How To Read a CT Scan of the Brain (Part 1)
- Who & When Name, Age, & Date: This crucial information is printed on each CT image. Be especially careful to check dates!
- Orientation: Right - Left, Anterior - Posterior, & Scale
- Region and
Planes: Head CT's are usually transaxial and extend from the foramen magnum to vertex. Other planes used are coronal and sagittal.
- Brain windows are standard. Bone windows and Subdural windows can make a big difference in resolution for these parts of the examination.
With practice, the difference between these 3 windows will become obvious to your eye. Until then, the WL and WW measures will enable you to distinguish each window type. Just to make things interesting, the WL and WW measures can appear in different places on the CT images depending on the machine, the technician and interaction between them.
WL = Window Level WW = Window Width
The yellow arrows point to the WL and WW labels on these scans...much easier to read in real life!
- Slice Thickness can vary from 1 mm to 10 mm. Thin cuts can help clarify imaging of small areas such as the internal auditory canals.
- Contrast Enhancement
- Axis = a line from the bottom of the feet to top of the head.