Use reversing film. Though whether you can get it in the correct size is another matter. It is used to change negatives (usually 35mm film) in to viewable positives.
I presume you are talking about film and not displayed images. The software on our latest Siemens fluoroscopy system has a soft switch that sets white bones or black bones. And I presume other systems have a similar setting. Robert
My spelling is not bad. I am typing this on a Medigenic keyboard and I blame that for all my typos.
Yes ... more information required. At what stage are we talking about? Immediate (first) display? Viewing (by the Radiologist), storage (archiving) ... ? Software, hardware?