Intensity modulated radiotherapy (IMRT) in head and neck cancers (HNC) has been in use for around two decades. It has clearly been seen that IMRT results not only in a better dose distribution profile to organs at risk (OAR) when compared to 3 dimensional conformal planning, but also in an improved overall survival, progression free survival, loco regional control and quality of life. IMRT has the unique capability of producing inhomogeneous dose distributions, allowing simultaneous delivery of different doses per fraction to different areas within the treatment field.
It has the potential radiobiological advantage of reducing the impact of accelerated repopulation in tumor colognes by using simultaneous integrated boost (SIB) technique. Increasing use of IMRT has also witnessed a growing concern regarding second malignancies as a result of an increase in the treatment time, worsening the accuracy of treatment due to increased intra fractional patient motion and reduction of patient throughput with economic consequences. Besides, it also leads to patient discomfort on the treatment couch and affects reproducibility of treatment position.

It has been seen in various studies that techniques like VMAT, first introduced in 2007, results in:
1. Fast delivery of radiation,
2. Provide better sparing of OARs and
3. Provide more uniform and conformal dose distributions to the target volumes as a result of various factors such as continuous modulation of multi leaf collimators (MLC), field shape, fluency rate, gantry rotation speed and collimator angle.
4. This may also enable more frequent online imaging.

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