This is a question along the lines of the age old 'What is a good plan?'

It really does depend on your facilities, expertise (all staff groups), diagnosis/site, and of course the individual patient.

Many departments will have both approaches available in their arsenal of techniques to be used as they feel appropriate.

If this is a 'planning study' I'd suggest just pick one (or both) and study it's output.

First of all, the answer depends on the region, size and shape of the recurrence. Is it an oligo-recurrence? Was it previously irradiated? yes if the answer is clear: IMRT or VMAT. The reasoning depends primarily on the objectives (curative or palliative), on the life expectancy, on the toxicities that you want to reduce to a minimum and then you choose a plan and a method that fulfills the chosen criteria

The most appropriate technique will depend on the clinical characteristics of the case and the previous radiotherapy treatment, but in general terms the VMAT technique achieves a better relationship between the treatment target and organs at risk.

Regards