[show abstract][hide abstract] ABSTRACT: In this study, a two-level full factorial design was used to identify the effects of the interactions between compositions in an N-isopropylacrylamide (NIPAM) gel dosimeter involving the following variables: (A) gelatin, (B) NIPAM, (C) the crosslinker N, N'-methylene-bis-acrylamide (Bis), and (D) the antioxidant tetrakis (hydroxymethyl) phosphonium chloride (THPC). The dose range was from 0 Gy to 5 Gy. Optical computed tomography was used to scan the polymer gel dosimeter. Each component was set to two levels for all four variables, including (A) 4% and 6%, (B) 4% and 6%, (C) 2% and 4%, as well as (D) 5 and 15 mM. Response surface methodology and a central composite design were adopted for the quantitative investigation of the respective interaction effects on the dose response curve of the gel. The results showed that the contributions of the interaction effects, i.e., AB (6.22%), AC (8.38%), AD (7.74%), BC (9.44%), ABC (18.24%), BCD (12.66%), and ABCD (13.4%), were greater than those of the four main effects, accounting for over 76.08% of the total variability. These results also indicated that the NIPAM gel recipe with the highest sensitivity was at 40%C (mass fraction of Bis).
PLoS ONE 01/2012; 7(10):e44905. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this study, the response to ionsing radiation of the normoxic polymer gel dosimeter comprising tetrakis (hydroxymethyl) phosphonium chloride (THPC) with methacrylic acid (MAA) and gelatin, named MAGAT, has been investigated. Using magnetic resonance imaging (MRI), the R2-dose response or change in R2 (DeltaR2) is evaluated for different concentrations of the component chemicals: THPC, MAA, gelatin and hydroquinone (HQ). The formulation for which the MAGAT polymer gel dosimeter had a maximum response was determined, and the spatial and temporal stability for this formulation analyzed. It was found that the formulation that provided the greatest change in R2 was 10 mM THPC, 0-0.05 mM HQ, 6-7% gelatin and 4-6% MAA (evaluated one day post-irradiation). MAGAT polymer gel dosimeters comprising 10mM THPC, 0.05 mM HQ, 6-9% MAA and 4-6% gelatin have shown potential for use in radiation therapy dosimetry.
Applied Radiation and Isotopes 11/2005; 63(4):443-56. · 1.18 Impact Factor
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