do you accept walking in with out appointment?

Haven't looked into it, but apparently you can get an appointment for x-ray now, like you can for any other service. Walk in is still an option.

I had an appointment for breast MRI

My experience is that it depends on the service you need. For a chest x-ray you can walk in. Might have to wait. I was told for a bone scan I needed to make an appointment. I'd recommend an appointment for any service if you have the luxury to make one.