Stage 2 liver cancer

I have just found out my mother has stage 2 liver cancer,and been given 3 months to live.She had a ct scan(i think thats wot it's called) this morning ,with the results coming in 2 weeks,It was the doctor who told my dad(i think from other tests).I would just like to know more information ,I dont know what a ct scan is,why bother if she only has 3 months, etc (more info the better please)My dad has not told my mam,he wants to get these results and let the doctor explain to her(she really likes and trusts her doctor)and perhaps it would be easier for my dad.ANY info or support would be gratefull(I am still trying to get my head round it all,think i am numb and not taken it in yet)