Welcome to healthcaremagic.
Do you have habit of smoking.Cough and chest pain
an be due to many cause like chest infection
, throat infection
,allergy GERD etc.
Although CT scan gives small radiation
dose to your thyroid , benefit of scan is more than the risk.So you should not worry much about scan.
If the throat scopy are normal , it rules out serious problems like cancer of throat.
I hope the CT scan will give further clue about your problem and rule out serious disease in your chest .