Do I need to clean my old cast iron hot water radiators?

I’ve owned my house 2 years and I have hot water cast iron radiators (not steam.) I plan to clean the boiler fins of dust myself but I was wondering if there anything I need to do to flush or clean the inside of the boiler and cast iron radiators themselves? The radiators have never been cleaned internally while I’ve lived here. They all work well and heat evenly. Is this something I could DIY? I saw some cleaning solutions that you somehow feed into the system, but I have no idea how you get the solution in there or flush it out…

Any help appreciated.