High dose sensitivity of N-(isobutoxymethyl)acrylamide polymer gel dosimeters with improved monomer solubility using acetone co-solvent

Abstract

Normoxic N-(isobutoxymethyl)acrylamide polymer gel (NIBMAGAT) dosimeters have been prepared in deionized water with acetone as a co-solvent for radiotherapy with very low levels of turbidity. The polymer gel dosimeters were irradiated in a cubic water phantom using a 6 MV X-ray radiation beam of a medical linear accelerator for doses from 1 to 20 Gy. A 0.5 Tesla nuclear magnetic resonance spectroscopy was used to measure the transverse relaxation rate (R2) of un-irradiated and irradiated gel samples. The polymer dosimeter presents a linear dose response for doses up to 10 Gy with significant R2 sensitivity of 0.4776 s−1 Gy−1. A higher NIBMA monomer concentration results from higher NIBMA solubility in water and acetone enhances significantly (i.e. more than six times) the performance of NIBMAGAT polymer gel dosimeters for radiotherapy dosimetry. The key parameters such as dose rate, radiation beam energy and post irradiation stability up to 10 days were investigated. We found these parameters had no significant effect on the dose response and dose sensitivity of NIBMAGAT gel dosimeters.