I have recieved 4 ct scans in my life. 3 with contrast and one without. last two i got in this past month. one of brain and one of chest/abdomen. i am worried about all the radiation and the cancer risks. are 4 ct scans very dangerous?

Not very dangerous: It is highly unlikely that one develops cancer from just having 4 CT scans. Life in the modern world causes cancer (and of course there was cancer before modern times) but having 4 CT scans will make no noticeable difference when compared to everything else we face in life. In California, "useless" signs are posted everywhere in stores, restaurants, etc..., warning about cancer-causing substances.