Can a CT scan of brain cause hair loss? I've had hair shedding consistent with telogen effluvium afterwards.

Having a CT scan of the head/brain will not in and of itself cause hair loss.  You should be seen by a physician that treats those with hair loss exclusively for an evaluation.  There are many causes of hair loss and a detailed history and physical examination of your scalp should be performed.  This will give the physician the information they would need in order to give recommendations for your best course of action.  
Best of luck to you,
Dr. Lee

No, a CT scan will not cause hair loss. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

When hair grows back after an episode of telogen effluvium it starts as fine, wispy hair. Over time the new hair will thicken.  More importantly, you have to identify the source of the stress and figure out a why to improve it such that hair loss will not continue to plague you. A CT scan of the brain should not affect hair growth. You may want to see a hair restoration surgeon just to make sure there are no other etiologies related to your hair loss.

No, a CT scan is unlikely the cause of hair loss. Be sure to see an expert for proper evaluation. If some hairs are weak and some are thick you may need to be evaluated for other diagnoses too besides just telogen effluvium.

A scan of the brain will not impact hair in any way. If you have a telogen effluvium history, you need to follow it with your doctor