It's just the way the machine works Roseyone. You lie on a table and get moved into a space where they scan you. You can take a CD or IPOD of your favourite music to take your mind off things. And tell the staff how you feel. Another option is to ask your doctor to prescribe a sedative but that's pretty heavy handed. There are lots of websites you can check out Roseyone but here is one:
http://hcd2.bupa.co.uk/fact_sheets/html/ctscan.html
Sometimes our fears can be allayed by knowing what we are facing. Hope this helps and good luck. Remember how lucky we are to have things like CT scanners to help diagnose things. It's not too long ago that there was much more guesswork involved in the lack of hard evidence and not nearly as many "nasties" were able to be picked up. And not so many people (like yourself) were able to be reassured that all is okay.