Characterization of radiochromic films as a micrometer‐resolution dosimeter by confocal Raman spectroscopy

Mirza, J. A.; Millares, Rodrigo Hernández; Kim, Geon Il; Park, So Yeon; Lee, Jaegi; Ye, Sung Joon

doi:10.1002/mp.13778

Cited by 5 publications

(25 citation statements)

References 41 publications

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“…Therefore, to avoid the long irradiation time, the calibration films were exposed to 200 kVp xrays. 4 The films which were in direct contact with the GNF were exposed to 50 and 120 kVp x-ray beam. The delivered dose to those films was 0.5 Gy, following the same irradiation procedure as previous films.…”

Section: B Preparation Of Radiochromic Films and Irradiationmentioning

confidence: 99%

“…A Raman mapping technique developed in our previous study was used in this work. 4 A CRS system with a 30-μm pinhole was used (DONGWOO OPTRON model Rambossstar, Korea). By utilizing a confocal system, the lateral resolution of a Raman scattering signal detection is significantly improved to approximately 0.6 µm.…”

Section: C Raman Spectroscopy For Dosimetrymentioning

confidence: 99%

“…The EBT-XD films exposed to different dose levels were placed in the central compartment of the L-shaped device. 4 The scanning was performed along the lateral axis, which, due to the 90-degree rotation, would measure Raman changes in the depth from the surface of the RCF. The RCF was immobilized entirely, and the excitation laser focused at 15 µm above the RCF.…”

Section: D Data Acquisition and Spatial Resolutionmentioning

confidence: 99%

“…Radiochromic films (RCF) have been widely employed and further studied to address this issue, especially in small field dosimetry. 4 Their high spatial resolution, tissue equivalency, energy independence, and the fact that they do not require any chemical treatment for data processing and analysis are advantageous over other dosimeters. 5 EBT-XD (Ashland Specialty Ingredients, Bridge Water NJ) is a type of radiochromic film that darkens when exposed to ionizing radiation.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, measuring the dose distribution at the micrometer scale has been a challenge in radiation dosimetry. Radiochromic films (RCF) have been widely employed and further studied to address this issue, especially in small field dosimetry 4 . Their high spatial resolution, tissue equivalency, energy independence, and the fact that they do not require any chemical treatment for data processing and analysis are advantageous over other dosimeters 5 .…”

Section: Introductionmentioning

confidence: 99%

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Radiosensitization by Au‐nanofilm at micrometer level using confocal Raman spectroscopy

et al. 2021

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Purpose: To measure the radiosensitization by an Au-nanofilm (GNF) at a micrometer level on a radiochromic film (RCF) using confocal Raman spectroscopy (CRS). Methods: Unlaminated radiochromic films were irradiated by 200 kVp x-ray from 0.3 to 50 Gy to obtain a calibration curve. Raman spectra of these films were measured by positioning the postirradiated RCF perpendicular to the CRS monochromatic beam and reading a depth profile of the film along the lateral axis. The Raman peak corresponding to the C ≡ C peak was obtained from a region of interest of 100 × 5 µm 2. To investigate the radiosensitization by GNF, two sets of RCF, one attached to a 100-nm thick GNF and the other without GNF were irradiated at 0.5 Gy by 50 and 120 kVp X-rays. The spatial resolution of the CRS on the RCF was quantified by the modulation transfer function method (MTF). Thus, in the spatial resolution determined by MTF, the doses deposited on the films were evaluated. The dose enhancement factor (DEF) was obtained in the measurable micro-size by comparing doses deposited on the RCFs with and without GNF. To verify the experimental results, Monte Carlo simulations following the experimental set up were performed using Geant4. In addition, analytical calculations for the radiosensitization by GNF were carried out. Results: The confocal Raman spectroscopy on the RCF achieved a spatial resolution of~6 μm. An experimental DEF within the first 6 μm depth from the surface of RCF was found to be 17.9 for 50 kVp and 14.7 for 120 kVp. The DEF for the same depth obtained by MC and analytical calculations was 13.53 and 9.75 for 50 kVp, and 10.63 and 6.67 for 120 kVp, respectively. Conclusions: The experimental DEF as a function of the distance from GNF was consistent with data from previous studies and the MC simulations, supporting that CRS in conjunction with the RCF is a feasible micrometer-resolution dosimeter.

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Section: B Preparation Of Radiochromic Films and Irradiationmentioning

confidence: 99%

Section: C Raman Spectroscopy For Dosimetrymentioning

confidence: 99%

Section: D Data Acquisition and Spatial Resolutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Radiosensitization by Au‐nanofilm at micrometer level using confocal Raman spectroscopy

et al. 2021

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High spatial resolution dosimetry with uncertainty analysis using Raman micro‐spectroscopy readout of radiochromic films

et al. 2021

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Purpose The purpose of this work is to develop a new approach for high spatial resolution dosimetry based on Raman micro‐spectroscopy scanning of radiochromic film (RCF). The goal is to generate dose calibration curves over an extended dose range from 0 to 50 Gy and with improved sensitivity to low (<2 Gy) doses, in addition to evaluating the uncertainties in dose estimation associated with the calibration curves. Methods Samples of RCF (EBT3) were irradiated at a broad dose range of 0.03–50 Gy using an Elekta Synergy clinical linear accelerator. Raman spectra were acquired with a custom‐built Raman micro‐spectroscopy setup involving a 500 mW, multimode 785 nm laser focused to a lateral spot diameter of 30 µm on the RCF. The depth of focus of 34 µm enabled the concurrent collection of Raman spectra from the RCF active layer and the polyester laminate. The preprocessed Raman spectra were normalized to the intensity of the 1614 cm−1 Raman peak from the polyester laminate that was unaltered by radiation. The mean intensities and the corresponding standard deviation of the active layer Raman peaks at 696, 1445, and 2060 cm−1 were determined for the 150 × 100 µm2 scan area per dose value. This was used to generate three calibration curves that enabled the conversion of the measured Raman intensity to dose values. The experimental, fitting, and total dose uncertainty was determined across the entire dose range for the dosimetry system of Raman micro‐spectroscopy and RCF. Results In contrast to previous work that investigated the Raman response of RCFs using different methods, high resolution in the dose response of the RCF, even down to 0.03 Gy, was obtained in this study. The dynamic range of the calibration curves based on all three Raman peaks in the RCF extended up to 50 Gy with no saturation. At a spatial resolution of 30 × 30 µm2, the total uncertainty in estimating dose in the 0.5–50 Gy dose range was [6–9]% for all three Raman calibration curves. This consisted of the experimental uncertainty of [5–8]%, and the fitting uncertainty of [2.5–4.5]%. The main contribution to the experimental uncertainty was determined to be from the scan area inhomogeneity which can be readily reduced in future experiments. The fitting uncertainty could be reduced by performing Raman measurements on RCF samples at further intermediate dose values in the high and low dose range. Conclusions The high spatial resolution experimental dosimetry technique based on Raman micro‐spectroscopy and RCF presented here, could become potentially useful for applications in microdosimetry to produce meaningful dose estimates in cellular targets, as well as for applications based on small field dosimetry that involve high dose gradients.

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Evaluation of the spatial resolution of Gafchromic™ HD-V2 radiochromic film characterized by the modulation transfer function

et al. 2023

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The Modulation Transfer Function (MTF) characteristics of radiochromic film (RCF) dosimetry with optical systems were evaluated with an RCF, HD-V2, which is transferred with the line patterns of the resolution test chart. In the evaluation using a GT-X980 flatbed scanner, a high contrast spatial resolution with an MTF of ≥0.8 is limited to about 83.3 μm due to artifacts such as scattering of the HD-V2 transmitted light. To achieve high contrast at higher spatial frequencies, a test bench microdensitometer (TBMD) was developed, and its optical performance, dose equivalent response, and spatial resolution characteristics with MTF were evaluated. The TBMD had a minimum readout focal diameter of 13 μm, and its high contrast spatial resolution with an MTF of ≥0.8 is about 11.9 μm. The result that the optical density error increases with decreasing focal diameter in the TBMD supports our hypothesis that these errors are based on the non-uniformity of the shading and surface roughness of the HD-V2 active layer monomers.

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Characterization of radiochromic films as a micrometer‐resolution dosimeter by confocal Raman spectroscopy

Cited by 5 publications

References 41 publications

Radiosensitization by Au‐nanofilm at micrometer level using confocal Raman spectroscopy

Radiosensitization by Au‐nanofilm at micrometer level using confocal Raman spectroscopy

High spatial resolution dosimetry with uncertainty analysis using Raman micro‐spectroscopy readout of radiochromic films

Evaluation of the spatial resolution of Gafchromic™ HD-V2 radiochromic film characterized by the modulation transfer function

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