Lung Nodules - 3 CTs OK shows a change

I had 3 CTs performed the first year with no change in the nodule.  Performing the CT I was upright slightly slanted back for the test.  I changed insurance and had to go to a new facility for what I thought would be my 4th & final CT scan.  This place asked me to take my bra off (never had to do that before) and lay completely down for the CT Scan of my Thorax w/o contrast.  (Completely different position from my last 3 CTs) They put my feet into the Scanner while I was laying down and my report says that my 7 mm nodule was now 1.1 cm.  The radiologist had no CD from any of my prior scans on hand to compare.   I am stumped.  Can the position your put in during the CT make a difference as to what the radiologist is look at?

Now they are recommending a PET scan and the radiologist said he may change his  report if he has acess to my other CT Scan.  I am dumbfounded, sad and mad.  

Can anyone give me any information on all of this - I really need help!  Thanks, Julie