The clinic you linked does not say much about Dr William Collins' background or credentials. It also does not address the equipment or databases he may use.

The most important question to ask a qEEG doc is what database they use. Does it have a mTBI/concussion aspect? What accuracy does it have for diagnosing mTBI/concussion?

There are a couple databases that accurately diagnose mTBI. Lexicor is one of them. I don't know the others offhand.

Dr Collins does not address these issues.

A Diffusion Tensor Imaging MRI can also indicate concussion damage.