For treatments using thermoplastic mask immobilaztion, when supplemental bolus is needed, what is your method for ensuring reproducibility of set-up and bolus effect efficacy?

In most cases, my bias is to place under the mask, so that I am more confident that bolus is flush against the skin and there is less room for airgap in the event of anatomic change / weight loss.

For areas of bony prominence (scalp, cheek, etc.) in cases where weight loss is not expected, placement...

I prefer to addd the bolus and then place mask over the bolus whenever possible. It allows you to place the bolus precisely where you need it and get a better fit to anatomy. If the need for bolus if found after the fact during planning I add it on top of the mask.

Above the mask