lung ct scan question

I recently had a small pneumothoracics  that I was treated for in the hospital.  That was a week ago.  Now I have severe burning in the front and back of my chest.  My pulminary DR ordered a chest CT scan stat.  When I got there the scan tech was perplexed as to why there was no contrast being used.  I have no known allergies. I didn't know either, and my DR is not available for me to ask.  Is there a specific reason that this would be done?

[National Jewish Health]

The need for using contrast depends on one's suspicion of what he/she is looking for.  Contrast is not needed for the CT diagnosis of pneumothorax but could be helpful if there is any suspicion that the pneumothorax was due to chest trauma and concern that the trachea or esophagus might have been damaged.

CT can also distinguish between a true pneumothorax and a large, thin walled, air containing bulla, especially in persons with chronic obstructive pulmonary disease (COPD).

If the air was aspirated, while you were in the hospital, the CT scan might provide evidence of injury at the time of aspiration.

Bottom line, you will have to discuss this with your doctor.