A CT head scan uses rotating x-rays and detectors to produce axial slices of the brain at different levels, which are interpreted using different window settings to highlight soft tissues, bones, and other structures. Key features examined include the lateral and third ventricles, pituitary fossa, pons, cisterns, and bones. Conditions like hydrocephalus and blood in the cisterns or ventricles can be identified.

1. CT HEAD SCAN

2. Modern helical CT scanning technique comprising a rotating x-ray tube
and a fixed array of detectors.

3. Hounsfield scale ranging from -1000 to + 1000
Interpreting CT images

7. Axial CT slice at the level of the lateral ventricles

8. Axial CT slice at the level of the third ventricle

9. Axial CT slice at the level of the pituitary fossa

10. Axial CT slice at the level of the pons

11. The importance of windowing:
Common window settings used when
interpreting a normal CT Brain scan.
A: Brain window (WW 80, WL 40)
B: Bone window (WW 3000, WL 500)
C: Soft tissue window (WW 260, WL 80)
D: Stroke window (WW 40, WL 40).

12. Hydrocephalus results from an excess of CSF, due to an
imbalance between CSF production and absorption, resulting
in increased intraventricular pressure.
B - blood
C - cisterns
B - brain
V - ventricles
B - bones
Blood Can Be Very Bad is a mnemonic that can be used
when faced with interpreting a CT head scan:

13. Blood

14. Cisterns
There are four key cisterns that which should be assessed for effacement, the presence of
blood and asymmetry:
Ambient cistern: surrounding the midbrain.
Suprasellar cistern: superior to the sella turcica.
Quadrigeminal cistern: adjacent to the corpora quadrigemina.
Sylvian cistern: across the insular surface and within the Sylvian fissure.

15. Brain

16. Ventricles

17. Bone

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