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Outpatient CT scans of the abdomen that were “combination” (double) scans

Description of Measure

A CT scan (also called a CAT scan) uses multiple x-rays to produce detailed pictures of the inside of the body (bones, organs, and other body parts). For some, 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. 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.

Why is this Important?

Standards of quality care say that most patients who are getting a CT scan of the chest should be given a single CT scan rather than a “combination” CT scan. Although combination CT scans are appropriate for some parts of the body and some medical conditions, combination scans are usually not appropriate for the chest.

The range for these measures is from 0% to 100%. For hospitals with higher percentages, it may mean that the facility is routinely giving patients combination CT scans of the chest or abdomen when a single scan is all they need.

Giving patients two scans when they only need one needlessly doubles their exposure to radiation:

  • Radiation exposure from a single CT scan of the chest is about 350 times higher than for an ordinary chest x-ray.
  • For combination CT scans, radiation exposure is 700 times higher than for a chest x-ray because the patient is given two scans.
  • For a combination CT scan, radiation exposure is 22 times higher than for an x-ray of the abdomen because the patient is given two scans.
  • Radiation exposure from a single CT scan of the abdomen is about 11 times higher than for an ordinary x-ray of the abdomen.

When contrast is used, there are risks that can include possible harm to the kidneys or allergic reactions (especially if the contrast is injected). To avoid unnecessary risk, contrast should be used only when it is needed. If you need to have a CT scan of the chest or abdomen, feel free to ask your doctor these questions to determine what’s best for your medical condition:

  • Do you need a single scan - either with or without contrast - or is a combination scan necessary? 
  • Is using contrast appropriate for your medical condition?
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All descriptions and data sources are reported from Hospital Compare.

Data reported are based on discharges from Third Quarter 2012 through Second Quarter 2013


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