Suggest Treatment For Sarcoidosis And Low Sodium Levels

I am a 60 year old female who has had sarcoidosis which left scarring in my one lung. I am suffering from low sodium for the first time in my life and saw a Nephrologist the beginning of the month. He ordered a chest CTC scan with contrast which I will have next week. I had an abdominal CTC scan (rule out sarcoid) last year in June due to a pain in my abdominal lower chest area for the past year. Just an FYI, I get regular checkups and bloodwork. I had a chest CT scan in April 2013. I am concerned that recent reports have come out to advise against frequent CT scans and that doctors should order an MRI instead of a CT scan. Is this a valid concern? I don't want to expose myself to more radiation than necessary. I had a concussion in 2001 so multiple scans afterward and due to respiratory issues and the fact that prior to 1985 I was a heavy smoker, I have had Xrays and scans almost yearly.