My doctor ordered a CAT scan to check for lung damage (I'd been coughing for many weeks.) He saw a dark spot. He wanted me to do another CAT scan a month later, to check for change. I refused, on the basis that I've heard that a CAT scan radiates as much as 300 times the power of a chest X-ray. He settled for a chest X-ray instead, which showed no change. Were my fears justified?