Dose verification of volumetric modulation arc therapy by using a NIPAM gel dosimeter combined with a parallel-beam optical computed tomography scanner

Volumetric modulated arc therapy (VMAT) was developed to shorten treatment time and increase target conformance. However, a true three-dimensional (3D) gel dosimeter is needed for dose verification. In this study, two clinic cases were adopted: a simple case of lung cancer and a complex case of larynx cancer. For each clinic case, two treatment plans were generated for the same planning target volume using VMAT and intensity modulated radiation therapy calculation software packages. An N-isopropylacrylamide (NIPAM) polymer gel dosimeter was used for 3D dose verification. In addition, the dose characteristics of the NIPAM gel dosimeter were investigated for the two clinic cases.