scalp x ray is harmful for babies?

Children as young as one day old get xrays if doctors think there is a problem. Assuming the xray is done by licensed proessional, and your doctor is certified, there's a good chance they wouldn't order something to harm your child. They usually weigh the options, and order xrays based on the assumption that being able to see what's going on is more valuable than not being able to see it. 

Here's some more information for you to look at:   http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_xray

 If you're really concerned talk to your doctor and radiologist. They'll be able to clear up and confusion or concerns you have. Good luck, and take care.