Gel dosimetry: The effect of gold nanoparticles on the dose enhancement in the external radiation therapy

Normoxic type MAGICA gel dosimeters are established for dose quantification in three dimensions for radiotherapy. The ability of MAGICA polymer gel was assessed by experimental measurements method for studying the effect of gold nanoparticles (GNPs) in dose enhancement under the external 18MV radiotherapy practices. The different GNPs concentrations were studied: 0.02mM, 0.05 mM and 0.1 mM. Then, a new formulation of MAGICA gel was synthesized. The fabricated gel was poured in the tubes (with and without the GNPs) located at the water phantom. The water phantom was irradiated to 18 MV beam of a Varian linac. After 24 hours, the irradiated gels were read using a Siemens 1.5 Tesla MRI scanner. The absolute dose sat the reference points and isodose curves resulted from the experimental measurements of the gels following the external radiotherapy practices were compared. The signal of non-irradiated gel samples containing GNPs showed maximum difference of the 1% compared to gel without nanoparticles. The dose enhancement factors were 1.014±0.07, 1.074±0.11and 1.161±0.15 for 0.02, 0.05 and 0.1 mM concentrations, respectively. The results demonstrate that use of GNPs embedded in polymer gels caused the enhancement of radiation. The results indicated that the polymer gel dosimetry method as developed and used in this study can be recommended as a reliable method for investigating the DEF of GNPs in external radiotherapy practices.