Applying the N-isopropylacrylamide gel dosimeter to quantify dynamic dose effects: A feasibility study.

Abstract

BACKGROUND: The gel dosimeter is a chemical as well as a relative dosimeter.OBJECTIVE: To evaluate the feasibility of using N-isopropylacrylamide (NIPAM) gel dosimeter to observe the dynamic dose effects and quantification of the respiration, and to help determine the safety margins.METHODS: The NIPAM gel dosimeter combined with the dynamic phantom was used to simulate radiotherapy of lung or upper abdominal tumor. The field set to 4 5 cm, simulate respiratory rate of 4 sec/cycle, and motion range 2 cm. MRI was used for reading, and MATLAB was used for analysis. The 3%/3 mm gamma passing rate 95% was used as a clinical basis for evaluation.RESULTS: The dynamic dose curve was compared with 4 5, 4 4, 4 3 cm TPS, and gamma passing rates were 74.32%, 54.83%, 30.18%. Gamma mapping demonstrated that the highest dose region was similar to the result of the 4 4 cm TPS. After appropriate selection and comparing that the 60% part of the dose curve with TPS, the gamma passing rate was 96.49%.CONCLUSIONS: Using the NIPAM gel dosimeter with dynamic phantom to simulate organ motion during respiration for dynamic dose measurement and quantified the dynamic dose effect is feasible. The results are consistent with clinical evaluation standards.