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GafChromic MD-55: investigated as a precision dosimeter
N V Klassen1, L van der Zwan, J Cygler
1National Research Council, Institute for National Measurement Standards, Ionizing Radiation Standards Group, Ottawa, Ontario, Canada. nklassen@irs.phy.nrc.ca
Medical Physics
|January 22, 1998
Summary
GafChromic MD-55 dosimeters accurately measure radiation doses around 6 Gy with less than 1% uncertainty. However, their optical density is influenced by light polarization, a key factor for precise dosimetry.
Area of Science:
- Medical Physics
- Radiation Dosimetry
- Materials Science
Background:
- GafChromic MD-55 is a thin-film dosimeter that changes color upon irradiation.
- Its absorbance increase correlates with absorbed radiation dose.
- Accurate radiation dose measurement is critical in various scientific and medical applications.
Purpose of the Study:
- To evaluate the precision of GafChromic MD-55 dosimeters for measuring 60Co gamma ray doses.
- To investigate the effect of light polarization on the dosimeter's optical density measurements.
- To analyze the layered structure of GafChromic MD-55 and its response to polarized light.
Main Methods:
- Irradiation of GafChromic MD-55 dosimeters with 60Co gamma rays.
- Utilizing a double irradiation method for dose calibration.
- Measuring optical density changes and analyzing the impact of polarized light.
- Examining the dosimeter's layered structure, including Mylar films.
Main Results:
- GafChromic MD-55 achieved a measurement uncertainty of less than 1% for doses near 6 Gy.
- The dosimeter's optical density readings were significantly affected by the polarization of the analyzing light.
- The response to polarized light varied across the entire dosimeter and its constituent Mylar layers.
Conclusions:
- GafChromic MD-55 is a viable tool for precise radiation dosimetry, particularly for doses around 6 Gy.
- The influence of light polarization must be accounted for to ensure accurate measurements with GafChromic MD-55.
- Further research into the dosimeter's layered structure and polarization response is warranted for optimizing its performance.