Dear patient Calcification is deposition of calcium at abnormal sites where normally it is not found for example in lung. You have hot calcification below clavicle and mostly in lung apex. Since you have been treated for rectal cancer with chemotherapy damage to vascular tissue and lung alveoli might have occurred which leads to abnormal calcification. Onother possibility is calcification of subclavian artery which lies just elow clavicle since you are having dizziness and fainting. You need to consult your oncologist and get I ourself examined. All the best.