Ina,
in my husband's case, the CT did not pick up the primary, only the enlarged lymph node. The PET/CT did pick up the primary, as well a little activity in a second lymph node. So in our case, the CT was a false negative for the primary.
I think the question to as in Joyce's case, is what would the doctors do with the additional information, and would it lead to an improved chance of cure or better quality of life. Of course, Joyce and the family would need to ask themselves a similar questions - for some, having a more definitive result (good or bad) is better than having less information.
I just lost my dad to congestive heart failure this spring, and my thoughts are with you and yours in this difficult time. Please remember that, as much as we wish, we cannot always give health and youth back to our parents. We can give love and care, and you are doing this as much as is humanly possible.
Maria