Quantitative magnetic resonance elastography for polymer-gel dosimetry phantoms

Area of Science:

• Medical Physics
• Materials Science
• Biophysics

Background:

• Conventional dosimetry methods face saturation dose limitations at high radiation levels.
• Polymer-gel dosimeters offer a promising alternative for high-dose measurements.
• Magnetic Resonance Elastography (MRE) is explored as a new technique for polymer-gel dosimetry.

Purpose of the Study:

• To develop and validate a novel dosimetry technique using polymer-gel phantoms and MRE.
• To investigate the relationship between radiation dose and the elastic properties of polymer-gel dosimeters.
• To assess the feasibility of MRE for quantitative dose assessment in tissue-mimicking materials.

Main Methods:

• Polymer-gel dosimeter phantoms were prepared using methacrylic acid, ascorbic acid, and gelatin.
• Phantoms were irradiated with gamma rays (10-50 Gy) and subjected to mechanical forces (100-400 Hz) to generate shear waves.
• Radiation-induced changes in shear modulus were measured using MRE and converted to elastograms.

Main Results:

• A linear relationship (R² = 0.996) was found between the integrated area and absorbed dose.
• Elastograms clearly indicated higher shear modulus values in irradiated regions.
• Quantitative shear modulus values were successfully estimated using MRE, correlating with absorbed dose.

Conclusions:

• MRE provides a sensitive and quantitative method for assessing absorbed radiation dose using polymer-gel dosimeters.
• This technique overcomes the saturation dose limitations of conventional dosimetry methods.
• Polymer-gel phantoms coupled with MRE show potential as advanced tissue-mimicking materials for radiation dosimetry.