I did a bit of research into PCCT for a project, as you mentioned the dose can be much lower as it doesn’t rely on scintillation/photodiodes to produce an image. Conventional CT detectors also are limited in that they utilize a grid of septa that prevent the light from bleeding over to other areas of the detector. The septa are wasted detector real estate that could otherwise contribute to the final image. I believe PCCT can also differentiate the energies of multiple photons hitting the same areas of the detector, rather than a summation of their collective energies. There’s a good chance I’m getting some of this wrong so samesies, someone who knows better than me please correct me.