"Combination" or "double" CT scans of the chest

CT scans of the chest can be helpful in diagnosing many conditions. For this measure, it is important to understand the different ways a CT scan can be performed.

For some CT scans, a substance called “contrast” is put into the patient’s body before the scan begins to help make parts of the body stand out more clearly on the x-rays. Contrast can be either swallowed or injected into a vein. Combination CT scan means that the patient gets two CT scans – one scan without contrast followed by a second scan with contrast.

Giving patients two scans when patients only need one needlessly doubles their exposure to radiation. There are also risks of injecting contrast, which include possible harm to the kidneys or allergic reactions.

Contrast shouldn’t be used if it is not needed. Most of the time, radiologists can get a good picture of the chest by just taking a CT scan without contrast.

About This Measure

This measure tracks the number of outpatient CT scans of the chest that were "combination" or double scans. The range for this measure is 0.0 to 1.0. A number very close to or higher than 1.0 may indicate that too many patients are being given a double scan when a single scan is all they need.

Note: In this case, a lower number is better.