CT Scan after 1 year of hair transplant.

CT scans or x-rays are needed if you have a medical condition that require it.  Discuss its risks and benefits with your doctor.  CT scans do not cause hair loss.

The radiation exposure from a conventional CT scan should not have any noticeable effect on your hair.

No, a CT scan of any kind should not have an impact on your hair transplant. In general at this point nothing will affect your transplanted hair differently than your natural hair.

Undergoing a CT scan will not affect your transplant or the growth. The underlying cause of why you needed the scan may cause hair loss, but the actual scan itself will not. 

At one year after Hair Transplant you are perfectly normal and a CT scan will not impact your hair at all. Don't worry.