QTR-Quadtone RIP

I prepare my work in PhotoshopCS2 and print on the Epson 2200 using 
the QuadtoneRIP. I have noted and am confused by references to Qimage. 
What role, if any, should QImage play in the workflow? What are the 
purported advantages? I would appreciate explanation of that program 
as it relates to QuatoneRIP. Thank you. Joachim