VMAT is a form of IMRT where the dose of radiation is applied to the tumour by treatment units continuously rotating 360º.
The dose distribution is applied precisely, shaping and adapting itself to the form of the tumour. Sessions may include one or more arcs for treatment and stop and start at particular angles.
This form of treatment requires the accelerators to meet very specific and demanding technical specifications such as high dose rates (dose delivery rate), strict control of the accelerator rotation speed and movement of the planes, etc.
In practice, this technique enables applying the treatment much more rapidly than other techniques, one full rotation. Treatment with a single arc of 360º can be applied in less than 2 minutes.