ABSTRACT
PURPOSE: This study aims to optimize the formulation of a methacrylic acid gelatine and tetrakis (hydroxymethyl) phosphonium chloride (MAGAT) gel dosimeter to achieve acceptable dosimetric characteristics and the lowest final costs. This study also evaluates the reusability of the dosimeter. METHODS: The MAGAT gel dosimeter formulation was optimized. Tetrakis (hydroxymethyl) phosphonium chloride (THPC) concentrations (2, 5, 8, 10, 20, and 65â¯mM), methacrylic acid (MA) concentrations (2.0, 2.5, 3.0, 3.5, and 4.0% w/w) and gelatin concentrations (4.36, 6.45, 8.36, and 10.45% w/w) were evaluated to provide an adequate dosimetric response. The final dosimeter formulation linearity and dose rate dependence were evaluated. The reutilization methodology of the optimized gel formulation, but containing 2â¯mM of THPC, which was previously irradiated with a dose of 2â¯Gy, is also presented. RESULTS: The optimized mass concentration of the dosimeter consists of 88.60% deionized water, 8.36% gelatin, 3.00% of MA and 0.04% THPC (5â¯mM). It presents a linear response for doses up to 10â¯Gy with a 1.16â¯Gy-1â¯s-1 sensitivity. A maximum sensitivity variation of less than 4.0% was found when varying the dose rate of the radiation beams from 300 to 500â¯cGy/min. It was possible to reuse the dosimeter, however the sensitivity decreased by 15% from the first to the second irradiation. CONCLUSIONS: A low-cost MAGAT gel dosimeter with optimized formulation that responds to radiation in a dose range of 0 to 10â¯Gy with small dose-rate dependence is presented. The MAGAT gel can be reused after a 2â¯Gy irradiation.
