I thought that the 2.2 gamma applied to windows and the 1.8 gamma applied to MAC? Am I missing something?
Gamma settings are not dictated by computer system platforms, for example many monitors have a native gamma, at, or closer, to 2.2 - unless there is a good reason don't force the monitor away from its native state.
Scanner - forget the 1.8 or 2.2 gamma settings, as set fast rules, and experiment with higher settings closer to 2.8
a higher gamma produces smoother, improved shadow detail,
no sudden contrast changes,
retains almost the same mid-tone to highlight contrast ratio
You need to experiment with different gamma settings. I often change the scanners gamma to higher settings for Velvia, especially those images captured in full light, with deep shadows. I lower the gamma, nearer 2.2, for specific negatives.