According to the Mayo Clinic, "A computerized tomography (CT) scan combines a series of X-ray images taken from different angles around your body and uses computer processing to create cross-sectional images (slices) of the bones, blood vessels and soft tissues inside your body. CT scan images provide more-detailed information than plain X-rays do.
A CT scan has many uses, but it's particularly well-suited to quickly examine people who may have internal injuries from car accidents or other types of trauma. A CT scan can be used to visualize nearly all parts of the body and is used to diagnose disease or injury as well as to plan medical, surgical or radiation treatment."
CT scans are good. They are a great first resort. But let me illustrate why they are just a first resort. I got TBI in an ice hockey game. I was unconscious for 3 minutes. My first memory was from the ambulance about 45 minutes later. I was brought to the hospital and ordered into a CT Scan. They sent me home that same night. The next day, they called me and said I need to come back: “There is a small hemorrhage, you need to come back”. I did. They did a check up scan. And sent me home. Again. I lived normally for two weeks. Then exactly two weeks after my hit, I couldn’t remember who I was. 12 weeks later, I finally got an MRI done. They found eight holes in my brain. This is not included to debate the competency of the doctors or the Finnish Healthcare system. This is included to highlight the differences in the accuracy of the CT Scan and the MRI scan.