If i have ct-scan for my ears, do i need lateral x-ray again to look for cholesteatoma?

If the purpose: Is to detect cholesteatoma the ct scan is the standard way to do this. Most findings of bone destruction due to cholesteatoma are far too subtle to be seen with plain x-ray.

Xray has no role: Ct of the temporal bones (or ct iac as it is sometimes called) is the gold standard for assessing for a potential cholesteatoma.

No - CT is the right: Examination to look for the bone destruction caused by cholesteatoma. A lateral xray (assuming of the skull) would be very unlikely to detect it, and would not provide enough detail to plan surgery.