My dad's cancer spread to the bones in the spine and rib cage. He told me it was incredibly challenging and exhausting to stay still during scans as it just hur

My dad's cancer spread to the bones in the spine and rib cage. He told me it was incredibly challenging and exhausting to stay still during scans as it just hurt so bad. Several times they had to redo scans as he moved. I can certainly imagine there are many similar scenarios where it's just not possible for a patient to be completely still, or it's better for them to avoid excessive rescans.