TY - JOUR
T1 - SU‐FF‐T‐231
T2 - Characterization and Real‐Time Optical Measurements of the Ionizing Radiation Dose Response for a New Radiochromic Medium
AU - Rink, A.
AU - Vitkin, A.
AU - Jaffray, D.
PY - 2005/6
Y1 - 2005/6
N2 - Purpose: Radiochromic films, generally used for two‐dimensional dose verification, have lately been considered for point‐based real‐time in vivo dosimetry. They have some advantages, including near water‐equivalency, over dosimeters used currently. In a recent study, GafChromic® MD‐55 showed reasonable performance, but some issues remained unresolved. A new film, GafChromic® EBT, has potential to overcome those issues and is investigated. Method and Materials: An optical fibre‐based setup, capable of real‐time measurements, was used to detect the increase in optical density over 630–640 nm range of the EBT film during and after exposure (6 MV X‐rays,Varian 2100 EX). Results: Change in optical density for EBT film, measured at the end of exposure to 1.9 Gy, was 7.7 times greater than that of MD‐55 film. EBT also exhibited less post‐exposure darkening, with a 12.5% increase over 18 hours, compared to 25% for MD‐55. Change in optical density during exposure for EBT film was non‐linear with time or dose. This was not due to a shift of the wavelength of maximum change in absorbance, which was stable at ∼636 nm during the entire exposure to 9.52 Gy. Increasing the spectral window over which optical density calculations were performed had little affect on the non‐linearity. The EBT film exhibited a small dose rate dependence for optical density measurements during exposure: standard deviation of change in optical density immediately at the end of a 9.52 Gy exposure increased from 0.9% to 1.8% when a six‐fold variation in dose rate was introduced. Conclusion: GafChromic EBT film has potential as a radiation dosimeter, including real‐time applications, due to its increased sensitivity, decreased post‐exposure darkening and spectral stability, but signal non‐linearity needs to be investigated further. This work was funded in part by National Institutes of Health / National Institute on Aging (R21/R33 AG19381).
AB - Purpose: Radiochromic films, generally used for two‐dimensional dose verification, have lately been considered for point‐based real‐time in vivo dosimetry. They have some advantages, including near water‐equivalency, over dosimeters used currently. In a recent study, GafChromic® MD‐55 showed reasonable performance, but some issues remained unresolved. A new film, GafChromic® EBT, has potential to overcome those issues and is investigated. Method and Materials: An optical fibre‐based setup, capable of real‐time measurements, was used to detect the increase in optical density over 630–640 nm range of the EBT film during and after exposure (6 MV X‐rays,Varian 2100 EX). Results: Change in optical density for EBT film, measured at the end of exposure to 1.9 Gy, was 7.7 times greater than that of MD‐55 film. EBT also exhibited less post‐exposure darkening, with a 12.5% increase over 18 hours, compared to 25% for MD‐55. Change in optical density during exposure for EBT film was non‐linear with time or dose. This was not due to a shift of the wavelength of maximum change in absorbance, which was stable at ∼636 nm during the entire exposure to 9.52 Gy. Increasing the spectral window over which optical density calculations were performed had little affect on the non‐linearity. The EBT film exhibited a small dose rate dependence for optical density measurements during exposure: standard deviation of change in optical density immediately at the end of a 9.52 Gy exposure increased from 0.9% to 1.8% when a six‐fold variation in dose rate was introduced. Conclusion: GafChromic EBT film has potential as a radiation dosimeter, including real‐time applications, due to its increased sensitivity, decreased post‐exposure darkening and spectral stability, but signal non‐linearity needs to be investigated further. This work was funded in part by National Institutes of Health / National Institute on Aging (R21/R33 AG19381).
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U2 - 10.1118/1.1997959
DO - 10.1118/1.1997959
M3 - Article
AN - SCOPUS:85024802220
SN - 0094-2405
VL - 32
JO - Medical physics
JF - Medical physics
IS - 6
ER -