None of the practices I'm familiar with utilize radiology assistants. I knew one at an academic center, but I was a student so it was difficult for me to judge her usefulness.
My understanding is that this is a skill set still looking for a niche. Because of the training pathway, RAs aren't that useful for interventionalists because they can't prescribe medications, etc., and straightforward procedures can easily be taught to a dedicated technologist without RA training. I'm not sure to what degree RAs are useful for providing preliminary reads for the radiologist, but I'd love to hear others' experiences.
You may find more answers on a different forum, maybe Aunt Minnie. SDN is largely for physicians and physicians in training. Good luck.
There were a couple RAs at my med school's hospital. They were 100% dedicated to a handful of procedures and fluoro. Seems like PAs would be more useful but I don't know, we don't have any where I am now.
If the radiologist assistant is hired by a department, it tends to be because of the person and not necessarily the degree. If the same person was a PA or NP (most prefer PA), most departments wouldn't care and would still hire the person. I don't know why anyone would become an RA. Becoming a PA gives you much more flexibility.