Characterization of a new N-vinylpyrrolidone-containing polymer gel dosimeter with Pluronic F-127 gel matrix

Abstract

This work reports on the characteristic of a 3D polymer gel dosimeter with poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127) gel matrix. The dosimeter (acronym: VIP3-Pluronic F-127) comprises 4% (w/w) N-vinylpyrrolidone (NVP), 4% (w/w) N,N′-methylenebisacrylamide (MBA), 4% (w/w) tert-butanol, 10 mM tetrakis (hydroxymethyl)phosphonium chloride (THPC) and 25% (w/w) Pluronic F-127. A medical ionizing radiation source was used for irradiation of VIP3-Pluronic F-127 and the dosimeter was measured with a nuclear magnetic resonance (NMR, 0.47 T) relaxometer. The mean dose sensitivity of VIP3-Pluronic F-127 amounted to 0.1873 ± 0.0091 Gy−1 s−1, the intercept was equal to 1.3614 ± 0.0511 s−1, the linear dose response was in the range of 1–20 Gy, the dynamic dose range was of 1–50 Gy and the threshold dose was of ~1 Gy. The manufacturing process of VIP3-Pluronic F-127 was repeatable and the dosimeter was stable for at least 8 days after irradiation (no measurements for longer period were performed). It was also found that the dose response of VIP3-Pluronic F-127 is independent of the radiation dose rate and energy, and type of radiation (photons and electrons). The results obtained indicate that VIP3-Pluronic F-127 is promising as a polymer gel dosimeter for use in radiotherapy dosimetry.