Is it possible to damage dna from single chest ct scan which can lead to cancer later in life? if yes then how long it will take to develop?

Stop worrying: Your dna is being damaged constantly as you go about your business. Your own body, especially your potassium atoms, are radioactive, and you are being bombarded constantly by cosmic rays. Scans are only one of thousands of sources of radiation. You can't avoid it, the exposure you get in a scan is hopefully worth the benefit, and you need keep it in perspective and get on with living your life.