Volumetric Modulated Arc Therapy, VMAT or Rapid Arc, delivers a precisely sculpted 3D dose distribution with a single 360-degree rotation of the gantry. The planning algorithm simultaneously changes three parameters during treatment: rotation speed of the gantry, shape of the multi-leaf collimators and delivery dose rate. VMAT differs from IMRT because it delivers the dose to the whole volume, rather than slice by slice. The algorithm ensures treatment precision, helping to spare normal healthy tissue.