Can Kidney Stone Be Diagnosed Through Another Test Apart From A CT Scan?

I had blood tests done a couple months ago, it showed a small reduction in my kidney function. Since then I have had pain in my side and it has recently gotten much worse. I think I have passed some kidney stones and I think I may have one that is too big to pass. The doctor suggested a CT scan, I read about them and I am very afraid to do this as the contrast dyes are damaging to the kidneys, is there any other way to find out what is going on, the pain is now all across my entire lower trunk.