This study aimed to investigate dosimeter characteristics by using a photon beam with and without the flattening filter of intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) by using a 3D N-isopropylacrylamide (NIPAM) polymer gel. A self-developed optical computed tomography scheme was used to measure the dose distribution. Gamma evaluation was performed between the dose distribution calculated by a treatment planning system and the measured dose distribution by using the criteria of 3% dose difference and 3 mm distance to agreement. Under these criteria, the passing rates showed no significant difference between IMRT and VMAT irradiation with and without the flattening filter. All these results revealed that the NIPAM gel dosimeter was for high-dose-rate radiation and clinical-pretreatment verifications.
