falls in elderly--rule out subdural or epidural bleeds (intracerebral hemorrhage less commonly)
trauma--rule out bleed, same as above
decreased level of consciousness--rule out bleed, stroke, space occupying lesion (usually cancer), evidence of infection as the clinical situation suggests. A CT is a MUST pre-lumbar puncture to insure that signs of increased ICP are not present as this could cause life-ending herniation of brain components)
* of note, head ct's miss 5% of subarachnoid hemorrhages. if this is suspected (sudden onset of severe headache with possible mental status changes) then lumbar puncture is needed to look for xanthochromia
Chest CT's (with contrast) (also called chest CT angiogram)
To rule out pulmonary embolus. This requires intravenous contrast, whereas most head CT's do not.
Abdominal CT's-(Abdominal CT angiogram)
-needed to look for abdominal pain with suspicion for mesenteric ischemia or clot
Spiral CT-common to look for stones/nephrolithiasis
Other common uses
-Appendicitis (ultrasound also used...debate is to which is better)
-CT angio of various vessels....subclavian, etc, if you suspect a clot in these areas.
-Aortic CT (no contrast generally needed) to look for aortic dissection in patient with chest pain. Alternative is transesophageal echo.
-CT's of abdomen also common to look for infections (abcesses), cancers, diverticulitis, obstruction (CT's identify where obstruction is in small bowel, large bowel, etc).
-CT's of various muskuloskeletal regions are also used--i.e. hip for fracture, pelvic for fractures. (mri's are somewhat more common for muskuloskeletal issues due to better soft tissue deliniation...i.e. acl tears, etc)
One thing CT's are NOT used for. Is to confirm the presence of intrauterine pregnancy.
Not unless you plan on interrupting organogenesis for a little while.
Therefore, if it is a child bearing woman, run an HCG before you get the scan.