<qa>  What is the general general name of the surgical cavity margins from the most recent surgical procedure?Recurrent gliomas Arm A If progression is diagnosed with the development of new enhancing tumor: The gross tumor volume GTV will be defined by the new contrast-enhanced T1 abnormality on the post-operative MRI scan. This will generally include the surgical cavity margins from the most recent surgical procedure. If progression is diagnosed with the development of new non-enhancing tumor: volumes will be defined through careful comparison of new and previous MRI scans in consultation with a neuro-radiologist. This will generally include the surgical cavity margins from the most recent surgical procedure. 