Absolute dosimetric characterization of Gafchromic EBT3 and HDv2 films using commercial flat-bed scanners and evaluation of the scanner response function variability

Abstract

Radiochromic films (RCF) are commonly used in dosimetry for a wide range of radiation sources (electrons, protons, and photons) for medical, industrial, and scientific applications. They are multi-layered, which includes plastic substrate layers and sensitive layers that incorporate a radiation-sensitive dye. Quantitative dose can be retrieved by digitizing the film, provided that a prior calibration exists. Here, to calibrate the newly developed EBT3 and HDv2 RCFs from Gafchromic™, we used the Stanford Medical LINAC to deposit in the films various doses of 10 MeV photons, and by scanning the films using three independent EPSON Precision 2450 scanners, three independent EPSON V750 scanners, and two independent EPSON 11000XL scanners. The films were scanned in separate RGB channels, as well as in black and white, and film orientation was varied. We found that the green channel of the RGB scan and the grayscale channel are in fact quite consistent over the different models of the scanner, although this comes at the cost of a reduction in sensitivity (by a factor ∼2.5 compared to the red channel). To allow any user to extend the absolute calibration reported here to any other scanner, we furthermore provide a calibration curve of the EPSON 2450 scanner based on absolutely calibrated, commercially available, optical density filters.

Absolute calibration of GafChromic film for very high flux laser driven ion beams

“…When comparing our result to other calibration results in the lower dose range done with 10 MeV photon source 22 or pulsed proton beams, 31 a fair agreement is found, which further validates our calibration (see Fig. 4).…”

“…1,3,4 Calibrations for proton energy deposition have been reported for various RCF types. [19][20][21][22] However, for pulsed ion beams driven by relativistic laser pulses, the single shot dose can reach extreme high doses exceeding kGy and dose rates in excess of 10 11 Gy/s. Absolute calibrations of the widely used versions of GafChromic RCF currently lack the very high doses and dose rates present in laser-plasma driven ion acceleration experiments.…”

Experimental evidence for short-pulse laser heating of solid-density target to high bulk temperatures

“…The composition of the stack was Al_1.425mm | HDv2(1) | EBT3(1) | Al_1.425mm | HDv2(1) | EBT3(2) | EBT3(3) | EBT3(4) |… | EBT3(10) | Al_216μm | EBT3(11) | Al_216μm | EBT3(12) |… | Al_216μm | EBT3(20). The stack was composed of two different types of RCF – HDv2 and EBT3 35 in order to extend its dose dynamic range. The distance from the proton source to the front of the stack was approximately 3.5 cm.…”

“…6a , the radiation dose in each RCF is inferred from the optical density change induced by the deposited proton energy, this according to the absolute calibration of the RCF given in ref. 35 . The energy deposition in each film is calculated using the code SRIM 37 .…”

Proton beam emittance growth in multipicosecond laser-solid interactions

“…After exposure, the pieces of film were digitized with an Epson V850 Pro flatbed scanner with 600dpi resolution. The raw RCF signal was first converted to optical density (OD=−log 10 (Exposed Signal/Unexposed Signal)) and then to deposited dose [40,41] in order to retrieve the proton fluence.…”