Thanks for your reply. I am inclined to agree that it’s an ROI issue but as they are all left sided, the ROI is still visible from the camera at the foot end of the bed. I might have a play on the next one with some treatment captures and see what the cameras can actually see.
The reason we have a floor twist for the SCF is because of the collimator angle on the tangential. We put a 90 degree kick on the floor and angle the gantry to match the previous collimator angle (both the tangs and the SCF are also half beam blocked).