Ferrous sulphate gels for determination of absorbed dose distributions using MRI technique: basic studies

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Biomedical Engineering

Background:

• Accurate absorbed dose measurement is crucial for radiotherapy.
• Soft tissue equivalent phantoms are used to simulate biological tissues in radiation studies.
• Ferrous sulphate dosimetry is a common method for measuring radiation doses.

Purpose of the Study:

• To evaluate the suitability of two gel phantoms (gelatin and agarose) for absorbed dose measurement.
• To assess the sensitivity and linearity of ferrous sulphate loaded gels compared to solution.
• To determine the minimum detectable absorbed dose for these gel dosemeters.

Main Methods:

• Ferrous sulphate solution was gelled with 4% gelatin and 1% agarose.
• Irradiation was performed using a 0.25 T NMR analyser.
• Absorbed dose distribution was measured and correlated with gel response.

Main Results:

• Both gelatin and oxygen-purged agarose gels showed a linear response (r=0.998 and r=0.997) with absorbed dose (0-40 Gy).
• Gelatin and agarose gels exhibited 2.2 and 4.0 times higher sensitivity, respectively, than ferrous sulphate solution.
• Minimum detectable absorbed dose was approximately 1.0 Gy for both gels and the solution.

Conclusions:

• Ferrous sulphate loaded gelatin and agarose gels are suitable for absorbed dose measurement in soft tissue equivalent phantoms.
• These gels offer increased sensitivity for radiation dosimetry applications, particularly in conjunction with MR imaging equipment.
• The gels maintain dose rate independence within typical radiotherapy accelerator parameters.