SU-E-T-197: Normoxic Polymer Gel Dosimetry for Intensity Modulated Radiation Therapy

Abstract

Purpose: To evaluate a tissue equivalent normoxic polymergeldosimeter as a tool for 3‐dimensional dosequality assurance for intensity modulated radiation therapy(IMRT) by measuring the dosecharacteristics of therapeuticradiation by Magnetic Resonance Imaging(MRI). Methods: Polymergel under normoxic conditions was synthesized using gelatin, methyacrylic acid (MAA), hydroquinone (HQ) and tetrakis hydroxymethyl phosphonium chloride (THPC), and polymergeldosimeter was fabricated by placing it into each phantom for the appropriate experiments. Co‐60 gamma‐rays and a 6 MV photon beam were used for the dose reaction experiments. The dose range was 0∼20 Gy. The dosecharacteristics of the polymergeldosimeter were compared with those of the ion chamber and Gafchromic EBT2 film using 3.0T MRI. Results: The linear correlation coefficient was r2=0.970, r2=0.999 and r2=0.972 for the polymergeldosimeter,ion chamber and film, respectively. The percentage depth dose at a depth of 50 mm was 85.8% and 84.6% for the polymergeldosimeter and ion chamber, respectively. The flatness and symmetry of the geldosimeter on the cross‐plane were 3.80% and 3.58%, respectively. After applying the geldosimeter to IMRT, the dosages measured in the 100% dose domain of therapeutic planning for the axial, sagittal and coronal planes were 96.2%, 103.0% and 100%, respectively. Conclusions: The results show a relatively high level of precision in the high dose range in IMRT, which is important in clinic sites. The possibility of this as a 3‐dimensional dosequality assurance tool of a polymergeldosimeter was confirmed This work was supported by National Research Foundation of Korea Grant funded by the Korean Government.