<qa>  How long is each CT scan?After the injection, scanning will begin immediately. You will have 3 PET scanning sessions with a PETCT scanner. Before each PET scan, you will have a CT scan to make sure you are in the right position for the PET scans. Each PET scan may last up to 1 hour. Each positioning CT scan should take about 5 minutes. You will have a 10 minute rest period between each PET scan. 