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- Title
Temperature and hydration effects on absorbance spectra and radiation sensitivity of a radiochromic medium.
- Authors
Rink, Alexandra; Lewis, David F.; Varma, Sangya; Vitkin, I. Alex; Jaffray, David A.
- Abstract
The effects of temperature on real time changes in optical density (ΔOD) of GAFCHROMIC® EBT film were investigated. The spectral peak of maximum change in absorbance (λmax) was shown to downshift linearly when the temperature of the film was increased from 22 to 38 °C. The ΔOD values were also shown to decrease linearly with temperature, and this decrease could not be attributed to the shift in λmax. A compensation scheme using λmax and a temperature-dependent correction factor was investigated, but provided limited improvement. Part of the reason may be the fluctuations in hydration of the active component, which were found to affect both position of absorbance peaks and the sensitivity of the film. To test the effect of hydration, laminated and unlaminated films were desiccated. This shifted both the major and minor absorbance peaks in the opposite direction to the change observed with temperature. The desiccated film also exhibited reduced sensitivity to ionizing radiation. Rehydration of the desiccated films did not reverse the effects, but rather gave rise to another form of the polymer with absorbance maxima upshifted further 20 nm. Hence, the spectral characteristics and sensitivity of the film can be dependent on its history, potentially complicating both real-time and conventional radiation dosimetry.
- Subjects
OPACITY (Optics); HYDRATION; TEMPERATURE; CHROMIUM isotopes; RADIATION
- Publication
Medical Physics, 2008, Vol 35, Issue 10, p4545
- ISSN
0094-2405
- Publication type
Article
- DOI
10.1118/1.2975483