Multiple ultrasound during 1st trimester

I am wondering if having weekly ultrasound safe on my first trimester? I read a few articles saying you will only need 4-5 in duration of whole pregnancy. I am on high risk pregnancy and had miscarried twice. Does it have any effect on the baby? Some say it still has radiation. Anyone had multiple scans too? It somehow gives me a peace of mind to see everything is going well due to my past experiences too. But also anxious whether am I harming my unborn child.