Do you perform an MRI after SpaceOAR Vue placement if you already have a pre-procedural MRI and are not doing a FLAME style boost?

I do, yes. I also obtain MRI for planning when there is no hydrogel spacer (as did many before me when no one was using spacers).

The apex and base are better demonstrated on MRI. This paper by McLaughlin et al., PMID 19515511 shows examples of common errors on CT-only contours.

I do focal RT boost on...

There are two questions to be addressed first:

1. Is there any value in the routine use of hydrogel in definitive prostate cases using common conventional or hypofractionated regimens?
2. Is there any value in routine fiducial placement if you're using daily CBCT?

Those debates are for another thread.

O...

If upon review of the radiotherapy planning CT, there is any question or doubt about SpaceOAR placement quality or rectal wall invasion, I order another MRI. MRI provides superior image quality. In the last year, I caught full-thickness rectal wall penetration by SpaceOAR Vue (fistula) and 1 with mi...

This is an excellent question and here are some of my thoughts.

In short, no. I generally do not order a second MRI simply to verify SpaceOAR VUE placement since a CT scan is sufficient.

In long, yes. But only in specific instances:

1. For prostate patients requiring definitive EBRT, my staff reflexively...