Hi all, wondering if someone would humour me enough to answer some very simple questions about radiotherapy? Mainly for stuff I can't quite find a clear answers for in books, etc.
To start -- how wide do you generally make the field/beam to cover the PTV and make up for any penumbra at the edges? For example, say you had a chest wall met you wanted to treat; you contour/volume it, give say a 0.5cm CTV margin, another 1cm PTV margin, etc. Then how much bigger should the beam be to make sure the PTV is covered? Another 1cm? More? Less?