The calibration procedures and the experimental methodologies proposed lead to good accuracy for internal breast dose estimation. In addition, these procedures can be successfully applied to validate MC codes for breast dosimetry at the local dose level. The agreement among the experimental and MC results not only shows the correctness of the empirical procedures used but also of the simulation parameters.

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n e t Δ R = Δ R - Δ R^{Control}

where ∆R is the reflectance change for a film exposed to x rays, calculated as

Δ R = \frac{1}{2^{16}} [P V_{italicBefore} - P V_{italicAfter}]

and ∆R Control is calculated using Eq. for an unexposed control film, which quantifies reflectance changes due to effects other than those due to x‐ray exposure.…”

Section: Methodsmentioning

confidence: 99%

Internal breast dosimetry in mammography: Experimental methods and Monte Carlo validation with a monoenergetic x‐ray beam

et al. 2018

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“…Those authors reported a significant variation (close to 190%) in XR-QA2 film response in that energy range, at the value of 80 mGy air kerma in air, a finding that motivates further investigations. In addition, Tomic et al 1 reported on the characterization of XR-QA2 film calibration curve by testing three fit functions (rational, linear exponential, and power); the power function was evaluated as the most appropriate for expressing the dose versus net optical reflectance curve, for reference radiochromic dosimetry with XR-QA2 films. The use of suitable fitting functions is fundamental for the proper interpolation of dose values from the available measurements, and great care is devoted to this assessment (e.g., Ref.…”

Section: Introductionmentioning

confidence: 99%

Energy dependent calibration of XR-QA2 radiochromic film with monochromatic and polychromatic x-ray beams

et al. 2016

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The XR-QA2 radiochromic film response showed a strong dependence on beam energy for both monochromatic and polychromatic beams in the range of half value layer values from 0.55 to 6.1 mm Al and corresponding effective energies from 18 to 46.5 keV. In this range, the film response varied by 170%, from a minimum sensitivity of 0.0127 to a maximum sensitivity of 0.0219 at 10 mGy air kerma in air. The more suitable function for air kerma calibration of the XR-QA2 radiochromic film was the power function. A significant batch-to-batch variation, up to 55%, in film response at 120 kV (46.5 keV effective energy) was observed in comparison with published data.

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“…Analysis of the GafChromic™ film was performed using open source software (ImageJ; National Institutes of Health, Bethesda, MD, USA) following the procedure reported in Fedon et al which is based on the method proposed by Tomic et al…”

Section: Methodsmentioning

confidence: 99%

Internal breast dosimetry in mammography: Monte Carlo validation in homogeneous and anthropomorphic breast phantoms with a clinical mammography system

2018

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PurposeTo validate Monte Carlo (MC)‐based breast dosimetry estimations using both a homogeneous and a 3D anthropomorphic breast phantom under polyenergetic irradiation for internal breast dosimetry purposes.MethodsExperimental measurements were performed with a clinical digital mammography system (Mammomat Inspiration, Siemens Healthcare), using the x‐ray spectrum selected by the automatic exposure control and a tube current‐exposure time product of 360 mAs. A homogeneous 50% glandular breast phantom and a 3D anthropomorphic breast phantom were used to investigate the dose at different depths (range 0–4 cm with 1 cm steps) for the homogeneous case and at a depth of 2.25 cm for the anthropomorphic case. Local dose deposition was measured using thermoluminescent dosimeters (TLD), metal oxide semiconductor field‐effect transistor dosimeters (MOSFET), and GafChromic™ films. A Geant4‐based MC simulation was modified to match the clinical experimental setup. Thirty sensitive volumes (3.2 × 3.2 × 0.38 mm3) on the axial‐phantom plane were included at each depth in the simulation to characterize the internal dose variation and compare it to the experimental TLD and MOSFET measurements. The experimental 2D dose maps obtained with the GafChromic™ films were compared to the simulated 2D dose distributions.ResultsDue to the energy dependence of the dosimeters and due to x‐ray beam hardening, dosimeters based on these three technologies have to be calibrated at each depth of the phantom. As expected, the dose was found to decrease with increasing phantom depth, with the reduction being ~93% after 4 cm for the homogeneous breast phantom. The 2D dose map showed nonuniformities in the dose distribution in the axial plane of the phantom. The mean combined standard uncertainty increased with phantom depth by up to 5.3% for TLD, 6.3% for MOSFET, and 9.6% for GafChromic™ film. In the case of a heterogeneous phantom, the dosimeters are able to detect local dose gradient variations. In particular, GafChromic™ film showed local dose variations of about 46% at the boundaries of two materials.ConclusionsResults showed a good agreement between experimental measurements (with TLD and MOSFET) and MC data for both homogeneous and anthropomorphic breast phantoms. Larger discrepancies are found when comparing the GafChromic™ dose values to the MC results due to the inherent less precise nature of the former.MC validations in a heterogeneous background at the level of local dose deposition and in absolute terms play a fundamental role in the development of an accurate method to estimate radiation dose. The potential introduction of a breast dosimetry model involving a nonhomogeneous glandular/adipose tissue composition makes the validation of internal dose distributions estimates crucial.

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Characterization of calibration curves and energy dependence GafChromic^TM XR-QA2 model based radiochromic film dosimetry system

Cited by 46 publications

References 18 publications

Internal breast dosimetry in mammography: Experimental methods and Monte Carlo validation with a monoenergetic x‐ray beam

Internal breast dosimetry in mammography: Experimental methods and Monte Carlo validation with a monoenergetic x‐ray beam

Energy dependent calibration of XR-QA2 radiochromic film with monochromatic and polychromatic x-ray beams

Internal breast dosimetry in mammography: Monte Carlo validation in homogeneous and anthropomorphic breast phantoms with a clinical mammography system

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Characterization of calibration curves and energy dependence GafChromicTM XR-QA2 model based radiochromic film dosimetry system

Cited by 46 publications

References 18 publications

Internal breast dosimetry in mammography: Experimental methods and Monte Carlo validation with a monoenergetic x‐ray beam

Internal breast dosimetry in mammography: Experimental methods and Monte Carlo validation with a monoenergetic x‐ray beam

Energy dependent calibration of XR-QA2 radiochromic film with monochromatic and polychromatic x-ray beams

Internal breast dosimetry in mammography: Monte Carlo validation in homogeneous and anthropomorphic breast phantoms with a clinical mammography system

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Characterization of calibration curves and energy dependence GafChromic^TM XR-QA2 model based radiochromic film dosimetry system