The final conclusion...

This test was a snap, not even ten minutes, clothed except for top shirt, and results were back a few days later. Only a score of 1 for a 67 yo man who had a high stress job many years and has followed LCHF for past five years!

(Almost) unbelievable, the doctor's note suggested that this test shows little calcified plaque, but not newer plaque in process (what test shows a problem before it happens? maybe your cholesterol will go up in the future?) and with the new AHA risk assessment cholesterol lowering medication may be considered. Even the doctor couldn't bring himself to say he would prescribe statins at this point, but he CYA'd his chart.

I of course cornered the poor technician for a discussion on radiation dose. The test results include dose now, and she gave it to me after the scan. CT's are measured in DLP and CTDI, and that can be converted to Milliseverts.
http://www.xrayrisk.com/index.php
The newest CT machines use a much lower dose than previously (and thanks to some lobbying, a state law requires imaging centers to use the lower dose machines by x date) and armed with the actual dose, and nifty conversion tables, this proved out. Where the estimate for a CAC was 3 in the above link, my DH's exposure (it will vary by person) was a little less than half that. So that's about three times a mammogram now, which is still exceedingly low. The tech also explained that the CAC exposure is focused only on a small rectangle over the left chest (my concern is right chest). So although she may have been doing a sales job for their $99 special, I was assured enough to go ahead myself.
Read up on this test, watch the WidowMaker, and consider it if a doctor starts using that S Word. Very reassuring.