The units the values are stored as in the database is 'hardcoded' (as much as anything is in an open source project!).
For display, one could simply add a conversion function to the event model and refer to it in the template. The values are stored as Gy.m^2, and are converted for display to cGy.m^2.
If you think it would be useful, we could add a feature request (issue) to have the unit user configurable. We'd have to work out if it would be modality type specific (DX vs fluoro) or something else?