Went to the er. due to chest pain and right arm pain my d diners was elevated at 660 but everything else was fine they said they had to do a c.t scan ?

Working diagnosis?: Whether not to peform a CT scan depends on the working diagnosis (wDx) of the ER physician. Did they suspect a pulmonary embolism (PE)? Pneumonia (Pna)? Problem of aorta? If Pna was the wDx, X-ray of the chest is an alternative; if PE was, some centers can ultrasound the legs for a DVT (90% of time it suffices) but PE-protocol chest CT is Gold Standard. Aortic dissection needs a CT scan of chest.

CT scan for embolism: The ER doctors likely recommended a CT scan of your chest because of the pain and the elevated D dimer level. They are probably concerned about a pulmonary embolism. I would follow their advice and have the scan done.