Radiation/scans & TTC?

Rosie
My hubby was meant to deploy a couple of weeks ago, but they have now been delayed and he is allowed home for two nights before they go... Luckily in my fertile week!
Anyway, I have a renal condition and after seeing my specialist last week I need another scan on my kidney. He said it is like an ultrasound, only it's higher reliability and a lot clearer. In my head, clearer means more exposure to harmful rays?
With all my other scans that included radiation, I've had to wait for AF before TTC again to ensure the foetus isn't affected by the radiation.
I'm just wondering if maybe this is the same as those scans since it's not a 'normal' ultrasound? 
It's a long shot, but does anyone have any experience with this? 
My specialist has now gone overseas and I forgot to ask :(