Volumetric Modulated Arc Therapy
Volumetric modulated arc therapy (VMAT) is a new radiotherapy technology developed on the basis of conventional intensity modulated radiotherapy technology. This approach treats cancer with single or multiple rotating arcs. Differing from conventional intensity modulated radiation therapy (IMRT), VMAT irradiates tumors through a continuous (or multiple) arc pathway using high-speed dynamic multi-leaf collimation, continuous variable dose rate, and variable gantry rotation speed. Compared with IMRT, VMAT has shorter treatment times, higher dose output efficiency, and generally better treatment quality. VMAT treatment technology has greatly reduced IMRT treatment time from 15-30 minutes to 2-6 minutes. This fast treatment speed may improve tumor control rate. The technology can also adjust and control the intensity of radiation within the tumor and avoid important organs that are surrounded by tumor such as the eye, spinal cord and small intestine. This may increase the tumor control rate, reduce the probability of normal tissue complications, and reduce the side effects after treatment. At present, GCCC Radiotherapy Department utilizes Varian RapidArc to deliver VMAT treatment.