We have now upgraded the projection screen material in MRI and this will be the default screen in the scanner moving forward.
Many of the existing projects that use "lower-level" calibration routines or are dependent on the use of the polarizer HAVE ALREADY BEEN USING THIS "NEW" SCREEN MATERIAL. Note that the "old" screens are still available for use by existing projects that have already acquired data - just remember that these screens will no longer be pre-loaded into the scanner by default and you will need to load them yourselves.
As usual, if you have any queries, please drop me a line.